CN114044502A - Monoclinic phase zinc pyrophosphate, preparation method and application thereof - Google Patents
Monoclinic phase zinc pyrophosphate, preparation method and application thereof Download PDFInfo
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- OMSYGYSPFZQFFP-UHFFFAOYSA-J zinc pyrophosphate Chemical compound [Zn+2].[Zn+2].[O-]P([O-])(=O)OP([O-])([O-])=O OMSYGYSPFZQFFP-UHFFFAOYSA-J 0.000 title claims abstract description 63
- 238000002360 preparation method Methods 0.000 title claims abstract description 19
- 238000006243 chemical reaction Methods 0.000 claims abstract description 14
- 239000000463 material Substances 0.000 claims abstract description 14
- 239000003054 catalyst Substances 0.000 claims abstract description 5
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 20
- 238000000034 method Methods 0.000 claims description 20
- 239000011701 zinc Substances 0.000 claims description 17
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims description 15
- 239000007789 gas Substances 0.000 claims description 14
- 229910052725 zinc Inorganic materials 0.000 claims description 14
- 230000009467 reduction Effects 0.000 claims description 12
- 239000000725 suspension Substances 0.000 claims description 12
- 239000003792 electrolyte Substances 0.000 claims description 11
- 239000006229 carbon black Substances 0.000 claims description 10
- 238000009792 diffusion process Methods 0.000 claims description 10
- 229910052759 nickel Inorganic materials 0.000 claims description 10
- 238000012360 testing method Methods 0.000 claims description 9
- 125000004430 oxygen atom Chemical group O* 0.000 claims description 8
- XIOUDVJTOYVRTB-UHFFFAOYSA-N 1-(1-adamantyl)-3-aminothiourea Chemical compound C1C(C2)CC3CC2CC1(NC(=S)NN)C3 XIOUDVJTOYVRTB-UHFFFAOYSA-N 0.000 claims description 7
- YASYEJJMZJALEJ-UHFFFAOYSA-N Citric acid monohydrate Chemical compound O.OC(=O)CC(O)(C(O)=O)CC(O)=O YASYEJJMZJALEJ-UHFFFAOYSA-N 0.000 claims description 7
- LFVGISIMTYGQHF-UHFFFAOYSA-N ammonium dihydrogen phosphate Chemical compound [NH4+].OP(O)([O-])=O LFVGISIMTYGQHF-UHFFFAOYSA-N 0.000 claims description 7
- 229910000387 ammonium dihydrogen phosphate Inorganic materials 0.000 claims description 7
- 229960002303 citric acid monohydrate Drugs 0.000 claims description 7
- XPPKVPWEQAFLFU-UHFFFAOYSA-J diphosphate(4-) Chemical compound [O-]P([O-])(=O)OP([O-])([O-])=O XPPKVPWEQAFLFU-UHFFFAOYSA-J 0.000 claims description 7
- 235000019837 monoammonium phosphate Nutrition 0.000 claims description 7
- 230000008569 process Effects 0.000 claims description 7
- 239000004575 stone Substances 0.000 claims description 7
- MOCSSSMOHPPNTG-UHFFFAOYSA-N [Sc].[Y] Chemical compound [Sc].[Y] MOCSSSMOHPPNTG-UHFFFAOYSA-N 0.000 claims description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 6
- 229910004856 P—O—P Inorganic materials 0.000 claims description 5
- 238000001354 calcination Methods 0.000 claims description 5
- 239000008367 deionised water Substances 0.000 claims description 5
- 229910021641 deionized water Inorganic materials 0.000 claims description 5
- 235000011180 diphosphates Nutrition 0.000 claims description 5
- 238000001035 drying Methods 0.000 claims description 5
- 238000003837 high-temperature calcination Methods 0.000 claims description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 claims description 5
- UGKDIUIOSMUOAW-UHFFFAOYSA-N iron nickel Chemical compound [Fe].[Ni] UGKDIUIOSMUOAW-UHFFFAOYSA-N 0.000 claims description 5
- 229910021607 Silver chloride Inorganic materials 0.000 claims description 3
- 238000010438 heat treatment Methods 0.000 claims description 3
- 229910052709 silver Inorganic materials 0.000 claims description 3
- 239000004332 silver Substances 0.000 claims description 3
- HKZLPVFGJNLROG-UHFFFAOYSA-M silver monochloride Chemical compound [Cl-].[Ag+] HKZLPVFGJNLROG-UHFFFAOYSA-M 0.000 claims description 3
- 238000003756 stirring Methods 0.000 claims description 3
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 2
- 239000008139 complexing agent Substances 0.000 claims description 2
- 229910052698 phosphorus Inorganic materials 0.000 claims description 2
- 239000011574 phosphorus Substances 0.000 claims description 2
- 230000001747 exhibiting effect Effects 0.000 claims 2
- 239000002994 raw material Substances 0.000 abstract description 4
- 239000010411 electrocatalyst Substances 0.000 abstract description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 abstract 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 abstract 1
- 229910002092 carbon dioxide Inorganic materials 0.000 abstract 1
- 239000001569 carbon dioxide Substances 0.000 abstract 1
- 229910002091 carbon monoxide Inorganic materials 0.000 abstract 1
- 230000003197 catalytic effect Effects 0.000 abstract 1
- 238000006722 reduction reaction Methods 0.000 description 16
- 239000000446 fuel Substances 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 4
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 4
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 3
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 230000007613 environmental effect Effects 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 238000003860 storage Methods 0.000 description 3
- 238000003786 synthesis reaction Methods 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 238000001157 Fourier transform infrared spectrum Methods 0.000 description 2
- 238000003917 TEM image Methods 0.000 description 2
- 238000002441 X-ray diffraction Methods 0.000 description 2
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- GTKRFUAGOKINCA-UHFFFAOYSA-M chlorosilver;silver Chemical compound [Ag].[Ag]Cl GTKRFUAGOKINCA-UHFFFAOYSA-M 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000002803 fossil fuel Substances 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 238000009776 industrial production Methods 0.000 description 2
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 description 2
- 239000002105 nanoparticle Substances 0.000 description 2
- 238000001228 spectrum Methods 0.000 description 2
- 238000001308 synthesis method Methods 0.000 description 2
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 description 1
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 1
- 239000005977 Ethylene Substances 0.000 description 1
- 241000271317 Gonystylus bancanus Species 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 229910007541 Zn O Inorganic materials 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000010531 catalytic reduction reaction Methods 0.000 description 1
- 238000012512 characterization method Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000002524 electron diffraction data Methods 0.000 description 1
- 235000019253 formic acid Nutrition 0.000 description 1
- 239000002223 garnet Substances 0.000 description 1
- 238000004817 gas chromatography Methods 0.000 description 1
- 239000003673 groundwater Substances 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000001000 micrograph Methods 0.000 description 1
- 230000000116 mitigating effect Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- 230000001699 photocatalysis Effects 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 238000001878 scanning electron micrograph Methods 0.000 description 1
- 238000013022 venting Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- 239000011787 zinc oxide Substances 0.000 description 1
Images
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B25/00—Phosphorus; Compounds thereof
- C01B25/16—Oxyacids of phosphorus; Salts thereof
- C01B25/26—Phosphates
- C01B25/38—Condensed phosphates
- C01B25/42—Pyrophosphates
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B1/00—Electrolytic production of inorganic compounds or non-metals
- C25B1/01—Products
- C25B1/23—Carbon monoxide or syngas
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- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
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Abstract
The invention discloses monoclinic phase zinc pyrophosphate, a preparation method and application thereof. The preparation method has the advantages of simple operation, easily obtained raw materials, low preparation cost, short reaction period and large-scale and high-yield preparation. The material can be used asThe low-cost and high-efficiency electrocatalyst is applied to the conversion reaction of carbon dioxide to carbon monoxide under industrial-grade current, and the CO local current density is up to-441 mA cm in a flow reaction tank under the potential of 870mV‑2. When applied to a zero-clearance electrolytic cell, the full cell energy efficiency of the material reaches 58 percent at most, and CO is reduced in an electrocatalysis mode2In the field of CO preparation, the catalyst has excellent catalytic performance.
Description
Technical Field
The invention relates to a preparation method and application of monoclinic phase zinc pyrophosphate, wherein the monoclinic phase zinc pyrophosphate is prepared by adopting a sol-gel and high-temperature calcination method, and is used as a catalyst for electrocatalytic reduction of CO2The method has excellent performance in the aspect of preparing CO, and has potential application value in the fields of other energy development and environmental protection.
Background
Fossil fuels drive economic growth, improving the living standard of most residents of the world by creating opportunities for employment to reduce poverty, while fossil fuel use also enables CO2Man-made emissions continue to increase, resulting in climate change that is difficult to reverse. In the pursuit of zero carbon emissions, the use of wind or solar energy to provide electrical energy in a sustainable manner, followed by electrochemical water splitting, has been one of the promising approaches to convert renewable energy sources into hydrogen fuels, but its intermittent limits their widespread use, while the storage and supply of renewable energy sources also present challenges. CO in the atmosphere at present2Concentrations in excess of 407ppm have required a more rapid, full-blown solution to this problem. Thus, it is recognized that innovative technologies are utilized to combat CO at the source and at various levels of the supply chain2Emission, is the mitigation of CO2Another effective way of venting.
In the reduction of CO2In terms of emissions problems, many strategies have been developed. The first method is to improve the efficiency of transportation and industrial production, reduce the energy input and thus reduce CO2And (4) discharging. At the same time, Carbon Capture and Storage (CCS) is also considered as a potential solution to capture CO from post-combustion exhaust gases2And stored in underground depleted natural gas and oil fields. However, CCS technology also poses controversy because it faces additional environmental risks, such as groundwater contamination and seepage issues. Near toIt was also claimed that CO could be introduced using some of the existing techniques2The waste is converted into value added chemicals. For example, the Sabatier reaction is a well-known and well-studied thermochemical process that converts CO2Reduction to methane, but this technique requires the use of hydrogen, along with higher operating temperatures and pressures. There is a particular technology that shows great potential to address CO2The problem of emission into the atmosphere is that of CO2Electrocatalytic reduction into valuable fuels and chemicals, such as formic acid, methanol, ethanol, ethylene, and CO. Electrocatalytic reduction of CO compared to photocatalytic and photoelectrochemical reactions2The yield of (a) is higher. CO 22The reduction reaction is usually carried out at room temperature and normal pressure and is driven by electricity, which may be derived from renewable energy sources such as solar energy and wind energy. In fact, CO2The reduction reaction has the ability to store intermittent renewable energy sources in the form of chemical fuels, which also helps to address CO2Storage issues transitioning to renewable resources. Furthermore, from CO2The value-added fuel and chemicals produced by the reduction reaction can be further applied to power generation, transportation fuel or chemical raw materials.
Disclosure of Invention
The invention aims to provide a sol-gel of monoclinic phase zinc pyrophosphate electrocatalyst, a high-temperature calcination preparation method and application thereof. The catalyst has the advantages of simple preparation method, low cost and excellent electro-catalytic reduction of CO2Selectivity for CO production and current density of commercial grade. No complex instrument is needed in the synthesis process, the operation is convenient, and the method is beneficial to large-scale industrial application.
In order to achieve the purpose, the invention adopts the following technical scheme:
a monoclinic phase zinc pyrophosphate is prepared by adopting zinc nitrate hexahydrate and ammonium dihydrogen phosphate as a zinc source and a phosphorus source respectively and citric acid monohydrate as a complexing agent through a sol-gel and high-temperature calcination method.
The invention also provides a preparation method of monoclinic phase zinc pyrophosphate, which comprises the following steps:
(1) 0.8-2.8 g of zinc nitrate hexahydrate and 0.4-1.6 g of ammonium dihydrogen phosphate are dissolved in deionized water, and the mixture is fully stirred to form a suspension. Then adding 0.2-1.0 g of citric acid monohydrate, stirring until the suspension is clear, and then placing the suspension in an oven at 100-140 ℃ for drying;
(2) and (2) transferring the material obtained in the step (1) into a crucible, and calcining the material in a muffle furnace at a heating rate of 5 ℃/min at 500-900 ℃ for 1-6 hours to obtain the gray monoclinic-phase zinc pyrophosphate with a typical scandium-yttrium stone structure.
Further, the entire structure of monoclinic zinc pyrophosphate having the typical scandium-yttrium-garnet structure consists of tetrahedrons of pyrophosphate alternating with zinc atomic layers, which are represented by 5 zinc sites with coordination number of 5 (distorted structure) surrounded by nearest neighboring oxygen atoms and zinc sites with coordination number of 6 (regular octahedron), and which exhibit 3.3 and 3
Two types of Zn-Zn bond lengths; two kinds of tetrahedra pyrophosphate share one oxygen atom, and the P-O-P bond angle is 130 degrees.
The invention also provides application of monoclinic phase zinc pyrophosphate serving as a catalyst for electrocatalytic reduction of CO2Application to the preparation of CO.
Further, the monoclinic phase zinc pyrophosphate is used for electrocatalytic reduction of CO2The application method for preparing CO comprises the following steps:
(1) in a flow reaction tank, 1.0-2.0M KOH solution is used as electrolyte, a gas diffusion electrode loaded with zinc pyrophosphate and carbon black is used as a working electrode, a silver/silver chloride electrode is used as a reference electrode, and foamed nickel is used as a counter electrode, and the test temperature is 0-40 ℃; when the current density is-300 mA cm-2Meanwhile, the Faraday efficiency of CO reaches 90-100%; when the current density is-500 mA cm-2When the voltage is lower than 0.87V vs. RHE, the local current density of CO products reaches-415 to-465 mA cm-2；
(2) In a zero-gap electrolytic cell, a 1.0-2.0M KOH solution is used as an electrolyte, a gas diffusion electrode loaded with zinc pyrophosphate and carbon black is used as a working electrode,Taking nickel-iron layered double hydroxide supported by foamed nickel as an anode, and testing at the temperature of 0-40 ℃; when the current density is-100 mA cm-2In the process, the Faraday efficiency of CO reaches 90-95%, and the energy efficiency of the full battery reaches 50-58%.
The invention has the beneficial effects that:
(1) the monoclinic phase zinc pyrophosphate is synthesized by adopting a simple sol-gel and high-temperature calcination method, the synthesis method is simple to operate, the raw materials are easy to obtain, the preparation cost is low, the reaction period is short, no complex instrument is needed in the synthesis process, the monoclinic phase zinc pyrophosphate can be synthesized in a large scale, and the large-scale industrial application is facilitated;
(2) monoclinic phase zinc pyrophosphate as electrocatalytic reduction CO2The results show that it has excellent electrocatalytic reduction of CO2The selectivity and activity of CO production are improved by applying a current density of-500 mA cm in a flow reaction cell-2When the potential is as low as 0.87V vs. RHE, the local current density of CO production reaches-415 to-465 mA cm-2(ii) a When a current density of-100 mA cm was applied in a zero-gap electrolytic cell-2Meanwhile, the Faraday efficiency of CO reaches 90-95%, and the energy efficiency of the full battery reaches 50-58%;
(3) in the preparation process, all reagents are commercial products and do not need further treatment;
(4) the synthesis method is simple, and the obtained material is easy to apply, is beneficial to popularization and application in industrial production, and has potential application value in other energy development and environmental protection fields.
Drawings
FIG. 1 is a digital photograph of monoclinic phase zinc pyrophosphate prepared in example 1;
FIG. 2 is an X-ray diffraction pattern of monoclinic phase zinc pyrophosphate prepared in example 1;
FIG. 3 is a schematic diagram showing a structural model of monoclinic phase zinc pyrophosphate prepared in example 1;
FIG. 4 is a graph of the X-ray absorption fine spectrum of monoclinic phase zinc pyrophosphate prepared in example 1;
FIG. 5 is a Fourier transform infrared spectrum of monoclinic zinc pyrophosphate prepared in example 1;
FIG. 6 is a scanning electron micrograph of monoclinic phase zinc pyrophosphate prepared in example 1;
FIG. 7 is a transmission electron micrograph of monoclinic phase zinc pyrophosphate prepared in example 1;
FIG. 8 is a graph of the Faraday efficiencies and corresponding potentials of the products of monoclinic zinc pyrophosphate prepared in example 1 at different current densities in a flow reaction cell using 2.0M KOH as the electrolyte;
FIG. 9 is a graph of the Faraday efficiencies of monoclinic zinc pyrophosphate prepared in example 1 for CO at different current densities in a zero gap cell using 1.0M KOH as the electrolyte;
FIG. 10 is a graph of the energy efficiency of CO and corresponding cell voltage for monoclinic phase zinc pyrophosphate prepared in example 1 at different current densities in a zero gap cell with 1.0M KOH as electrolyte.
Detailed Description
The following detailed description of the present invention will be made with reference to the accompanying drawings and examples, but the scope of the present invention should not be limited thereby.
The "ranges" disclosed herein are in the form of lower and upper limits. There may be one or more lower limits, and one or more upper limits, respectively. The given range is defined by the selection of a lower limit and an upper limit. The selected lower and upper limits define the boundaries of the particular range. All ranges that can be defined in this manner are inclusive and combinable, i.e., any lower limit can be combined with any upper limit to form a range. For example, ranges of 60 to 120 and 80 to 110 are listed for particular parameters, with the understanding that ranges of 60 to 110 and 80 to 120 are also contemplated. Furthermore, if the minimum range values 1 and 2 are listed, and if the maximum ranges 3, 4, and 5 are listed, the following ranges are all contemplated: 1 to 2, 1 to 4, 1 to 5, 2 to 3, 2 to 4 and 2 to 5.
In the present invention, unless otherwise stated, the numerical range "a-b" represents a shorthand representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, a numerical range of "0 to 5" means that all real numbers between "0 to 5" have been listed herein, and "0 to 5" is simply a shorthand representation of the combination of these values.
In the present invention, all embodiments and preferred embodiments mentioned herein may be combined with each other to form a new technical solution, if not specifically stated.
In the present invention, all the technical features mentioned herein and preferred features may be combined with each other to form new technical solutions, if not specifically mentioned.
The preferred embodiments of the present invention will be described in detail with reference to the following examples, but it should be understood that those skilled in the art can reasonably change, modify and combine the examples to obtain new embodiments without departing from the scope defined by the claims, and that the new embodiments obtained by changing, modifying and combining the examples are also included in the protection scope of the present invention.
Example 1
Step one, preparation of monoclinic phase zinc pyrophosphate
1.78g of zinc nitrate hexahydrate and 1.04g of ammonium dihydrogen phosphate were dissolved in deionized water and stirred well to form a suspension. 0.63g of citric acid monohydrate was then added, stirred until the suspension was clear and then placed in an oven at 120 ℃ for drying. And transferring the material into a crucible, and calcining the material in a muffle furnace at 700 ℃ for 1 hour at a heating rate of 5 ℃/min to obtain the monoclinic-phase zinc pyrophosphate which is gray and has a typical scandium-yttrium stone structure.
Step two, performance characterization test
Through a CHI660 electrochemical workstation, in a flow reaction tank, a standard three-electrode system is adopted, 2.0M KOH solution is used as electrolyte, a gas diffusion electrode loaded with zinc pyrophosphate and carbon black is used as a working electrode, a silver/silver chloride electrode is used as a reference electrode, and foamed nickel is used as a counter electrode; in a zero-gap electrolytic cell, monoclinic phase zinc pyrophosphate and carbon black are loaded on a gas diffusion electrode as a working electrode, nickel-iron layered double hydroxide supported by foamed nickel is used as an anode, and the test temperature is room temperature. Gas chromatography (RAMIN, GC2060, GC on-line test) on CO2Electric deviceThe crude gas product is analyzed with a flame ionization detector (FID, for CO, CH)4，C2H4) And a thermal conductivity detector (TCD, detection H)2) Ar is used as a carrier.
Fig. 1 is a digital photograph of the product prepared in example 1, and it can be seen that monoclinic phase zinc pyrophosphate prepared is gray powder.
FIG. 2 is an X-ray diffraction pattern of monoclinic phase zinc pyrophosphate prepared in example 1 at a scanning speed of 3 ℃ min-1The scanning range is 10-80 degrees, and the diffraction peak of the material is well corresponding to the monoclinic phase of zinc pyrophosphate (PDF #97-005-6297) without any impurities.
FIG. 3 is a schematic diagram showing a structural model of monoclinic zinc pyrophosphate prepared in example 1, which has a typical scandium-yttrium-stone structure in which pyrophosphate groups are arranged alternately and comprise two types of pyrophosphoric tetrahedra sharing an oxygen atom, and the P-O-P bond angle is 130 °. The complete structure consists of pyrotetrahedra alternating with zinc atom layers, represented by 5 zinc sites with coordination number 5 (distorted structure) and zinc sites with coordination number 6 (regular octahedron) surrounded by nearest neighbor oxygen atoms, and exhibiting
And
the two Zn-Zn bonds are long.
FIG. 4 is a graph of the X-ray absorption fine spectrum of monoclinic phase zinc pyrophosphate prepared in example 1, wherein: curve 1 is a standard sample of metallic zinc foil, curve 2 is a standard sample of zinc oxide, and curve 3 is monoclinic phase zinc pyrophosphate prepared in example 1. As is clear from FIG. 4, the monoclinic phase zinc pyrophosphate retains a +2 valence in the bulk phase, and has both Zn-O bonds and Zn-P bonds.
FIG. 5 is a Fourier transform infrared spectrum of monoclinic zinc pyrophosphate prepared in example 1, further confirming the presence of symmetric P-O bonds, asymmetric P-O bonds and P-O-P bonds in monoclinic zinc pyrophosphate prepared in example 1.
FIG. 6 is a scanning electron microscope image of monoclinic phase zinc pyrophosphate prepared in example 1, and the material is irregularly stacked nanoparticles as can be seen by observing the morphology of the sample.
FIG. 7 is a transmission electron micrograph of monoclinic zinc pyrophosphate prepared in example 1, interconnected nanoparticles can be observed, and the corresponding selected region electron diffraction pattern further confirms the existence of (22-2), (20-8) and (42-10) crystal planes in the monoclinic zinc pyrophosphate.
Fig. 8 is a diagram showing the faraday efficiencies and corresponding potential of the products of example 1, prepared monoclinic zinc pyrophosphate, in a flow reaction cell, at different current densities and with 2.0M KOH as an electrolyte, under a standard three-electrode system, monoclinic zinc pyrophosphate and carbon black loaded on a gas diffusion electrode as a working electrode, a silver-silver chloride electrode as a reference electrode, foamed nickel as a counter electrode, and a test temperature of room temperature. CO measured on a GC2060 gas chromatograph with a constant overpotential applied by a CHI660 electrochemical workstation2The faradaic efficiency of the reduction product showed that the applied current density was-300 mA cm-2Meanwhile, the Faraday efficiency of CO reaches 99%; when the current density is-500 mA cm-2During the process, the overpotential is as low as 0.87V vs. RHE, and the local current density of CO production reaches-441 mA cm-2。
Figure 9 is a graph of the faradaic efficiency of monoclinic zinc pyrophosphate prepared in example 1 at various current densities in a zero gap cell using 1.0M KOH as the electrolyte, monoclinic zinc pyrophosphate and carbon black supported on a gas diffusion electrode as the working electrode, a nickel-iron layered double hydroxide supported on foamed nickel as the anode, and the test temperature at room temperature. Faradaic efficiencies of the CO products measured on a GC2060 gas chromatograph with a constant overpotential applied by the CHI660 electrochemical workstation showed-100 mAcm when the current density was applied-2The faradaic efficiency of CO reaches 94%.
FIG. 10 is a graph of the energy efficiency of CO and corresponding cell voltage at different current densities when monoclinic phase zinc pyrophosphate prepared in example 1 was electrolyzed in a zero gap cell with 1.0M KOH and applied current density of-100 mA cm-2At times, the cell voltage is as low as 2.15V, and the full cell energy efficiency of the CO productThe rate reaches 58 percent.
With existing electrocatalytic reduction of CO2Compared with the preparation method of the material for generating CO, the invention has the following advantages: the material synthesis operation is simple, and large-scale preparation can be realized; the raw material has rich earth reserves, low cost, excellent selectivity and activity for producing CO by electrocatalysis, and can realize high-efficiency CO under the conditions of low energy transmission and industrial-grade current2To CO conversion.
Example 2
0.8g of zinc nitrate hexahydrate and 0.4g of ammonium dihydrogen phosphate were dissolved in deionized water and stirred well to form a suspension. 0.2g of citric acid monohydrate was then added, stirred until the suspension was clear and then placed in an oven at 120 ℃ for drying. And calcining the mixture in a muffle furnace at the temperature rise rate of 5 ℃/min for 1 hour at 700 ℃ to obtain the monoclinic phase zinc pyrophosphate which is gray and has a typical scandium-yttrium-stone structure. The characteristics and properties are similar to those of example 1.
Example 3
2.8g of zinc nitrate hexahydrate and 1.6g of ammonium dihydrogen phosphate were dissolved in deionized water and stirred well to form a suspension. Then 1.0g of citric acid monohydrate was added, stirred until the suspension was clear, and then placed in an oven at 130 ℃ for drying. And calcining the mixture in a muffle furnace at the temperature rise rate of 5 ℃/min for 1 hour at 700 ℃ to obtain the monoclinic phase zinc pyrophosphate which is gray and has a typical scandium-yttrium-stone structure. The characteristics and properties are similar to those of example 1.
The material obtained by the invention is applied to electrocatalytic reduction of CO2CO is generated. Application of monoclinic phase zinc pyrophosphate in preparing CO by electrocatalysis reduction2The CO generation is carried out at normal temperature and normal pressure, and a 1.0-2.0M KOH solution is used as an electrolyte. A standard three-electrode system is used in a flow reaction tank, wherein a gas diffusion electrode loaded with monoclinic phase zinc pyrophosphate and carbon black is used as a working electrode, a silver-silver chloride electrode is used as a reference electrode, and foamed nickel is used as a counter electrode; in the zero-gap reaction tank, a gas diffusion electrode loaded with monoclinic phase zinc pyrophosphate and carbon black is used as a working electrode, and a nickel-iron layered double hydroxide loaded on foamed nickel is used as an anode. The foregoing is only a preferred embodiment of this invention and is not intended to be exhaustive or to limit the invention to the precise form disclosedAll equivalent changes and modifications should be considered within the scope of the present invention.
Claims (7)
1. A monoclinic phase zinc pyrophosphate is characterized in that zinc nitrate hexahydrate and ammonium dihydrogen phosphate are respectively used as a zinc source and a phosphorus source, citric acid monohydrate is used as a complexing agent, and the monoclinic phase zinc pyrophosphate with a typical scandium-yttrium stone structure is prepared by a sol-gel and high-temperature calcination method.
2. Monoclinic zinc pyrophosphate according to claim 1, characterized in that the entire structure of monoclinic zinc pyrophosphate with typical scandium-yttrium structure consists of tetrahedra pyrophosphate alternating with zinc atomic layers, exhibiting 5 zinc sites with coordination number 5 and zinc sites with coordination number 6 surrounded by the nearest 5 oxygen atoms, exhibiting 3.3 and 3.3
Two types of Zn-Zn bond lengths; two kinds of tetrahedra pyrophosphate share one oxygen atom, and the P-O-P bond angle is 130 degrees.
3. A preparation method of monoclinic phase zinc pyrophosphate comprises the following steps:
(1) dissolving 0.8-2.8 g of zinc nitrate hexahydrate and 0.4-1.6 g of ammonium dihydrogen phosphate in deionized water, and fully stirring to form a suspension; then adding 0.2-1.0 g of citric acid monohydrate, stirring until the suspension is clear, and then placing the suspension in an oven at 100-140 ℃ for drying;
(2) and (2) transferring the material obtained in the step (1) into a crucible, and calcining the material in a muffle furnace at a heating rate of 5 ℃/min at 500-900 ℃ for 1-6 hours to obtain the gray monoclinic-phase zinc pyrophosphate with a typical scandium-yttrium stone structure.
4. The method according to claim 2, wherein the entire structure of monoclinic zinc pyrophosphate having typical scandium-yttrium structure is composed of tetrahedral pyrophosphate groups alternating with zinc atomic layersAs a result, it was shown that the zinc sites with coordination number 5 and the zinc sites with coordination number 6 surrounded by 5 nearest neighbor oxygen atoms exhibited 3.3 and
two types of Zn-Zn bond lengths; two kinds of tetrahedra pyrophosphate share one oxygen atom, and the P-O-P bond angle is 130 degrees.
5. Application of monoclinic phase zinc pyrophosphate as catalyst for electrocatalytic reduction of CO2Application to the preparation of CO.
6. The use according to claim 5, characterized in that the method of application is as follows: in a flow reaction tank, 1.0-2.0M KOH solution is used as electrolyte, a gas diffusion electrode loaded with zinc pyrophosphate and carbon black is used as a working electrode, a silver/silver chloride electrode is used as a reference electrode, and foamed nickel is used as a counter electrode, and the test temperature is 0-40 ℃; when the current density is-300 mA cm-2In the process, the Faraday efficiency of the CO product reaches 90-100%; when the current density is-500 mA cm-2When the voltage is lower than 0.87V vs. RHE, the local current density of CO products reaches-415 to-465 mA cm-2。
7. The use according to claim 5, characterized in that the method of application is as follows: in a zero-gap electrolytic cell, 1.0-2.0M KOH solution is used as electrolyte, a gas diffusion electrode loaded with zinc pyrophosphate and carbon black is used as a working electrode, nickel-iron layered double hydroxide supported by foamed nickel is used as an anode, and the test temperature is 0-40 ℃; when the current density is-100 mA cm-2In the process, the Faraday efficiency of CO reaches 90-95%, and the energy efficiency of the full battery reaches 50-58%.
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