阅读说明：本技术 一种Pt纳米颗粒负载二氧化钼/氢氧化镍纳米片阵列结构材料及其制备方法和应用 (Pt nanoparticle loaded molybdenum dioxide/nickel hydroxide nanosheet array structure material and preparation method and application thereof ) 是由 吴正翠 张吴正知 高峰 于 2020-06-11 设计创作，主要内容包括：本发明公开了一种Pt纳米颗粒负载二氧化钼/氢氧化镍纳米片阵列结构材料及其制备方法和应用,将镍盐、钼盐、还原剂和铂源水溶液溶解于氨水中,加入甲醇,搅拌均匀后,继续加入铂源水溶液混合均匀,将混合溶液转移至反应釜中,将泡沫镍倾斜置于溶液中,进行溶剂热反应,反应结束后冷却至室温,产物经洗涤、干燥,制备得到产物；产物中的MoO<Sub>2</Sub>的金属性使其作为电子供体存在于材料中,极大降低Ni(OH)<Sub>2</Sub>与泡沫镍基底以及Ni(OH)<Sub>2</Sub>与Pt纳米颗粒之间的肖特基势垒,加快反应过程的电子转移；同时,高价的Mo离子能够很好地稳定界面上活性Ni<Sup>2+</Sup>离子,进一步提高材料的催化稳定性；其作为析氢或全水分解反应阴极催化剂材料,具有催化活性高、稳定性优异以及制备工艺简单的优点。(The invention discloses a Pt nanoparticle loaded molybdenum dioxide/nickel hydroxide nanosheet array structure material and a preparation method and application thereof.A nickel salt, a molybdenum salt, a reducing agent and a platinum source aqueous solution are dissolved in ammonia water, methanol is added, the mixture is uniformly stirred, the platinum source aqueous solution is continuously added and uniformly mixed, the mixed solution is transferred to a reaction kettle, foamed nickel is obliquely placed in the solution for solvothermal reaction, the reaction is cooled to room temperature after the reaction is finished, and a product is washed and dried to prepare a product; MoO in the product 2 Is metallic in that itPresent as an electron donor in the material, greatly reducing Ni (OH) 2 With foamed nickel substrate and Ni (OH) 2 A Schottky barrier between the Pt nano particles and the Schottky barrier accelerates electron transfer in the reaction process; meanwhile, the high-valence Mo ions can well stabilize active Ni on the interface 2+ Ions are used for further improving the catalytic stability of the material; the catalyst is used as a cathode catalyst material for hydrogen evolution or total moisture decomposition reaction, and has the advantages of high catalytic activity, excellent stability and simple preparation process.)

1. Pt nanoparticle loaded MoO₂/Ni(OH)₂The preparation method of the nano-sheet array structure material is characterized by comprising the following steps:

dissolving nickel salt, molybdenum salt, reducing agent and platinum source aqueous solution in ammonia water, adding methanol, stirring uniformly, continuing to add platinum source aqueous solution, mixing uniformly, transferring the mixed solution to a reaction kettle, and obliquely placing foamed nickel in the reaction kettleCarrying out solvothermal reaction in the solution, cooling to room temperature after the reaction is finished, washing and drying the product to obtain the Pt nano particle loaded MoO₂/Ni(OH)₂A nanosheet array structure material.

2. The method according to claim 1, wherein the nickel salt is nickel nitrate hexahydrate; the molybdenum salt is ammonium heptamolybdate tetrahydrate; the reducing agent is sodium borohydride; the platinum source water solution is chloroplatinic acid water solution.

3. The method according to claim 1, wherein the volume ratio of the aqueous ammonia to the anhydrous methanol is 3: 1.

4. The method according to claim 1, wherein the ratio of the amounts of the nickel salt, the molybdenum salt, the reducing agent and the platinum source is 0.175 to 1.225:0.175:1:0.00375 to 0.0075.

5. The production method according to any one of claims 1 to 4, wherein the concentration of the reducing agent in the mixed solution is 0.05M.

6. The production method according to claim 1 or 2, characterized in that the concentration of the platinum source aqueous solution is 0.03M; the volume ratio of the platinum source water solution added in the first time to the platinum source water solution added in the second time is 1: 5-9.

7. The method according to claim 1 or 2, wherein the solvothermal reaction is carried out at 150 ℃ for 8 hours.

8. The preparation method of any one of claims 1 to 7, wherein the Pt nano-particle loaded MoO is prepared by the method₂/Ni(OH)₂A nanosheet array structure material.

9. The Pt nanoparticle-supported MoO of claim 8₂/Ni(OH)₂Nano-sheetApplication of array structure material as Hydrogen Evolution Reaction (HER) electrocatalyst.

10. The Pt nanoparticle-supported MoO of claim 8₂/Ni(OH)₂The nano-sheet array structure material is applied as a full-water decomposition cathode catalyst material.

Technical Field

The invention belongs to the field of nano material preparation methods and electrocatalysis application, and particularly relates to a Pt nano particle loaded MoO₂/Ni(OH)₂A nano-sheet array structure material, a preparation method and application thereof.

Background

Hydrogen energy is a pollution-free, sustainable, clean energy source. The hydrogen production by electrolyzing water in alkaline environment is one of the important sources of hydrogen. It is well known that Pt is an excellent hydrogen evolution reaction catalyst. However, the water dissociation efficiency of the Pt surface in an alkaline environment is low and the cost is expensive, which makes it difficult to apply it to industrial production applications on a large scale. Because the performance of the non-noble metal electrocatalyst reported at present is generally lower than that of a Pt-based catalyst, the method for reducing the Pt dosage and improving the overall water dissociation efficiency of the material is a feasible method.

The transition metal hydroxide can effectively break HO-H bonds, and the material with good hydrogen evolution catalytic activity can be obtained by combining the HO-H bonds with platinum. Nevertheless, electron transfer between the material components is greatly hindered due to the weak conductivity of the hydroxide itself and the presence of schottky barriers at the interfaces of the metal hydroxide and the substrate and Pt and metal hydroxide. MoO₂The metal semiconductor has a twisted rutile structure, and has obvious metal performance and high conductivity. The Schottky barrier existing in the material can be greatly weakened by introducing the composite material into a Pt/hydroxide composite structure, and the interface charge transmission rate is accelerated. Meanwhile, the expensive Mo ions can also stabilize the active Ni on the interface²⁺Ions. Thus, Pt and MoO are mixed₂And Ni (OH)₂The combination of the three substances is expected to design a hydrogen evolution electrocatalyst with low cost, high activity and high stability.

In the prior art, the synthesis method of the Pt nanoparticle supported metal hydroxide catalyst is mostly a complicated two-step reaction, it is difficult to uniformly deposit Pt nanoparticles on a previously prepared support, and the negative effect of the schottky barrier on the material performance is generally not eliminated or reduced.

Disclosure of Invention

The invention aims to provide a Pt nano particle loaded MoO₂/Ni(OH)₂A nano-sheet array structure material and a preparation method thereof are disclosed, wherein a low-temperature chemical liquid phase method is utilized to directly synthesize Pt nano-particles loaded MoO on a conductive foam nickel substrate in one step₂/Ni(OH)₂The nano-sheet array structure material has simple synthesis process and low cost.

Another purpose of the invention is to provide a Pt nanoparticle loaded MoO₂/Ni(OH)₂The nanosheet array structure material is applied as an electrocatalyst for Hydrogen Evolution Reaction (HER) or total moisture decomposition reaction.

The invention provides a Pt nano particle loaded MoO₂/Ni(OH)₂The preparation method of the nano-sheet array structure material comprises the following steps: dissolving nickel salt, molybdenum salt, a reducing agent and a platinum source aqueous solution in ammonia water, adding methanol, stirring uniformly, continuing to add the platinum source aqueous solution, mixing uniformly, transferring the mixed solution to a reaction kettle, obliquely placing foamed nickel in the solution, carrying out a solvothermal reaction, cooling to room temperature after the reaction is finished, washing and drying a product to obtain the Pt nano-particle loaded MoO₂/Ni(OH)₂A nanosheet array structure material.

Further, the nickel salt is nickel nitrate hexahydrate; the molybdenum salt is ammonium heptamolybdate tetrahydrate; the reducing agent is sodium borohydride; the platinum source water solution is chloroplatinic acid water solution.

The volume ratio of the ammonia water to the anhydrous methanol is 3: 1.

The ratio of the amounts of the nickel salt, the molybdenum salt, the reducing agent and the platinum source is 0.175-1.225: 0.175:1: 0.00375-0.0075, and preferably 0.7:0.175:1: 0.006.

The concentration of the reducing agent in the mixed solution was 0.05M.

The concentration of the platinum source aqueous solution was 0.03M.

The volume ratio of the platinum source water solution added in the first time to the platinum source water solution added in the second time is 1: 5-9, and the preferred volume ratio is 1: 7.

The solvothermal reaction condition is that the reaction is carried out for 8 hours at 150 ℃.

The foam Nickel (NF) needs to be cleaned before use, and the specific cleaning steps are as follows: soaking in 6M hydrochloric acid for 15min to remove oxide film on the surface, and cleaning with deionized water and anhydrous ethanol for 3-5 times; when in use, the foam nickel is cut into the size of 2 multiplied by 3 cm.

The washing is 3-5 times by using deionized water and absolute ethyl alcohol respectively.

The drying is carried out in a vacuum drying oven at 60 ℃ for 6-12 h.

The invention also provides Pt nano particle loaded MoO prepared by the preparation method₂/Ni(OH)₂A nanosheet array structure material. The Pt nano-particle loaded MoO₂/Ni(OH)₂The shape of the nano-sheet array structure material is an array structure formed by crossing nano-sheets with the transverse dimension of 90-120 nm; in MoO₂/Ni(OH)₂Pt nano particles with the average size of 3.1nm are uniformly distributed on the nano-sheets.

The invention also provides a Pt nanoparticle loaded MoO₂/Ni(OH)₂The nano-sheet array structure material is applied as a Hydrogen Evolution Reaction (HER) or total moisture decomposition cathode catalyst material.

The Pt nano-particle loaded MoO₂/Ni(OH)₂When the nano-sheet array structure material is applied as a hydrogen evolution reaction electrocatalyst, the specific method comprises the following steps: MoO loaded Pt nanoparticles prepared on foamed nickel₂/Ni(OH)₂The nanosheet array structure material is cut into a size of 0.5 multiplied by 0.5cm to be used as a working electrode, 1M KOH solution is used as electrolyte, and a CHI 760E electrochemical workstation is used for testing. Carbon rods and Ag/AgCl electrodes were used as counter and reference electrodes, respectively. Linear Sweep Voltammetry (LSV) at 5.0mV · s^-1The polarization curve is obtained at a scanning rate of 90% with ohmic compensation; stability was obtained by measuring the current density time curve at constant voltage. By scanning at different rates (120, 160, 200, 240, 280, 320 and 360 mV. multidot.s) in the absence of significant Faraday regions^-1) Measurement of double layer capacitance (C) by Cyclic Voltammetry (CV)_dl) Evaluating an electrochemically active area (ECSA); electrochemical Impedance (EIS) in the frequency range of 100kHz to 0.1HzThe test was carried out at an overpotential of 65 mV. MoO on foamed nickel with commercial Pt/C, respectively₂/Ni(OH)₂The nanosheet array material was used as a working electrode and HER performance was measured for comparison.

The Pt nano-particle loaded MoO₂/Ni(OH)₂When the nano-sheet array structure material is used as a cathode catalyst material for total hydrolysis reaction, the specific method comprises the following steps: MoO loaded Pt nanoparticles prepared on foamed nickel₂/Ni(OH)₂Nano-sheet array structure material and self-made NiFe₂O₄The NiFe LDH nanosheet array structure material is cut into 0.5 multiplied by 0.5cm in size and is assembled in a double-electrode electrolytic cell as a cathode and an anode respectively, and the full-water decomposition performance is tested through an LSV polarization curve compensated by 90% iR. As a comparison, the noble metal RuO supported on nickel foam in a two-electrode electrolyzer was investigated₂LSV polarization curves as anode and Pt/C as cathode.

In the present invention, MoO₂Mo in (1)⁴⁺Mo produced by ion and surface oxidation⁶⁺The ions can well stabilize the active Ni on the interface²⁺Ions. At the same time, MoO₂The unique metallic property has high conductivity, greatly reduces Ni (OH)₂With foamed nickel substrate and Ni (OH)₂Schottky barrier with Pt nanoparticles, thereby accelerating the charge transfer rate. Ni (OH)₂The surface hydrophilic hydroxyl groups adsorb water molecules through hydrogen bonds, and then gain electrons from the electrodes, so that the adsorbed water molecules are split into-OH and-H. The adsorbed hydrogen atoms are then recombined on the surface of the Pt nanoparticles to form hydrogen gas, while OH^-Ion exchange from MoO₂/Ni(OH)₂And (5) desorbing the surface of the nanosheet. Thus, Pt nanoparticles, MoO₂And Ni (OH)₂The three cooperate with each other to promote HER catalytic efficiency. Wherein, MoO₂The nano-sheet exists as an electron donor, reduces Schottky barrier existing in the material, accelerates charge transfer rate, and is Ni (OH)₂The nanosheet interface catalyzes a Volmer process of water dissociation, and the surface of the Pt nanoparticle optimizes the adsorption energy of H atoms, so that the H atoms are compounded into hydrogen through a Tafel process.

Compared with the prior art, the utility modelThe invention promotes OH by a one-step solvothermal method and utilizing the alkaline environment provided by ammonia water^-Ions and Ni²⁺Ion Generation of Ni (OH)₂Nanosheets. Simultaneously, sodium borohydride reduces the + 6-valent molybdenum in the molybdenum salt to + 4-valent molybdenum to form MoO₂And Ni (OH)₂Forming a mixed phase nanosheet structure. Then, H₂PtCl₆Reducing the Pt nano particles into Pt nano particles by sodium borohydride, and uniformly loading the Pt nano particles on the nano sheets of the mixed phase. The Pt nano-particle loaded MoO provided by the invention₂/Ni(OH)₂The catalyst with the nanosheet array structure has excellent catalytic activity and stability on HER in alkaline electrolyte, is simple in preparation process and environment-friendly, and has a great value on the practical application of hydrogen-producing electro-catalytic electrode materials.

Drawings

FIG. 1 shows MoO loaded on Pt nanoparticles prepared in example 1₂/Ni(OH)₂An X-ray powder diffraction (XRD) pattern of the nanoplatelets;

FIG. 2 shows MoO loaded on Pt nanoparticles prepared in example 1₂/Ni(OH)₂A Raman spectrum of the nanosheet;

FIG. 3 shows MoO loaded on Pt nanoparticles prepared in example 1₂/Ni(OH)₂An energy dispersive X-ray spectroscopy (EDX) profile of the nanoplatelets;

FIG. 4 shows MoO loaded on Pt nanoparticles prepared in example 1₂/Ni(OH)₂A Scanning Electron Microscope (SEM) image of the nanoplatelets;

FIG. 5 shows MoO loaded Pt nanoparticles prepared in example 1₂/Ni(OH)₂A Transmission Electron Microscope (TEM) image of the nanoplatelets;

FIG. 6 shows MoO loaded Pt nanoparticles prepared in example 1₂/Ni(OH)₂High Resolution Transmission Electron Microscopy (HRTEM) images of the nanoplates;

FIG. 7 shows MoO loaded Pt nanoparticles prepared in example 1₂/Ni(OH)₂Scanning electron microscope images and corresponding element distribution images of the nanosheets;

FIG. 8 shows MoO loaded Pt nanoparticles prepared in example 1₂/Ni(OH)₂A graph of nanoplatelet contact angle measurements;

FIG. 9 shows MoO loading of Pt nanoparticles with Pt loadings of 0.84% and 1.25% prepared in example 2₂/Ni(OH)₂An energy dispersive X-ray spectroscopy (EDX) profile of the nanoplatelets;

FIG. 10 shows MoO loaded Pt nanoparticles with 0.84% Pt loading prepared in example 2₂/Ni(OH)₂A Scanning Electron Microscope (SEM) image of the nanoplatelets;

FIG. 11 shows MoO loaded Pt nanoparticles with a Pt loading of 1.25% prepared in example 2₂/Ni(OH)₂A Scanning Electron Microscope (SEM) image of the nanoplatelets;

FIG. 12 shows MoO loaded Pt nanoparticles with 0.84% Pt loading prepared in example 2₂/Ni(OH)₂A Transmission Electron Microscope (TEM) image of the nanoplatelets;

FIG. 13 shows MoO loaded Pt nanoparticles with a Pt loading of 1.25% prepared in example 2₂/Ni(OH)₂A Transmission Electron Microscope (TEM) image of the nanoplatelets;

FIG. 14 shows MoO loading of Pt nanoparticles for different Pt loadings (0.84%, 1.07% and 1.25%) prepared in examples 1 and 2₂/Ni(OH)₂LSV profile of nanoplatelet Hydrogen Evolution Reaction (HER);

FIG. 15 shows MoO loading of Pt nanoparticles in example 3₂/Ni(OH)₂Nanosheet material, MoO₂/Ni(OH)₂LSV plot of nanoplatelet, Hydrogen Evolution Reaction (HER) of Pt/C;

FIG. 16 shows MoO loaded on Pt nanoparticles of example 3₂/Ni(OH)₂Nanoplatelet, current density time profile of Hydrogen Evolution Reaction (HER) of Pt/C;

FIG. 17 shows MoO loaded on Pt nanoparticles in example 3₂/Ni(OH)₂Nanosheet material, MoO₂/Ni(OH)₂A capacitance current diagram of the nanosheet material at different sweep rates;

FIG. 18 shows MoO supported on Pt nanoparticles of example 3₂/Ni(OH)₂Nanosheet material, MoO₂/Ni(OH)₂An impedance plot of the nanosheet material;

FIG. 19 shows example 3Pt nanoparticlesLoaded MoO₂/Ni(OH)₂Nanoplatelet, mass activity plot of Pt/C;

FIG. 20 shows MoO supported on Pt nanoparticles in example 4₂/Ni(OH)₂Polarization curve of the nanosheet material in a two-electrode system for total water splitting (inset is the polarization curve at high current density).

Detailed Description

The invention is described in detail below with reference to the following examples and the accompanying drawings.