Platinum-loaded molybdenum dioxide hybrid nano material, preparation method and electrocatalysis application thereof
阅读说明：本技术 一种铂负载二氧化钼杂化纳米材料及其制备方法和电催化应用 (Platinum-loaded molybdenum dioxide hybrid nano material, preparation method and electrocatalysis application thereof ) 是由 郭晓辉 邱雨 于 2021-07-13 设计创作，主要内容包括：本发明提供一种铂负载二氧化钼杂化纳米材料及其制备方法和电催化应用,属于纳米材料制备方法及电催化应用技术领域。本发明将钼盐、配位剂溶于水中,调节反应液的pH至4～5,并于30～80℃水浴反应2～3h,反应结束后,产物经洗涤、干燥,在氩气保护气氛中,600～650℃条件下进行热解1～2h,制备得到富含空位缺陷的MoO-2纳米棒；随后将MoO-2纳米棒作为载体,加入铂源、络合剂、还原性溶剂,经溶剂热还原法将铂以单原子或簇的形式负载于MoO-2纳米棒载体上,形成Pt负载MoO-2纳米棒材料。本发明中MoO-2纳米棒提供的空位缺陷很好的锚定了Pt单原子或簇,进一步提高材料的催化稳定性；其作为酸性、碱性、中性电解液的产氢催化剂材料,具有催化活性高、稳定性优异以及制备工艺简单的优点。(The invention provides a platinum-loaded molybdenum dioxide hybrid nano material, a preparation method and an electrocatalysis application thereof, and belongs to the technical field of nano material preparation methods and electrocatalysis application. Dissolving molybdenum salt and a complexing agent in water, adjusting the pH value of a reaction solution to 4-5, carrying out water bath reaction at 30-80 ℃ for 2-3 h, washing and drying a product after the reaction is finished, and carrying out pyrolysis at 600-650 ℃ for 1-2 h in an argon protective atmosphere to prepare the MoO rich in vacancy defects 2 A nanorod; then MoO is added 2 The nano-rod is used as a carrier, a platinum source is added, and complexation is performedAn agent and a reducing solvent, and the platinum is loaded on the MoO in the form of single atom or cluster by a solvothermal reduction method 2 Forming Pt loaded MoO on the nanorod carrier 2 A nanorod material. MoO in the invention 2 The vacancy defect provided by the nanorod anchors Pt monoatomic atoms or clusters well, so that the catalytic stability of the material is further improved; the catalyst material is used as hydrogen production catalyst material of acidic, alkaline and neutral electrolyte, and has the advantages of high catalytic activity, excellent stability and simple preparation process.)
1. A preparation method of a platinum-loaded molybdenum dioxide hybrid material is characterized by comprising the following steps:
step 1, MoO rich in vacancy defects2Preparation of the carrier: dissolving a molybdenum salt and a complexing agent in water, adjusting the pH value of the solution to 4-5 with an acid, carrying out water bath reaction at 30-80 ℃ for 2-3 h, after the reaction is finished, carrying out suction filtration, washing and drying on a product, carrying out pyrolysis on the product for 1-2 h at 600-650 ℃ in an argon protective atmosphere, and preparing the MoO rich in vacancy defects2A nanorod;
step 2, in the MoO rich in vacancy defects2Loading platinum on the carrier: adding MoO2The nano-rod is taken as a carrier, a platinum source, a complexing agent and a reducing solvent are added, and the platinum is loaded on MoO in the form of single atom or cluster by a solvothermal reduction method2Preparing Pt loaded MoO on a nanorod carrier2A nanorod material.
2. The method for preparing the platinum-supported molybdenum dioxide hybrid material as claimed in claim 1, wherein the molybdenum salt is ammonium heptamolybdate tetrahydrate; the complexing agent is ethylenediamine; the acid is 1mol/L dilute hydrochloric acid; the platinum source is potassium tetrachloroplatinate; the complexing agent is polyvinylpyrrolidone; the reducing solvent is ethylene glycol.
3. The preparation method of the platinum-supported molybdenum dioxide hybrid material as claimed in claim 1, wherein in step 1, the ratio of molybdenum salt: a complexing agent: the ratio of water was 2.48 g: 1.78 mL: 30 mL.
4. The preparation method of the platinum-loaded molybdenum dioxide hybrid material as claimed in claim 1, wherein the suction filtration in step 1 is vacuum filtration, and the washing is sequentially carried out by washing with water and ethanol.
5. The preparation method of the platinum-loaded molybdenum dioxide hybrid material as claimed in claim 1, wherein the drying temperature in step 1 is 30-100 ℃.
6. The method for preparing the platinum-supported molybdenum dioxide hybrid material as claimed in claim 1, wherein in the step 2, a reducing solution is used as a reaction solution, and the ratio of the platinum source: complexing agent: MoO2And (3) nano-rods: the ratio of the reducing solvent is 5-35 mg: 30-50 mg: 100 mg: 35 mL.
7. The preparation method of the platinum-loaded molybdenum dioxide hybrid material as claimed in claim 6, wherein in the step 2, a platinum source and a complexing agent are respectively ultrasonically dissolved in a reducing solvent to obtain a platinum source/reducing solution and a complexing agent/reducing solution, and MoO is added2Dispersing the nano-rods in a reducing solution to obtain MoO2Nanorod/reducing solution;
the platinum source/reducing solution and the complexing agent/reducing solution were added drop-wise to the MoO simultaneously2Reacting in the nano rod/reducing solution to prepare Pt loaded MoO2A nanorod material.
8. The preparation method of the platinum-supported molybdenum dioxide hybrid material as claimed in claim 7, wherein in the step 2, the reaction is carried out at 90-120 ℃ for 15-25 h.
9. A platinum loaded MoO prepared by any of the methods of claims 1-82A nanorod material.
10. The platinum-supported MoO of claim 92The application of the nano-rod material in the preparation of hydrogen evolution reaction electro-catalysts.
Technical Field
The invention relates to the technical field of a preparation method of a nano material and electrocatalysis application, and particularly relates to a platinum-loaded molybdenum dioxide hybrid nano material and a preparation method and electrocatalysis application thereof.
Background
Energy and environment are the most major problems involved in the sustainable development of human society. The global 80% of energy demand is derived from fossil fuels, which ultimately leads to exhaustion of fossil fuels, and the use thereof also leads to serious environmental pollution. The gradual shift from fossil fuels to non-fossil energy sources that can be sustainably developed without pollution is a necessary trend of development. Hydrogen is one of ideal clean energy sources, is also an important chemical raw material, and is widely regarded by all countries in the world. The hydrogen production by water electrolysis has rich raw material sources and high hydrogen production purity, can be used together with systems such as solar power generation, wind power generation and the like, and is an important research direction at present. Platinum (Pt) is currently the most efficient catalyst, with the lowest hydrogen evolution overpotential and fast hydrogen evolution reaction kinetics (due to the near zero hydrogen binding energy). However, Pt is the most effective electrolytic water hydrogen evolution catalyst, but its large-scale application is limited due to its scarcity and high price. Therefore, it is of great significance to reduce the Pt content in the catalyst. For this reason, many studies have been made to develop a monatomic Pt catalyst in order to reduce the amount of Pt used. Loading Pt single atoms or clusters on a support is an ideal way to reduce cost. However, the synthesis of conventional Pt monatomic or cluster catalysts typically involves harsh conditions, techniques, or expensive equipment, such as atomic layer deposition techniques (ALD). Therefore, it is important to develop a simple and low-cost method for synthesizing Pt single-atom or cluster catalysts.
In the preparation of monatomic or cluster catalysts, the nature of the support plays an important role in determining the catalytic activity and stability of the metal supported catalyst. It is well known that structural defects within metal oxides, including oxygen defects and/or metal defects, can modify or anchor metal atoms or act as active sites themselves. In particular, the introduction of new metallic phases into structural defects will inevitably alter the electronic structure of the active sites and affect the catalytic performance. Thus allowing the supported metal phase to react with the oxygen of the supportStrong interaction is generated among the vacancies, and the catalytic activity is promoted. So far, various oxygen-rich vacancies (O)vac) Of metal oxides, e.g. TiOx，CoOx，MoOx，WOx，CeOx，NiOxAs a support for platinum-based catalysts, extensive studies have been made. Although these catalysts have excellent catalytic activity, the activity and stability of these catalysts are not sufficient for industrial applications, especially stability at high current densities. Particularly, few catalysts can simultaneously have stable hydrogen production performance with long-term large current density under acidic and alkaline neutral conditions. Therefore, the development of efficient electrocatalysts in the all-acid-base electrolyte range, especially in neutral environments, remains a great challenge.
Disclosure of Invention
The invention aims to provide a platinum-loaded molybdenum dioxide hybrid nano material, a preparation method and an electrocatalysis application thereof, which reduce the use amount of noble metal Pt to the maximum extent, achieve the best hydrogen production effect by electrolyzing water, and create a cost-effective industrial load type catalyst Pt/MoO for electrolyzing water2. The preparation process is simple, low in cost, low in requirement on required equipment, easy to realize industrial amplification and batch preparation, and good in industrial prospect.
The first purpose of the invention is to provide a preparation method of a platinum-loaded molybdenum dioxide hybrid material, which comprises the following steps:
step 1, MoO rich in vacancy defects2Preparation of the carrier: dissolving a molybdenum salt and a complexing agent in water, adjusting the pH value of the solution to 4-5 with an acid, carrying out water bath reaction at 30-80 ℃ for 2-3 h, after the reaction is finished, carrying out suction filtration, washing and drying on a product, carrying out pyrolysis on the product for 1-2 h at 600-650 ℃ in an argon protective atmosphere, and preparing the MoO rich in vacancy defects2A nanorod;
step 2, in the MoO rich in vacancy defects2Loading platinum on the carrier: adding MoO2The nano-rod is taken as a carrier, a platinum source, a complexing agent and a reducing solvent are added, and the platinum is loaded on MoO in the form of single atom or cluster by a solvothermal reduction method2Preparing Pt loaded MoO on a nanorod carrier2A nanorod material.
Preferably, the molybdenum salt is ammonium heptamolybdate tetrahydrate; the complexing agent is ethylenediamine; the acid is 1mol/L dilute hydrochloric acid; the platinum source is potassium tetrachloroplatinate; the complexing agent is polyvinylpyrrolidone; the reducing solvent is ethylene glycol.
Preferably, in step 1, the ratio of molybdenum salt: a complexing agent: the ratio of water was 2.48 g: 1.78 mL: 30 mL.
Preferably, the suction filtration mode in the step 1 is vacuum filtration, and water and ethanol are used for washing in sequence during washing.
Preferably, the drying temperature in step 1 is 30-100 ℃.
Preferably, in step 2, the reducing solution is used as the reaction solution, and the ratio of the platinum source: complexing agent: MoO2And (3) nano-rods: the ratio of the reducing solvent is 5-35 mg: 30-50 mg: 100 mg: 35 mL.
Preferably, in step 2, a platinum source and a complexing agent are respectively ultrasonically dissolved in a reducing solvent to obtain a platinum source/reducing solution and a complexing agent/reducing solution, and MoO is added2Dispersing the nano-rods in a reducing solution to obtain MoO2Nanorod/reducing solution;
the platinum source/reducing solution and the complexing agent/reducing solution were added drop-wise to the MoO simultaneously2Reacting in the nano rod/reducing solution to prepare Pt loaded MoO2A nanorod material.
Preferably, in the step 2, the reaction condition is 90-120 ℃ for 15-25 h.
The second object of the present invention is a platinum-supported MoO prepared according to the above preparation method2A nanorod material of said platinum loaded MoO2The nano-rod material is of a nano-rod structure with the diameter of 100-600 nm and the length of 1-10 mu m; platinum nanoclusters or platinum monoatomic atoms with average size of less than 3nm are uniformly distributed in MoO2On the nano-rod.
The third purpose of the invention is to provide the platinum-loaded MoO2The application of the nano-rod material in the preparation of hydrogen evolution reaction electro-catalysts.
Compared with the prior art, the invention has the following beneficial effects:
the invention synthesizes MoO2Nanorods, Pt supported on MoO in the form of single atom or cluster2On the nano-rod. The use amount of noble metal Pt is reduced to the maximum extent, the best hydrogen production effect by water electrolysis is achieved, and a cost-effective industrial supported catalyst Pt/MoO for water electrolysis is created2. The supported catalyst is acidic (0.5M H)2SO4) Can be used as excellent hydrogen evolution catalyst under the conditions of alkalinity (1M KOH) and neutrality (1M PBS).
Drawings
FIG. 1 shows the MoO carrier provided in examples 1 to 32Wherein (a) is an SEM image at a magnification of 30000 and (b) is an SEM image at a magnification of 6000;
FIG. 2 shows a platinum monatomic or cluster-supported molybdenum dioxide electrocatalyst (1.1 wt% Pt/MoO) provided in example 12) Wherein (a) is the molybdenum dioxide electrocatalyst supported on platinum single atoms or clusters (1.1 wt% Pt/MoO) provided in example 12) Partial SEM images of (a); (b) the platinum monatomic or cluster-supported molybdenum dioxide electrocatalyst (1.1 wt% Pt/MoO) provided for example 12) A single TEM image of; (c) the platinum monatomic or cluster-supported molybdenum dioxide electrocatalyst (1.1 wt% Pt/MoO) provided for example 12) High resolution TEM images loaded with a large number of platinum single atoms; (d) the platinum monatomic or cluster-supported molybdenum dioxide electrocatalyst (1.1 wt% Pt/MoO) provided for example 12) The lattice distance, lattice defect, and a high-resolution TEM image of the supported platinum monoatomic; (e) the platinum monatomic or cluster-supported molybdenum dioxide electrocatalyst (1.1 wt% Pt/MoO) provided for example 12) The linear element distribution energy spectrogram; (f) the platinum monatomic or cluster-supported molybdenum dioxide electrocatalyst (1.1 wt% Pt/MoO) provided for example 12) A TEM image of the area surface element distribution of (a);
FIG. 3 is a scanned image of a platinum monatomic or cluster-supported molybdenum dioxide electrocatalyst, wherein (a) is the platinum monatomic or cluster-supported molybdenum dioxide electrocatalyst (2.48 wt% Pt/MoO) provided in example 22) Partial SEM image of (a). (b) Electrocatalysis of platinum monatomic or cluster-supported molybdenum dioxide as provided for example 3Agent (5.6 wt% Pt/MoO)2) Partial SEM images of (a);
FIG. 4 shows a platinum monatomic or cluster-supported molybdenum dioxide electrocatalyst (2.48 wt% Pt/MoO) provided in example 22) High resolution TEM images loaded with a large number of platinum monoatomic atoms and platinum clusters;
FIG. 5 is a TEM image of the molybdenum dioxide electrocatalyst supported on platinum monoatomic or cluster provided in example 3, wherein (a) is the molybdenum dioxide electrocatalyst supported on platinum monoatomic or cluster provided in example 3 (5.6 wt% Pt/MoO)2) High resolution TEM images loaded with a large number of platinum clusters; (b) the platinum monatomic or cluster-supported molybdenum dioxide electrocatalyst (5.6 wt% Pt/MoO) provided for example 32) TEM images of Pt cluster lattice distances of (a);
FIG. 6 shows the platinum monatomic or cluster-supported molybdenum dioxide electrocatalysts (x wt% Pt/MoO) provided in examples 1-32X ═ 1.1, 2.48, 5.6) and the XRD pattern of pure molybdenum dioxide;
FIG. 7 shows a platinum monatomic or cluster-supported molybdenum dioxide electrocatalyst (1.1 wt% Pt/MoO) provided in example 12) And electron spin resonance spectra of pure molybdenum dioxide;
FIG. 8 shows a platinum monatomic or cluster-supported molybdenum dioxide electrocatalyst (1.1 wt% Pt/MoO) provided in example 12) And an X-ray photoelectron spectrum of O1s of pure molybdenum dioxide;
FIG. 9 shows the platinum monatomic or cluster-supported molybdenum dioxide electrocatalysts (x wt% Pt/MoO) provided in examples 1-32X ═ 1.1, 2.48, 5.6) and LSV curves of pure molybdenum dioxide, 20 wt% Pt/C under acidic conditions;
FIG. 10 shows the platinum monatomic or cluster-supported molybdenum dioxide electrocatalysts (x wt% Pt/MoO) provided in examples 1-32X ═ 1.1, 2.48, 5.6) and LSV curves of pure molybdenum dioxide, 20 wt% Pt/C under neutral conditions;
FIG. 11 shows the platinum monatomic or cluster-supported molybdenum dioxide electrocatalysts (x wt% Pt/MoO) provided in examples 1-32X ═ 1.1, 2.48, 5.6) and LSV curves of pure molybdenum dioxide, 20 wt% Pt/C under alkaline conditions;
FIG. 12 shows a platinum monatomic or cluster-supported molybdenum dioxide electrocatalyst (1.1 wt% P) provided in example 1t/MoO2) And a constant current stability curve of 20 wt% Pt/C under various conditions, wherein (a) is the molybdenum dioxide electrocatalyst supported on platinum monoatomic or cluster (1.1 wt% Pt/MoO) provided in example 12) And a constant current stability curve of 20 wt% Pt/C under acidic conditions; (b) the platinum monatomic or cluster-supported molybdenum dioxide electrocatalyst (1.1 wt% Pt/MoO) provided for example 12) And a constant current stability curve of 20 wt% Pt/C under alkaline conditions; (c) the platinum monatomic or cluster-supported molybdenum dioxide electrocatalyst (1.1 wt% Pt/MoO) provided for example 12) And a constant current stability curve of 20 wt% Pt/C under neutral conditions.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
A preparation method of a platinum-loaded molybdenum dioxide electrocatalyst comprises the following steps:
(1) MoO rich in vacancy defects2Preparation of the carrier: 2.48g of ammonium heptamolybdate tetrahydrate and 1778. mu.L of ethylenediamine were dissolved in 30mL of distilled water, and 1M hydrochloric acid was added dropwise to the solution while stirring to adjust the pH of the solution to about 4-5, and a white precipitate gradually precipitated during the adjustment. Then the adjusted solution is put into a water bath at 50 ℃ to be slowly stirred and reacted for 2 hours. And then cleaning the reaction white precipitate product by vacuum filtration, flushing with 500mL of distilled water, then flushing with 100mL of ethanol in the washing process, drying the obtained white precipitate product in an oven at 70 ℃ for 3h, finally putting the dried white precipitate product into a tubular furnace, raising the temperature to 650 ℃ at the rate of 5 ℃/min under 20mL/min of nitrogen flow, keeping the temperature for 2h, naturally cooling, and finally obtaining the MoO rich in vacancy defects2And (3) a carrier.
(2) MoO loaded with platinum monoatomic or platinum cluster in vacancy defect-rich state2On a carrier: weighing 35ml ethylene glycol, dividing into three parts, respectively 25ml ethylene glycol and two parts of 5ml ethylene glycol, firstly, 100mg MoO2Ultrasonic dispersion was carried out for 10min in 25mL of ethylene glycol, which was then placed in a 100 ℃ oil bath and vigorously stirred for 1h to obtain solution C. Subsequently, 5mg of potassium tetrachloroplatinate was dispersed ultrasonically for 10min in 5mL of ethylene glycol to form a homogeneous solution A. At the same time, 30mg of polyvinylpyrrolidone (PVP, Mr. 10000) required was dispersed ultrasonically for 10min in another 5mL of ethylene glycol to form a homogeneous solution B. Solution a and solution B were then added simultaneously very slowly, drop by drop, to solution C. Stirring at 100 deg.C for 20 hr to obtain black precipitate, washing with anhydrous ethanol for several times to remove ethylene glycol solvent, and drying at 70 deg.C for 10 hr to obtain platinum monatomic supported MoO2Recorded as 1.1 wt% Pt/MoO2And (4) nanorods.
Example 2
A preparation method of a platinum monatomic or cluster-loaded molybdenum dioxide electrocatalyst comprises the following steps:
(1) MoO rich in vacancy defects2Preparation of the carrier: 2.48g of ammonium heptamolybdate tetrahydrate and 1778. mu.L of ethylenediamine were dissolved in 30mL of distilled water, and 1M hydrochloric acid was added dropwise to the solution while stirring to adjust the pH of the solution to about 4-5, and a white precipitate gradually precipitated during the adjustment. Then the adjusted solution is put into a water bath at 50 ℃ to be slowly stirred and reacted for 2 hours. And then cleaning the reaction white precipitate product by vacuum filtration, flushing with 500mL of distilled water, then flushing with 100mL of ethanol in the washing process, drying the obtained white precipitate product in an oven at 70 ℃ for 3h, finally putting the dried white precipitate product into a tubular furnace, raising the temperature to 650 ℃ at the rate of 5 ℃/min under 20mL/min of nitrogen flow, keeping the temperature for 2h, naturally cooling, and finally obtaining the MoO rich in vacancy defects2And (3) a carrier.
(2) MoO loaded with platinum monoatomic or platinum cluster in vacancy defect-rich state2On a carrier: weighing 35ml of ethylene glycol, dividing into three parts, namely 25ml of ethylene glycol and two parts of 5ml of ethylene glycolAlcohol, first 100mg MoO2Ultrasonic dispersion was carried out for 10min in 25mL of ethylene glycol, which was then placed in a 100 ℃ oil bath and vigorously stirred for 1h to obtain solution C. Subsequently, 12mg of potassium tetrachloroplatinate was dispersed ultrasonically for 10min in 5mL of ethylene glycol to form a homogeneous solution A. Meanwhile, 40mg of polyvinylpyrrolidone (PVP, Mr. 10000) required was ultrasonically dispersed for 10min in another 5mL of ethylene glycol to form a homogeneous solution B. Solution a and solution B were then added simultaneously very slowly, drop by drop, to solution C. Then stirring for 20 hours at 100 ℃, washing the black precipitate product with absolute ethyl alcohol for multiple times to remove the ethylene glycol solvent, and drying for 10 hours at 70 ℃ to obtain the MoO loaded by the platinum monoatomic atoms and platinum clusters2Recorded as 2.48 wt% Pt/MoO2And (4) nanorods.
Example 3
A preparation method of a platinum monatomic or cluster-loaded molybdenum dioxide electrocatalyst comprises the following steps:
(1) MoO rich in vacancy defects2Preparation of the carrier: 2.48g of ammonium heptamolybdate tetrahydrate and 1778. mu.L of ethylenediamine were dissolved in 30mL of distilled water, and 1M hydrochloric acid was added dropwise to the solution while stirring to adjust the pH of the solution to about 4-5, and a white precipitate gradually precipitated during the adjustment. Then the adjusted solution is put into a water bath at 50 ℃ to be slowly stirred and reacted for 2 hours. And then cleaning the reaction white precipitate product by vacuum filtration, flushing with 500mL of distilled water, then flushing with 100mL of ethanol in the washing process, drying the obtained white precipitate product in an oven at 70 ℃ for 3h, finally putting the dried white precipitate product into a tubular furnace, raising the temperature to 650 ℃ at the rate of 5 ℃/min under 20mL/min of nitrogen flow, keeping the temperature for 2h, naturally cooling, and finally obtaining the MoO rich in vacancy defects2And (3) a carrier.
(2) MoO loaded with platinum monoatomic or platinum cluster in vacancy defect-rich state2On a carrier: weighing 35ml ethylene glycol, dividing into three parts, respectively 25ml ethylene glycol and two parts of 5ml ethylene glycol, firstly, 100mg MoO2Ultrasonic dispersion was carried out for 10min in 25mL of ethylene glycol, which was then placed in a 100 ℃ oil bath and vigorously stirred for 1h to obtain solution C. Subsequently, 35mg of potassium tetrachloroplatinate were dispersed ultrasonicallyA homogeneous solution A was formed in 5mL of ethylene glycol for 10 min. At the same time, 50mg of polyvinylpyrrolidone (PVP, Mr. 10000) required was dispersed ultrasonically for 10min in another 5mL of ethylene glycol to form a homogeneous solution B. Solution a and solution B were then added simultaneously very slowly, drop by drop, to solution C. Then stirring for 20 hours at 100 ℃, washing the black precipitate product with absolute ethyl alcohol for multiple times to remove the ethylene glycol solvent, and drying for 10 hours at 70 ℃ to obtain the platinum cluster supported MoO2Recorded as 5.6 wt% Pt/MoO2And (4) nanorods.
Example 4
A preparation method of a platinum monatomic or cluster-loaded molybdenum dioxide electrocatalyst comprises the following steps:
(1) MoO rich in vacancy defects2Preparation of the carrier: 2.48g of ammonium heptamolybdate tetrahydrate and 1778. mu.L of ethylenediamine were dissolved in 30mL of distilled water, and 1M hydrochloric acid was added dropwise to the solution while stirring to adjust the pH of the solution to about 4-5, and a white precipitate gradually precipitated during the adjustment. Then the adjusted solution is put into a water bath with the temperature of 30 ℃ to be slowly stirred and react for 3 hours. And then cleaning the reaction white precipitate product by vacuum filtration, flushing with 500mL of distilled water, then flushing with 100mL of ethanol in the washing process, drying the obtained white precipitate product in an oven at 70 ℃ for 3h, finally putting the dried white precipitate product into a tubular furnace, heating to 600 ℃ at a heating rate of 5 ℃/min under 20mL/min of nitrogen flow, keeping the temperature for 1h, naturally cooling, and finally obtaining the MoO rich in vacancy defects2And (3) a carrier.
(2) MoO loaded with platinum monoatomic or platinum cluster in vacancy defect-rich state2On a carrier: weighing 35ml ethylene glycol, dividing into three parts, respectively 25ml ethylene glycol and two parts of 5ml ethylene glycol, firstly, 100mg MoO2Ultrasonic dispersion was carried out for 10min in 25mL of ethylene glycol, which was then placed in a 100 ℃ oil bath and vigorously stirred for 1h to obtain solution C. Subsequently, 35mg of potassium tetrachloroplatinate was dispersed ultrasonically for 10min in 5mL of ethylene glycol to form a homogeneous solution A. At the same time, 50mg of polyvinylpyrrolidone (PVP, Mr. 10000) required was dispersed ultrasonically for 10min in another 5mL of ethylene glycol to form a homogeneous solution B. Then the solution A and the solution are mixedB was added simultaneously very slowly, drop by drop, to solution C. Then stirring for 25 hours at 90 ℃, washing the black precipitate product with absolute ethyl alcohol for multiple times to remove the ethylene glycol solvent, and drying for 10 hours at 70 ℃ to obtain the platinum cluster-supported MoO2Recorded as 5.6 wt% Pt/MoO2And (4) nanorods.
Example 5
A preparation method of a platinum monatomic or cluster-loaded molybdenum dioxide electrocatalyst comprises the following steps:
(1) MoO rich in vacancy defects2Preparation of the carrier: 2.48g ammonium heptamolybdate tetrahydrate and 1778. mu.L ethylenediamine were dissolved in 30mL of distilled water, and 1M hydrochloric acid was added dropwise to the solution with stirring to adjust the pH of the solution to about 4-5, preferably about 4.5, with white precipitate gradually precipitating out during the adjustment. Then the adjusted solution is put into a water bath with the temperature of 80 ℃ to be slowly stirred and react for 2 hours. And then cleaning the reaction white precipitate product by vacuum filtration, flushing with 500mL of distilled water, then flushing with 100mL of ethanol in the washing process, drying the obtained white precipitate product in an oven at 70 ℃ for 3h, finally putting the dried white precipitate product into a tubular furnace, raising the temperature to 650 ℃ at the rate of 5 ℃/min under 20mL/min of nitrogen flow, keeping the temperature for 1h, naturally cooling, and finally obtaining the MoO rich in vacancy defects2And (3) a carrier.
(2) MoO loaded with platinum monoatomic or platinum cluster in vacancy defect-rich state2On a carrier: weighing 35ml ethylene glycol, dividing into three parts, respectively 25ml ethylene glycol and two parts of 5ml ethylene glycol, firstly, 100mg MoO2Ultrasonic dispersion was carried out for 10min in 25mL of ethylene glycol, which was then placed in a 100 ℃ oil bath and vigorously stirred for 1h to obtain solution C. Subsequently, 35mg of potassium tetrachloroplatinate was dispersed ultrasonically for 10min in 5mL of ethylene glycol to form a homogeneous solution A. At the same time, 50mg of polyvinylpyrrolidone (PVP, Mr. 10000) required was dispersed ultrasonically for 10min in another 5mL of ethylene glycol to form a homogeneous solution B. Solution a and solution B were then added simultaneously very slowly, drop by drop, to solution C. After subsequent stirring at 120 ℃ for 15 hours, the black precipitate is washed several times with absolute ethanol to remove the ethylene glycol solvent and dried at 70 ℃Drying for 10h to obtain the MoO loaded with platinum clusters2Recorded as 5.6 wt% Pt/MoO2And (4) nanorods.
FIG. 1 shows the MoO carrier provided in examples 1 to 32FIG. 1 shows that the MoO carrier2Is a uniform one-dimensional nano rod-shaped structure
FIG. 2 is an electron microscope image of the platinum monatomic or cluster-supported molybdenum dioxide electrocatalyst provided in example 1, and it can be seen from FIG. 2 that the molybdenum dioxide electrocatalyst is supported on a carrier MoO2After the platinum monoatomic is loaded, the microscopic appearance is basically kept unchanged, and the loaded platinum monoatomic successfully enters MoO2The simultaneous distribution of the element energy spectrum shows that all elements are uniformly distributed on the whole nanorod, which shows that platinum is in the carrier MoO2High degree of uniform dispersion.
FIG. 3 is a scanned image of a molybdenum dioxide electrocatalyst supported on a single atom or cluster of platinum on a MoO support2After the platinum monoatomic group and the platinum cluster are loaded, the microscopic morphology is basically kept unchanged and is still a uniform one-dimensional nanorod, which indicates that the loading of the platinum has no influence on the structure of the carrier.
FIG. 4 is a high resolution TEM image of a platinum monatomic or cluster-supported molybdenum dioxide electrocatalyst supporting a plurality of platinum monatomic and platinum clusters provided in example 2; as can be seen from fig. 4, as the platinum loading increases from 1.1 wt% to 2.48 wt%, the loading form of platinum changes from the presence of only platinum monoatomic species to the presence of platinum clusters, and the platinum loading occurs in both monoatomic and cluster forms.
Fig. 5 is a TEM image of the platinum monatomic or cluster-supported molybdenum dioxide electrocatalyst provided in example 3, wherein when the platinum loading is again increased to 5.6 wt%, the supported form of platinum ends up with only platinum clusters present.
FIG. 6 is an XRD spectrum of the platinum monatomic or cluster-supported molybdenum dioxide electrocatalyst and pure molybdenum dioxide provided in examples 1-3; pure carrier MoO2And 1.1 wt% Pt/MoO after platinum Loading2、2.48wt％Pt/MoO2And 5.6 wt% Pt/MoO2In the case of the crystal diffraction peak of the catalyst at an angle of 5-80 degrees, the peak shape after platinum loading is basically kept unchanged, and meanwhile, no platinum diffraction peak exists. Shows that platinum is loaded on the MoO carrier in the form of single atom or cluster2The above.
FIG. 7 is an electron spin resonance spectrum of a platinum monatomic or cluster-supported molybdenum dioxide electrocatalyst and pure molybdenum dioxide provided in example 1; as can be seen from FIG. 7, the pure support MoO2Has an oxygen vacancy concentration much greater than 1.1 wt% Pt/MoO2Oxygen vacancy concentration of (2) indicating that the supported platinum atom occupies the carrier MoO2The oxygen vacancy content is reduced.
FIG. 8 is an X-ray photoelectron spectrum of O1s of the molybdenum dioxide electrocatalyst supported on platinum single atom or cluster and pure molybdenum dioxide provided in example 1; as can be seen from FIG. 8, the analysis of the fitting of X-ray photoelectron spectroscopy to O1s showed that MoO was present on the support2After the platinum atom is loaded, the oxygen vacancy concentration is reduced, and the fact that the loaded platinum atom occupies the carrier MoO is proved2Oxygen vacancies of (a).
To further verify Pt/MoO2Nanorod Performance at different pH values (0.5M H)2SO4The pH value is 0.3; 1M KOH, pH 14; or 1M phosphate buffer, pH 7), using an Ag/AgCl electrode as a reference electrode and a graphite electrode as a counter electrode, coated with Pt/MoO prepared in examples 1 to 32The glassy carbon electrode of the nanorod was used as the working electrode and the three-electrode test was performed on Chenghua CHI660E electrochemical workstation. Coated with Pt/MoO prepared in examples 1-32The preparation of the glassy carbon electrode of the nano rod comprises the following steps: 5mg of the catalyst and 100. mu.L of 5wt 5% Nafion solution were dispersed in 900. mu.L of ethanol and sonicated for 30 minutes to form a uniform ink, and 5. mu.L of the ink was dropped onto a glassy carbon electrode having a diameter of 3mm and a loading of 0.21mg cm-2。
Linear Sweep Voltammetry (LSV) at 5 mV.s-1The polarization curve is obtained at a scanning rate of 90% with ohmic compensation; the voltage range is 0V to-0.7V, the Cyclic Voltammetry (CV) test is firstly carried out for 50 circles of stable catalyst, and the sweep rate is 50 mV.s-1. As shown in FIGS. 9 to 11, it can be seen from FIG. 9 that 1.1 wt% Pt/MoO is contained in the acidic electrolyte2The catalyst showed the best electrocatalytic hydrogen evolution activity due to the synergistic effect of the platinum single atom and the oxygen vacancy, 2.48 wt% Pt/MoO2And 5.6 wt% Pt/MoO2The catalyst showed 20 wt% compared with the commercial catalystThe Pt/C catalyst has similar electrocatalytic hydrogen evolution activity, even better. As can be seen from FIG. 10, in the neutral electrolyte, 1.1 wt% Pt/MoO2，2.48wt％Pt/MoO2And 5.6 wt% Pt/MoO2The catalysts all showed better electrocatalytic hydrogen evolution activity than the commercial 20 wt% Pt/C catalyst. As can be seen from FIG. 11, in the neutral electrolyte, 1.1 wt% Pt/MoO2，2.48wt％Pt/MoO2And 5.6 wt% Pt/MoO2The catalysts all showed better electrocatalytic hydrogen evolution activity than the commercial 20 wt% Pt/C catalyst. Then, a constant current measurement was performed on the voltage-time curve to obtain a stability curve, as shown in FIG. 12, it can be seen from FIG. 12 that the long-term large current density electrocatalytic hydrogen evolution in acidic, neutral, and alkaline electrolytes is 1.1 wt% Pt/MoO2The catalysts all showed more stable hydrogen evolution catalytic stability than the commercial 20 wt% Pt/C catalyst.
The basic principle of hydrogen evolution activity of electrolytes with different acidity is as follows:
in an acid electrolyte:
in neutral and alkaline electrolytes:
while preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.