阅读说明：本技术 一种用于酸性电解水制氢的低铂复合材料的制备方法 (Preparation method of low-platinum composite material for hydrogen production by acidic electrolyzed water ) 是由 闫海静 付宏刚 杨淦曾 田春贵 于 2020-05-07 设计创作，主要内容包括：本发明涉及解决目前酸性电解水析氢催化剂成本高、活性较低等问题,而提供的一种低贵金属担载的磷化物/石墨烯材料的制备方法,以氧化石墨为载体,利用聚乙烯亚胺修饰氧化石墨使其表面带正电荷,随后加入磷钼酸,经静电组装和水热处理获得磷钼酸/氧化石墨复合体,将磷钼酸/氧化石墨复合体进行高温磷化,冷却后洗涤得到磷化钼/石墨烯复合体,将获得的磷化钼/石墨烯复合体分散于氯铂酸溶液中,在氙灯照射条件下进行光照还原,最终获得低铂负载的磷化钼/石墨烯复合体。通过本方法制得的低铂负载的磷化钼/石墨烯材料具有纳米颗粒尺寸小、高分散的特点,并且展现出优异的酸性电解水析氢活性。(The invention relates to a preparation method of a low-noble-metal-supported phosphide/graphene material, which solves the problems of high cost, low activity and the like of the existing acidic electrolysis hydrogen evolution catalyst. The low-platinum-load molybdenum phosphide/graphene material prepared by the method has the characteristics of small nanoparticle size and high dispersion, and shows excellent acidic electrolyzed water hydrogen evolution activity.)

1. A preparation method of a low-platinum composite material for hydrogen production by acidic electrolyzed water is characterized by comprising the following steps:

step one, adding graphite oxide prepared in advance into deionized water, and stirring to form uniform dispersion liquid;

step two, adding polyethyleneimine into the graphite oxide dispersion liquid, and mutually combining the polyethyleneimine and the graphite oxide dispersion liquid due to different charges of the polyethyleneimine and the graphite oxide dispersion liquid which are mutually attracted;

adding the phosphomolybdic acid solution into the suspension of the polyethyleneimine and the graphite oxide under stirring, obtaining phosphomolybdic acid-polyethyleneimine-graphite oxide suspension due to electrostatic attraction, and continuing stirring to ensure full combination; the mass ratio of the phosphomolybdic acid to the graphite oxide-polyethyleneimine is (0.5-2): 1, and the stirring is carried out for 12-24 hours;

placing the suspension obtained in the previous step into a stainless steel reaction kettle with a polytetrafluoroethylene lining, carrying out hydrothermal treatment at 160-200 ℃ for 12-24 hours, cooling, and carrying out suction filtration to obtain a phosphomolybdic acid/graphite oxide composite material;

putting the obtained phosphomolybdic acid/graphite oxide complex into a tubular furnace, taking phosphine generated by thermal decomposition of sodium hypophosphite as a phosphorus source, carrying out phosphorization calcination at 500-900 ℃ for 2-4 hours, naturally cooling to room temperature along with the furnace, soaking and washing with dilute sulfuric acid to remove impurities, and thus obtaining a molybdenum phosphide/graphene complex;

and step six, adding a certain amount of 7.72mM chloroplatinic acid solution into the complex obtained in the last step, adding 20mL deionized water, and fully combining the two under stirring. Obtaining chloroplatinic acid and molybdenum phosphide/graphene suspension;

and seventhly, carrying out photoreduction on the suspension obtained in the last step under the irradiation of a xenon lamp with certain illumination intensity and continuous stirring for 10-30 min under stirring, so that the chloroplatinic acid is uniformly reduced in the system. And then centrifuging, washing and drying to obtain the low-platinum-load molybdenum phosphide/graphene complex.

2. The preparation method of the low-platinum composite material for hydrogen production through acidic electrolysis of water according to claim 1, wherein the mass ratio of graphite oxide to deionized water in the first step is regulated and controlled to be 1 (100-200).

3. The preparation method of the low-platinum composite material for hydrogen production through acidic electrolysis of water according to claim 1, wherein the mass ratio of polyethyleneimine to graphite oxide in the second step is regulated and controlled to be (0.5-2): 1.

4. The preparation method of the low-platinum composite material for hydrogen production through acidic electrolysis of water according to claim 1, wherein the mass ratio of phosphomolybdic acid to graphite oxide-polyethyleneimine in the step three is regulated and controlled to be (0.5-2): 1, and stirring is regulated and controlled to be 12-24 hours.

5. The preparation method of the low-platinum composite material for hydrogen production by acidic electrolyzed water according to claim 1, wherein in the fourth step, the hydrothermal temperature is regulated and controlled between 160 ℃ and 200 ℃, and the hydrothermal time is regulated and controlled between 12 hours and 24 hours.

6. The preparation method of the low-platinum composite material for hydrogen production through acidic electrolyzed water according to claim 1, wherein the phosphorization calcination temperature in the fifth step is 500-900 ℃, and the calcination time is regulated and controlled within 2-4 hours.

7. The preparation method of the low-platinum composite material for hydrogen production through acidic electrolyzed water according to claim 1, wherein the amount of the chloroplatinic acid solution in the sixth step is regulated and controlled within 2.4-9.6 mL, and the stirring time is regulated and controlled within 3-6 hours.

8. The preparation method of the low-platinum composite material for hydrogen production through acidic electrolyzed water according to claim 1, wherein the illumination intensity of a xenon lamp light source in the seventh step is 200-300W/m²The distance between the light source and the system is 10-30 cm, and the irradiation time is regulated and controlled within 10-30 min.

Technical Field

The invention relates to a preparation method of a low-precious metal loaded composite material, in particular to a preparation method of a low-platinum composite material for hydrogen production by acidic electrolyzed water.

Background

Hydrogen is a green, clean, new energy source with the potential to replace traditional fossil fuels. Hydrogen is obtained by a gas reforming method and an aqueous solution electrolysis method. Compared with the hydrogen production by methane steam reforming and the hydrogen production by alkaline decomposed water, the hydrogen production by acidic decomposed water has higher conversion efficiency (90%), higher response speed and higher hydrogen production purity, and meanwhile, the diaphragm technology (proton exchange membrane) of the acidic electrolytic cell is mature and the proton exchange membrane is applied in mass production, so the hydrogen production by acidic decomposed water is technically feasible. The traditional noble metal (Pt) base acid hydrogen production catalyst has overhigh cost and relatively unsatisfactory stability. Therefore, it is necessary to develop a catalyst having high catalytic activity and stability at low cost in an acidic medium. The transition metal phosphide has the characteristics of excellent conductivity, excellent stability under acidic conditions and the like due to the electronic structure of the phosphide. The catalyst has wide application in the fields of industrial catalytic hydrogenation reduction, hydroisomerization, water electrolysis and the like. The phosphide can be used as a noble metal cocatalyst to improve the catalytic performance of the noble metal. Because the noble metal is combined with phosphide, the catalytic activity of the noble metal is obviously improved due to electron transfer and synergistic action. The size of the catalyst is a very important factor affecting its catalytic performance. The selection of a suitable substrate (e.g., a carbon substrate) facilitates the controlled growth of the phosphide promoter. However, the existing synthesis method for growing and synthesizing phosphide with controllable size and uniform dispersion on a carbon-based material is less, and the preparation process is relatively complex and tedious. Meanwhile, the noble metal nanoparticles are grown, and the particles are aggregated due to nonuniform reduction, which is not favorable for performance. The exploration of a novel effective synthesis method to realize the preparation of phosphide and the loading of noble metal has important theoretical and practical significance for the commercial application of high-efficiency water electrolysis hydrogen production.

Disclosure of Invention

The invention aims to solve the problems of high cost and low activity of the existing acidic water splitting hydrogen production electrocatalyst, and provides a preparation method of a low-platinum composite material for acidic water electrolysis hydrogen production.

The method for preparing the low-platinum-load molybdenum phosphide/graphene complex is realized according to the following steps:

step one, adding graphite oxide prepared in advance into deionized water, and stirring to form uniform dispersion liquid;

step two, adding polyethyleneimine into the graphite oxide dispersion liquid, and mutually combining the polyethyleneimine and the graphite oxide dispersion liquid due to different charges of the polyethyleneimine and the graphite oxide dispersion liquid which are mutually attracted;

adding the phosphomolybdic acid solution into the suspension of the polyethyleneimine and the graphite oxide under stirring, obtaining phosphomolybdic acid-polyethyleneimine-graphite oxide suspension due to electrostatic attraction, and continuing stirring to ensure full combination;

placing the suspension obtained in the step into a stainless steel reaction kettle with a polytetrafluoroethylene lining for hydrothermal treatment, cooling and performing suction filtration to obtain a phosphomolybdic acid/graphite oxide composite material;

putting the obtained phosphomolybdic acid/graphite oxide complex into a tubular furnace, carrying out phosphorization calcination by taking phosphine generated by thermal decomposition of sodium hypophosphite as a phosphorus source, and then washing and drying to obtain a molybdenum phosphide/graphene complex;

and step six, adding a certain amount of chloroplatinic acid solution and deionized water into the complex obtained in the step six, and fully combining the chloroplatinic acid solution and the deionized water under stirring. Obtaining chloroplatinic acid and molybdenum phosphide/graphene suspension;

and seventhly, carrying out photoreduction on the suspension obtained in the step under stirring to ensure that the chloroplatinic acid is uniformly reduced in the system. And then centrifuging, washing and drying to obtain the low-platinum-load molybdenum phosphide/graphene composite.

The invention discloses a method for preparing a low-platinum-load molybdenum phosphide/graphene complex based on electrostatic assembly and photoreduction, wherein the obtained low-platinum-load molybdenum phosphide/graphene complex has the advantages of tight combination of components, small size of molybdenum phosphide and platinum nanoparticles, high dispersion, easy regulation and control of components and the like, and is used as an electrocatalyst for hydrogen production by water decomposition under acidic conditions. When the complex is used as a catalyst for preparing hydrogen by acidic electrolyzed water, the concentration of 10mA cm^-2Has a potential of 18mV lower than the commercial Pt/C activity (39mV) purchased, which is mass activity at-0.1V potential (60.2mA μ g Pt)^-1) Is a commercial Pt catalyst (5.45mA μ g Pt)^-1) 11.6 times of the total weight of the powder. The catalyst greatly improves the activity of the hydrogen production reaction by electrolyzing water under the catalytic acidic condition of the Pt-based catalyst, and reduces the consumption of noble metal Pt, thereby having certain application significance and laying a foundation for developing high-efficiency acidic hydrogen production catalysts in the future.

In summary, the invention also comprises the following beneficial effects:

1. the amount of noble metal used in the present invention is much lower than the noble metal loading of commercial catalysts and therefore relatively inexpensive.

2. The invention can realize the controllable synthesis of the composite material by regulating and controlling the variables such as the material feeding proportion, the heat treatment temperature and time, the photoreduction time and the like.

3. The invention synthesizes the low platinum-loaded molybdenum phosphide/graphene composite material through simple electrostatic adsorption. Compared with the traditional preparation method, the synthesis method of the composite material has the characteristics of relative simplicity, low energy consumption, environmental friendliness and the like. And the method can be applied to the mass synthesis of the composite material.

4. The molybdenum phosphide/graphene complex with low platinum load prepared by the method disclosed by the invention has the advantages that the molybdenum phosphide is used as a cocatalyst, the catalytic activity of the Pt-based catalyst is effectively improved, the aim of greatly improving the reaction activity of catalyzing acid decomposition water to prepare hydrogen by the Pt catalyst while the Pt dosage is reduced is initially achieved, and the method has important guiding significance for design and practical commercial application of electrocatalysis acid decomposition water to prepare hydrogen in future.

Drawings

FIG. 1 is a scanning electron microscope image of a low platinum loading molybdenum phosphide/graphene composite obtained in example one;

FIG. 2 is a linear sweep voltammogram of a low platinum loading molybdenum phosphide/graphene complex with a commercial Pt/C catalyst;

figure 3 is a mass activity comparison of a low platinum loading molybdenum phosphide/graphene composite with a commercial Pt/C catalyst.

Detailed Description