阅读说明：本技术 一种仿生结构的纳米粒子-石墨烯-泡沫镍复合材料及其制备方法 (Nano particle-graphene-foam nickel composite material with bionic structure and preparation method thereof ) 是由 孙立贤 康莉 李晶华 徐芬 于 2020-05-15 设计创作，主要内容包括：本发明公开了一种具有骨架-皮肤-毛发仿生结构的纳米粒子-石墨烯-泡沫镍复合材料,泡沫镍起骨架作用,石墨烯起皮肤作用,纳米粒子起毛发作用,其宏观形貌为块体状,所述纳米粒子为CoNiP纳米粒子,呈纳米片层结构。其制备方法为：1)骨架-皮肤结构的石墨烯-泡沫镍复合载体的制备；2)石墨烯-泡沫镍负载CoNi前驱体的制备；3)石墨烯-泡沫镍负载CoNi前驱体的磷化处理。作为硼氢化物水解制氢催化剂的应用,最大产氢速率为6681.34 mL·min<Sup>-1</Sup>g<Sup>-1</Sup>,放氢量为理论值的100%,活化能为<I>E</I><Sub>a</Sub>=31.2 kJ·mol<Sup>-1</Sup>,可以实现按需制氢、即时控制反应启停的效果,15次回收/重复使用后仍保留初始催化活性的74.8％。(The invention discloses a nano particle-graphene-foam nickel composite material with a skeleton-skin-hair bionic structure, wherein foam nickel plays a skeleton role, graphene plays a skin role, nano particles play a hair role, the macro morphology of the nano particle is in a block shape, and the nano particles are CoNiP nano particles and are in a nano lamellar structure. The preparation method comprises the following steps: 1) preparing a graphene-foam nickel composite carrier with a skeleton-skin structure; 2) preparing a precursor of the graphene-foam nickel-loaded CoNi; 3) and (4) carrying out phosphating treatment on the CoNi precursor loaded by the graphene-foamed nickel. The catalyst is used as a catalyst for hydrogen production by hydrolysis of borohydride, and the maximum hydrogen production rate is 6681.34 mL/min ‑1 g ‑1 The hydrogen release amount is 100% of the theoretical value, and the activation energy is E a =31.2 kJ·mol ‑1 The effects of hydrogen production according to requirements and reaction start and stop control in real time can be realized, and 74.8 percent of the initial catalytic activity is still reserved after 15 times of recovery/reuse.)

1. A nano particle-graphene-foam nickel composite material with a bionic structure is characterized in that: the micro-topography has a biomimetic structure of a skeleton-skin-hair structure, wherein,

the foam nickel plays a role of a skeleton, and particularly, the foam nickel can avoid stacking of graphene and enable the graphene to be fully spread;

the graphene plays a skin role, specifically, oxygen-containing functional groups existing on the surface of the graphene are used as active sites for the growth of the nanoparticles, and play an inducing role in the growth process of the nanoparticles, and the active sites play an anchoring role in the attractive force generated by the nanoparticles, like hair follicles on the surface of skin;

the nanoparticles play a role in hair, specifically uniformly grow on the surface of graphene, and serve as active sites for catalytic reaction.

2. The biomimetic structured nanoparticle-graphene-nickel foam composite material according to claim 1, wherein: the macro morphology of the nano particle-graphene-nickel foam composite material with the bionic structure is blocky.

3. The biomimetic structured nanoparticle-graphene-nickel foam composite material according to claim 1, wherein: the nano particles are CoNiP nano particles and are in a nano lamellar structure.

4. The biomimetic structured nanoparticle-graphene-nickel foam composite material according to claim 3, wherein: the preparation method comprises the steps of taking nickel foam, graphene oxide, cobalt nitrate hexahydrate, nickel nitrate hexahydrate, ammonium fluoride, urea and sodium dihydrogen hypophosphite as raw materials, preparing a graphene-nickel foam composite carrier with a skeleton-skin structure through the nickel foam and the graphene oxide, then loading a nano particle precursor, and finally carrying out phosphating treatment to obtain the nano particle-graphene-nickel foam composite material with the bionic structure.

5. A preparation method of a nano particle-graphene-foam nickel composite material with a bionic structure is characterized by comprising the following steps:

step 1) preparing a graphene-foam nickel composite carrier with a skeleton-skin structure, namely repeatedly washing foam nickel with a certain specification by using acetone, a hydrochloric acid solution, ethanol and deionized water in sequence, putting the washed foam nickel into a graphene oxide suspension liquid under a certain condition for water bath soaking, and washing and drying to obtain the graphene-foam nickel composite carrier with the skeleton-skin structure;

step 2) preparing a graphene-nickel foam loaded CoNi precursor, dissolving cobalt nitrate hexahydrate, nickel nitrate hexahydrate, ammonium fluoride and urea in deionized water according to a certain substance quantity ratio to prepare a mixed solution, adding the graphene-nickel foam composite carrier obtained in the step 1) into the mixed solution, carrying out hydrothermal reaction under a certain condition, washing and drying a reaction product to obtain the graphene-nickel foam loaded CoNi precursor;

and 3) carrying out phosphating treatment on the graphene-nickel foam loaded CoNi precursor, reacting the graphene-nickel foam loaded CoNi precursor obtained in the step 2) with sodium dihydrogen hypophosphite under a certain condition, cooling to room temperature after the reaction is finished, washing and drying a reaction product, and thus obtaining the CoNiP nano particle-graphene-nickel foam composite material with a skeleton-skin-hair bionic structure.

6. The method of claim 5, wherein: the water bath soaking condition in the step 1) is that the concentration of the graphene oxide suspension is 2-5 mg/mL, the water bath soaking temperature is 60-80 ℃, and the water bath soaking time is 24-30 h.

7. The method of claim 5, wherein: the amount ratio of cobalt nitrate hexahydrate, nickel nitrate hexahydrate, ammonium fluoride and urea substances in the step 2) is 1:1:8: 10; the hydrothermal reaction in the step 2) is carried out under the conditions that the reaction temperature is 100-120 ℃ and the reaction time is 7-9 h.

8. The method of claim 5, wherein: the reaction conditions of the step 3) are that the reaction heating rate is 2-5 ℃/min, the reaction temperature is 300-.

9. The application of the nano particle-graphene-nickel foam composite material with the bionic structure as a catalyst for hydrogen production by borohydride hydrolysis is characterized in that: the maximum hydrogen production rate provided under 323K is 6681.34mL min^-1g^-1The hydrogen release amount is 100% of the theoretical value, and the activation energy of catalytic hydrogen release isE _a= 31.2 kJ· mol^-1The block structure of the composite material can realize the effects of hydrogen production as required and reaction start and stop control in time, and the composite material and NaBH are controlled₄The solution is contacted to control the start, stop and rate of the reaction.

10. The application of the nanoparticle-graphene-nickel foam composite material with the bionic structure as the catalyst for hydrogen production by borohydride hydrolysis, which is characterized in that: it remained as a NaBH after 15 recoveries/reuses at 323K₄74.8% of the initial catalytic activity of the hydrolysis.

Technical Field

The invention relates to the technical field of hydrogen production by catalyzing hydrolysis of sodium borohydride, in particular to a nano particle-graphene-nickel foam composite material with a bionic structure and a preparation method thereof.

Background

With the increasing exhaustion of global energy resources and a series of environmental problems caused by the large utilization of fossil energy, the search for green energy which can be continuously developed is urgent. Hydrogen energy is a pollution-free and clean secondary energy and is the important research in the current energy science community. However, hydrogen storage and production technology remains a key technology that limits the commercial application of hydrogen energy. In the existing hydrogen storage method, metal hydride hydrogen storage has the characteristics of high-efficiency hydrogen storage efficiency, simple reaction conditions, easy control, safe operation and the like, and becomes a hotspot for research in the field of domestic and foreign hydrogen storage.

Sodium borohydride (NaBH)₄) Due to the high hydrogen density (10.8 wt%), good storage stability, non-toxic and safe reaction conditions, is considered one of the most potential chemical hydrogen storage materials. The borohydride releases H by pyrolysis or hydrolysis due to strong hydrogen bonding₂. Hydrolysis of borohydrides can be carried out at room temperature, but generally the kinetics are slow, thus requiring the use of highly efficient catalysts. Noble metal-based materials such as ruthenium, platinum, palladium, and related alloys have the best overall catalytic performance, but are expensive and rare. Therefore, the development of a high-performance and low-cost alternative catalyst is of great significance.

For these reasons, non-noble metal catalysts have been developed and have shown good catalytic activity, especially cobalt-based and nickel-based catalysts. In addition, the combination of the non-metal atom (e.g., P or B) with the transition metal (e.g., Co or Ni) changes the electronic state of the active metal, thereby improving the catalytic performance. For example, Co-B has a higher catalytic activity than the original Co catalyst, which is resistant to NaBH₄Has good catalytic efficiency. In addition, Co-P is cheaper than Co-B, so the development of high performance Co-P alloy catalyst for hydrolysis of borohydride has great research interest and practical value. Prior document 1(Patel N, Fernandes R, Miotello A. hydrogen Generation By Hydrolysis OfNaBH)₄With Efficient Co-P-B Catalyst:A Kinetic Study[J]The Co-P-B alloy powder catalyst is synthesized by a chemical reduction method in Journal of Power sources,2009,188(2): 411-420), and the alloying of P forms a new Co cluster as an active siteThe dots enhance the inherent activity of the nano-particles to NaBH₄Has good catalytic effect. Although the catalytic efficiency of the transition metal cobalt-based catalyst for hydrolysis of borohydride can be improved by adding the non-metal atom P, the powdery catalyst has the defects of difficult separation, easy polymerization and the like. In addition, some cobalt catalysts are not well recycled because they exhibit poor durability and support adhesion. Compared with the catalyst, the nano-array integrated monolithic catalyst has the advantages of no aggregation, easy and quick recovery of a reaction system, reusability, hydrogen production according to needs and the like.

Regarding the nano-array integrated monolithic catalyst, there is document 2(Wang Y, Li G, Wu S, et. hydrogen generation from alkaline NaBH)₄solution using nanostructured Co-Ni-P catalysts[J]International journal of hydrogen energy,2017,42:16529-16537.) nanostructured Co-Ni-P thin film catalysts were successfully prepared on copper plates by means of electroplating. Although the synergistic effect between cobalt nickel phosphorous promotes the hydrolysis of sodium borohydride. However, this method is mainly affected by the low adhesion of the particle substrate, and therefore the catalytic performance is also poor, and the maximum hydrogen production rate is 2172.4mL min^-1g^-1And the activation energy is as high as 53.5 kJ.mol^-1。

Further, there is a conventional document 3(Kai, Li, Min, et al. Monolithically integrated NiCoPnanosteet array on Ti mesh: An effective and reusable catalyst in NaBH₄alkaline media toward on-demand hydrogen generation[J]International journal Hydrogen Energy,2017,42: 19028-. NaBH in alkaline medium by impregnation method on titanium mesh (NiCoP NA/Ti) using NiCoP nanoarrays₄A catalyst for hydrolysis. The adhesion of the particle substrate is low, and agglomeration phenomenon exists, so that the catalytic performance is poor, and the maximum hydrogen production rate is 3016.79 mL-min^{- 1}g^-1The activation energy was 52.68 kJ. mol^-1。

Researches show that the graphene is an ideal supporting material and can be used for anchoring high-dispersion metal nano particles to solve the problem of low adhesion of particle carriers. Prior document 4(Shi L, Xie W, Jian Z, et al. graphene modified Co-B catalysts for rapid hydrogen production from NaBH)₄hydrolysis[J]International Journal of Hydrogen Energy,2019,44: 17954-17962) graphene-modified Co-B catalysts of particularly high activity were prepared by a simple chemical reduction reaction. However, the inevitable polymerization packing of two-dimensional graphene sheets by pi-pi bonds and van der waals forces may reduce the effective surface area of such graphene-based catalysts.

In addition, although the introduction of the carrier can effectively increase the specific surface area of the catalyst and increase the specific surface area to NaBH₄The efficiency of the hydrolysis. However, it is well known that the activity of catalysts is sensitively dependent on their morphology and structure. For example, with nanocatalysts (Co-Mn-B, Co-Ni-P/Pd-TiO)₂Etc.) can provide more active catalytic reaction sites due to the presence of more edges, corners and faces, thereby providing higher catalytic performance. Therefore, the special morphology of the material plays an important role in improving the catalytic performance.

In addition to the above technical problems of the control of the catalytic reaction process, the powder form also has the following technical problems. The early-stage research of the subject group of the inventor shows that (patent 1: a cobalt-based MOFs material, a preparation method and application thereof, 201710788415.3[ P ] 2018-01-12), the conventional recovery method of the powder catalyst is centrifugation, suction filtration and then recovery and recycling. The conventional recovery method has the characteristics of damage to the microscopic morphology of the material, quality loss in the recovery process and complex operation, so that the cycle performance is reduced, and the hydrogen production rate after 5 times of cycle is only 47% of the first catalytic performance.

In order to solve the above problems, the present inventors have made a group of problems to recover a material by utilizing magnetism of a cobalt element-containing catalyst itself. Greatly reduces the damage to the microscopic morphology of the catalyst material in the recovery process, thereby effectively improving the recovery rate and the cycle performance of the material (patent 2: a nitrogen-doped porous carbon material loaded with CoB nano particles, a preparation method and application thereof, 201910438482.1[ P ] 2019-08-16.).

Obviously, not all catalyst materials, including catalyst materials containing iron, cobalt and nickel, have magnetic characteristics, and even catalyst materials containing cobalt have one of the research targets of reducing the dosage of the cobalt element serving as a catalytic active material and improving the catalytic efficiency. When the cobalt element content is low, the magnetism is low, so that the magnetic recovery cannot be realized, and the technical problem of catalyst recovery can be effectively solved by designing the catalyst into a block shape.

Therefore, when the non-metal atom P is combined with the transition metals Co and Ni 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. the carrier adhesion of the common carrier-loaded particles is low;

3. the catalyst with the two-dimensional structure is easy to stack and has a lower effective surface area;

4. the conventional recovery method has low recovery rate and poor cycle performance.

Disclosure of Invention

The invention aims to provide a nano particle-graphene-nickel foam composite material with a bionic structure, a preparation method thereof and application of the nano particle-graphene-nickel foam composite material as a catalyst for hydrogen production by sodium borohydride hydrolysis.

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

1. firstly, the unique three-dimensional structure of the foam nickel is used as a template, and the graphene is coated on the surface of the foam nickel, so that the graphene can be uniformly spread, the problem of accumulation is effectively solved, the effective surface area of the catalyst is increased, and the catalytic efficiency is improved;

2. the functional groups on the graphene-nickel foam composite carrier attract and combine the nano particles, 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. the cobalt-nickel-phosphorus nanosheets are constructed by metal doping, and the hetero-ions are introduced to excite the synergistic effect, so that the oxidation-reduction sites are enriched, and the active sites of the catalytic reaction are exposed to the maximum extent;

4. the catalyst material is in a block structure by adopting a skeleton-skin-hair structure, so that the process difficulty in the recovery process and the damage to the micro-morphology of the material are greatly reduced, and the catalytic reaction process can be controlled timely and effectively.

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

a nano particle-graphene-foamed nickel composite material with a bionic structure is prepared by taking foamed nickel, graphene oxide, cobalt nitrate hexahydrate, nickel nitrate hexahydrate, ammonium fluoride, urea and sodium dihydrogen hypophosphite as raw materials, preparing a graphene-foamed nickel composite carrier with a skeleton-skin structure through the foamed nickel and the graphene oxide, then loading a nano particle precursor, and finally performing phosphating treatment.

Step 1) preparing a graphene-foam nickel composite carrier with a skeleton-skin structure, namely repeatedly washing foam nickel with the size of 2 x 4cm by using acetone, 6mol/L hydrochloric acid solution, ethanol and deionized water in sequence, placing the washed foam nickel into graphene oxide suspension with the concentration of 3mg/mL for water bath soaking under the conditions that the water bath temperature is 60-80 ℃ and the water bath time is 24-30h, and washing and drying to obtain the graphene-foam nickel composite carrier with the skeleton-skin structure, which is recorded as Ni/GF;

step 2) preparing a graphene-nickel foam loaded CoNi precursor, namely dissolving cobalt nitrate hexahydrate, nickel nitrate hexahydrate, ammonium fluoride and urea in deionized water according to the mass ratio of 1:1:8:10 to prepare a mixed solution, then adding the graphene-nickel foam composite carrier obtained in the step 1) into the mixed solution, carrying out hydrothermal reaction at the temperature of 100-120 ℃ for 7-9h, and washing and drying a reaction product to obtain the graphene-nickel foam loaded CoNi precursor, which is recorded as CoNi/Ni/GF;

and 3) carrying out phosphating treatment on the graphene-nickel foam loaded CoNi precursor, reacting the graphene-nickel foam loaded CoNi precursor obtained in the step 2) with sodium dihydrogen hypophosphite at the heating rate of 2-5 ℃/min, the reaction temperature of 300-350 ℃ for 2-3h, cooling the reaction product to room temperature after the reaction is finished, and washing and drying the reaction product to obtain the CoNiP nano particle-graphene-nickel foam composite material with the skeleton-skin-hair bionic structure, wherein the CoNiP nano particle-graphene-nickel foam composite material is marked as CoNiP/Ni/GF.

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

the SEM detection shows that: the CoNiP nano particle-graphene-foam nickel composite material presents a microstructure of skeleton-skin-hair;

the XRD detection shows that: CoNiP nano particles are successfully loaded on the surface of a graphene-foam nickel composite carrier with a skeleton-skin structure;

according to TEM detection, the invention can be known as follows: the CoNiP nano particles are uniformly distributed on the graphene-foamed nickel composite carrier;

the detection of hydrogen production by hydrolysis of the invention shows that: the maximum hydrogen production rate provided under the 323K condition is 6681.34mL min^-1g^-1；

The reaction kinetics performance detection shows that: apparent activation energy of reaction E_a＝31.2kJ·mol^-1；

The invention can be known through cycle performance detection that: after 15 times of circulation under 323K condition, the NaBH still remains₄74.8% of the initial catalytic activity of the hydrolysis;

after circulation, XRD detection shows that: the components of the CoNiP nano particle-graphene-foam nickel composite material are not changed in the circulating process;

the SEM detection after the circulation of the invention shows that: the microstructure of the CoNiP nano particle-graphene-foamed nickel composite material is not changed in the circulating process.

The actual application detection of the invention for hydrogen production by hydrolysis shows that: by controlling the composite material and NaBH₄The contact of the solution can realize the effects of hydrogen production according to requirements and the control of the reaction start-stop and the reaction speed in real time.

Therefore, the experimental detection of SEM, XRD, TEM and the like shows that the nano particle-graphene-nickel foam composite material with the bionic structure has the following advantages compared with the prior art:

firstly, the microscopic morphology of the invention has a bionic structure of a skeleton-skin-hair structure,

1) the foam nickel is used as a skeleton structure and provides support for a graphene coating of a skin structure so as to form a three-dimensional structure, the defect that a two-dimensional graphene material is easy to accumulate is overcome, the catalyst has a large surface area, and active sites are obviously exposed;

2) the graphene is used as a skin structure, and abundant functional groups on the surface of the graphene can attract and control the nano particles to be combined with the graphene, so that the graphene provides growth sites for hairs similar to hair follicles on the skin and plays a role in anchoring;

3) the CoNiP nano particles are used as hair structures and uniformly dispersed on graphene skin, so that the agglomeration of the nano particles is effectively improved, and the adhesion and catalytic activity with a carrier are improved.

The macro morphology of the invention is block-shaped, which greatly reduces the process difficulty in the recovery process and the damage to the micro morphology of the material, and can better maintain the original shape of the catalyst, thereby improving the recovery rate and the cycle performance of the material.

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 catalyst is applied as a catalytic hydrogen production material, the CoNiP nano particle-graphene-foam nickel catalytic material with a bionic structure has high-efficiency hydrogen production performance by catalyzing sodium borohydride hydrolysis, and the maximum hydrogen production rate provided under 323K is 6681.34 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＝31.2kJ·mol^-1(ii) a The block structure of the composite material can realize the effects of hydrogen production as required and reaction start and stop control in time, and the composite material and NaBH are controlled₄The solution is contacted to control the start, stop and rate of the reaction.

Application of the catalyst in preparing hydrogen by using CoNiP nano particle-graphene-foam nickel catalyst with bionic structureThe material has excellent cycle performance, and retains NaBH after being cycled for 15 times under 323K condition₄74.8% of the initial catalytic activity of the hydrolysis.

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 photograph of nickel foam of example 1;

FIG. 2 is a scanning electron microscope photograph of Ni/GF in example 1;

FIG. 3 is a scanning electron microscope photograph of CoNi/Ni/GF in example 1;

FIG. 4 is a scanning electron micrograph of CoNiP/Ni/GF in example 1

FIG. 5 is an X-ray diffraction pattern of CoNiP/Ni/GF in example 1;

FIG. 6 is a TEM image of CoNiP/Ni/GF in example 1;

FIG. 7 is a graph showing the hydrogen evolution from CoNiP/Ni/GF catalyzed sodium borohydride hydrolysis at different temperatures in example 1;

FIG. 8 is a graph of the activation energy of CoNiP/Ni/GF in example 1;

FIG. 9 is a graph of the cycle performance of CoNiP/Ni/GF in example 1 in catalyzing sodium borohydride hydrolysis hydrogen discharge cycle at 323K for 15 cycles;

FIG. 10 is a scanning electron microscope photograph of CoNiP/Ni/GF catalyzing sodium borohydride to hydrolyze and dehydrogenate at 323K temperature for 15 cycles in example 1;

FIG. 11 is a graph showing hydrogen evolution from the hydrolysis of sodium borohydride catalyzed by example 1, comparative example 2, and comparative example 3 at 303K.

Detailed Description

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