阅读说明：本技术 一种Co-B-P-O纳米粒子负载还原氧化石墨烯复合材料及其制备方法和应用 (Co-B-P-O nanoparticle loaded reduced graphene oxide composite material and preparation method and application thereof ) 是由 孙立贤 桑振 徐芬 康莉 李天硕 布依婷 荚鑫磊 刘昭宇 李彬 罗玉梅 邹勇进 于 2021-03-04 设计创作，主要内容包括：本发明公开了一种Co-B-P-O纳米粒子负载还原氧化石墨烯复合材料,通过改进的Hummers的方法得到氧化石墨烯材料,然后通过化学原位还原的方法将Co-B-P-O负载到还原氧化石墨烯上,得到Co-B-P-O纳米粒子负载还原氧化石墨烯复合材料,其比表面积为62-120 m～2g～(-1),孔径分布为12-14 nm。其制备方法包括以下步骤：1,氧化石墨烯纳米片载体的制备；2,Co-B-P-O纳米粒子负载还原氧化石墨烯复合材料的制备。作为硼氢化钠水解催化剂的应用,在298 K下提供的最大放氢速率达到9036.3 mL·min～(-1)g～(-1),放氢量为理论值的100%,催化放氢的活化能为E-a=28.64 kJ·mol～(-1)；10次循环使用后仍保留了其对硼氢化钠水解初始催化活性的88.9%。本发明具有高催化性能、高循环性能、工艺简单、反应周期短的特点。(The invention discloses a Co-B-P-O nanoparticle loaded reduced graphene oxide composite material, which is prepared by obtaining a graphene oxide material by an improved Hummers method, then loading Co-B-P-O on reduced graphene oxide by a chemical in-situ reduction method to obtain Co-B-P-O nanoparticle loaded reduced graphene oxideAn olefinic composite having a specific surface area of 62 to 120 m 2 g ‑1 The pore size distribution is 12-14 nm. The preparation method comprises the following steps: 1, preparing a graphene oxide nanosheet carrier; and (3) preparing the 2, Co-B-P-O nanoparticle loaded reduced graphene oxide composite material. The application of the catalyst as a sodium borohydride hydrolysis catalyst provides the maximum hydrogen release rate of 9036.3 mL.min at 298K ‑1 g ‑1 The hydrogen release amount is 100% of the theoretical value, and the activation energy of catalytic hydrogen release is E a =28.64 kJ•mol ‑1 (ii) a After 10 times of recycling, the catalyst still retains 88.9 percent of the initial catalytic activity of the catalyst on the hydrolysis of sodium borohydride. The invention has the characteristics of high catalytic performance, high cycle performance, simple process and short reaction period.)

1. A Co-B-P-O nanoparticle loaded reduced graphene oxide composite material is characterized in that: obtaining a graphene oxide material by an improved Hummers method, then loading Co-B-P-O on reduced graphene oxide by a chemical in-situ reduction method to obtain a Co-B-P-O nanoparticle loaded reduced graphene oxide composite material with a specific surface area of 62-120 m²g^-1The pore size distribution is 12-14 nm.

2. The preparation method of the Co-B-P-O nanoparticle-loaded reduced graphene oxide composite material according to claim 1, which is characterized by comprising the following two steps:

step 1, preparing a graphene oxide nanosheet carrier, namely adding raw materials including concentrated sulfuric acid, sodium nitrate, flaky graphite and potassium permanganate which meet a certain mass ratio into water under a certain condition to obtain a mixed solution; then, reacting the mixed solution under a certain condition, and after the reaction is finished, dropwise adding hydrogen peroxide into the mixed solution under a certain condition to react to remove excessive potassium permanganate; finally, repeatedly centrifuging, washing with hydrochloric acid and washing with deionized water until the pH value of the solution is 7 to obtain a graphene oxide solution, and freeze-drying to obtain a graphene oxide nanosheet carrier, namely GO;

step 2, preparing a raw material by using cobalt chloride hexahydrate, sodium hypophosphite monohydrate, sodium borohydride and the graphene oxide nanosheet carrier obtained in the step 1 to meet a certain mass ratio, uniformly mixing the graphene oxide nanosheet carrier obtained in the step 1 and ultrapure water in a mass ratio of 1:1 under an ultrasonic condition to obtain graphene oxide dispersion liquid, and preparing sodium borohydride into a sodium borohydride solution with the mass fraction of 5-6 wt%;

then, under the stirring condition, adding cobalt chloride hexahydrate and sodium hypophosphite monohydrate into the graphene oxide dispersion liquid for dissolving to obtain reaction liquid; then, dropwise adding a sodium borohydride solution into the reaction solution under a certain condition; and finally, washing, filtering and drying the reaction product to obtain the Co-B-P-O nanoparticle loaded reduced graphene oxide composite material, which is marked as Co-B-P-O/rGO.

3. The method of claim 2, wherein: the fineness of the flaky graphite in the step 1 is 300 meshes; in the step 1, the mass ratio of concentrated sulfuric acid to sodium nitrate to graphite powder to potassium permanganate is (46-55.2) to 1:1 (4-6).

4. The method of claim 2, wherein: the mixing condition in the step 1 is that the mixture is stirred under the condition of ice-water bath at the temperature of 0-5 ℃; the reaction condition of the mixed solution in the step 1 is that the mixed solution is stirred under the condition of constant-temperature water bath at 35-40 ℃ and the reaction time is 7-9 h.

5. The method of claim 2, wherein: the condition of dropwise adding the hydrogen peroxide in the step 1 is that before the hydrogen peroxide is dropwise added, the temperature of the mixed solution is reduced to 0-5 ℃, the ice water bath condition of 0-5 ℃ is kept when the hydrogen peroxide is dropwise added, stirring is carried out, the dropwise adding amount of the hydrogen peroxide is determined by the color of the mixed solution, and specifically, the dropwise adding of the hydrogen peroxide is stopped when the mixed solution is changed from brownish black to bright yellow; wherein the hydrogen peroxide is added to react to remove excessive potassium permanganate in the mixed solution.

6. The method of claim 5, wherein: the method for reducing the temperature of the mixed solution to 0-5 ℃ in the step 1 is that ice blocks are added into the mixed solution according to the mass ratio of the ice blocks to the mixed solution of (19-31) to (50-75), wherein the effect of adding the ice blocks into the mixed solution not only reduces the temperature of the mixed solution, but also dilutes the mixed solution to be acidic.

7. The method of claim 2, wherein: in the step 2, the mass ratio of the cobalt chloride hexahydrate, the sodium hypophosphite monohydrate, the sodium borohydride and the graphene oxide nanosheet carrier is (59-71): (159) -185: (57-66): 1.

8. The method of claim 2, wherein: and 2, dropwise adding the sodium borohydride solution under the condition of keeping an ice water bath at 0-5 ℃ and stirring vigorously to prepare Co-B-P-O nano particles, and after dropwise adding, continuously stirring for 10-12 h to ensure that the graphene oxide in the reaction liquid is completely reduced into the reduced graphene oxide.

9. The method of claim 2, wherein: the washing condition of the step 2 is that the washing is repeated for 3 to 5 times by adopting a water washing and ethanol washing mode; the drying condition of the step 2 is vacuum drying, the drying temperature is 50-60 ℃, and the drying time is 4-6 h.

10. The application of the Co-B-P-O nanoparticle-supported reduced graphene oxide composite material as a sodium borohydride hydrolysis catalyst according to claim 1, which is characterized in that: the maximum hydrogen release rate provided at 298K reaches 9036.3 mL^{- 1}g^-1The hydrogen release amount is 100% of the theoretical value, and the activation energy of catalytic hydrogen release is E_a=28.64 kJ•mol^-1(ii) a Can be used for 10 timesAfter that, 88.9% of the initial catalytic activity for the hydrolysis of sodium borohydride was retained.

Technical Field

The invention relates to the technical field of catalytic chemistry, in particular to a Co-B-P-O nanoparticle loaded reduced graphene oxide composite material and a preparation method and application thereof.

Background

The development of human society is not open to high-quality energy and advanced energy technologies. In the world, people are concerned about more about the development and utilization of energy sources, so that environmental protection is a common concern of human beings and is also a primary problem of economic development in China. However, fossil fuels have heretofore been used as the primary source of energy, with the CO produced during combustion₂、SO₂And the pollutants seriously cause global warming, environmental pollution, critical extinction of organisms and the like. Face the current world energy shortage and global security is threatenedUnder the circumstances, the discovery of clean energy and the use of alternative energy are effective ways to fundamentally solve these problems.

Molecular hydrogen (H) relative to any other hydrogen-carbon fuel₂) Has the lightest mass and the weight energy density (120 MJ/kg)^-1) The highest, and pollution-free by-product (water) is considered to be a promising candidate for future energy supply. Furthermore, molecular hydrogen (H)₂) Are considered to be a promising candidate for future energy supply. However, hydrogen is not naturally occurring and must therefore be handled in a different way. The greatest challenge is to produce hydrogen on a large scale in a sustainable manner. Today, commercial hydrogen is typically provided by high temperature reformulations of non-renewable resources (e.g., coal, natural gas, and petroleum). Other methods of producing hydrogen include electrolysis of water, decomposition or hydrolysis of hydrogen-containing species (amines, hydrides, etc.), solar-driven photocatalytic hydrogen production, and biological hydrogen production. Among the above routes, metal hydrides (NaBH) are included₄And LiBH₄) The catalytic hydrolysis of hydrogen-containing species of (a) is considered to be a convenient, economical and efficient way of producing hydrogen.

In particular, sodium borohydride (NaBH)₄) Due to its good hydrogen storage capacity (weight density up to 10.8 wt%), non-flammable characteristics and excellent resistance to alkaline solutions without any catalyst, it is considered a good candidate for hydrogen storage and generation by hydrolysis reactions. NaBH₄Due to the fact that daily storage of NaBH requires an excellent alkali-resistant solution, it is desired to use NaBH₄Hydrolysis rapidly produces hydrogen for practical applications, including particularly hydrogen fuel cell vehicles. As a result, a suitable catalyst is used to catalyze the controlled release of pure hydrogen NaBH₄And (4) hydrolyzing the alkaline solution. Furthermore, sodium metaborate, the only by-product, is water soluble and environmentally friendly, and the sodium borohydride hydrolysis hydrogen production reaction is shown below:

NaBH₄+2H₂ONaBO₂+4H₂

however, hydroborationThe hydrolysis kinetics of sodium are slow in natural conditions and the hydrogen evolved is only a small part of the theoretical yield, due to the reaction by-product NaBO₂Medium BO₂ ^-The large accumulation of the hydrogen is to cause the pH value of the reaction system to rise and the hydrolysis reaction to be inhibited, so that the hydrogen is released from the sodium borohydride by finding a high-efficiency, simple and low-cost technical means, which is a main problem facing the practical application of the hydrogen. The reaction rate is generally increased by catalyst, acid addition or system temperature increase, and the use of high-efficiency catalyst is the most effective method for realizing rapid reaction start and increasing the hydrogen production rate.

The research on sodium borohydride hydrolysis catalysts is largely divided into homogeneous and heterogeneous catalysts. The homogeneous catalyst can make the system produce hydrogen continuously, but the catalyst and the reaction liquid are difficult to separate, and the reaction is difficult to control effectively. Therefore, research on sodium borohydride hydrolysis catalysts has mainly focused on heterogeneous catalysts, which are mainly divided into noble metal catalysts and non-noble metal catalysts.

Although noble metal catalysts have good stability and catalytic activity, these catalysts are expensive and have limited reserves, so that they cannot be widely used, and therefore, research and development of a series of non-noble metal catalysts with low price and high catalytic activity are required. The non-noble metal catalyst is mainly transition metal Co, Ni, Fe, Cu, Mn, etc. Cobalt-based and nickel-based catalysts have been the most widely studied in recent years. The cobalt-based and nickel-based catalysts have strong regularity, the number of electrons in a d orbit of the cobalt-based and nickel-based catalysts is also not full, and the cobalt-based and nickel-based catalysts have abundant unsaturated active sites. Therefore, the non-noble metal catalyst has higher activity. In addition, the combination of the non-metal atom (e.g., P or B) with the transition metal changes the electronic state of the active metal, thereby improving the catalytic activity.

Wherein, compared with the original Co catalyst, the Co-B has higher catalytic activity, and the Co-P catalyst has good catalytic efficiency to sodium borohydride. Prior document 1(Fernandes R, Patel N, Miotello A, et al, students on catalytic behavior of Co-Ni-B in hydrogen production by hydrolysis of NaBH₄[J]Journal of Molecular Catalysis A Chemical, 2009, 298(1-2):1-6.) Co-B, Ni-B and Co-Ni-B catalyst powders with different Co/Ni molar ratios were synthesized by Chemical in-situ reduction, and Co-Ni-B with a Co/(Co + Ni) mass ratio of 0.85 showed better activity and highest H content compared to other powdered catalysts₂The increase in the rate of formation, Co-Ni-B powder catalyst activity, can be attributed to: the active surface area of the catalyst is large and electron transfer is performed by alloying a large amount of B on the active centers Co and Ni on the surface of the catalyst.

In addition, in the process of catalyzing sodium borohydride to produce hydrogen, the catalytic activity of the metal nanoparticles is reduced in the catalysis process due to the fact that the metal nanoparticles are easy to agglomerate. Prior document 2(Patel N, Fernandes R, Miotello A. Hydrogen generation by hydrolysis of NaBH₄ with efficient Co-P-B catalyst: A kinetic study[J]411 and 420) the amorphous Co-P-B catalyst alloy powder prepared by the normal-temperature chemical reduction method has better hydrogen production performance, and the hydrogen production efficiency is slightly reduced after each operation in the process of carrying out a cycle test, probably because NaBO is generated in the reaction process₂Resulting in partial deactivation of the catalyst surface. Thus, the metal nanoparticles can be supported on a carrier using a supported catalyst. The supported catalyst has many advantages such as cost reduction, and the use of active metals can be reduced by using a proper carrier, and higher catalytic activity can still be maintained; the carrier can improve the specific surface area of the catalyst, so that the catalyst is dispersed more uniformly; the mechanical strength of the catalyst is improved, and the service life is prolonged; suitable carriers can slow down the agglomeration and deactivation phenomena of the catalyst to a certain extent.

Prior document 3 (Santa S, Das D, Das N S, et al. Effective Surface Area Tuning of Noble Metal-Free CuBO)₂ /rGO Nanohybrid for Efficient Hydrogen Production with "On-Off" Switching[J]Acs Applied Energy Materials, 2018,2(1):260-₂Hybrid nano/rGO material, CuBO₂Three-dimensional (D) ofThe hybrid material with star-shaped hierarchical nano structure and optimized high-efficiency specific surface area is used for improving NaBH₄The key of the hydrogen release performance is that the optimized composite material catalyzes NaBH₄The catalyst shows excellent catalytic performance in the hydrogen releasing process, and the hydrogen production rate is 2500.0 mL.min^-1g^-1Activation energy of 49.8 kJ^-1The catalytic activity of the catalyst after the 10 cycle test was 71% of the first time due to the loss of catalyst during collection and washing.

Further, there is a conventional document 4(ZHao X, Xu D, Liu K, et al. Remarkable enhancement of PdAg/rGO catalyst activity for use in micro acid dehydrogenation by factor boron-knocking through NaBH)₄ reduction[J]Applied Surface Science, 2020, 512: 145746) also strongly supports the above. A simple aqueous phase chemical reduction method is adopted to synthesize a novel boron-doped PdAg alloy taking graphene oxide as a carrier. GO has high specific surface area, excellent chemical resistance and special electron transmission performance, and oxygen-containing functional groups rich in surface, so that PdAg particles are easy to anchor and disperse, the performance of catalyzing sodium borohydride to produce hydrogen is improved, and PdAg/rGO catalyzes NaBH₄The hydrogen release activation energy is 20.7 kJ^-1During the cycle performance tests, a significant loss of activity was observed during the third catalytic run, probably due to accumulation of rGO during the reaction and also loss of catalyst during recycling.

In the prior art, reduced graphene oxide prepared by an improved Hummers method and a chemical in-situ reduction method is used as a carrier, the reduced graphene oxide has a large specific surface area, the dispersibility of a catalyst is improved, the agglomeration of nano particles is prevented, the surface of the reduced graphene oxide contains a large number of oxygen-containing functional groups, the reduced graphene oxide is favorable for the combination of the reduced graphene oxide and heteroatoms, meanwhile, a large number of active sites are generated on the surface of the carrier by a P element, an electron density required by catalytic activity is provided for metal active sites by a B element, and the active sites play a critical role in the hydrolysis process of sodium borohydride and improve the catalytic performance of the catalyst.

Therefore, when the nonmetal atoms B, P are combined with the transition metal Co to be used as a catalyst, the technical problem to be solved is to select a microstructure suitable for hydrogen production by hydrolysis, and the microstructure is kept unchanged during heating, and in order to solve the above problems, the following problems need to be solved:

1. in a common reduction method, reduced metal particles are not uniformly distributed and are easy to agglomerate;

2. generally, the carrier adhesion of the carrier-supported particles is low.

Disclosure of Invention

The invention aims to provide a Co-B-P-O nanoparticle loaded reduced graphene oxide composite material, which is a preparation method for preparing a graphene oxide material with a large specific surface area by an improved Hummers method, loading metallic cobalt and non-metallic boron and phosphorus by a one-step chemical in-situ reduction method, and application of the graphene oxide composite material as a catalyst for hydrogen production by hydrolysis of sodium borohydride.

Aiming at the technical problems in the prior art, the invention adopts the following modes to solve the problems:

1. firstly, preparing graphene oxide by adopting an improved Hummers method, wherein the graphene oxide has a lamellar structure, so that the specific surface area of the catalyst is increased, and the catalytic performance is improved;

2. the nano particles are attracted and combined through rich oxygen-containing functional groups on the surface of the graphene oxide, so that the nano particles are uniformly dispersed on the carrier, the agglomeration of the nano particles is effectively improved, and the adhesion with the carrier is improved;

3. by utilizing the metal-doped graphene oxide nanosheets, hetero-ions are introduced to excite a synergistic effect, so that redox sites are enriched, catalytic reaction active sites are exposed to the maximum extent, B, P elements are further introduced, P elements generate a large number of active sites on the surface of the carrier, and B elements provide electron density required by catalytic activity for the metal active sites;

4. Co-B-P-O is uniformly dispersed on the flexible reduced graphene oxide, so that the aggregation of the nano particles is greatly reduced, and the process difficulty in the recovery process and the damage to the microscopic morphology of the material can be effectively reduced.

The technical scheme for realizing the purpose of the invention is as follows:

a Co-B-P-O nanoparticle loaded reduced graphene oxide composite material is prepared by obtaining a graphene oxide material through an improved Hummers method, then loading Co-B-P-O onto reduced graphene oxide through a chemical in-situ reduction method to obtain the Co-B-P-O nanoparticle loaded reduced graphene oxide composite material, wherein the specific surface area of the Co-B-P-O nanoparticle loaded reduced graphene oxide composite material is 62-120 m²g^-1The pore size distribution is 12-14 nm.

A preparation method of a Co-B-P-O nanoparticle loaded reduced graphene oxide composite material comprises the following two steps:

step 1, preparing a graphene oxide nanosheet carrier, namely adding raw materials including concentrated sulfuric acid, sodium nitrate, flaky graphite and potassium permanganate which meet a certain mass ratio into water under a certain condition to obtain a mixed solution; then, reacting the mixed solution under a certain condition, and after the reaction is finished, dropwise adding hydrogen peroxide into the mixed solution under a certain condition to react to remove excessive potassium permanganate; finally, repeatedly centrifuging, washing with hydrochloric acid and washing with deionized water until the pH value of the solution is 7 to obtain a graphene oxide solution, and freeze-drying to obtain a graphene oxide nanosheet carrier, namely GO;

the fineness of the flaky graphite in the step 1 is 300 meshes; in the step 1, the mass ratio of concentrated sulfuric acid to sodium nitrate to graphite powder to potassium permanganate is (46-55.2) to 1:1 (4-6);

the mixing condition in the step 1 is that the mixture is stirred under the condition of ice-water bath at the temperature of 0-5 ℃; the reaction condition of the mixed solution in the step 1 is that the mixed solution is stirred under the condition of constant-temperature water bath at 35-40 ℃ and the reaction time is 7-9 h;

the condition of dropwise adding the hydrogen peroxide in the step 1 is that before the hydrogen peroxide is dropwise added, the temperature of the mixed solution is reduced to 0-5 ℃, the ice water bath condition of 0-5 ℃ is kept when the hydrogen peroxide is dropwise added, stirring is carried out, the dropwise adding amount of the hydrogen peroxide is determined by the color of the mixed solution, and specifically, the dropwise adding of the hydrogen peroxide is stopped when the mixed solution is changed from brownish black to bright yellow; wherein, the function of adding hydrogen peroxide is to react off excessive potassium permanganate in the mixed solution;

the method for reducing the temperature of the mixed solution to 0-5 ℃ in the step 1 comprises the steps of adding ice blocks into the mixed solution according to the mass ratio of the ice blocks to the mixed solution of (19-31) to (50-75), wherein the effect of adding the ice blocks into the mixed solution not only reduces the temperature of the mixed solution, but also dilutes the mixed solution to be acidic;

it should be particularly noted that the technical features of conventional addition of ice cubes to a water bath solution can only achieve the effect of lowering the temperature of the mixed solution in an ice-water bath, but do not have the effect of diluting the acidity of the mixed solution, i.e. the distinguishing technical features have technical effects which cannot be achieved by conventional operations;

step 2, preparing a raw material by using cobalt chloride hexahydrate, sodium hypophosphite monohydrate, sodium borohydride and the graphene oxide nanosheet carrier obtained in the step 1 to meet a certain mass ratio, uniformly mixing the graphene oxide nanosheet carrier obtained in the step 1 and ultrapure water in a mass ratio of 1:1 under an ultrasonic condition to obtain graphene oxide dispersion liquid, and preparing sodium borohydride into a sodium borohydride solution with the mass fraction of 5-6 wt%;

then, under the stirring condition, adding cobalt chloride hexahydrate and sodium hypophosphite monohydrate into the graphene oxide dispersion liquid for dissolving to obtain reaction liquid; then, dropwise adding a sodium borohydride solution into the reaction solution under a certain condition; finally, washing, filtering and drying the reaction product to obtain a Co-B-P-O nanoparticle loaded reduced graphene oxide composite material, which is marked as Co-B-P-O/rGO;

in the step 2, the mass ratio of cobalt chloride hexahydrate, sodium hypophosphite monohydrate, sodium borohydride and graphene oxide nanosheet carrier is (59-71): (159) -185): (57-66): 1;

the condition of dropwise adding the sodium borohydride solution in the step 2 is that the sodium borohydride solution is slowly dropwise added into the reaction liquid to prepare Co-B-P-O nano particles under the condition of keeping ice water bath at 0-5 ℃ and stirring vigorously, and after dropwise adding is finished, stirring is continued for 10-12 hours to ensure that the graphene oxide in the reaction liquid is completely reduced into reduced graphene oxide;

the washing condition of the step 2 is that the washing is repeated for 3 to 5 times by adopting a water washing and ethanol washing mode; the drying condition of the step 2 is vacuum drying, the drying temperature is 50-60 ℃, and the drying time is 4-6 h.

The application of the Co-B-P-O nanoparticle-loaded reduced graphene oxide composite material as a sodium borohydride hydrolysis catalyst provides that the maximum hydrogen release rate reaches 9036.3 mL.min under 298K^-1g^-1The hydrogen release amount is 100% of the theoretical value, and the activation energy of catalytic hydrogen release is E_a=28.64 kJ•mol^-1(ii) a After 10 times of recycling, the catalyst still retains 88.9 percent of the initial catalytic activity of the catalyst on the hydrolysis of sodium borohydride.

The technical effects of the invention are detected by experiments, and the specific contents are as follows:

the SEM detection shows that: the graphene oxide nanosheets are in a layered wrinkled shape, and the Co-B-P-O nanoparticle loaded reduced graphene oxide composite material is in a microstructure in which nanoparticles are uniformly loaded on the reduced graphene oxide nanosheets.

According to TEM detection, the invention can be known as follows: the graphene oxide presents a layered folded shape, and the Co-B-P-O nano particles are uniformly loaded on the surface of the reduced graphene oxide carrier.

The XRD detection shows that: the reduced graphene oxide composite loaded by the Co-B-P-O nano particles is in an amorphous structure.

The infrared spectrum detection shows that: oxygen-containing group of GO is covered by H₂PO₂ ^-And BH₄ ^-Is chemically reduced.

The Raman spectrum detection shows that: the Co-B-P-O nano particles are loaded on the reduced graphene oxide carrier.

The detection of hydrogen production by hydrolysis of the invention shows that: the maximum hydrogen production rate provided under the condition of 298K is 9036.3 mL^-1g^-1。

The reaction kinetics performance detection shows that: apparent activation energy of reaction E_a=28.64 kJ•mol^-1。

The invention can be known through cycle performance detection that: after 10 times of circulation under the condition of 298K, 88.9 percent of the initial catalytic activity of the sodium borohydride on hydrolysis is still kept.

The inventionThe alloying of P to form new Co cluster as active site can raise its inherent activity, and the hydrophilicity of nano sheet structure and the synergistic effect of element P, B are favorable to H₂The dissociation of O weakens the adsorption of H on the surface and inhibits the oxidation of Co. The method improves the problem of easy agglomeration of metal and ensures good catalytic activity while reducing the cost of raw materials.

Therefore, the experimental detection of SEM, XRD, TEM, Raman, infrared and the like shows that the reduced graphene oxide loaded Co-B-P-O nanoparticle composite material has the following advantages compared with the prior art:

in the aspect of micro morphology, Co-B-P-O is uniformly dispersed on the flexible reduced graphene oxide, so that the aggregation of nano particles is greatly reduced, the process difficulty in the recovery process and the damage to the micro morphology of the material can be effectively reduced, the original shape of the catalyst can be well maintained, and the recovery rate and the cycle performance of the material are improved.

Secondly, the invention uses the alloying of P to form a new Co cluster as an active site to enhance the inherent activity, and the hydrophilicity of the nano flaky structure and the synergistic effect of the element P, B are beneficial to H₂The dissociation of O weakens the adsorption of H on the surface and inhibits the oxidation of Co. The method improves the problem of easy agglomeration of metal and ensures good catalytic activity while reducing the cost of raw materials.

The raw materials used in the invention all belong to chemical raw materials which are already industrially produced, are available in the market and are easily obtained, and the synthesis process is simple, the reaction period is short, the energy consumption in the reaction process is low, and the pollution is low.

Fourthly, the Co-B-P-O nanoparticle loaded reduced graphene oxide composite material has high-efficiency hydrogen production performance by catalyzing sodium borohydride hydrolysis, and the maximum hydrogen production rate provided under 298K is 9036.3 mL.min^-1g^-1(ii) a The hydrogen release amount is 100 percent of the theoretical value; the activation energy of catalytic hydrogen discharge is E_a=28.64kJ•mol^-1。

And fifthly, the Co-B-P-O nanoparticle loaded reduced graphene oxide composite material has excellent cycle performance and still retains 88.9% of the initial catalytic activity of the composite material on the hydrolysis of sodium borohydride after 10 times of cycle under the condition of 298K. Therefore, compared with the prior art, the invention has better catalytic performance of hydrogen production by hydrolysis of sodium borohydride, improves the stability of the catalyst material, and has wide application prospect in the fields of hydrogen production materials, fuel cells and the like.

Description of the drawings:

FIG. 1 is a scanning electron microscope picture of GO in example 1;

FIG. 2 is a transmission electron microscope photograph of GO in example 1;

FIG. 3 is an X-ray diffraction pattern of GO, Co-B-P-O, Co-B-P-O/rGO in example 1;

FIG. 4 is an infrared spectrum of GO, Co-B-P-O/rGO in example 1;

FIG. 5 is a Raman spectrum of rGO, Co-B-P-O, Co-B-P-O/rGO of example 1;

FIG. 6 is a scanning electron micrograph and EDS energy spectrum of Co-B-P-O/rGO in example 1;

FIG. 7 is a TEM image and EDS energy spectrum of Co-B-P-O/rGO in example 1;

FIG. 8 is a graph of catalytic sodium borohydride hydrogen evolution by hydrolysis under different Co-B-P-O/rGO mass conditions in example 1;

FIG. 9 is a graph of the hydrogen evolution from the catalytic sodium borohydride hydrolysis of Co-B-P-O/rGO in example 1 at different sodium borohydride concentrations;

FIG. 10 is a graph of the catalytic sodium borohydride hydrolysis hydrogen evolution of Co-B-P-O/rGO in example 1 at different temperatures;

FIG. 11 is a graph of the activation energy of Co-B-P-O/rGO in example 1;

FIG. 12 is a graph of the performance of Co-B-P-O/rGO in example 1 in catalyzing the hydrolysis of sodium borohydride at 298K for 10 cycles;

FIG. 13 is a graph comparing the performance of Co-B-P-O/rGO in example 1 at 298K with different comparative catalytic sodium borohydride.

Detailed Description

The invention is further described in detail by the embodiments and the accompanying drawings, but the invention is not limited thereto.

Example 1

A preparation method of a Co-B-P-O nanoparticle loaded reduced graphene oxide composite material comprises the following specific steps:

step 1, preparing a graphene oxide nanosheet carrier, namely adding 60 mL of concentrated sulfuric acid, 2 g of sodium nitrate, 2 g of flaky graphite and 12 g of potassium permanganate serving as raw materials into water at the temperature of 0 ℃ to obtain a mixed solution; then, the mixed solution is reacted at the temperature of 0 ℃, after the reaction is finished, the mixed solution is magnetically stirred for 7 hours under the condition of 35 ℃ constant temperature water bath,

then adding 200 mL of ice blocks into the mixed solution, reducing the temperature of the mixed solution to 0 ℃, dropwise adding 15mL of hydrogen peroxide into the mixed solution under the condition of magnetic stirring after the ice blocks are melted, changing the mixed solution from brown black to bright yellow, stopping dropwise adding the hydrogen peroxide, and reacting to remove excessive potassium permanganate; finally, repeatedly centrifuging, washing with hydrochloric acid and washing with deionized water until the pH of the solution is 7 to obtain a graphene oxide solution, and freeze-drying for 72 hours to obtain a graphene oxide nanosheet carrier, which is marked as GO;

in order to prove that GO obtained in the step 1 is of a nanosheet structure, SEM and TEM tests are carried out on the graphene oxide nanosheets. The test results are shown in fig. 1 and 2, and the morphology of graphene oxide in a lamellar fold is shown in fig. 1 and 2.

In order to prove that the graphene oxide nanosheet is synthesized, infrared spectroscopy testing is performed on the substance synthesized in step 1. The test results are shown in FIG. 4, the spectra of GO are 1089, 1630 and 1736 cm^-1The peaks of (a) are respectively attributed to C-O, C = C bond stretching vibration of the epoxy group and C = O stretching vibration of GO, and these oxygen-containing groups easily form hydrogen bonds with water, have good hydrophilicity, and are proved to be GO.

Step 2, preparing a Co-B-P-O nanoparticle load reduction graphene oxide composite material, namely taking cobalt chloride hexahydrate, sodium hypophosphite monohydrate, sodium borohydride and the graphene oxide nanosheet carrier obtained in the step 1 as raw materials, uniformly mixing 20 mg of the graphene oxide nanosheet carrier obtained in the step 1 with 20 mL of ultrapure water under an ultrasonic condition to obtain graphene oxide dispersion liquid, and adding 1.1349 g of sodium borohydride into 20 mL of ultrapure water to prepare a sodium borohydride solution with the mass fraction of 5.7 wt%;

then, under the stirring condition, 1.1897 g of cobalt chloride hexahydrate and 3.1797 g of sodium hypophosphite monohydrate are added into the graphene oxide dispersion liquid for dissolving to obtain a reaction liquid; then, slowly dropwise adding a sodium borohydride solution into the reaction solution to prepare Co-B-P-O nanoparticles in an ice water bath at 0 ℃ under the condition of vigorous stirring, and continuously stirring for 10 hours after dropwise adding is finished to ensure that the graphene oxide in the reaction solution is completely reduced into reduced graphene oxide; and finally, repeatedly washing the reaction product for 3 times by using water and ethanol, filtering, and drying for 4 hours at the temperature of 50 ℃ under a vacuum drying condition to obtain the Co-B-P-O nanoparticle-loaded reduced graphene oxide composite material, which is marked as Co-B-P-O/rGO.

In order to prove that GO in the reaction system is reduced into rGO, XRD test and infrared spectrum test are carried out on the Co-B-P-O/rGO composite material.

The XRD test result is shown in figure 3, the Co-B-P-O and Co-B-P-O/rGO catalysts have no obvious diffraction peak, only have a broad peak near 2 theta =45 degrees, and present an amorphous structure. After the supported catalyst was formed, the diffraction peak at 2 θ =45 ° became very pronounced. The X-ray diffraction pattern of Co-B-P-O/rGO compared to GO did not detect a characteristic peak at 2 θ =11 °, with a broad but not very distinct peak appearing between 17 ° and 35 °, indicating that GO was reduced to rGO in this reaction system.

And (3) carrying out infrared spectrogram testing on the GO obtained in the step (1) and the Co-B-P-O/rGO obtained in the step (2). The test results are shown in FIG. 4, and the spectrum of Co-B-P-O/rGO is 1736 cm^-1The peak disappeared, confirming that the oxygen-containing group was substituted with H₂PO₂ ^-And BH₄ ^-Chemical reduction, i.e. proof of successful reduction of GO to rGO.

According to the test results, the substance synthesized in the step 1 is graphene oxide, and GO in the reaction system is reduced into rGO.

In order to prove that Co-B-P-O nano particles are successfully loaded on the surface of a reduced graphene oxide nanosheet carrier, SEM and TEM tests and Raman spectrum characterization are carried out on the Co-B-P-O/rGO composite material.

The Raman spectrum characterization result is shown in FIG. 5, and a D peak and a G peak of rGO and an A peak of Co-B-P-O exist on a Raman curve of Co-B-P-O/rGO at the same time, which indicates that the rGO is successfully loaded by the Co-B-P-O nanoparticles.

The SEM test result is shown in fig. 6, the graphene oxide nanosheet carrier is in a lamellar structure, and the nanoparticles uniformly grow on the surface of the reduced graphene oxide; EDS (electron-dispersive spectroscopy) spectrogram tests show that the surface of the composite material simultaneously contains five elements of Co, B, P, O and C and is uniformly distributed; therefore, the test result shows that the Co-B-P-O nano particles are successfully loaded on the reduced graphene oxide.

The TEM test results are shown in fig. 7, where the nanoparticles uniformly grow on the surface of the lamellar reduced graphene oxide; EDS (electron-dispersive spectroscopy) spectrogram tests show that five elements of Co, B, P, O and C are uniformly distributed on the surface of the composite material, so that the test results show that the CO-B-P-O nano particles are successfully loaded on the surface of the reduced graphene oxide.

According to the test results, the Co-B-P-O nano particles are successfully loaded on the surface of the reduced graphene oxide carrier.

In order to prove that the Co-B-P-O nanoparticle-loaded reduced graphene oxide composite material is used as a catalyst, the influence of the dosage of the catalyst on the hydrogen production performance in the hydrogen production reaction by sodium borohydride hydrolysis is realized, namely the reaction is a first-order reaction, and hydrogen production tests with different dosages of the catalyst are carried out. The specific test method comprises the following steps: first 1.5 wt.% NaBH₄And 5 wt.% NaOH solution are put into a constant temperature water bath to reach equilibrium, and then are respectively added into 4 jars, and 10 mL of the solution is added into each jar; then, 0.025 g, 0.05 g, 0.075 g and 0.100 g of Co-B-P-O nanoparticle-loaded reduced graphene oxide composite material serving as a catalyst are added into 4 jars respectively, and a hydrogen production test is carried out at the temperature of 298K after sealing; the generated hydrogen is collected by a drainage method, and the volume of the generated hydrogen in unit time is recorded, so that the hydrogen discharge rate can be obtained. The hydrogen production rate test results are shown in Table 1 and FIG. 8, and the catalyst dosage and NaBH are determined under the condition of 298K₄The hydrolysis reaction is in a linear relation, namely the Co-B-P-O nano particle loaded reduced graphene oxide composite material is boronThe sodium hydride hydrolysis hydrogen production reaction is a first order reaction kinetics relative to the amount of catalyst.

TABLE 1 corresponding relationship between catalyst amount and hydrogen desorption rate

Catalyst mass/g	0.025	0.05	0.075	0.100
					Hydrogen evolution rate/mL.min-1g-1	5047.8	6351.2	7527.0	9036.3

In order to prove the influence of the concentration of sodium borohydride on the hydrogen production performance in the hydrolysis hydrogen production reaction of sodium borohydride, hydrogen production tests with different concentrations of sodium borohydride are carried out. The specific test method comprises the following steps: the concentration of NaBH was 0.5 wt.%, 1.0 wt.%, 1.5 wt.%, 2.0 wt.%, respectively₄After the solution and the 5 wt.% NaOH solution are put into a constant-temperature water bath to reach equilibrium, 10 mL of each solution is respectively added into 4 wide-mouth bottles; then, 0.1 g of Co-B-P-O nanoparticle-loaded reduced graphene oxide composite material is added into 4 wide-mouth bottles respectively to serve as a catalyst, and hydrogen production test is carried out at the temperature of 298K after sealing; the generated hydrogen is collected by a drainage method, and the volume of the generated hydrogen in unit time is recorded, so that the hydrogen discharge rate can be obtained. The hydrogen production rate test result is shown in fig. 9, which indicates that the reaction of hydrogen production by hydrolysis of sodium borohydride by using the Co-B-P-O nanoparticle-loaded reduced graphene oxide composite material under the condition of 298K does not depend on the concentration of the catalyst, i.e. NaBH₄To NaBH concentration₄The hydrolytic hydrogen evolution of (2) has no effect.

In order to prove the effect and the reaction kinetics of the Co-B-P-O nanoparticle-loaded reduced graphene oxide composite material as a catalyst for hydrogen production by hydrolysis of sodium borohydride, the following steps are carried outAnd (5) performing a hydrolysis hydrogen production test. The test method comprises the following specific steps: first, 1.5 wt.% NaBH₄And 5 wt.% NaOH, then taking out 10 mL of the solution, adding the solution into a wide-mouth bottle containing the catalyst, sealing, respectively testing at 288K, 298K, 308K, 318K and 328K, collecting the generated hydrogen by a drainage method, and recording the volume of the generated hydrogen in unit time to obtain the hydrogen release rate. The test results of hydrogen production rate are shown in table 2 and fig. 10, and the maximum hydrogen production rate provided under the condition of 298K is 9036.3 mL^-1g^-1。

TABLE 2 corresponding Hydrogen desorption rate tables at different temperatures

temperature/K	288	298	308	318	328
						Hydrogen evolution rate/mL.min-1g-1	6395.4	9036.3	11975.0	14707.4	17408.5

The reaction kinetics test results are fitted by the Arrhenius equation, and the apparent activation energy E of the reaction is shown in FIG. 11_a=28.64 kJ•mol^-1。

TABLE 3 hydrolysis of sodium borohydride with different catalysts to produce hydrogen rate and activation energy

Catalyst and process for preparing same	Preparation method	Activation energy (kJ. mol.)-1)	Maximum hydrogen production rate (mL. min.)-1g-1)	Temperature (K)	Prior Art
						CoB-Spirulina microalgae strain	Phosphoric acid treatment	35.25	3940	303	[1]
Ni2P-CoP nanoarrays	Electrodeposition and phosphating	30.2	4323	298	[2]
						Fe/CoP Nanoarray	Low temperature phosphating	39.6	6060	298	[3]
[email protected]	Chemical reduction	36.2	5520	303	[4]
						Co-B-P	Plasma treatment	49.11	3976	303	[5]
Co-B	Chemical reduction	64.87	1100	293	[6]
						Chitosan-mediated Co-Ce-B	Chemical reduction and carbonization	33.1	4760	303	[7]
CoP nanosheet arrays	Electrodeposition and calcination	42.01	6100	298	[8]
						NiCo2O4	Hydrothermal and calcination	52.211	1000	298	[9]
CoB/open-CNTs	Wet impregnation and chemical reduction	44.43	3041	298	[10]
						Co-B-P-O/rGO	Chemical reduction	28.64	9036.3	298	The invention

The prior art cited in table 3 is:

[1] Cafer Saka, Mustafa Kaya, Mesut Bekirogullari. Spirulina Platensis microalgae strain modified with phosphoric acid as a novel support material for Co-B catalysts: Its application to hydrogen production[J]. International Journal of Hydrogen Energy, 2020, 45(4):2872-2883

[2] A, Jingya Guo , et al. Rugae-like Ni₂P-CoP nanoarrays as a bi-functional catalyst for hydrogen generation: NaBH₄ hydrolysis and water reduction. Applied Catalysis B: Environmental, 2020, 265:118584.

[3] Tang C , Zhang R , Lu W , et al. Fe-Doped CoP Nanoarray: A Monolithic Multifunctional Catalyst for Highly Efficient Hydrogen Generation[J]. Advanced Materials, 2017, 29(2):1602441.

[4] Dinh T D , Andrew K Y . Ruthenium supported on ZIF-67 as an Enhanced Catalyst for Hydrogen Generation from Hydrolysis of Sodium Borohydride[J]. Chemical Engineering Journal, 2018, 351:48-55.

[5] mer, ahin, Duygu, et al. The effects of plasma treatment on electrochemical activity of Co-B-P catalyst for hydrogen production by hydrolysis of NaBH₄[J]. Journal of the Energy Institute, 2017, 90(3):466-475.

[6] Jeong S U , Kim R K , Cho E A , et al. A study on hydrogen generation from NaBH₄ solution using the high-performance Co-B catalyst[J]. Journal of Power Sources, 2005, 144(1):129-134.

[7] Zou Y , Yin Y , Gao Y , et al. Chitosan-mediated Co-Ce-B nanoparticles for catalyzing the hydrolysis of sodium borohydride[J]. International Journal of Hydrogen Energy, 2018, 43(10):4912-4921.

[8] Liu T , Wang K , Du G , et al. Self-supported CoP nanosheet arrays: a non-precious metal catalyst for efficient hydrogen generation from alkaline NaBH₄ solution[J]. Journal of Materials Chemistry A, 2016, 4(34):13053-13057.

[9]Jadhav A R , Bandal H A , Kim H . NiCo₂O₄ hollow sphere as an efficient catalyst for hydrogen generation by NaBH₄ hydrolysis[J]. Materials Letters, 2017, 198:50-53.

[10] Li F , Li Q , Kim H . CoB/open-CNTs catalysts for hydrogen generation from alkaline NaBH₄ solution[J]. Chemical Engineering Journal, 2012, 210:316-324.

as can be seen from Table 3, the maximum hydrogen production rate and the activation energy of the method for catalyzing hydrolysis of sodium borohydride are 9036.3 mL^-1g^-1And 28.64 kJ. mol^-1And cited reference [5 ]]Compared with Co-B-P, the maximum hydrogen production rate is improved by 127.3 percent, and the activation energy of hydrolysis hydrogen production is improved by 42 percent, which shows that the addition of the reduced graphene oxide as a substrate can obviously improve the hydrogen release performance of sodium borohydride, and the material of the invention has hydrolysis performance by taking the reduced graphene oxide as the substrateThe reason for the great increase.

Compared with Co-B of the cited document [6], the activation energy of hydrogen production by hydrolysis is improved by 56 percent; compared with Co-P of the document [8], the activation energy of hydrogen production by hydrolysis is improved by 32%. The hydrogen production performance of the single Co-B or Co-P pair for catalyzing the hydrolysis of the sodium borohydride to produce hydrogen is lower than that of the Co-B-P-O nano particle loaded reduced graphene oxide composite material.

From the above analysis, it can be seen that the significant improvement of the catalytic performance of the present invention can be attributed to the following reasons:

(1) reduced graphene oxide is used as a support material, so that the catalyst has a large specific surface area, and active sites are obviously exposed;

(2) the graphene oxide is used as a supporting material, and rich functional groups on the surface of the graphene oxide can attract and control the combination of the nano particles with the graphene oxide, so that growth sites are provided for metal and non-metal atoms, and an anchoring effect is achieved;

(3) the Co-B-P-O nano particles can be uniformly dispersed on the graphene, and the agglomeration of the nano particles is effectively improved.

In order to prove the influence of the reduced graphene oxide loaded Co-B-P-O nanoparticle composite material on the cycle performance, a cycle performance test is carried out. The cycle performance test method comprises the following steps: and recovering the Co-B-P-O nano particle loaded reduced graphene oxide composite material subjected to the hydrogen release test in a suction filtration mode, then drying in vacuum, and then performing the hydrogen release test again to obtain the hydrogen release rate after circulation, namely the circulation performance. The results are shown in FIG. 12, which retained 88.9% of its initial catalytic activity for hydrolysis of sodium borohydride after 10 cycles at 298K.

The results are summarized in Table 4 together with the cycle performance described in the prior art.

TABLE 4 number and performance of cycles for the hydrolysis of sodium borohydride catalyzed by different catalysts

Catalyst and process for preparing same	Number of cycles	Cycle performance	Prior Art
				Co-P/CNTs-Ni foam	8	74.0%	[11]
Cu-Co-P/γ-Al2O3	6	66.0%	[12]
				Co/Fe3O4-CNTs	8	65.0%	[13]
Co3O4	4	60.0%	[14]
				CoO-Co2P	4	60.0%	[15]
MGCell-PEI+	5	78.0 ± 5.0%	[16]
				Co-B-10CNTs	5	64.0%	[17]
m-Dex microgels-TETA-HCl	10	80.0%	[18]
				Co0.92-xFe0.08Rux/TiO2	10	63.0%	[19]
Co-B-P-O/rGO	10	88.9%	The invention

The prior art cited in table 4 is:

[11] Wang F , Zhang Y , Wang Y , et al. Co-P nanoparticles supported on dandelion-like CNTs-Ni foam composite carrier as a novel catalyst for hydrogen generation from NaBH₄ methanolysis[J]. International Journal of Hydrogen Energy, 2018, 43(18):8805-8814.

[12] Zhong, Li, Lina, et al. Properties of CuCoP/γ-Al₂O₃ catalysts for efficient hydrogen generation by hydrolysis of alkaline NaBH₄ solution[J]. International Journal of Hydrogen Energy, 2017, 42(9):5749-5757.

[13] Bandal H A , Jadhav A R , Kim H . Cobalt impregnated magnetite-multiwalled carbon nanotube nanocomposite as magnetically separable efficient catalyst for hydrogen generation by NaBH₄ hydrolysis[J]. Journal of Alloys and Compounds, 2016, 699(Complete):1057-1067.

[14] Wang Q , Wei L , Ma M , et al. Hydrogen generation from the hydrolysis of sodium borohydride using Co₃O₄ hollow microspheres as high-efficient catalyst precursor synthesized by facile bio-template method[J]. Energy Sources Part A Recovery Utilization and Environmental Effects, 2020:1-10.

[15] Liu H , Shi Q , Yang Y , et al. CoO-Co₂P composite nanosheets as highly active catalysts for sodium borohydride hydrolysis to generate hydrogen[J]. Functional Materials Letters, 2020.

[16] Can M , Demirci S , Sunol A K , et al. Natural Celluloses as Catalysts in Dehydrogenation of NaBH₄ in Methanol for H₂ Production[J]. ACS Omega, 2020, 5 (25), 15519-15528.

[17] Shi L , Chen Z , Jian Z , et al. Carbon nanotubes-promoted Co-B catalysts for rapid hydrogen generation via NaBH₄ hydrolysis[J]. International journal of hydrogen energy, 2019, 44(36):19868-19877.

[18] Inger E , Sunol A K , Sahiner N . Catalytic activity of metal‐free amine‐modified dextran microgels in hydrogen release through methanolysis of NaBH₄[J]. International Journal of Energy Research, 2020, 44(7): 5990-6001.

[19] Akanyldrm E . An effective trimetalic crystalline catalyst for sodium borohydride hydrolysis[J]. Energy Sources Part A Recovery Utilization and Environmental Effects, 2020(1):1-12.

as can be seen from Table 2, the catalyst of the present invention still retained 88.9% of its initial catalytic activity for hydrolysis of sodium borohydride after 10 times of recovery. Compared with the cited documents [11] to [17], the cycle performance is still improved after the cycle number is improved by 1-2 times; compared with the cited documents [18] and [19], the cycle performance is respectively improved by 11.1 percent and 41.1 percent after the same cycle times.

From the above analysis, it can be seen that the significant improvement in cycle performance of the present invention can be attributed to the following reasons:

the Co-B-P-O nanoparticle-loaded reduced graphene oxide composite catalyst has good stability and strong binding force between the nanoparticles and the carrier, namely the graphene oxide nanosheet carrier has good anchoring effect on the nanoparticles, the overall microstructure is not easy to collapse in the reaction process, and the catalyst can be effectively catalyzed.

In order to prove the influence of the substrate material on the catalytic performance of the composite material, namely the influence of the reduced graphene oxide nanosheet carrier on the catalytic performance of the composite material, comparative example 1 is provided, and the experiment of directly synthesizing the Co-B-P-O nano particles is carried out without adding the reduced graphene oxide.

Comparative example 1

A preparation method of a Co-B-P-O nanoparticle material without a reduced graphene oxide substrate comprises the following steps of: step 1 is to directly carry out step 2 without preparing graphene oxide, and step two is to replace graphene oxide dispersion liquid with ultrapure water, and the obtained material is marked as Co-B-P-O.

The obtained Co-B-P-O material is subjected to a test of hydrogen production by catalytic hydrolysis of sodium borohydride at the temperature of 298K, and the test method is the same as that of the example 1. The test results are shown in FIG. 13, with the highest Co-B-P-O/rGO at 298K in comparative example 1The hydrogen production rate is 2711.0 mL.min^-1g^-1Example 1 the highest hydrogen production rate was 9036.3 ml.min^-1g^-1. The comparison shows that the hydrogen releasing performance of the embodiment 1 is improved by 233 percent compared with the comparative example 1.

The experiments prove that in the structure of the invention using the reduced graphene oxide nanosheet carrier as the substrate material, the graphene oxide surface contains a large number of functional groups which can provide nano particle growth sites, can attract metal particles, and induces and controls the growth of Co-B-P-O on the surface thereof so as to enable the Co-B-P-O to be in a nano lamellar structure.

To demonstrate the synergistic effect of the Co element with element P, B, comparative examples 2 and 3 were provided, with two catalysts, Co-P and Co-B, respectively, being prepared.

Comparative example 2

A method for preparing Co-P nanoparticles, which comprises the same steps as example 1 except that: in the step 3, instead of using sodium borohydride as a reducing agent, 10 mL of hydrazine hydrate is added to replace the sodium borohydride, and the obtained material is marked as Co-P.

The obtained Co-P material is subjected to a test of hydrogen production by catalytic hydrolysis of sodium borohydride at the temperature of 298K, and the test method is the same as that of the example 1. The test results are shown in FIG. 13, and the highest hydrogen production rates of Co-B-P-O, Co-P in comparative example 1 and comparative example 2 at 298K are 2711.0 mL^-1g^-1、277.3 mL•min^-1g^-1The comparison shows that the hydrogen releasing performance of the comparative example 1 is improved by 1067 percent compared with that of the comparative example 2.

Comparative example 3

A method for preparing Co-B nanoparticles, which comprises the same steps as example 1 except that: no NaH is added in the step 3₂PO₂•H₂O, and the resulting material is designated Co-B.

The obtained Co-B material is subjected to a test of hydrogen production by catalytic hydrolysis of sodium borohydride at the temperature of 298K, and the test method is the same as that of the example 1. The test results are shown in FIG. 13, and the highest hydrogen production rates of Co-B-P-O, Co-B in comparative example 1 and comparative example 2 at 298K are 2711.0 mL^-1g^-1、958.9 mL•min^-1g^-1The comparison shows that the hydrogen releasing performance of the comparative example 1 is improved by 183 percent compared with that of the comparative example 2.

The experiments show that the performance of Co-B-P-O is greatly improved compared with Co-P, Co-B, and the synergistic effect among Co, B and P in the hydrolysis process of sodium borohydride is proved.

In order to prove the influence of the composite nanoparticles on the hydrogen desorption performance of sodium borohydride, namely the influence of metallic simple substance cobalt on the hydrogen desorption performance of sodium borohydride, comparative example 4 is provided, and the simple substance cobalt is prepared by a hydrothermal method.

Comparative example 4

A method for preparing Co nanoparticles, which comprises the same steps as in example 1 except that: adding 10 mL of hydrazine hydrate in the step 2 without adding NaBH₄And NaH₂PO₂•H₂And O, then putting the mixture into a reaction kettle, and carrying out hydrothermal treatment at 160 ℃ for 16 h to obtain the material marked as Co.

The obtained simple substance Co material is subjected to a test of hydrogen production by catalytic hydrolysis of sodium borohydride at the temperature of 298K, and the test method is the same as that of the example 1. The test results are shown in FIG. 13, and the highest hydrogen production rate of Co in comparative example 4 at 298K is 232.4 mL. min^-1g^-1Example 1 the highest hydrogen production rate was 9036.3 ml.min^-1g^-1. The comparison shows that the hydrogen releasing performance of the embodiment 1 is improved by 3788 percent compared with the comparative example 4.

In order to prove the influence of a single substrate material on the hydrogen evolution performance of sodium borohydride, namely the influence of reduced graphene oxide on the hydrogen evolution performance of sodium borohydride, comparative example 5 is provided, and reduced graphene oxide is prepared by an in-situ reduction method.

Comparative example 5

A preparation method of rGO nanosheets has the same steps as those in example 1 except that: and (3) taking 200 mg of the graphene oxide prepared in the step 1 out, adding 10 mL of hydrazine hydrate, then putting the graphene oxide into a three-neck flask, and carrying out condensation reflux for 12 h at 90 ℃, wherein the obtained material is marked as rGO.

And (3) carrying out a test of hydrogen production by catalytic sodium borohydride hydrolysis on the obtained simple substance rGO material at the temperature of 298K, wherein the test method is the same as that of the example 1. The test results are shown in fig. 13, and comparative example 5 has almost no hydrolysis property.

The experiments prove that the hydrogen production performance of the Co-B-P-O/rGO by catalyzing the hydrolysis of sodium borohydride is obviously superior to that of a single metal or a substrate supporting material.

By combining the embodiment 1, the comparative example 2 and the comparative example 3, the Co-B-P-O loaded reduced graphene oxide composite material has more remarkable improvement on the catalytic performance than a single boride, a metal phosphide and a metal borophosphide. The reason is that a synergistic effect exists among Co, B and P in the hydrolysis process of sodium borohydride, and the graphene oxide surface contains a large number of functional groups which can provide a nanoparticle growth site, attract metal particles, induce and control the growth of Co-B-P-O on the surface of the graphene oxide, so that the nanoparticles can be uniformly anchored.