JP5904545B2 - Visible light responsive semiconductor photoelectrode - Google Patents
Visible light responsive semiconductor photoelectrode Download PDFInfo
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Description
本発明は、可視光応答性半導体光電極、特に、保護膜で安定化された可視光応答性半導体光電極に関する。 The present invention relates to a visible light responsive semiconductor photoelectrode, and more particularly to a visible light responsive semiconductor photoelectrode stabilized by a protective film.
近年、狭いバンドギャップを持つ半導体光電極を使用したＨ2、Ｏ2への水分解は、太陽光エネルギー変換および蓄積のために広く研究されてきている（特許文献１、２参照）。なかでも、湿式塗布法によって作製された導電性ガラス基板上にコートされたＦｅ2Ｏ3、ＷＯ3、ＢｉＶＯ4のようないくつかの酸化物結晶光電極は、安価で且つ大面積化させやすいという実用的な点で優れている。しかしながら、これら酸化物半導体光電極の太陽光エネルギー変換効率はまだ十分に高い値ではない。 In recent years, water decomposition into H 2 and O 2 using a semiconductor photoelectrode having a narrow band gap has been extensively studied for solar energy conversion and accumulation (see Patent Documents 1 and 2). Among them, some oxide crystal photoelectrodes such as Fe 2 O 3 , WO 3 , and BiVO 4 coated on a conductive glass substrate manufactured by a wet coating method are inexpensive and easy to increase in area. It is excellent in practical points. However, the solar energy conversion efficiency of these oxide semiconductor photoelectrodes is not yet sufficiently high.
そこで、酸化物半導体光電極の太陽光エネルギー変換効率を向上させる研究が種々なされてきているが、近年、２種類以上の半導体を積層することで効率を大きく向上させること、及びその性能は電解液に依存し、炭酸塩水溶液を用いると非常に良くなることがわかっている（非特許文献１参照）。 Therefore, various studies have been made to improve the solar energy conversion efficiency of oxide semiconductor photoelectrodes. Recently, two or more kinds of semiconductors are stacked to greatly improve the efficiency, and the performance of the electrolyte solution It is known that the use of an aqueous carbonate solution is very good (see Non-Patent Document 1).
しかしながら、一方で、酸化物半導体光電極の安定性については充分とは言えない。すなわち、エネルギー変換デバイスとして利用する場合は、長期間の安定性向上が非常に重要である。長期安定性を向上する場合は一般にその反応溶液に対して安定な物質で被覆すれば良いと思われるが、その場合は一般的には効率が低下する問題を生じる。 However, on the other hand, it cannot be said that the stability of the oxide semiconductor photoelectrode is sufficient. That is, when used as an energy conversion device, it is very important to improve long-term stability. In order to improve the long-term stability, it is generally considered that the reaction solution should be coated with a stable substance. However, in this case, there is a problem that the efficiency generally decreases.
また、光電気化学的な反応では、光による半導体の光溶解という特殊な溶解促進効果がＺｎＯやＣｄＳの単純酸化物や単純硫化物では知られている。暗時には安定でも、光照射で溶解が進行する特殊な現象である。ｎ型半導体では、光で生成した正孔が半導体自身を酸化溶解する機構と考えられている。
そこで、ＣｄＳでは、反応溶液中に硫化物イオン、Ｓ2-、硫化水素イオン、ＳＨ-や亜硫酸イオン、ＳＯ3 2-などの犠牲還元剤と呼ばれる化学種を添加することで安定化することが知られている。ｎ型の酸化物系半導体では同様に有機物などの犠牲還元剤を添加することで安定化することが知られている。しかし、犠牲還元剤は時間とともに消費されるので、常に還元剤を追加する必要が有るという問題があった。
In addition, in the photoelectrochemical reaction, a special dissolution promoting effect of light dissolution of a semiconductor by light is known for simple oxides and simple sulfides of ZnO and CdS. Although it is stable in the dark, it is a special phenomenon in which dissolution proceeds with light irradiation. In an n-type semiconductor, it is considered that holes generated by light oxidize and dissolve the semiconductor itself.
Thus, CdS can be stabilized by adding chemical species called sacrificial reducing agents such as sulfide ions, S 2− , hydrogen sulfide ions, SH 2 − , sulfite ions, SO 3 2− to the reaction solution. Are known. Similarly, it is known that an n-type oxide semiconductor is stabilized by adding a sacrificial reducing agent such as an organic substance. However, since the sacrificial reducing agent is consumed with time, there is a problem that it is always necessary to add a reducing agent.
また、ＢｉＶＯ4光電極に関して、その表面に一部Ａｇ+、Ｃｒ3+、Ｐｄ2+、Ａｕ3+、Ｒｈ3+、Ｆｅ3+等の金属イオン層でコートしておくと、光エネルギー変換効率を向上させることができるとともに、安定化するという報告があるが（特許文献３参照）、１８００秒（３０分）程度の評価であり、その方法での安定性は不十分であった。 In addition, when the surface of the BiVO 4 photoelectrode is partially coated with a metal ion layer such as Ag + , Cr 3+ , Pd 2+ , Au 3+ , Rh 3+ , Fe 3+ , light energy conversion is performed. Although there is a report that the efficiency can be improved and stabilized (see Patent Document 3), the evaluation is about 1800 seconds (30 minutes), and the stability in the method is insufficient.
以上のような背景から、本発明は、発明者らによるこれまでの検討をさらに深化、発展させて、その半導体材料の光反応中の安定性を向上させ、且つ効率が低下しない、安定化された可視光応答性半導体光電極を提供することを課題としている。 From the background as described above, the present invention has been further stabilized and developed by further studying the inventors' previous studies, improving the stability of the semiconductor material during the photoreaction and not reducing the efficiency. Another object of the present invention is to provide a visible light responsive semiconductor photoelectrode.
本発明者らは、上記課題を解決するために鋭意検討し、可視光応答性半導体の安定化手法を探索研究した結果、特殊な組成を持つ保護膜を可視光応答性の半導体上に被覆することにより安定化できることを見出し、本発明を完成するに至った。 The inventors of the present invention have made extensive studies to solve the above-mentioned problems, and as a result of exploring and researching a stabilization method for visible light responsive semiconductors, cover a visible light responsive semiconductor with a protective film having a special composition. As a result, the present invention was completed.
すなわち、この本発明は以下のことを特徴としている。
［１］構成元素としてＢｉ、Ｖ、Ｗ、及び酸素を含有してなる可視光応答性の半導体からなる半導体層上に、Ｎｂ、Ｓｎ、Ｚｒ、Ｌａ、Ｔｉ、Ｂｉ、Ｔａからなる群から選ばれた１種以上の元素を含む化合物からなる保護膜が被覆されていることを特徴とする安定化された可視光応答性半導体電極。
［２］前記半導体が、ＢｉＶＯ4及びＷＯ3を含むことを特徴とする［１］に記載の安定化された可視光応答性半導体電極。
［３］前記保護膜に含まれる元素の量が、単位面積あたりの半導体の量に対して、安定酸化物換算で０.２〜２０質量％であることを特徴とする［１］又は［２］に記載の安定化された可視光応答性半導体電極。
［４］前記可視光応答性半導体電極が、炭酸塩の電解質を含む水溶液中における反応に用いる光電極であることを特徴とする［１］〜［３］のいずれかに記載の安定化された可視光応答性半導体電極。
［５］半導体光電極として、請求項１〜４のいずれか１項に記載の安定化された可視光応答性半導体電極を用いたことを特徴とする水分解反応装置。
That is, the present invention is characterized by the following.
[1] Selected from the group consisting of Nb, Sn, Zr, La, Ti, Bi and Ta on a semiconductor layer made of a visible light responsive semiconductor containing Bi, V, W and oxygen as constituent elements. A stabilized visible light responsive semiconductor electrode, wherein a protective film made of a compound containing at least one element is coated.
[2] The stabilized visible light responsive semiconductor electrode according to [1], wherein the semiconductor contains BiVO 4 and WO 3 .
[3] The amount of the element contained in the protective film is 0.2 to 20% by mass in terms of stable oxide with respect to the amount of semiconductor per unit area [1] or [2 ] The stabilized visible light responsive semiconductor electrode of description.
[4] The stabilized light according to any one of [1] to [3], wherein the visible light-responsive semiconductor electrode is a photoelectrode used for a reaction in an aqueous solution containing a carbonate electrolyte. Visible light responsive semiconductor electrode.
[5] A water splitting reaction apparatus using the stabilized visible light responsive semiconductor electrode according to any one of claims 1 to 4 as a semiconductor photoelectrode.
本発明は特に、水分解用の半導体光電極において、半導体材料の光反応中の安定性を向上させ、且つ効率が低下しない、安定化した可視光応答性半導体光電極を提供できる。また、本発明の安定化された光電極における手法は、粉末光触媒反応や、光センサー用途の半導体に対しても有効な方法として提供できる。 In particular, the present invention can provide a stabilized visible light-responsive semiconductor photoelectrode that improves the stability during photoreaction of a semiconductor material and does not decrease the efficiency in a semiconductor photoelectrode for water splitting. Moreover, the method for the stabilized photoelectrode of the present invention can be provided as an effective method for powder photocatalytic reactions and semiconductors for photosensor applications.
本発明は、可視光応答性の半導体からなる半導体電極において、半導体層上に、Ｎｂ、Ｓｎ、Ｚｒ、Ｌａ、Ｔｉ、Ｂｉ、Ｔａからなる群から選ばれた１種以上の元素を含む化合物からなる保護膜を被覆することにより、可視光応答性の半導体電極が安定化されていることを特徴とするものである。
なお、上記特許許文献１には、ＢｉＶＯ4半導体の表面の一部にＡｇ+、Ｃｒ3+、Ｐｄ2+、Ａｕ3+、Ｒｈ3+、Ｆｅ3+等の金属イオンをイオン交換した層で形成しておくと安定化するという表面改質の報告があるが、本発明では、半導体そのものを改質して安定化するのではなく、半導体膜の上に特別な組成の保護膜を被覆することで安定化を行う点で従来技術と大きく異なる。
The present invention relates to a semiconductor electrode made of a visible light responsive semiconductor, and a compound containing one or more elements selected from the group consisting of Nb, Sn, Zr, La, Ti, Bi, Ta on the semiconductor layer. By covering the protective film, the visible light responsive semiconductor electrode is stabilized.
In Patent Document 1, a layer in which metal ions such as Ag + , Cr 3+ , Pd 2+ , Au 3+ , Rh 3+ , and Fe 3+ are ion-exchanged on a part of the surface of the BiVO 4 semiconductor. However, in the present invention, the semiconductor itself is not modified and stabilized, but a protective film having a special composition is coated on the semiconductor film. This is very different from the prior art in that it stabilizes.
本発明の可視光応答性半導体電極は、構成元素として、Ｂｉ、Ｖ、Ｗ、及び酸素を含有してなる可視光応答性の半導体からなるが、特に半導体として、ＢｉＶＯ4、ＷＯ3等の金属酸化物含む半導体電極に対して効果があり、その中でも、好ましくは、ＢｉＶＯ4を含む半導体電極、より好ましくはＢｉＶＯ4及びＷＯ3を含む半導体電極に対して、効果が大きい。なお、２種以上の金属酸化物を含む場合、それらを混合して用いても良いし、或いは、異なる金属酸化物を積層したものであってもよい。 The visible light responsive semiconductor electrode of the present invention is composed of a visible light responsive semiconductor containing Bi, V, W, and oxygen as constituent elements. In particular, the semiconductor is a metal such as BiVO 4 or WO 3. It is effective against a semiconductor electrode comprising an oxide, among which, preferably, a semiconductor electrode comprising BiVO 4, the semiconductor electrode and more preferably comprising BiVO 4 and WO 3, a large effect. In addition, when 2 or more types of metal oxides are included, they may be mixed and used, or different metal oxides may be laminated.
本発明において、保護膜に用いる化合物には、Ｎｂ、Ｓｎ、Ｚｒ、Ｌａ、Ｔｉ、Ｂｉ、Ｔａからなる群から選ばれた、２種類以上の元素を含む化合物であってもよい。
また、Ｎｂ、Ｓｎ、Ｚｒ、Ｌａ、Ｔｉ、Ｂｉ、Ｔａからなる群から選ばれた１種以上の元素を含有する化合物からなる保護膜の被覆量は、半導体電極が、Ｎｂ、Ｓｎ、Ｚｒ、Ｌａ、Ｔｉ、Ｂｉ、Ｔａからなる群から選ばれた１種以上の元素で充分に被覆される量である必要がある。但し、被覆量があまりに多すぎると、半導体と反応液との電気的な接触が阻害されるので、最適な量を選択する。
保護膜をできるだけ薄くすれば、少ない量で半導体への表面被覆率が１００％に近くなる。単位面積あたりの半導体の量に対して、添加する元素の量は、安定酸化物換算で０．２〜２０質量％、より好ましくは１〜１０％である。
In the present invention, the compound used for the protective film may be a compound containing two or more kinds of elements selected from the group consisting of Nb, Sn, Zr, La, Ti, Bi, and Ta.
Further, the coating amount of the protective film made of a compound containing one or more elements selected from the group consisting of Nb, Sn, Zr, La, Ti, Bi, and Ta is such that the semiconductor electrode has Nb, Sn, Zr, The amount needs to be sufficiently covered with one or more elements selected from the group consisting of La, Ti, Bi, and Ta. However, if the coating amount is too large, electrical contact between the semiconductor and the reaction solution is hindered, so an optimal amount is selected.
If the protective film is made as thin as possible, the surface coverage on the semiconductor will be close to 100% with a small amount. The amount of the element to be added is 0.2 to 20% by mass, more preferably 1 to 10% in terms of stable oxide, with respect to the amount of semiconductor per unit area.
本発明の半導体を水分解用の光電極として用いる場合は、電解質を含む水溶液を用いる。電解質としては特に炭酸塩を使う場合に性能が大きく向上することが知られている。本発明の電解質は炭酸塩に限定されないが、効率向上と安定性向上を両立する意味では炭酸塩水溶液にも耐えうる半導体材料が好ましい。その意味では上記の元素Ｍの化合物を被覆した半導体はその条件を満たしている。
また、上記元素の化合物を被覆する方法としては、上記元素を含む溶液を半導体に塗布して加熱する湿式熱分解法や含浸法、ＣＶＤ法、噴霧法、スパッタ法などがある。これらの被覆する方法により、酸素を含む雰囲気の場合は、元素はその酸化物の保護膜を半導体表面に形成する。
When the semiconductor of the present invention is used as a water splitting photoelectrode, an aqueous solution containing an electrolyte is used. As an electrolyte, it is known that the performance is greatly improved particularly when carbonate is used. The electrolyte of the present invention is not limited to a carbonate, but a semiconductor material that can withstand an aqueous carbonate solution is preferable in terms of achieving both efficiency improvement and stability improvement. In that sense, the semiconductor coated with the compound of the element M satisfies the condition.
Examples of a method for coating the compound of the element include a wet pyrolysis method in which a solution containing the element is applied to a semiconductor and heating, a impregnation method, a CVD method, a spray method, and a sputtering method. By these coating methods, in the case of an atmosphere containing oxygen, the element forms a protective film of the oxide on the semiconductor surface.
以下、本発明の可視光応答性半導体電極を用いた装置について、一例として、光分解反応装置について説明するが、本発明の可視光応答性半導体電極は、これに限られるものではない。 Hereinafter, as an example of a device using the visible light responsive semiconductor electrode of the present invention, a photolysis reaction device will be described. However, the visible light responsive semiconductor electrode of the present invention is not limited to this.
図１は、水分解反応に用いる装置の一例を示すものであり、水槽内に半導体電極（作用極）と対極を配置し、半導体電極と対極とに導線を接続して外部短絡線を構成している。外部短絡線には、ポテンションスタットが設けられ、ポテンションスタットによって半導体電極と対極との間の電位差を制御し、それによって回路中に生じる電流を計測している。また、水槽には、電解反応の溶液抵抗を下げるための安定な支持電解質を貯留している。さらに、水槽外部から太陽光などの光が半導体電極（作用極）に照射されて光水電解を行なう。 FIG. 1 shows an example of an apparatus used for a water splitting reaction. A semiconductor electrode (working electrode) and a counter electrode are arranged in a water tank, and a lead wire is connected to the semiconductor electrode and the counter electrode to form an external short-circuit line. ing. A potentiostat is provided on the external short-circuit line, and a potential difference between the semiconductor electrode and the counter electrode is controlled by the potentiostat, thereby measuring a current generated in the circuit. In addition, a stable supporting electrolyte for lowering the solution resistance of the electrolytic reaction is stored in the water tank. Furthermore, light such as sunlight is applied to the semiconductor electrode (working electrode) from the outside of the water tank to perform photowater electrolysis.
ｎ型半導体を電極として用いて水を分解する動作原理について説明する。半導体電極に光を照射すると、半導体電極に光が吸収されて、伝導帯に電子が生成し、価電子帯に正孔が生成する。半導体電極の表面に移動した正孔は、水を酸化して酸素を生成する。一方、生成した電子（ｅ-）は、半導体電極中の基材に移動した後、外部短絡線を通り対極に移動する。その際、ｎ型半導体の伝導体は水素の発生電位よりも高いため、バイアス電位をかけて電子のエネルギーを高くする。この電子は、対極上に水を還元し、水素を生成する。 The operation principle of decomposing water using an n-type semiconductor as an electrode will be described. When the semiconductor electrode is irradiated with light, the semiconductor electrode absorbs light, generating electrons in the conduction band and generating holes in the valence band. The holes that have moved to the surface of the semiconductor electrode oxidize water to generate oxygen. On the other hand, the generated electrons (e − ) move to the base material in the semiconductor electrode, and then move to the counter electrode through the external short-circuit line. At this time, since the n-type semiconductor conductor is higher than the hydrogen generation potential, a bias potential is applied to increase the electron energy. The electrons reduce water on the counter electrode to generate hydrogen.
以下、本発明を実施例によりさらに具体的に説明するが、本発明はこの実施例によって何ら限定されるものではない。
（実施例１〜４、比較例１）
ＢｉＶＯ4光電極は有機金属熱分解法で作製した。導電性基板（Ｆ−ＳｎＯ2膜：ＦＴＯ）上にＷＯ3膜（約２００ｎｍ）を成膜し、その上にＢｉＶＯ4膜(約１００ｎｍ)を成膜した。ＷＯ3膜を入れることで光電流は向上することがわかっている。ＷＯ3膜はタングステン過酸化物水溶液（１.４ｍｏｌ／Ｌ）をスピンコートし、５００℃で空気焼成して作製した。その後、ＢｉＶＯ4光電極は、有機金属熱分解（ＭＯＤ）法で作製した。市販（シンメトリックス社製）のＢｉ−ＭＯＤ溶液とＶ−ＭＯＤ溶液（濃度：各０.２ｍｏｌ／Ｌ）を１：１で混合し、ＷＯ3／ＦＴＯ膜にスピンコートし、５５０℃度で空気焼成して作製した。これを３回繰り返した。
次に、このＢｉＶＯ4／ＷＯ3／ＦＴＯ膜に対して、市販のＭ−ＭＯＤ溶液（Ｍ＝Ｎｂ、濃度は０.０１〜０.１ｍｏｌ／Ｌ）をスピンコートし、５５０℃で空気焼成して作製した。光電極上の添加金属元素量(μｍｏｌ／ｃｍ2)はＸＲＦ測定により計算した。Ｍ−ＭＯＤ溶液をコートしていないＢｉＶＯ4／ＷＯ3／ＦＴＯ膜を比較例１とした。ＢｉＶＯ4膜及びＷＯ3膜の成膜量（ｍｇ／ｃｍ2）は、Ｂｉ2Ｏ3、Ｖ2Ｏ5、ＷＯ3に換算して、それぞれ０.０３９、０.０１５、０.０３７であった。半導体の酸化物質量の合計は０.０９１ｍｇ／ｃｍ2であった。
Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the examples.
(Examples 1-4, Comparative Example 1)
The BiVO 4 photoelectrode was produced by an organometallic pyrolysis method. A WO 3 film (about 200 nm) was formed on a conductive substrate (F-SnO 2 film: FTO), and a BiVO 4 film (about 100 nm) was formed thereon. It has been found that the photocurrent is improved by inserting a WO 3 film. The WO 3 film was prepared by spin-coating a tungsten peroxide aqueous solution (1.4 mol / L) and air firing at 500 ° C. Thereafter, the BiVO 4 photoelectrode was produced by a metal organic pyrolysis (MOD) method. Commercially available (made by Symmetrics) Bi-MOD solution and V-MOD solution (concentration: 0.2 mol / L each) were mixed at 1: 1, spin-coated on WO 3 / FTO film, and air at 550 ° C. Prepared by firing. This was repeated three times.
Next, a commercially available M-MOD solution (M = Nb, concentration is 0.01 to 0.1 mol / L) is spin-coated on the BiVO 4 / WO 3 / FTO film and air-fired at 550 ° C. Made. The amount of added metal element (μmol / cm 2 ) on the photoelectrode was calculated by XRF measurement. A BiVO 4 / WO 3 / FTO film not coated with the M-MOD solution was used as Comparative Example 1. The film formation amounts (mg / cm 2 ) of the BiVO 4 film and the WO 3 film were 0.039, 0.015, and 0.037, respectively, in terms of Bi 2 O 3 , V 2 O 5 , and WO 3. It was. The total oxide mass of the semiconductor was 0.091 mg / cm 2 .
光電極の性能と安定性評価は、疑似太陽光照射下（直径６ｍｍマスク付き）での光電流の時間変化測定により行った。パイレックスガラス製の1室セルに２.５ｍｏｌ／ＬのＫＨＣＯ3電解液を入れ、光電極、Ｐｔ対極、Ａｇ／ＡｇＣｌ対極をセットし、ポテンショスタットで一定電位（１Ｖ vs.Ａｇ／ＡｇＣｌ)で光電流を測定した。 The performance and stability of the photoelectrode were evaluated by measuring changes in photocurrent with time under simulated sunlight irradiation (with a 6 mm diameter mask). Place a 2.5 mol / L KHCO 3 electrolyte in a Pyrex glass single-chamber cell, set the photoelectrode, Pt counter electrode, and Ag / AgCl counter electrode. The current was measured.
図１に、実施例２の典型的な経時変化を示す。光照射すると光電流が観測され、時間とともに少し光電流が向上した。４５分(２７００秒)では明確な劣化は見られなかった。
表１に光電流の低下率を示す。実施例２〜４のＮｂ濃度では、低下率は１００％より少し大きくなった。一方、比較例１では４５分で低下率３１％と大きく劣化していることがわかる。初期光電流で比較すると、比較例１は実施例１〜４より大きくみえるが、Ｎｂコート膜では光電流が途中で向上するため、最高の光電流はほとんど比較例１と変わらなかった。
以上より、本実施例の手法は、半導体材料の光反応中の安定性を向上させ、且つ効率がほぼ低下しないことがわかった。
FIG. 1 shows a typical time course of Example 2. Photocurrent was observed when irradiated with light, and the photocurrent improved slightly over time. There was no clear degradation at 45 minutes (2700 seconds).
Table 1 shows the reduction rate of the photocurrent. In the Nb concentrations of Examples 2 to 4, the decrease rate was slightly larger than 100%. On the other hand, in Comparative Example 1, it can be seen that the deterioration rate is as large as 31% in 45 minutes. When compared with the initial photocurrent, Comparative Example 1 seems larger than Examples 1 to 4, but the photocurrent was improved in the middle in the Nb coating film, so that the maximum photocurrent was almost the same as Comparative Example 1.
From the above, it has been found that the method of this example improves the stability of the semiconductor material during the photoreaction and the efficiency is not substantially lowered.
（実施例５〜１０）
実施例１のＭ＝Ｎｂの代わりに、Ｍ＝Ｌａ、Ｔｉ、Ｓｎ、Ｚｒ、Ｂｉ、Ｔａを用いた。
結果を表１に示す。光電流の低下率が比較例よりも大きく向上し、安定性が良くなっていることがわかる。また、初期光電流も大きな低下はなかった。
以上より、本実施例の手法は、半導体材料の光反応中の安定性を向上させ、且つ効率がほぼ低下しないことがわかった。
(Examples 5 to 10)
Instead of M = Nb in Example 1, M = La, Ti, Sn, Zr, Bi, and Ta were used.
The results are shown in Table 1. It can be seen that the reduction rate of the photocurrent is greatly improved as compared with the comparative example, and the stability is improved. Also, the initial photocurrent did not decrease greatly.
From the above, it has been found that the method of this example improves the stability of the semiconductor material during the photoreaction and the efficiency is not substantially lowered.
本発明により、水分解用の半導体光電極において、半導体材料の光反応中の安定性を向上させ、且つ効率が低下しない安定化手法を提供することにより、太陽エネルギーを利用した水素製造に利用できる。また、この手法は水分解用や環境浄化用の粉末光触媒反応や、光センサー用途の半導体に対しても有効な安定化手法を提供できる。 INDUSTRIAL APPLICABILITY According to the present invention, a semiconductor photoelectrode for water splitting can be used for hydrogen production using solar energy by providing a stabilization method that improves the stability of a semiconductor material during a photoreaction and does not reduce the efficiency . This technique can also provide an effective stabilization technique for powder photocatalytic reactions for water splitting and environmental purification, and semiconductors for photosensor applications.
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