JP6767202B2 - Metal-containing nanoparticles-supported electrode and carbon dioxide reduction device - Google Patents

Metal-containing nanoparticles-supported electrode and carbon dioxide reduction device Download PDF

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JP6767202B2
JP6767202B2 JP2016162416A JP2016162416A JP6767202B2 JP 6767202 B2 JP6767202 B2 JP 6767202B2 JP 2016162416 A JP2016162416 A JP 2016162416A JP 2016162416 A JP2016162416 A JP 2016162416A JP 6767202 B2 JP6767202 B2 JP 6767202B2
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英樹 會澤
英樹 會澤
吉則 風間
吉則 風間
稲森 康次郎
康次郎 稲森
俊夫 谷
俊夫 谷
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THE FURUKAW ELECTRIC CO., LTD.
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Description

本発明は、金属含有ナノ粒子担持電極および二酸化炭素還元装置に関するものである。 The present invention relates to a metal-containing nanoparticle-supporting electrode and a carbon dioxide reduction device.

一般に、触媒とは、化学反応を起こす物質系の反応速度を変え、自らは化学変化しない物質をいい、触媒の種類(材料や形態など)によって特定の化学反応への選択性や、反応効率が異なる。 In general, a catalyst is a substance that changes the reaction rate of a substance system that causes a chemical reaction and does not chemically change by itself. Depending on the type of catalyst (material, form, etc.), the selectivity for a specific chemical reaction and the reaction efficiency can be determined. different.

また、触媒材料としては、金属材料が広く用いられており、特に反応性の良さから貴金属材料が重用されている。例えば、特許文献1では、特定の反応において選択性のある貴金属触媒が開示されている。また、近年では、酸化物触媒も着目されてきており、特許文献2では、触媒活性および選択性に優れた酸化物触媒が開示されている。 Further, as a catalyst material, a metal material is widely used, and a noble metal material is particularly heavily used because of its good reactivity. For example, Patent Document 1 discloses a noble metal catalyst that is selective in a specific reaction. Further, in recent years, an oxide catalyst has also attracted attention, and Patent Document 2 discloses an oxide catalyst having excellent catalytic activity and selectivity.

特開2007−090164号公報JP-A-2007-090164 特開2007−301470号公報JP-A-2007-301470

しかしながら、二酸化炭素の還元反応においては、選択性をもった化学反応の制御が未だ十分にできておらず、目的物を高い反応効率で得ることはできていなかった。そのため、特に二酸化炭素の還元反応において、反応を良好に促進・制御し得る触媒の開発が望まれている。 However, in the reduction reaction of carbon dioxide, the chemical reaction having selectivity has not yet been sufficiently controlled, and the target product has not been obtained with high reaction efficiency. Therefore, it is desired to develop a catalyst capable of satisfactorily promoting and controlling the reaction, particularly in the reduction reaction of carbon dioxide.

そこで、本発明は、上記課題に鑑みてなされたものであり、特に二酸化炭素の還元反応に対し良好な触媒性能(例えば、触媒活性や選択性等)を有し、二酸化炭素の還元反応を良好に促進・制御し得る金属含有ナノ粒子担持電極および二酸化炭素還元装置を提供することを目的とする。 Therefore, the present invention has been made in view of the above problems, and has particularly good catalytic performance (for example, catalytic activity, selectivity, etc.) for the reduction reaction of carbon dioxide, and the reduction reaction of carbon dioxide is good. It is an object of the present invention to provide a metal-containing nanoparticle-supporting electrode and a carbon dioxide reducing device that can be promoted and controlled.

本発明者らは上記課題を解消するために鋭意検討した結果、ある特定の金属を含んでなる金属含有ナノ粒子を基材に担持した電極が、特に二酸化炭素の還元反応に対し良好な触媒性能を発現し得ることを見出した。 As a result of diligent studies to solve the above problems, the present inventors have found that an electrode on which metal-containing nanoparticles containing a specific metal are supported on a base material has particularly good catalytic performance for a carbon dioxide reduction reaction. It was found that can be expressed.

すなわち、本発明の要旨構成は、以下のとおりである。
〔1〕 二酸化炭素を還元するために用いられる金属含有ナノ粒子担持電極であって、
前記金属含有ナノ粒子担持電極は、基材電極上に金属含有ナノ粒子が担持されてなり、
前記金属含有ナノ粒子が、金、銀、銅、白金、ロジウム、パラジウム、ニッケル、コバルト、鉄、マンガン、クロム、イリジウム、亜鉛、チタンおよびルテニウムから選択される少なくとも1種の金属原子(M)を含有する、金属含有ナノ粒子担持電極。
〔2〕 前記金属含有ナノ粒子の一次粒径が、0.5〜100nmである、上記〔1〕に記載の金属含有ナノ粒子担持電極。
〔3〕 前記基材電極に対する前記金属含有ナノ粒子の担持割合[金属含有ナノ粒子の質量(mg)/基材電極の表面積(cm)]が、0.001〜1mg/cmである、上記〔1〕または〔2〕に記載の金属含有ナノ粒子担持電極。
〔4〕 前記金属含有ナノ粒子は、金属含有ナノ粒子担持触媒として前記基材電極上に担持されており、
前記金属含有ナノ粒子担持触媒は、担体上に前記金属含有ナノ粒子が担持されてなる、上記〔1〕〜〔3〕のいずれか1項に記載の金属含有ナノ粒子担持電極。
〔5〕 前記担体が、半導体粒子である、上記〔4〕に記載の金属含有ナノ粒子担持電極。
〔6〕 前記担体に対する前記金属含有ナノ粒子の質量比率[(金属含有ナノ粒子の質量/担体の質量)×100]が、0.001〜1%である、上記〔4〕または〔5〕に記載の金属含有ナノ粒子担持電極。
〔7〕 前記金属含有ナノ粒子が、前記金属原子(M)を含有するクラスターである、上記〔1〕〜〔6〕のいずれか1項に記載の金属含有ナノ粒子担持電極。
〔8〕 前記金属原子(M)が、銅である、上記〔1〕〜〔7〕のいずれか1項に記載の金属含有ナノ粒子担持電極。
〔9〕 前記銅の平均価数が、0〜1.5である、上記〔8〕に記載の金属含有ナノ粒子担持電極。
〔10〕 上記〔1〕〜〔9〕のいずれか1項に記載の金属含有ナノ粒子担持電極を備える、二酸化炭素還元装置。
That is, the gist structure of the present invention is as follows.
[1] A metal-containing nanoparticle-supporting electrode used for reducing carbon dioxide.
The metal-containing nanoparticles-supporting electrode is formed by supporting metal-containing nanoparticles on a base electrode.
The metal-containing nanoparticles contain at least one metal atom (M) selected from gold, silver, copper, platinum, rhodium, palladium, nickel, cobalt, iron, manganese, chromium, iridium, zinc, titanium and ruthenium. A metal-containing nanoparticle-supporting electrode containing.
[2] The metal-containing nanoparticles-supporting electrode according to the above [1], wherein the primary particle size of the metal-containing nanoparticles is 0.5 to 100 nm.
[3] The carrier ratio of the metal-containing nanoparticles to the base electrode [mass of metal-containing nanoparticles (mg) / surface area of base electrode (cm 2 )] is 0.001 to 1 mg / cm 2 . The metal-containing nanoparticle-supporting electrode according to the above [1] or [2].
[4] The metal-containing nanoparticles are supported on the base electrode as a metal-containing nanoparticles-supporting catalyst.
The metal-containing nanoparticles-supporting electrode according to any one of the above [1] to [3], wherein the metal-containing nanoparticles-supporting catalyst is a carrier on which the metal-containing nanoparticles are supported.
[5] The metal-containing nanoparticle-supporting electrode according to [4] above, wherein the carrier is a semiconductor particle.
[6] In the above [4] or [5], the mass ratio of the metal-containing nanoparticles to the carrier [(mass of metal-containing nanoparticles / mass of carrier) × 100] is 0.001 to 1%. The metal-containing nanoparticle-supporting electrode according to the above.
[7] The metal-containing nanoparticle-supporting electrode according to any one of [1] to [6] above, wherein the metal-containing nanoparticles are clusters containing the metal atom (M).
[8] The metal-containing nanoparticle-supporting electrode according to any one of [1] to [7] above, wherein the metal atom (M) is copper.
[9] The metal-containing nanoparticle-supporting electrode according to [8] above, wherein the average valence of copper is 0 to 1.5.
[10] A carbon dioxide reducing device comprising the metal-containing nanoparticle-supporting electrode according to any one of the above [1] to [9].

本発明の金属含有ナノ粒子担持電極は、特に二酸化炭素の還元反応に対し良好な触媒性能を発現する。 The metal-containing nanoparticles-supporting electrode of the present invention exhibits good catalytic performance particularly for the reduction reaction of carbon dioxide.

図1は、電解装置を概略的に示す構成図である。FIG. 1 is a configuration diagram schematically showing an electrolyzer. 図2は、図1に示す電解装置のうち、電解セル(二酸化炭素還元セル装置)の構成を示す、断面概略図である。FIG. 2 is a schematic cross-sectional view showing the configuration of an electrolytic cell (carbon dioxide reduction cell apparatus) among the electrolytic devices shown in FIG.

本発明に従う金属含有ナノ粒子担持電極および二酸化炭素還元装置の実施形態について、以下で詳細に説明する。 Embodiments of the metal-containing nanoparticle-supporting electrode and the carbon dioxide reduction device according to the present invention will be described in detail below.

本実施形態に係る金属含有ナノ粒子担持電極は、基材電極上に金属含有ナノ粒子が担持されてなり、この金属含有ナノ粒子は、金(Au)、銀(Ag)、銅(Cu)、白金(Pt)、ロジウム(Rh)、パラジウム(Pd)、ニッケル(Ni)、コバルト(Co)、鉄(Fe)、マンガン(Mn)、クロム(Cr)、イリジウム(Ir)、亜鉛(Zn),チタン(Ti)およびルテニウム(Ru)から選択される少なくとも1種の金属原子(M)を含有することを特徴とする。 The metal-containing nanoparticles-supporting electrode according to the present embodiment comprises metal-containing nanoparticles supported on a substrate electrode, and the metal-containing nanoparticles are gold (Au), silver (Ag), copper (Cu), or the like. Platinum (Pt), Rhodium (Rh), Palladium (Pd), Nickel (Ni), Cobalt (Co), Iron (Fe), Manganese (Mn), Chromium (Cr), Ruthenium (Ir), Zinc (Zn), It is characterized by containing at least one metal atom (M) selected from titanium (Ti) and ruthenium (Ru).

このような金属含有ナノ粒子担持電極は、二酸化炭素の還元反応に対し優れた触媒性能を発現するため、ニ酸化炭素を還元するための電極として好適に用いられる。 Such a metal-containing nanoparticle-supporting electrode exhibits excellent catalytic performance for the reduction reaction of carbon dioxide, and is therefore preferably used as an electrode for reducing carbon dioxide.

金属含有ナノ粒子は、上記のような金属原子(M)を含むものであれば特に限定されず、金属原子(M)の単体、金属原子(M)を含む合金、金属原子(M)を含む金属酸化物あるいは金属原子(M)を含む複合酸化物のいずれかからなるナノ粒子であってもよい。なお、金属原子(M)を含む合金または複合酸化物は、Au、Ag、Cu、Pt、Rh、Pd、Ni、Co、Fe、Mn、Cr、Ir、Zn、TiおよびRuから選択される少なくとも1種の金属原子を含む合金または複合酸化物であればよく、上記から選択される2種以上の金属原子を含む合金または複合酸化物、あるいは金属原子(M)と合金化または複合化し得る上記以外の金属原子を含む合金または複合酸化物であってもよい。また、金属含有ナノ粒子は、特に金属原子(M)の単体または金属原子(M)を含む合金からなることが好ましい。 The metal-containing nanoparticles are not particularly limited as long as they contain the metal atom (M) as described above, and include a single metal atom (M), an alloy containing the metal atom (M), and the metal atom (M). It may be nanoparticles composed of either a metal oxide or a composite oxide containing a metal atom (M). The alloy or composite oxide containing the metal atom (M) is at least selected from Au, Ag, Cu, Pt, Rh, Pd, Ni, Co, Fe, Mn, Cr, Ir, Zn, Ti and Ru. It may be an alloy or composite oxide containing one kind of metal atom, and may be alloyed or composited with an alloy or composite oxide containing two or more kinds of metal atoms selected from the above, or a metal atom (M). It may be an alloy or a composite oxide containing a metal atom other than the above. Further, the metal-containing nanoparticles are particularly preferably made of a simple substance of a metal atom (M) or an alloy containing a metal atom (M).

また、金属含有ナノ粒子は、上記金属原子(M)を含有するクラスター(以下、単に「金属含有クラスター」という。)であることが好ましい。このような金属含有ナノ粒子は、二酸化炭素の還元反応において、特に優れた触媒活性と選択性を発揮する。なお、本明細書において、「クラスター」とは、複数個の原子が結合した原子集団を意味する。このような金属含有クラスターは、例えば、下記一般式(1)で表される、金属原子(M)の単体または金属原子(M)を含む金属酸化物であることが好ましい。
・・・(1)
上記(1)式において、Mは上述の金属原子(M)を、Oは、酸素を表す。
Further, the metal-containing nanoparticles are preferably clusters containing the metal atom (M) (hereinafter, simply referred to as “metal-containing clusters”). Such metal-containing nanoparticles exhibit particularly excellent catalytic activity and selectivity in the reduction reaction of carbon dioxide. In addition, in this specification, a "cluster" means an atomic group in which a plurality of atoms are bonded. Such a metal-containing cluster is preferably, for example, a simple substance of a metal atom (M) or a metal oxide containing a metal atom (M) represented by the following general formula (1).
M n O m ... (1)
In the above equation (1), M represents the above-mentioned metal atom (M) and O represents oxygen.

また、上記(1)式において、mは、nとの関係で、m/nの比が0〜2であることが好ましく、より好ましくは0.5〜1.8、さらに好ましくは0.55〜0.75、特に好ましくは0.6〜0.7、一層好ましくは0.67である。上記範囲とすることにより、二酸化炭素の還元効率が高まる。なお、上記(1)式において、m/nが0のとき、金属含有クラスターは、金属原子(M)の単体からなる。 Further, in the above equation (1), m preferably has a ratio of m / n of 0 to 2, more preferably 0.5 to 1.8, and further preferably 0.55 in relation to n. It is ~ 0.75, particularly preferably 0.6 to 0.7, and even more preferably 0.67. Within the above range, the reduction efficiency of carbon dioxide is enhanced. In the above equation (1), when m / n is 0, the metal-containing cluster is composed of a single metal atom (M).

金属含有ナノ粒子に含まれる金属原子(M)は、Au、Ag、Cu、Pt、Rh、Pd、Ni、Co、Fe、Mn、Cr、Ir、Zn、TiおよびRuから選択される少なくとも1種である。このような金属含有ナノ粒子は、二酸化炭素の還元反応に卓越した性能を発揮する。中でも、金属原子(M)は、優れた還元性能の観点からCu、Ag、Au、Ni、ZnおよびPdから選択される1種であることが好ましく、特に、二酸化炭素の還元反応において選択的に炭化水素(メタンやエチレン等)を生成できる点で、Cuであることがより好ましく 、選択的にギ酸を生成できる点で、Agであることもより好ましい。 The metal atom (M) contained in the metal-containing nanoparticles is at least one selected from Au, Ag, Cu, Pt, Rh, Pd, Ni, Co, Fe, Mn, Cr, Ir, Zn, Ti and Ru. Is. Such metal-containing nanoparticles exhibit excellent performance in the reduction reaction of carbon dioxide. Among them, the metal atom (M) is preferably one selected from Cu, Ag, Au, Ni, Zn and Pd from the viewpoint of excellent reduction performance, and is particularly selectively selected in the reduction reaction of carbon dioxide. Cu is more preferable because it can generate hydrocarbons (methane, ethylene, etc.), and Ag is more preferable because it can selectively produce formic acid.

特に金属含有ナノ粒子が銅原子を含有する場合には、銅の平均価数は0〜1.5であることが好ましく 、1.2〜1.4であることがより好ましい。上記のような銅の平均価数を有する金属含有ナノ粒子としては、例えば銅原子と酸素原子を含有するクラスター等が挙げられる。 In particular, when the metal-containing nanoparticles contain a copper atom, the average valence of copper is preferably 0 to 1.5, more preferably 1.2 to 1.4. Examples of the metal-containing nanoparticles having the average valence of copper as described above include clusters containing copper atoms and oxygen atoms.

また、金属含有ナノ粒子の一次粒径は、0.5〜100nmであることが好ましく 、より好ましくは0.5〜55nmであり、さらに好ましくは0.5〜2.0nmである。上記範囲とすることにより、金属含有ナノ粒子を構成する原子数が数個から数10個になり、バルクの結晶面とは異なる二酸化炭素分子や、反応中間体、生成物との相互作用が可能となり、活性が格段に向上する。 The primary particle size of the metal-containing nanoparticles is preferably 0.5 to 100 nm, more preferably 0.5 to 55 nm, and even more preferably 0.5 to 2.0 nm. Within the above range, the number of atoms constituting the metal-containing nanoparticles is changed from several to several tens, and it is possible to interact with carbon dioxide molecules different from the bulk crystal plane, reaction intermediates, and products. The activity is significantly improved.

なお、本明細書において、一次粒径は、透過型電子顕微鏡(TEM)、走査型電子顕微鏡(SEM)等により、一次粒子(他の粒子と凝集していない、単独の粒子)の画像を撮影し、これを画像解析することにより算出した値とする。具体的には、TEM等で撮影された画像から、無作為に100個の粒子(一次粒子)を選択し、画像処理装置により、粒子毎の投影面積を求め、それらの合計から粒子の合計の占有面積を算出する。この合計の占有面積を、選択した粒子の個数(100個)で割って、1粒子あたりの平均占有面積を算出し、この面積に相当する円の直径(1粒子あたりの平均円相当直径)を、一次粒径とする(以下において同じ)。 In the present specification, for the primary particle size, an image of primary particles (single particles that are not aggregated with other particles) is photographed by a transmission electron microscope (TEM), a scanning electron microscope (SEM), or the like. Then, this is used as a value calculated by image analysis. Specifically, 100 particles (primary particles) are randomly selected from the images taken by TEM or the like, the projected area of each particle is obtained by an image processing device, and the total of the particles is calculated from the total of them. Calculate the occupied area. Divide this total occupied area by the number of selected particles (100 particles) to calculate the average occupied area per particle, and calculate the diameter of the circle corresponding to this area (average circle equivalent diameter per particle). , The primary particle size (same below).

また、基材電極としては、導電性を確保できる材料であればよく、銅(Cu)、金(Au)、銀(Ag)、白金(Pt)、ロジウム(Rh)、パラジウム(Pd)、ニッケル(Ni)、コバルト(Co)、鉄(Fe)、マンガン(Mn)、クロム(Cr)、イリジウム(Ir)、亜鉛(Zn)、チタン(Ti)、ルテニウム(Ru)から選択される1種の金属や、これらの金属を1種以上含む合金材料(例えば、SUS等)、ダイヤモンド、カーボンナノチューブ、グラッシーカーボン、カーボンからなる電極が好ましく挙げられる。中でも、銅または銅合金からなる基材電極が好ましい。銅(純銅)からなる基材電極には、例えば、タフピッチ銅TPC、リン脱酸銅PDC、無酸素銅OFCを様々に形状加工したものや、電解銅箔を用いることができる。また、銅合金からなる基材電極には、銅−スズ系合金、銅−鉄系合金、銅−ジルコニウム系合金、銅−クロム系合金等の銅合金を用いることができる他、コルソン合金系等などの第二成分以降の成分が0.01〜5質量%程度の、固溶または析出強化された銅基希薄合金を用いることもできる。なお、合金系の電極の場合、銀以外の成分の添加量が増すほど、導電率が低くなり、基材電極としての基本特性を低下させる傾向にあるため、銀以外の成分の添加量は少ないほど好ましい。また、基材電極の形態は、特に限定されず、平板状のほか、メッシュや多孔質形状のものも用いることができ、中でも平板状のものが好ましい。 The base electrode may be any material that can ensure conductivity, such as copper (Cu), gold (Au), silver (Ag), platinum (Pt), rhodium (Rh), palladium (Pd), and nickel. One selected from (Ni), cobalt (Co), iron (Fe), manganese (Mn), chromium (Cr), iridium (Ir), zinc (Zn), titanium (Ti), ruthenium (Ru). Preferred examples include a metal, an alloy material containing one or more of these metals (for example, SUS, etc.), diamond, carbon nanotube, glassy carbon, and an electrode made of carbon. Of these, a base electrode made of copper or a copper alloy is preferable. For the base electrode made of copper (pure copper), for example, tough pitch copper TPC, phosphorylated copper PDC, oxygen-free copper OFC processed in various shapes, or electrolytic copper foil can be used. Further, as the base electrode made of a copper alloy, a copper alloy such as a copper-tin alloy, a copper-iron alloy, a copper-zyrosine alloy, or a copper-chromium alloy can be used, and a Corson alloy or the like can be used. It is also possible to use a solid-dissolved or precipitation-strengthened copper-based dilute alloy in which the components after the second component such as are about 0.01 to 5% by mass. In the case of alloy-based electrodes, as the amount of components other than silver added increases, the conductivity tends to decrease and the basic characteristics of the base electrode tend to decrease, so the amount of components other than silver added is small. Is more preferable. The form of the base electrode is not particularly limited, and a flat plate shape, a mesh or a porous shape can be used, and a flat plate shape is preferable.

また、基材電極に対する金属含有ナノ粒子の担持割合[金属含有ナノ粒子の質量(mg)/基材電極の表面積(cm)]は、0.001〜1mg/cmであることが好ましく、 より好ましくは0.01〜0.16mg/cmである。上記範囲とすることにより、基材電極から供給される電子が効率的に二酸化炭素の還元に利用されるようになり、金属含有ナノ粒子の質量当たりの活性が最も高くなる。 Further, the loading ratio of the metal-containing nanoparticles to the base electrode [mass of the metal-containing nanoparticles (mg) / surface area of the base electrode (cm 2 )] is preferably 0.001 to 1 mg / cm 2 . More preferably, it is 0.01 to 0.16 mg / cm 2 . Within the above range, the electrons supplied from the base electrode can be efficiently used for the reduction of carbon dioxide, and the activity of the metal-containing nanoparticles per mass becomes the highest.

また、本実施形態に係る金属含有ナノ粒子担持電極では、金属含有ナノ粒子は基材電極上に担持されていればよく、その形態は、使用の形態等に応じて適宜選択することができる。例えば、基材電極上に直接金属含有ナノ粒子を析出、担持させてもよいし、担体上に金属含有ナノ粒子が担持されてなる金属含有ナノ粒子担持触媒として予め作製し、この触媒を基材電極上に担持させてもよい。特に、二酸化炭素の還元反応に対してより優れた触媒活性を発揮させる観点からは、金属含有ナノ粒子は、基材電極上に直接担持されていることが好ましい。 Further, in the metal-containing nanoparticles-supporting electrode according to the present embodiment, the metal-containing nanoparticles may be supported on the base electrode, and the form thereof can be appropriately selected depending on the mode of use and the like. For example, metal-containing nanoparticles may be deposited and supported directly on the base electrode, or a metal-containing nanoparticles-supporting catalyst in which the metal-containing nanoparticles are supported on a carrier are prepared in advance, and this catalyst is used as a base material. It may be supported on an electrode. In particular, from the viewpoint of exerting more excellent catalytic activity for the reduction reaction of carbon dioxide, it is preferable that the metal-containing nanoparticles are directly supported on the base electrode.

また、金属含有ナノ粒子担持電極の製造の容易さおよび自由度の高さ、金属含有ナノ粒子担持触媒の汎用性の良さ、活性部位の露出しやすさ等の観点からは、金属含有ナノ粒子は、金属含有ナノ粒子担持触媒として、基材電極上に担持されていることが好ましい。金属含有ナノ粒子担持触媒によれば、基材電極に関わらず、金属含有ナノ粒子を個別に作製、保管できるため、所望のタイミングで、所望の大きさおよび数量の基材電極に対して、また比較的容易な方法(後述するコーティング方法)で、金属含有ナノ粒子を担持させることができ、製造に関する条件の自由度を高めることができる。また、金属含有ナノ粒子担持触媒は、本発明以外の他の用途にも用いることができ、それ自体も触媒として用いることができるため、まとめて作製すれば様々な用途に使用でき、汎用性に優れる。 In addition, from the viewpoints of ease of manufacture of metal-containing nanoparticles-supported electrodes, high degree of freedom, versatility of metal-containing nanoparticles-supported catalysts, and ease of exposure of active sites, metal-containing nanoparticles are used. As a metal-containing nanoparticle-supporting catalyst, it is preferably supported on a substrate electrode. According to the metal-containing nanoparticles-supported catalyst, metal-containing nanoparticles can be individually produced and stored regardless of the base electrode, so that the metal-containing nanoparticles can be produced and stored individually at a desired timing and for a desired size and quantity of base electrodes. Metal-containing nanoparticles can be supported by a relatively simple method (coating method described later), and the degree of freedom in manufacturing conditions can be increased. In addition, the metal-containing nanoparticles-supporting catalyst can be used for other purposes than the present invention, and can be used as a catalyst by itself. Therefore, if they are collectively produced, they can be used for various purposes and are versatile. Excellent.

このような金属含有ナノ粒子担持触媒は、担体上に金属含有ナノ粒子が担持されてなることが好ましい。
ここで、担体としては、例えば半導体粒子や、金属粒子やカーボン素材などが挙げられ、中でも半導体粒子であることが好ましい。このような半導体粒子は、例えば酸化物半導体であることが好ましく、より具体的には酸化チタンや、酸化錫、酸化亜鉛、酸化ニオブ、チタン酸カルシウム、酸化ガリウム、酸化タンタル、チタン酸ストロンチウム、酸化タングステン、酸化セリウム、窒化ガリウム、窒化アルミニウムガリウム、ヒ化ガリウム、ヒ化アルミニウムガリウム等が挙げられ、上記のうち2種以上を混合して利用してもよい。中でも酸化チタン、チタン酸カルシウム、酸化ニオブ、酸化ガリウム、酸化タンタルが好ましい。
In such a metal-containing nanoparticles-supporting catalyst, it is preferable that the metal-containing nanoparticles are supported on the carrier.
Here, examples of the carrier include semiconductor particles, metal particles, carbon materials, and the like, and among them, semiconductor particles are preferable. Such semiconductor particles are preferably, for example, oxide semiconductors, and more specifically, titanium oxide, tin oxide, zinc oxide, niobium oxide, calcium titanate, gallium oxide, tantalum oxide, strontium titanate, and oxidation. Examples thereof include tungsten, cerium oxide, gallium nitride, gallium aluminum nitride, gallium arsenide, gallium aluminum arsenide, and the like, and two or more of the above may be mixed and used. Of these, titanium oxide, calcium titanate, niobium oxide, gallium oxide, and tantalum oxide are preferable.

また、半導体粒子の一次粒径は、50nm〜100μmであることが好ましく、より好ましくは200nm〜10μmである。上記範囲とすることにより、半導体粒子の表面に光触媒活性の高い面が形成され、かつ十分な表面積が得られ、二酸化炭素還元反応の活性が高くなる。 The primary particle size of the semiconductor particles is preferably 50 nm to 100 μm, more preferably 200 nm to 10 μm. Within the above range, a surface having high photocatalytic activity is formed on the surface of the semiconductor particles, a sufficient surface area is obtained, and the activity of the carbon dioxide reduction reaction is increased.

また、担体に対する金属含有ナノ粒子の質量比率[(金属含有ナノ粒子の質量/担体の質量)×100]は、0.001〜1%であることが好ましく 、より好ましくは、0.05〜0.5%である。上記範囲とすることにより、該触媒によって生じた電子が効率的に二酸化炭素の還元に利用されるようになり、金属含有ナノ粒子の質量当たりの活性が最も高くなる。 The mass ratio of the metal-containing nanoparticles to the carrier [(mass of metal-containing nanoparticles / mass of carrier) × 100] is preferably 0.001 to 1%, more preferably 0.05 to 0. It is 5.5%. Within the above range, the electrons generated by the catalyst can be efficiently used for the reduction of carbon dioxide, and the activity of the metal-containing nanoparticles per mass becomes the highest.

本発明に係る金属含有ナノ粒子担持電極の製造方法は、特に限定されず、公知の方法によって製造することができるが、不均一系析出法にて行うことが好ましい。不均一系析出法によれば、基材電極または担体の表面に特定の金属を析出させることができる。 The method for producing the metal-containing nanoparticle-supporting electrode according to the present invention is not particularly limited and can be produced by a known method, but it is preferably performed by a heterogeneous precipitation method. According to the non-homogeneous precipitation method, a specific metal can be precipitated on the surface of the base electrode or the carrier.

以下では、不均一系析出法による金属含有ナノ粒子担持電極の製造方法の例として、<1>金属含有ナノ粒子を直接基材電極上に担持させる場合の一例、および<2>金属含有ナノ粒子担持触媒として基材電極上に担持させる場合の一例を、それぞれ説明する。 In the following, as an example of a method for producing a metal-containing nanoparticle-supported electrode by a heterogeneous precipitation method, <1> an example in which metal-containing nanoparticles are directly supported on a substrate electrode, and <2> metal-containing nanoparticles are supported. An example of the case where the carrier electrode is supported on the base electrode as a carrier catalyst will be described.

<1>金属含有ナノ粒子を直接基材電極上に担持させる場合
まずは、析出させたい金属に対応する金属イオンが溶解した溶液を調製する。次に、この溶液に基材電極となる基材を浸漬し、さらにこの溶液に水素化ホウ素ナトリウムなどの還元剤を加えて、溶液中の金属イオンを還元し、基材上で金属を析出させる方法等により、金属含有ナノ粒子担持電極を作製できる。得られた金属含有ナノ粒子担持電極は、上記反応溶液から引き上げて、さらに必要に応じて、蒸留水等で洗浄、乾燥、酸化処理等を行ってもよい。また、金属イオンが溶解した溶液としては、例えば、水やアルコール等の公知の溶媒に、析出させたい金属に対応する金属塩(例えば、塩化銅や、硝酸銀等)を溶解させたもの等を用いることができる(以下において同じ)。
<1> When the metal-containing nanoparticles are directly supported on the base electrode First, a solution in which the metal ions corresponding to the metal to be precipitated are dissolved is prepared. Next, the base material to be the base material electrode is immersed in this solution, and a reducing agent such as sodium boron hydride is further added to this solution to reduce the metal ions in the solution and precipitate the metal on the base material. A metal-containing nanoparticle-supporting electrode can be produced by a method or the like. The obtained metal-containing nanoparticles-supporting electrode may be pulled up from the above reaction solution and further washed, dried, oxidized or the like with distilled water or the like, if necessary. Further, as the solution in which the metal ion is dissolved, for example, a solution in which a metal salt (for example, copper chloride, silver nitrate, etc.) corresponding to the metal to be precipitated is dissolved in a known solvent such as water or alcohol is used. Can be (same below).

<2>金属含有ナノ粒子担持触媒として基材電極上に担持させる場合
まず、半導体粒子と、析出させたい金属に対応する金属イオンとが分散した溶液を準備し、(1)この分散溶液に水素化ホウ素ナトリウムなどの還元剤を加えて金属イオンを還元し、半導体粒子上で金属を析出させる方法や、(2)この分散溶液を加熱して溶媒を除去し、半導体粒子上に金属またはその塩を析出させる方法などにより、金属含有ナノ粒子担持触媒を作製できる。さらに、得られた金属含有ナノ粒子担持触媒は、上記反応溶液から分離して、さらに必要に応じて、蒸留水等で洗浄、乾燥、酸化処理等を行ってもよい。
<2> When supporting on a substrate electrode as a metal-containing nanoparticle-supporting catalyst First, a solution in which semiconductor particles and metal ions corresponding to the metal to be precipitated are dispersed is prepared, and (1) hydrogen is added to this dispersion solution. A method of adding a reducing agent such as sodium boron oxide to reduce metal ions to precipitate a metal on semiconductor particles, or (2) heating this dispersion solution to remove a solvent, and metal or a salt thereof on the semiconductor particles. A metal-containing nanoparticle-supporting catalyst can be produced by a method of precipitating or the like. Further, the obtained metal-containing nanoparticles-supporting catalyst may be separated from the above reaction solution and further washed, dried, oxidized or the like with distilled water or the like, if necessary.

次に、上記のようにして得られた金属含有ナノ粒子担持触媒を、スピンコーティング法や、スプレーコーティング法、濾過法、バーコーティング法などの一般的なコーティング方法により、基材電極となる基材上に積層形成して、金属含有ナノ粒子担持電極を作製することができる。 Next, the metal-containing nanoparticles-supporting catalyst obtained as described above is subjected to a base material as a base material electrode by a general coating method such as a spin coating method, a spray coating method, a filtration method, or a bar coating method. A metal-containing nanoparticle-supporting electrode can be produced by laminating on the electrode.

また、本発明に係る金属含有ナノ粒子担持電極は、二酸化炭素の還元反応に対し良好な触媒性能を発現する。そのため、ニ酸化炭素を還元するための二酸化炭素還元装置に好適に用いられる。 In addition, the metal-containing nanoparticles-supporting electrode according to the present invention exhibits good catalytic performance for the reduction reaction of carbon dioxide. Therefore, it is suitably used in a carbon dioxide reduction device for reducing carbon dioxide.

以下に、本発明の属含有ナノ粒子担持電極が、二酸化炭素の電気化学的還元(電解還元、カソード還元)のカソード電極として用いられる場合の一例について説明する。 Hereinafter, an example will be described in which the genus-containing nanoparticles-supporting electrode of the present invention is used as a cathode electrode for electrochemical reduction (electrolytic reduction, cathode reduction) of carbon dioxide.

図1は、二酸化炭素の電気化学的還元を行う電解装置1の構成を示すブロック図である。電解装置1は、主に、電解セル3、ガス回収装置5、電解液循環装置7、二酸化炭素供給部9、電源11等で構成される。 FIG. 1 is a block diagram showing a configuration of an electrolytic device 1 that electrochemically reduces carbon dioxide. The electrolytic device 1 is mainly composed of an electrolytic cell 3, a gas recovery device 5, an electrolytic solution circulation device 7, a carbon dioxide supply unit 9, a power supply 11, and the like.

電解セル3は、対象物質を還元する部位であり、本発明のカソード電極が含まれる部位でもあり、二酸化炭素(溶液において、溶存二酸化炭素のほか、炭酸水素イオンである場合も含む。以下、単に二酸化炭素等とする。)を還元する部位である。電解セル3には、電源11から電力が供給される。 The electrolytic cell 3 is a site for reducing the target substance, a site including the cathode electrode of the present invention, and carbon dioxide (including dissolved carbon dioxide and hydrogen carbonate ion in the solution. Hereinafter, simply It is a part that reduces carbon dioxide, etc.). Electric power is supplied to the electrolytic cell 3 from the power source 11.

電解液循環装置7は、電解セル3のカソード電極に対して、カソード側電解液を循環させる部位である。電解液循環装置7は、例えば槽およびポンプであり、二酸化炭素供給部9から所定の二酸化炭素濃度となるように、二酸化炭素等が供給されて電解液中に溶解され、電解セル3との間で電解液を循環可能である。 The electrolytic solution circulation device 7 is a portion for circulating the cathode side electrolytic solution with respect to the cathode electrode of the electrolytic cell 3. The electrolytic solution circulation device 7 is, for example, a tank and a pump, and carbon dioxide or the like is supplied from the carbon dioxide supply unit 9 so as to have a predetermined carbon dioxide concentration and is dissolved in the electrolytic solution, and is between the electrolytic solution cell 3 and the electrolytic solution cell 3. The electrolytic solution can be circulated at.

ガス回収装置5は、電解セル3によって還元されて発生したガスを回収する部位である。ガス回収装置5では、電解セル3のカソード電極で発生する炭化水素等のガスを捕集することが可能である。なお、ガス回収装置5において、ガス種類毎にガスを分離可能としてもよい。 The gas recovery device 5 is a portion that recovers the gas generated by the reduction by the electrolytic cell 3. The gas recovery device 5 can collect gases such as hydrocarbons generated at the cathode electrode of the electrolytic cell 3. In the gas recovery device 5, the gas may be separated for each gas type.

電解装置1は、以下のように機能する。前述の通り、電解セル3には電源11からの電解電位が付与される。電解セル3のカソード電極には、電解液循環装置7によって電解液が供給される(図中矢印A)。電解セル3のカソード電極においては、供給される電解液中の二酸化炭素等が還元される。二酸化炭素等が還元されると、主にエタンやエチレン等の炭化水素が生成される。 The electrolyzer 1 functions as follows. As described above, the electrolytic cell 3 is provided with the electrolytic potential from the power source 11. The electrolytic solution is supplied to the cathode electrode of the electrolytic cell 3 by the electrolytic solution circulation device 7 (arrow A in the figure). At the cathode electrode of the electrolytic cell 3, carbon dioxide and the like in the supplied electrolytic solution are reduced. When carbon dioxide and the like are reduced, hydrocarbons such as ethane and ethylene are mainly produced.

カソード電極で生成された炭化水素ガスは、ガス回収装置5により回収される(図中矢印B)。ガス回収装置5では、必要に応じてガスを分離し貯留することが可能である。 The hydrocarbon gas generated at the cathode electrode is recovered by the gas recovery device 5 (arrow B in the figure). In the gas recovery device 5, it is possible to separate and store the gas as needed.

カソード電極で二酸化炭素等が還元されて消費されることで、電解液中の二酸化炭素等の濃度が減少する。還元反応によって減少した二酸化炭素等は常に補充され、その濃度は常に所定範囲内に保たれる。具体的は、電解液の一部が電解液循環装置7により回収されて(図中矢印C)、所定濃度の電解液が常に供給される(図中矢印A)。以上により、電解セル3において、常に一定の条件で炭化水素を生成することができる。 The concentration of carbon dioxide and the like in the electrolytic solution is reduced by reducing and consuming carbon dioxide and the like at the cathode electrode. Carbon dioxide and the like reduced by the reduction reaction are always replenished, and the concentration is always kept within a predetermined range. Specifically, a part of the electrolytic solution is recovered by the electrolytic solution circulation device 7 (arrow C in the figure), and the electrolytic solution having a predetermined concentration is always supplied (arrow A in the figure). As described above, the electrolytic cell 3 can always generate hydrocarbons under constant conditions.

次に、電解セル3について説明する。図2は、電解セル3の構成を示す図である。電解セル3は、主に、カソード槽である槽16a、金属メッシュ17、カソード電極19、陽イオン交換膜21、アノード電極20、アノード槽である槽16b等から構成される。電解セル3においては、板状の各構成が積層されて構成される。 Next, the electrolytic cell 3 will be described. FIG. 2 is a diagram showing the configuration of the electrolytic cell 3. The electrolytic cell 3 is mainly composed of a tank 16a which is a cathode tank, a metal mesh 17, a cathode electrode 19, a cation exchange membrane 21, an anode electrode 20, a tank 16b which is an anode tank, and the like. In the electrolytic cell 3, each plate-shaped structure is laminated.

槽16a、16bには、それぞれ電解液15a、15bが保持される。カソード電極側の槽16aの上部には、生成ガスを回収するための孔が形成され、図示を省略したガス回収装置に接続される。すなわち、カソード電極で生成されるガスは、当該孔から回収される。また、槽16aには、配管等が接続され、図示を省略した電解液循環装置7と接続される。すなわち、槽16a内の電解液15aは常に電解液循環装置7によって循環可能である。なお、必要に応じて、槽15b側の電解液も同様に循環可能としてもよい。 Electrolyte solutions 15a and 15b are held in the tanks 16a and 16b, respectively. A hole for recovering the produced gas is formed in the upper part of the tank 16a on the cathode electrode side, and is connected to a gas recovery device (not shown). That is, the gas generated at the cathode electrode is recovered from the pores. Further, a pipe or the like is connected to the tank 16a, and is connected to an electrolytic solution circulation device 7 (not shown). That is, the electrolytic solution 15a in the tank 16a can always be circulated by the electrolytic solution circulation device 7. If necessary, the electrolytic solution on the tank 15b side may also be circulated in the same manner.

カソード電解液である電解液15aとしては、二酸化炭素等を多量に溶解できる電解液であることが好ましく、例えば、水酸化ナトリウム水溶液、水酸化カリウム水溶液、炭酸ナトリウム、炭酸カリウム、炭酸水素ナトリウム、炭酸水素カリウム等のアルカリ性溶液、モノメタノールアミン、メチルアミン、その他液状のアミン、またはそれら液状のアミンと電解質水溶液の混合液などが用いられる。また、アセトニトリル、ベンゾニトリル、塩化メチレン、テトラヒドロフラン、炭酸プロピレン、ジメチルホルムアミド、ジメチルスルホキシド、メタノール、エタノール等を用いることができる。 The electrolytic solution 15a, which is the cathode electrolytic solution, is preferably an electrolytic solution capable of dissolving a large amount of carbon dioxide and the like. For example, sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, sodium carbonate, potassium carbonate, sodium hydrogen carbonate, carbonic acid. An alkaline solution such as potassium hydrogen, monomethanolamine, methylamine, other liquid amines, or a mixed solution of these liquid amines and an aqueous electrolyte solution is used. Further, acetonitrile, benzonitrile, methylene chloride, tetrahydrofuran, propylene carbonate, dimethylformamide, dimethyl sulfoxide, methanol, ethanol and the like can be used.

また、アノード電解液である電解液15bとしては、前記のカソード電解液を用いるか、または適当な純水や水溶液を用いることができる。 Further, as the electrolytic solution 15b which is the anode electrolytic solution, the above-mentioned cathode electrolytic solution can be used, or an appropriate pure water or aqueous solution can be used.

金属メッシュ17は、参照電極18と共に電源11の負極側に接続され、カソード電極19に対して通電するための部材である。金属メッシュ17としては、例えば銅製のメッシュやステンレス製のメッシュであり、参照電極18には銀/塩化銀電極などが使用できる。 The metal mesh 17 is connected to the negative electrode side of the power supply 11 together with the reference electrode 18, and is a member for energizing the cathode electrode 19. The metal mesh 17 is, for example, a copper mesh or a stainless steel mesh, and a silver / silver chloride electrode or the like can be used as the reference electrode 18.

陽イオン交換膜21としては、例えば、公知のナフィオン系などを用いることができる。アノード反応で酸素と共に発生する水素イオンをカソード側へ移動させ得る。 As the cation exchange membrane 21, for example, a known Nafion system or the like can be used. Hydrogen ions generated with oxygen in the anodic reaction can be moved to the cathode side.

アノード電極20は電源11の正極に接続される。アノード電極20としては酸素発生過電圧の小さい電極、チタンやステンレスなどの基体上に被覆した酸化イリジウムや白金、ロジウム、或いは酸化物電極やステンレス、或いは鉛などを用いることができる。 The anode electrode 20 is connected to the positive electrode of the power supply 11. As the anode electrode 20, an electrode having a small oxygen evolution overvoltage, an iridium oxide, platinum, rhodium coated on a substrate such as titanium or stainless steel, an oxide electrode, stainless steel, or lead can be used.

なお、アノード電極20は、光触媒によって構成することもできる。すなわち、光を照射することで起電力を生じるようにすることができる。このようにすることで、アノード電極に太陽光などの光を照射して起電力を生じさせ、この起電力を電解セル3における電解電位として利用することができる。 The anode electrode 20 can also be configured by a photocatalyst. That is, it is possible to generate an electromotive force by irradiating light. By doing so, the anode electrode is irradiated with light such as sunlight to generate an electromotive force, and this electromotive force can be used as an electrolytic potential in the electrolytic cell 3.

カソード電極19では、電解液中の二酸化炭素等が還元される。二酸化炭素は、水に溶解し、溶存二酸化炭素や炭酸水素イオンの状態で電解液中に存在し、カソード電極に供給される。通常、銅系以外の材料からなるカソード電極の場合、水素や一酸化炭素が多く発生する傾向にあり、炭化水素は殆ど生成されない。これに対し、銅系の材料からなるカソード電極の場合、比較的効率良く炭化水素を生成することができる。 At the cathode electrode 19, carbon dioxide and the like in the electrolytic solution are reduced. Carbon dioxide is dissolved in water, exists in the electrolytic solution in the form of dissolved carbon dioxide and bicarbonate ions, and is supplied to the cathode electrode. Usually, in the case of a cathode electrode made of a material other than copper, hydrogen and carbon monoxide tend to be generated in a large amount, and hydrocarbons are hardly generated. On the other hand, in the case of a cathode electrode made of a copper-based material, hydrocarbons can be generated relatively efficiently.

本実施形態に係るカソード電極19は、本発明の電極触媒で構成されている。すなわち、カソード電極19は、基材電極上に、酸化銅層が形成されてなり、さらに酸化銅層の表面には、チタンまたはチタン合金等からなる表面保護層が薄く形成されていてもよい。このようなカソード電極を用いることで、二酸化炭素を効率よく分解還元でき、エネルギーとして有用な炭化水素を高いエネルギー効率で生成できる。 The cathode electrode 19 according to the present embodiment is composed of the electrode catalyst of the present invention. That is, the cathode electrode 19 may have a copper oxide layer formed on the base electrode, and a surface protective layer made of titanium, a titanium alloy, or the like may be thinly formed on the surface of the copper oxide layer. By using such a cathode electrode, carbon dioxide can be efficiently decomposed and reduced, and hydrocarbons useful as energy can be generated with high energy efficiency.

以上、本発明の実施形態について説明したが、本発明は上記実施形態に限定されるものではなく、本発明の概念および特許請求の範囲に含まれるあらゆる態様を含み、本発明の範囲内で種々に改変することができる。 Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, but includes all aspects included in the concept of the present invention and the scope of claims, and varies within the scope of the present invention. Can be modified to.

次に、本発明の効果をさらに明確にするために、実施例および比較例について説明するが、本発明はこれら実施例に限定されるものではない。 Next, in order to further clarify the effect of the present invention, Examples and Comparative Examples will be described, but the present invention is not limited to these Examples.

(実施例1)
塩化銅(和光純薬工業株式会社製)を水に溶解し、0.004mol/L塩化銅水溶液を調製した。続いて、この塩化銅水溶液に、基材として銅板(純銅、株式会社ニラコ製、幅10mm×長さ50mm×厚さ1mm)を入れた。さらに、水素化ホウ素ナトリウム(シグマ アルドリッチ ジャパン合同会社製)を加えて混合し、水素化ホウ素ナトリウムの濃度を0.005mol/Lとした。
上記混合溶液を室温で1時間撹拌した。続いて銅板を取り出し、蒸留水で洗浄を行い、基材としての銅板上に銅ナノ粒子が担持された金属含有ナノ粒子担持電極を得た。
(Example 1)
Copper chloride (manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved in water to prepare a 0.004 mol / L copper chloride aqueous solution. Subsequently, a copper plate (pure copper, manufactured by Nirako Co., Ltd., width 10 mm × length 50 mm × thickness 1 mm) was put into this copper chloride aqueous solution as a base material. Further, sodium borohydride (manufactured by Sigma-Aldrich Japan GK) was added and mixed to adjust the concentration of sodium borohydride to 0.005 mol / L.
The mixed solution was stirred at room temperature for 1 hour. Subsequently, the copper plate was taken out and washed with distilled water to obtain a metal-containing nanoparticle-supporting electrode in which copper nanoparticles were supported on the copper plate as a base material.

(実施例2)
実施例1と同じ方法で作製した金属含有ナノ粒子担持電極を、さらに150℃で30分加熱処理して銅ナノ粒子を酸化させ、酸化した銅ナノ粒子が基材に担持された金属含有ナノ粒子担持電極を得た。
(Example 2)
The metal-containing nanoparticles-supporting electrode produced by the same method as in Example 1 was further heat-treated at 150 ° C. for 30 minutes to oxidize the copper nanoparticles, and the oxidized copper nanoparticles were supported on the substrate. A supported electrode was obtained.

(実施例3)
実施例1と同じ方法で作製した金属含有ナノ粒子担持電極に対する加熱処理の時間を1時間とした以外は、実施例2と同じ方法により金属含有ナノ粒子担持電極を得た。
(Example 3)
A metal-containing nanoparticle-supported electrode was obtained by the same method as in Example 2 except that the heat treatment time for the metal-containing nanoparticle-supported electrode produced by the same method as in Example 1 was set to 1 hour.

(実施例4)
0.004mol/L塩化銅水溶液に替えて、硝酸銀(キシダ化学株式会社製)を水に溶解して調製した0.003mol/L硝酸銀水溶液を用いた以外は、実施例1と同じ方法により、基材に銀ナノ粒子が担持された金属含有ナノ粒子担持電極を得た。
(Example 4)
The group was prepared by the same method as in Example 1 except that a 0.003 mol / L silver nitrate aqueous solution prepared by dissolving silver nitrate (manufactured by Kishida Chemical Co., Ltd.) in water was used instead of the 0.004 mol / L copper chloride aqueous solution. A metal-containing nanoparticle-supporting electrode in which silver nanoparticles were supported on the material was obtained.

(実施例5)
実施例4と同じ方法で作製した金属含有ナノ粒子担持電極を、さらに130℃で15分加熱処理して銀ナノ粒子を酸化させ、基材に酸化した銀ナノ粒子が担持された金属含有ナノ粒子担持電極を得た。
(Example 5)
The metal-containing nanoparticles-supporting electrode produced by the same method as in Example 4 was further heat-treated at 130 ° C. for 15 minutes to oxidize the silver nanoparticles, and the metal-containing nanoparticles on which the oxidized silver nanoparticles were supported on the base material. A supported electrode was obtained.

(実施例6)
実施例4と同じ方法で作製した金属含有ナノ粒子担持電極に対する加熱処理の時間を30分とした以外は、実施例5と同じ方法により金属含有ナノ粒子担持電極を得た。
(Example 6)
A metal-containing nanoparticle-supporting electrode was obtained by the same method as in Example 5, except that the heat treatment time for the metal-containing nanoparticle-supporting electrode produced by the same method as in Example 4 was 30 minutes.

(実施例7)
0.004mol/L塩化銅水溶液に替えて、0.4mol/L塩化銅水溶液を用いた以外は、実施例1と同じ方法により金属含有ナノ粒子担持電極を得た。
(Example 7)
A metal-containing nanoparticle-supporting electrode was obtained by the same method as in Example 1 except that a 0.4 mol / L copper chloride aqueous solution was used instead of the 0.004 mol / L copper chloride aqueous solution.

(実施例8)
0.004mol/L塩化銅水溶液に替えて、0.02mol/L塩化銅水溶液を用いた以外は、実施例1と同じ方法により金属含有ナノ粒子担持電極を得た。
(Example 8)
A metal-containing nanoparticle-supporting electrode was obtained by the same method as in Example 1 except that a 0.02 mol / L copper chloride aqueous solution was used instead of the 0.004 mol / L copper chloride aqueous solution.

(実施例9)
実施例1と同じ方法で作製した金属含有ナノ粒子担持電極に対する加熱処理の時間を3時間とした以外は、実施例2と同じ方法により金属含有ナノ粒子担持電極を得た。
(Example 9)
A metal-containing nanoparticle-supported electrode was obtained by the same method as in Example 2 except that the heat treatment time for the metal-containing nanoparticle-supported electrode produced by the same method as in Example 1 was set to 3 hours.

(実施例10)
還元剤として、水素化ホウ素ナトリウムの代わりに、シアノ水素化ホウ素ナトリウム(東京化成工業株式会社製)を用いた以外は、実施例1と同じ方法により金属含有ナノ粒子担持電極を得た。
(Example 10)
A metal-containing nanoparticle-supporting electrode was obtained by the same method as in Example 1 except that sodium cyanoborohydride (manufactured by Tokyo Chemical Industry Co., Ltd.) was used as the reducing agent instead of sodium borohydride.

(実施例11)
まず、担体として、半導体粒子である一次粒径が253nmの酸化チタン(TiO、石原産業株式会社製)を5質量%となるように水に分散させ、担体が分散した溶液を得た。次に、この分散溶液に塩化銅(同上)を加えて溶解し、塩化銅の濃度を0.004mol/Lとした。さらに、この塩化銅の分散溶液に、水素化ホウ素ナトリウム(同上)を加えて、混合し、水素化ホウ素ナトリウムの濃度が0.005mol/Lである溶液を得た。
(Example 11)
First, as a carrier, titanium oxide (TiO 2 , manufactured by Ishihara Sangyo Co., Ltd.) having a primary particle size of 253 nm, which is a semiconductor particle, was dispersed in water so as to be 5% by mass to obtain a solution in which the carrier was dispersed. Next, copper chloride (same as above) was added to this dispersion solution to dissolve it, and the concentration of copper chloride was adjusted to 0.004 mol / L. Further, sodium borohydride (same as above) was added to this dispersion solution of copper chloride and mixed to obtain a solution having a concentration of sodium borohydride of 0.005 mol / L.

得られた溶液を、室温で1時間撹拌した。続いてこの溶液を、回転数5,000rpmで10分間遠心分離し、生成物(銅ナノ粒子がTiO粒子に担持された触媒)を沈降させた。その後、(1)上澄み溶液を捨て、水を加えて、生成物を再分散させた。さらに、(2)分散溶液を、回転数5,000rpmで10分間遠心分離した。上記(1)から(2)と同様の手順をさらに2回繰り返し、生成物を洗浄した。最後に、遠心分離後の上澄み溶液を除去した状態で、40℃で24時間乾燥し、銅ナノ粒子がTiO粒子に担持された金属含有ナノ粒子担持触媒を得た。 The resulting solution was stirred at room temperature for 1 hour. The solution was then centrifuged at 5,000 rpm for 10 minutes to precipitate the product (catalyst with copper nanoparticles supported on TiO 2 particles). Then, (1) the supernatant solution was discarded and water was added to redisperse the product. Further, (2) the dispersion solution was centrifuged at a rotation speed of 5,000 rpm for 10 minutes. The same procedure as (1) to (2) above was repeated twice more to wash the product. Finally, with the supernatant solution removed after centrifugation, the mixture was dried at 40 ° C. for 24 hours to obtain a metal-containing nanoparticle-supporting catalyst in which copper nanoparticles were supported on TiO 2 particles.

得られた金属含有ナノ粒子担持触媒を20mg/mLの濃度でメタノールに分散させた分散液を調製し、スピンコーティング法により、基材としての銅板(同上)に担持して、金属含有ナノ粒子担持電極を得た。 A dispersion prepared by dispersing the obtained metal-containing nanoparticles-supporting catalyst in methanol at a concentration of 20 mg / mL was supported on a copper plate (same as above) as a base material by a spin coating method to support metal-containing nanoparticles. An electrode was obtained.

(実施例12)
実施例11と同じ方法で作製した触媒を、さらに150℃で30分加熱処理して、銅ナノ粒子を酸化させ、酸化した銅ナノ粒子がTiO粒子に担持された触媒を作製し、該触媒を用いた以外は、実施例11と同じ方法で金属含有ナノ粒子担持電極を得た。
(Example 12)
The catalyst prepared by the same method as in Example 11 was further heat-treated at 150 ° C. for 30 minutes to oxidize the copper nanoparticles, and the oxidized copper nanoparticles were supported on the TiO 2 particles to prepare a catalyst. A metal-containing nanoparticle-supported electrode was obtained in the same manner as in Example 11 except that

(実施例13)
実施例11と同じ方法で作製した触媒に対する加熱処理の時間を1時間とした以外は、実施例12と同じ方法により金属含有ナノ粒子担持電極を得た。
(Example 13)
A metal-containing nanoparticle-supporting electrode was obtained by the same method as in Example 12, except that the heat treatment time for the catalyst produced by the same method as in Example 11 was set to 1 hour.

(実施例14)
0.004mol/L塩化銅水溶液に替えて、硝酸銀(キシダ化学株式会社製)を水に溶解して調製した0.003mol/L硝酸銀水溶液を用いて、銀ナノ粒子がTiO粒子に担持された触媒を作製し、該触媒を用いた以外は、実施例11と同じ方法により金属含有ナノ粒子担持電極を得た。
(Example 14)
Silver nanoparticles were supported on TiO 2 particles using a 0.003 mol / L silver nitrate aqueous solution prepared by dissolving silver nitrate (manufactured by Kishida Chemical Co., Ltd.) in water instead of the 0.004 mol / L copper chloride aqueous solution. A catalyst was prepared, and a metal-containing nanoparticle-supporting electrode was obtained by the same method as in Example 11 except that the catalyst was used.

(実施例15)
実施例14と同じ方法で作製した触媒を、さらに130℃で15分加熱処理して、銀ナノ粒子を酸化させ、酸化した銀ナノ粒子がTiO粒子に担持された触媒を作製し、該触媒を用いた以外は、実施例11と同じ方法により金属含有ナノ粒子担持電極を得た。
(Example 15)
The catalyst prepared by the same method as in Example 14 was further heat-treated at 130 ° C. for 15 minutes to oxidize the silver nanoparticles, to prepare a catalyst in which the oxidized silver nanoparticles were supported on TiO 2 particles, and the catalyst was prepared. A metal-containing nanoparticle-supported electrode was obtained by the same method as in Example 11 except that the above was used.

(実施例16)
実施例14と同じ方法で作製した触媒に対する加熱処理の時間を30分とした以外は、実施例15と同じ方法により金属含有ナノ粒子担持電極を得た。
(Example 16)
A metal-containing nanoparticle-supported electrode was obtained by the same method as in Example 15 except that the heat treatment time for the catalyst prepared by the same method as in Example 14 was set to 30 minutes.

(実施例17)
まず、塩化銅(同上)を水に溶解し、0.21質量%の塩化銅水溶液を調製した。次に、この塩化銅水溶液に、担体として、半導体粒子である一次粒径が2.5μmの酸化ガリウム(Ga、株式会社高純度化学研究所製)を添加し、分散させ、Gaの濃度が21質量%の分散溶液を得た。次に、この分散溶液を、アルゴン雰囲気下、400℃、2時間の条件で加熱し、溶媒を除去して、銅ナノ粒子がGa粒子に担持された金属含有ナノ粒子担持触媒を作製した。このようにして得られた触媒を用いた以外は、実施例11と同じ方法により金属含有ナノ粒子担持電極を得た。
(Example 17)
First, copper chloride (same as above) was dissolved in water to prepare a 0.21% by mass copper chloride aqueous solution. Next, gallium oxide (Ga 2 O 3 , manufactured by High Purity Chemical Laboratory Co., Ltd.), which is a semiconductor particle having a primary particle size of 2.5 μm, was added to this copper chloride aqueous solution as a carrier, dispersed, and Ga 2 the concentration of O 3 was obtained 21 mass% of the dispersion solution. Next, this dispersion solution was heated under an argon atmosphere at 400 ° C. for 2 hours to remove the solvent to prepare a metal-containing nanoparticle-supporting catalyst in which copper nanoparticles were supported on Ga 2 O 3 particles. did. A metal-containing nanoparticle-supporting electrode was obtained by the same method as in Example 11 except that the catalyst thus obtained was used.

(実施例18)
金属含有ナノ粒子担持触媒の担体として、半導体粒子である一次粒径が1.7μmの酸化ニオブ(Nb、実験合成品:参考文献 Akatsuka, K.; Takanashi, G.; Ebina, Y.; Sakai, N.; Haga, M.-a.; Sasaki, T. Electrochemical and Photoelectrochemical Study on Exfoliated Nb3O8Nanosheet. J. Phys. Chem. Solids 2008, 69, 1288-1291)を用いた以外は、実施例11と同じ方法により金属含有ナノ粒子担持電極を得た。
(Example 18)
As a support for the metal-containing nanoparticles supported catalyst, a semiconductor particle primary particle diameter of niobium oxide 1.7μm (Nb 3 O 8, Experiment synthetic: References Akatsuka, K .; Takanashi, G .; Ebina, Y. Sakai, N .; Haga, M.-a .; Sasaki, T. Electrochemical and Photoelectrochemical Study on Exfoliated Nb 3 O 8 Nanosheet. J. Phys. Chem. Solids 2008, 69, 1288-1291) , A metal-containing nanoparticle-supporting electrode was obtained by the same method as in Example 11.

(実施例19)
金属含有ナノ粒子担持触媒の担体として、半導体粒子である一次粒径が2.2μmのチタン酸カルシウム(CaTiO、実験合成品:参考文献 H. Yoshida, L. Zhang, M. Sato, T. Morikawa, T. Kajino, T. Sekito, S. Matsumoto and H. Hirata, Catal. Today, 2015, 251, 132.)を用いた以外は、実施例11と同じ方法により金属含有ナノ粒子担持電極を得た。
(Example 19)
As a carrier for a metal-containing nanoparticle-supporting catalyst, calcium titanate (CaTIO 3 , experimentally synthesized product: References H. Yoshida, L. Zhang, M. Sato, T. Morikawa), which is a semiconductor particle and has a primary particle size of 2.2 μm. , T. Kajino, T. Sekito, S. Matsumoto and H. Hirata, Catal. Today, 2015, 251, 132.), A metal-containing nanoparticle-supported electrode was obtained by the same method as in Example 11. ..

(実施例20)
金属含有ナノ粒子担持触媒の担体として、一次粒径が250nmのTiO粒子(石原産業株式会社製)を用いると共に、水素化ホウ素ナトリウムの濃度を0.05mol/Lとして該触媒を作製した以外は、実施例11と同じ方法により金属含有ナノ粒子担持電極を得た。
(Example 20)
As the carrier of the metal-containing nanoparticles-supporting catalyst, TiO 2 particles (manufactured by Ishihara Sangyo Co., Ltd.) having a primary particle size of 250 nm were used, and the catalyst was prepared with a concentration of sodium boron hydride of 0.05 mol / L. , A metal-containing nanoparticle-supporting electrode was obtained by the same method as in Example 11.

(実施例21)
金属含有ナノ粒子担持触媒の担体として、一次粒径が45nmのTiO粒子(石原産業株式会社製)を用いた以外は、実施例11と同じ方法により金属含有ナノ粒子担持電極を得た。
(Example 21)
A metal-containing nanoparticle-supporting electrode was obtained by the same method as in Example 11 except that dio 2 particles (manufactured by Ishihara Sangyo Co., Ltd.) having a primary particle size of 45 nm were used as the carrier of the metal-containing nanoparticle-supporting catalyst.

(実施例22)
金属含有ナノ粒子担持触媒の担体として、一次粒径が173μmのTiO粒子(石原産業株式会社製)を用いた以外は、実施例11と同じ方法により金属含有ナノ粒子担持電極を得た。
(Example 22)
A metal-containing nanoparticle-supporting electrode was obtained by the same method as in Example 11 except that TiO 2 particles (manufactured by Ishihara Sangyo Co., Ltd.) having a primary particle size of 173 μm were used as a carrier for the metal-containing nanoparticles-supporting catalyst.

(実施例23)
塩化銅の分散溶液の塩化銅濃度を0.004mol/Lから0.4mmol/Lに変更して金属含有ナノ粒子担持触媒を作製した以外は、実施例11と同じ方法により金属含有ナノ粒子担持電極を得た。
(Example 23)
A metal-containing nanoparticle-supporting electrode was produced by the same method as in Example 11 except that the copper chloride concentration of the copper chloride dispersion solution was changed from 0.004 mol / L to 0.4 mmol / L to prepare a metal-containing nanoparticle-supporting catalyst. Got

(実施例24)
塩化銅の分散溶液の塩化銅濃度を0.004mol/Lから0.2mol/Lに変更して金属含有ナノ粒子担持触媒を作製した以外は、実施例11と同じ方法により金属含有ナノ粒子担持電極を得た。
(Example 24)
A metal-containing nanoparticle-supporting electrode was produced by the same method as in Example 11 except that the copper chloride concentration of the copper chloride dispersion solution was changed from 0.004 mol / L to 0.2 mol / L to prepare a metal-containing nanoparticle-supporting catalyst. Got

(実施例25)
実施例11と同じ方法で作製した触媒に対する加熱処理の時間を3時間とした以外は、実施例12と同じ方法により金属含有ナノ粒子担持電極を得た。
(Example 25)
A metal-containing nanoparticle-supporting electrode was obtained by the same method as in Example 12, except that the heat treatment time for the catalyst produced by the same method as in Example 11 was set to 3 hours.

(実施例26)
還元剤として、水素化ホウ素ナトリウムの代わりに、シアノ水素化ホウ素ナトリウム(同上)を用いて金属含有ナノ粒子担持触媒を作製した以外は、実施例11と同じ方法により金属含有ナノ粒子担持電極を得た。
(Example 26)
A metal-containing nanoparticle-supporting electrode was obtained by the same method as in Example 11 except that a metal-containing nanoparticle-supporting catalyst was prepared using sodium cyanoborohydride (same as above) instead of sodium borohydride as a reducing agent. It was.

(比較例1)
銅板に替えて、ガラス板(幅10mm×長さ50mm×厚さ1mm、日本板硝子株式会社製)を基材として用いた以外は、実施例1と同じ方法により、基材上に銅ナノ粒子が担持された金属含有ナノ粒子担持体を得た。
(Comparative Example 1)
Copper nanoparticles were formed on the base material by the same method as in Example 1 except that a glass plate (width 10 mm × length 50 mm × thickness 1 mm, manufactured by Nippon Sheet Glass Co., Ltd.) was used as the base material instead of the copper plate. A supported metal-containing nanoparticle carrier was obtained.

(比較例2)
銅板の代わりにPET(ポリエチレンテレフタレート)の板(幅10mm×長さ50mm×厚さ1mm、古河電気工業株式会社製)を基材として用いた以外は、実施例1と同じ方法により、基材上に銅ナノ粒子が担持された金属含有ナノ粒子担持体を得た。
(Comparative Example 2)
On the base material by the same method as in Example 1 except that a PET (polyethylene terephthalate) plate (width 10 mm × length 50 mm × thickness 1 mm, manufactured by Furukawa Denki Kogyo Co., Ltd.) was used as the base material instead of the copper plate. A metal-containing nanoparticle carrier on which copper nanoparticles were supported was obtained.

(比較例3)
銅板(同上)を、そのまま電極とした。
(Comparative Example 3)
The copper plate (same as above) was used as an electrode as it was.

[評価]
上記実施例および比較例に係る電極等について、下記に示す各種測定および特性評価を行った。各特性の評価条件は下記の通りである。結果を表1に示す。
[Evaluation]
The electrodes and the like according to the above Examples and Comparative Examples were subjected to various measurements and characteristic evaluations shown below. The evaluation conditions for each characteristic are as follows. The results are shown in Table 1.

[1]金属含有ナノ粒子の組成および金属(M)の平均価数
基材上に担持された金属含有ナノ粒子について、X線光電子分光分析法を用いて、組成と、銅および銀の平均価数を測定した。
[1] Composition of metal-containing nanoparticles and average valence of metal (M) The composition of metal-containing nanoparticles supported on a substrate and the average value of copper and silver using X-ray photoelectron spectroscopy. The number was measured.

[2]金属含有ナノ粒子の粒径
基材上に担持された金属含有ナノ粒子について、透過型電子顕微鏡(TEM、日本電子株式会社製)を用いて、一次粒子の輪郭が明確に認識できる倍率で、金属含有ナノ粒子の一次粒子を撮影した。得られた画像を上述の条件で解析し、一次粒径を算出した。また一次粒子のサイズから、金属含有ナノ粒子がクラスターであるかどうかを確認した。一次粒子の粒径が2nm以下であるものはクラスターと判断した。
[2] Particle size of metal-containing nanoparticles A magnification at which the outline of primary particles can be clearly recognized using a transmission electron microscope (TEM, manufactured by Nippon Denshi Co., Ltd.) for metal-containing nanoparticles supported on a substrate. Then, the primary particles of the metal-containing nanoparticles were photographed. The obtained image was analyzed under the above conditions, and the primary particle size was calculated. It was also confirmed from the size of the primary particles whether the metal-containing nanoparticles were clusters. Those having a primary particle size of 2 nm or less were judged to be clusters.

[3]基材に対する金属含有ナノ粒子の担持割合
(i)直接基材上に金属含有ナノ粒子が担持されている金属含有ナノ粒子担持電極(または担持体)については(実施例1〜10、比較例1および2)、金属含有ナノ粒子担持前の基材の質量と、金属含有ナノ粒子担持後の金属含有ナノ粒子担持電極(または担持体)の質量とを測定し、その差から金属含有ナノ粒子の質量を求めた。
(ii)金属含有ナノ粒子担持触媒として、基材上に金属含有ナノ粒子が担持されている金属含有ナノ粒子担持電極については(実施例11〜26)、該触媒の担持前の基材の質量と、該触媒担持後の金属含有ナノ粒子担持電極の質量とを測定し、その差から該触媒の質量を求め、さらに該触媒の質量に触媒中の金属含有ナノ粒子の質量割合をかけることで、金属含有ナノ粒子の質量を求めた。
上記(i)および(ii)で求められたそれぞれの金属含有ナノ粒子の質量を、基材の表面積で割り、基材に対する金属含有ナノ粒子の担持割合[金属含有ナノ粒子の質量(mg)/基材の表面積(cm)]をそれぞれ算出した。
[3] Support ratio of metal-containing nanoparticles to the base material (i) Regarding the metal-containing nanoparticles-supporting electrode (or carrier) in which the metal-containing nanoparticles are directly supported on the base material (Examples 1 to 10, Comparative Examples 1 and 2), the mass of the base material before supporting the metal-containing nanoparticles and the mass of the metal-containing nanoparticles-supporting electrode (or carrier) after supporting the metal-containing nanoparticles were measured, and the difference between them was used to measure the metal content. The mass of the nanoparticles was determined.
(Ii) As the metal-containing nanoparticles-supporting catalyst, for the metal-containing nanoparticles-supporting electrodes in which the metal-containing nanoparticles are supported on the base material (Examples 11 to 26), the mass of the base material before the catalyst is supported. And the mass of the metal-containing nanoparticles-supporting electrode after the catalyst was supported, the mass of the catalyst was obtained from the difference, and the mass of the catalyst was multiplied by the mass ratio of the metal-containing nanoparticles in the catalyst. , The mass of the metal-containing nanoparticles was determined.
The mass of each metal-containing nanoparticles obtained in (i) and (ii) above is divided by the surface area of the base material, and the loading ratio of the metal-containing nanoparticles to the base material [mass of metal-containing nanoparticles (mg) / The surface area of the base material (cm 2 )] was calculated respectively.

[4]担体の一次粒径
実施例11〜26で作製した金属含有ナノ粒子担持触媒については、担体となる各種半導体粒子について、一次粒径を測定した。具体的には、触媒作製前に、走査型電子顕微鏡(SEM、株式会社日立ハイテクノロジーズ製)を用いて、一次粒子の輪郭が明確に認識できる倍率で一次粒子を撮影し、得られた画像を上述の条件で解析して、一次粒径を算出した。
[4] Primary particle size of the carrier With respect to the metal-containing nanoparticles-supporting catalyst produced in Examples 11 to 26, the primary particle size of various semiconductor particles serving as a carrier was measured. Specifically, before preparing the catalyst, a scanning electron microscope (SEM, manufactured by Hitachi High-Technologies Corporation) was used to photograph the primary particles at a magnification at which the contours of the primary particles could be clearly recognized, and the obtained image was taken. The primary particle size was calculated by analysis under the above conditions.

[5]担体に対する金属含有ナノ粒子の質量比率
実施例11〜26で作製した金属含有ナノ粒子担持触媒については、担体に対する金属含有ナノ粒子の質量比率(%)を測定した。具体的には、得られた触媒を、誘導結合プラズマ(ICP、株式会社日立ハイテクサイエンス製)で分析し、金属含有ナノ粒子を構成する金属元素(CuまたはAg)および担体(半導体粒子)を構成する一部の元素(TiOの場合はTi、Gaの場合はGa、Nbの場合はNb、CaTiOの場合はCa)の濃度をそれぞれ算出した。これらの値を用いて金属含有ナノ粒子の質量濃度および担体の質量濃度を求め、これらの比から担体に対する金属含有ナノ粒子の質量比率[(金属含有ナノ粒子の質量/担体の質量)×100]を算出した。
[5] Mass Ratio of Metal-Containing Nanoparticles to Carrier For the metal-containing nanoparticles-supporting catalyst prepared in Examples 11 to 26, the mass ratio (%) of metal-containing nanoparticles to the carrier was measured. Specifically, the obtained catalyst is analyzed by inductively coupled plasma (ICP, manufactured by Hitachi High-Tech Science Co., Ltd.) to form a metal element (Cu or Ag) and a carrier (semiconductor particles) that constitute metal-containing nanoparticles. (for TiO 2 Ti, in the case of Ga 2 O 3 if Ga, the Nb 3 O 8 if Nb, of CaTiO 3 Ca) part of the elements that were calculated concentration of each. Using these values, the mass concentration of the metal-containing nanoparticles and the mass concentration of the carrier were obtained, and from these ratios, the mass ratio of the metal-containing nanoparticles to the carrier [(mass of metal-containing nanoparticles / mass of carrier) × 100]. Was calculated.

[6]還元試験
実施例1〜26および比較例1〜3で得られた電極等を、二酸化炭素のカソード還元装置のカソード電極として用い、二酸化炭素の還元試験を行った。二酸化炭素のカソード還元装置の概略は、上述のとおりである(図1および2)。
なお、電解液は、50mMの炭酸水素カリウム水溶液を用い、各槽15a、15bに30mLずつ用いた。アノード電極20には、白金板(株式会社ニラコ製)を用いた。電気分解は、電流値2mA、電圧2.8Vで60分の条件で行った。また、電気分解中は、供給管25より、二酸化炭素ガスを10mL/分でバブリングした(図中矢印B方向)。
[6] Reduction Test A carbon dioxide reduction test was conducted using the electrodes and the like obtained in Examples 1 to 26 and Comparative Examples 1 to 3 as the cathode electrode of the carbon dioxide cathode reduction device. The outline of the carbon dioxide cathode reduction device is as described above (FIGS. 1 and 2).
As the electrolytic solution, a 50 mM potassium hydrogen carbonate aqueous solution was used, and 30 mL was used in each of the tanks 15a and 15b. A platinum plate (manufactured by Nirako Co., Ltd.) was used as the anode electrode 20. The electrolysis was carried out under the conditions of a current value of 2 mA and a voltage of 2.8 V for 60 minutes. During electrolysis, carbon dioxide gas was bubbled from the supply pipe 25 at 10 mL / min (in the direction of arrow B in the figure).

なお、カソード電極における反応生成物としては、一酸化炭素(CO)、ギ酸(HCOOH)、メタン(CH)、エチレン(C)およびエタン(C)の生成量を分析した。
生成物のうち一酸化炭素、メタン、エチレンおよびエタンは、分析管23により収集し(図中矢印C方向)、ガスクロマトグラフ質量分析計(GCMS−QP2010、株式会社島津製作所製)を用いて分析した。カラムは、SUPELCO CARBOXEN 1010PLOT 30m×032mmlDを用い、検出機は水素炎イオン検出器(FID)を用いた。
また、ギ酸については、上記疑似代用光源を10時間照射した後の反応液を高速液体クロマトグラフィー(HPLC、株式会社島津製作所製)で分析した。
また、これらの生成物の総量から、一酸化炭素、メタン、エチレン、エタン、またはギ酸に還元された二酸化炭素の量を算出した。
本実施例では、一酸化炭素、メタン、エチレン、エタン、またはギ酸に還元された二酸化炭素量が0.3mmol以上を合格レベルとし、0.5mmol以上を更に良好と評価した。
As reaction products at the cathode electrode, the amounts of carbon monoxide (CO), formic acid (HCOOH), methane (CH 4 ), ethylene (C 2 H 4 ) and ethane (C 2 H 6 ) were analyzed. ..
Of the products, carbon monoxide, methane, ethylene and ethane were collected by an analyzer 23 (direction arrow C in the figure) and analyzed using a gas chromatograph mass spectrometer (GCMS-QP2010, manufactured by Shimadzu Corporation). .. The column used was SUPELCO CARBOXEN 1010PLOT 30 m × 032 mlD, and the detector used was a hydrogen flame ion detector (FID).
For formic acid, the reaction solution after being irradiated with the above pseudo-substitute light source for 10 hours was analyzed by high performance liquid chromatography (HPLC, manufactured by Shimadzu Corporation).
In addition, the amount of carbon dioxide reduced to carbon monoxide, methane, ethylene, ethane, or formic acid was calculated from the total amount of these products.
In this example, the acceptable level was when the amount of carbon dioxide reduced to carbon monoxide, methane, ethylene, ethane, or formic acid was 0.3 mmol or more, and 0.5 mmol or more was evaluated as even better.

Figure 0006767202
Figure 0006767202

表1の結果より、本発明の実施例1〜26に係る金属含有ナノ粒子担持電極は、基材(銅板)が導電性を有する基材電極であり、該基材電極上に金属含有ナノ粒子が担持されてなるため、二酸化炭素の還元反応に対し良好な触媒性能を発揮し、二酸化炭素の還元反応を良好に促進・制御し得ることが確認された。特に、実施例1〜6、8〜19、21、22、25および26にかかる金属含有ナノ粒子担持電極は、一酸化炭素、メタン、エチレン、エタン、またはギ酸に還元された二酸化炭素量が0.5mmol以上であり、二酸化炭素の還元反応に対してより卓越した触媒活性および選択性を発現することが確認された。 From the results in Table 1, the metal-containing nanoparticles-supporting electrode according to Examples 1 to 26 of the present invention is a base electrode having a conductive base material (copper plate), and the metal-containing nanoparticles are placed on the base material electrode. It was confirmed that the carbon dioxide reduction reaction can be promoted and controlled satisfactorily by exhibiting good catalytic performance for the carbon dioxide reduction reaction. In particular, the metal-containing nanoparticle-supporting electrodes according to Examples 1 to 6, 8 to 19, 21, 22, 25 and 26 have 0 carbon monoxide, methane, ethylene, ethane, or carbon dioxide reduced to formic acid. It was confirmed that it was 5.5 mmol or more and exhibited more excellent catalytic activity and selectivity for the reduction reaction of carbon dioxide.

これに対し、比較例1および2に係る金属含有ナノ粒子担持体は、基材(ガラス板およびPETの板)が導電性を有していないため、二酸化炭素の還元電極として用いることができないことが確認された。また比較例3に係る電極は、金属含有ナノ粒子が担持されていない、銅板からなる電極であるため二酸化炭素の還元反応の効率が低いことが確認された。 On the other hand, the metal-containing nanoparticle carrier according to Comparative Examples 1 and 2 cannot be used as a carbon dioxide reducing electrode because the base material (glass plate and PET plate) does not have conductivity. Was confirmed. Further, it was confirmed that the electrode according to Comparative Example 3 is an electrode made of a copper plate on which metal-containing nanoparticles are not supported, and therefore the efficiency of the carbon dioxide reduction reaction is low.

1……………電解装置
3…………電解セル(COカソード還元試験装置)
5…………ガス回収装置
7…………電解液循環装置
9…………二酸化炭素供給部
11…………電源
15a、15b………電解液
16a、16b………槽
17………金属メッシュ
18………参照電極(銀/塩化銀)
19………カソード電極
20………アノード電極
21………陽イオン交換膜
23………分析管
25………供給管
27………シール部材
1 ……………… Electrolytic device 3 ………… Electrolytic cell (CO 2 cathode reduction test device)
5 ………… Gas recovery device 7 ………… Electrolyte circulation device 9 ………… Carbon dioxide supply unit 11 ………… Power supply 15a, 15b ………… Electrode solution 16a, 16b ………… Tank 17 ………… … Metal mesh 18 ……… Reference electrode (silver / silver chloride)
19 ………… Cathode electrode 20 ………… Anode electrode 21 ………… Cation exchange membrane 23 ………… Analytical tube 25 ………… Supply tube 27 ………… Sealing member

Claims (7)

二酸化炭素を還元するために用いられる金属含有ナノ粒子担持電極であって、
前記金属含有ナノ粒子担持電極は、基材電極上に金属含有ナノ粒子が担持されてなり、
前記金属含有ナノ粒子が、銀および銅から選択される少なくとも1種の金属原子(M)の単体または金属原子(M)を含む金属酸化物からなり、
前記金属含有ナノ粒子の一次粒径が、0.5〜100nmであり、
前記基材電極に対する前記金属含有ナノ粒子の担持割合[金属含有ナノ粒子の質量(mg)/基材電極の表面積(cm )]が、0.01〜0.16mg/cm であり、
前記金属含有ナノ粒子は、金属含有ナノ粒子担持触媒として前記基材電極上に担持されており、
前記金属含有ナノ粒子担持触媒は、担体上に前記金属含有ナノ粒子が担持されてなり、
前記担体に対する前記金属含有ナノ粒子の質量比率[(金属含有ナノ粒子の質量/担体の質量)×100]が、0.05〜0.5%である、金属含有ナノ粒子担持電極。
A metal-containing nanoparticle-supported electrode used to reduce carbon dioxide.
The metal-containing nanoparticles-supporting electrode is formed by supporting metal-containing nanoparticles on a base electrode.
The metal-containing nanoparticles consist of a simple substance of at least one metal atom (M) selected from silver and copper or a metal oxide containing a metal atom (M).
The primary particle size of the metal-containing nanoparticles is 0.5 to 100 nm.
The loading ratio of the metal-containing nanoparticles to the base electrode [mass of metal-containing nanoparticles (mg) / surface area of base electrode (cm 2 )] is 0.01 to 0.16 mg / cm 2 .
The metal-containing nanoparticles are supported on the base electrode as a metal-containing nanoparticles-supporting catalyst.
The metal-containing nanoparticles-supporting catalyst comprises the metal-containing nanoparticles supported on a carrier.
The mass ratio of the metal-containing nanoparticles to carrier [(mass of the mass / carrier of the metal-containing nanoparticles) × 100] is Ru 0.05% to 0.5% der, metal-containing nanoparticles loaded electrode.
前記担体の一次粒径が50nm〜100μmである、請求項1に記載の金属含有ナノ粒子担持電極。The metal-containing nanoparticle-supporting electrode according to claim 1, wherein the primary particle size of the carrier is 50 nm to 100 μm. 前記担体が、半導体粒子である、請求項1または2に記載の金属含有ナノ粒子担持電極。 The metal-containing nanoparticle-supporting electrode according to claim 1 or 2 , wherein the carrier is a semiconductor particle. 前記金属含有ナノ粒子が、前記金属原子(M)を含有し、一次粒子の粒径が2nm以下であるクラスターである、請求項1〜のいずれか1項に記載の金属含有ナノ粒子担持電極。 The metal-containing nanoparticles-supporting electrode according to any one of claims 1 to 3 , wherein the metal-containing nanoparticles are clusters containing the metal atom (M) and having a particle size of primary particles of 2 nm or less. .. 前記金属原子(M)が、銅である、請求項1〜のいずれか1項に記載の金属含有ナノ粒子担持電極。 The metal-containing nanoparticle-supporting electrode according to any one of claims 1 to 4 , wherein the metal atom (M) is copper. 前記銅の平均価数が、0〜1.5である、請求項に記載の金属含有ナノ粒子担持電極。 The metal-containing nanoparticle-supporting electrode according to claim 5 , wherein the average valence of copper is 0 to 1.5. 請求項1〜のいずれか1項に記載の金属含有ナノ粒子担持電極を備える、二酸化炭素還元装置。 A carbon dioxide reducing device comprising the metal-containing nanoparticle-supporting electrode according to any one of claims 1 to 6 .
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