Preparation method of nanosheet-shaped Hf-Ni2P-Fe2P-FeNi3 / NF composite electro-catalytic material

Abstract

The invention discloses a method for preparing a nano sheet-shaped Hf-Ni2P-Fe2P-FeNi3 / NF composite electro-catalytic material loaded by alloy particles, and the nano sheet-shaped Hf-Ni2P-Fe2P-FeNi3 / NF composite electro-catalytic material By optimizing the preparation process, one-step preparation of the phosphide and alloy composite nano material is realized. The preparation method comprises the following steps: firstly, synthesizing a high-valence hafnium ion doped NiFe-LDH / NF precursor (Hf-NiFe-LDH / NF) by adopting a traditional solvothermal method; and then, the Hf-NiFe-LDH / NF and a certain amount of sodium hypophosphite are subjected to a chemical gas phase pyrolysis reaction in an argon and hydrogen mixed atmosphere, and finally, the Hf-Ni2P-Fe2P-FeNi3 / NF nano material is obtained. According to the preparation method, optimal reactants and reaction conditions are determined through screening of experimental conditions, and a phosphide nanosheet and alloy particle embedded structure is realized through simple and easy-to-operate one-step chemical vapor pyrolysis. The whole preparation process is simple and convenient to operate, the structure uniformity is easy to guarantee, the cost is relatively controllable, and certain technical enlightenment is provided for synthesis of the doped metal ion-binary metal phosphide-alloy composite nanostructure.

Description

Technical Field

[0001] The present invention discloses a method for 4+ Preparation of Hf-Ni nanosheets by one-step chemical vapor pyrolysis using NiFe-LDH / NF as a precursor 2 P-Fe 2 P-FeNi 3 / NF composite electrocatalytic material method. Background Art

[0002] Ni 2 P and Fe 2 P has attracted much attention in the field of electrocatalytic hydrogen production in recent years due to its abundant raw materials and low cost. Among them, Ni and Fe are relatively abundant elements in the earth's crust and have 3d orbital characteristics similar to those of precious metals, which make them exhibit good catalytic performance; P acts as a site for capturing protons (H*), reducing H* (ΔG H* ) adsorption energy. And the interaction between different metal elements in multi-metal composite phosphides can improve the conductivity of the structure and enhance the electron conduction ability, thereby providing more electrochemical sites and optimal hydrogen adsorption energy, and ultimately improving the catalytic activity. However, the difference in electronegativity between metal and phosphorus in metal phosphides will limit the escape of electrons, affecting the improvement of their catalytic performance, and the surface of phosphides is easily oxidized under harsh conditions, resulting in poor stability. In contrast, the half-filled antibonding orbitals in alloy materials will cause M-OH coupling, promote *OH adsorption, and at the same time form a protective layer on the catalyst surface to block the external oxidizing environment, thereby improving solubility resistance and stability. Therefore, the composite of phosphides and alloys to construct a nanostructure that is more conducive to interfacial electron transport is an effective way to improve the efficiency of electrocatalytic hydrogen production.

[0003] At present, most of the reports on metal phosphide and alloy composite nanomaterials are synthesized by two or more steps such as gas phase pyrolysis-hydrothermal / solvothermal or gas phase pyrolysis-electrochemical deposition. The above synthesis methods have the disadvantages of complex preparation process, many influencing factors, and poor repeatability. Therefore, it is very important to find a controllable preparation method that is easy to operate and has good reproducibility for the development of metal phosphide / alloy composite nano-electrocatalytic materials.

[0004] Chemical vapor pyrolysis (CVP) is a process in which a o C to 500 o C) is a method for preparing nano-functional materials by redox reaction of the gas generated by the thermal decomposition of the precursor and the decomposition of the reactant. This method avoids the problems of phase change and particle growth that may occur at high temperatures, and can accurately control the composition, structure and morphology of the product by adjusting parameters such as reaction temperature, pressure, and gas composition.

[0005] The present invention discloses a method for synthesizing a metal nanoparticle-loaded hafnium-doped bimetallic phosphide (Hf-Ni 2 P-Fe 2 P-FeNi 3 The chemical vapor pyrolysis method of heterogeneous nanosheets (NF) was used to control the amount of sodium hypophosphite and Ar / H 2 The gas flow rate and reaction temperature reduce the precursor to Hf-Ni 2 P-Fe 2 P-FeNi 3 / NF vertical intercalation nanosheet materials. Compared with other synthesis methods, chemical vapor pyrolysis has the characteristics of simple operation process, adjustable film formation rate, controllable temperature, high product purity and uniform morphology, making it a promising candidate for Hf-Ni 2 P-Fe 2 P-FeNi 3 A simple preparation method for / NF electrocatalytic materials. Summary of the invention

[0006] The present invention aims to provide a one-step phosphating-alloying chemical vapor pyrolysis technology, which can synthesize nanoparticle-embedded sheet-like Hf-Ni at a relatively low temperature by using cheap reactants and simple operation methods. 2 P-Fe 2 P-FeNi 3 / NF composite electrocatalytic materials.

[0007] The present invention is achieved through the following technical solutions:

[0008] A metal nanoparticle-loaded Hf-Ni 2 P-Fe 2 P-FeNi 3 The chemical vapor phase pyrolysis method of / NF multiphase nanosheets is characterized by being carried out according to the following steps:

[0009] Hafnium-doped nickel-iron layered double hydroxide (Hf-NiFe-LDH / NF) and sodium hypophosphite were mixed in a certain ratio and then pyrolyzed in the gas phase to obtain a sheet-like Hf-Ni nanoparticle-embedded 2 P-Fe 2 P-FeNi 3 / NF nano-electrocatalytic materials.

[0010] Furthermore, the Hf-NiFe-LDH / NF is prepared by dissolving nickel nitrate hexahydrate, iron nitrate nonahydrate, urea, ammonium fluoride and hafnium tetrachloride in a mixed solution of 25 ml of deionized water and 5 ml of anhydrous ethanol at room temperature, and then transferring the mixture with nickel foam to an autoclave and heating at 120 o C for 8 h, and finally washed with deionized water and ethanol and oC and dried under vacuum to obtain Hf-NiFe-LDH / NF.

[0011] Furthermore, the phosphating ratios are 1:10, 1:20 and 1:30.

[0012] Further, the phosphating temperature is 300 o C. 350 o C and 400 o C.

[0013] Further, the gas phase condition is Ar / H 2 Mixed atmosphere.

[0014] Compared with the existing preparation method, the present invention has the following advantages: 2 The metal phosphide and alloy composites are obtained by one-step pyrolysis in an Ar / H atmosphere; solid materials that are cheap and readily available on the market are used; the chemical vapor pyrolysis method with simple operation and low cost is used for preparation. First, the precursor is prepared by a solvothermal method, and then, in an Ar / H 2 Hf-NiFe-LDH / NF was pyrolyzed under mixed atmosphere to obtain Hf-Ni with nanoparticles uniformly loaded into vertical cross-lamellar structure. 2 P-Fe 2 P-FeNi 3 / NF nano-electrocatalytic materials.

[0015] In summary, the synthesis of Hf-Ni 2 P-Fe 2 P-FeNi 3 The low-heat gas-phase pyrolysis reaction method of / NF multiphase nanomaterials is not only a relatively simple synthesis scheme at present, but also has certain discussions and summaries on the phosphating ratio and temperature of the synthesis, so that the present invention has certain technical inspiration for the synthesis of multiphase metal composites in the future. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Preparation of Hf-Ni for the present invention 2 P-Fe 2 P-FeNi 3 / X-ray diffraction pattern of NF;

[0017] Figure 2 Preparation of Hf-Ni for the present invention 2 P-Fe 2 P-FeNi 3 Field emission scanning electron microscopy image of / NF;

[0018] Figure 3 Preparation of Hf-Ni for the present invention 2 P-Fe 2P-FeNi 3 High magnification transmission electron microscopy image of / NF. DETAILED DESCRIPTION

[0019] The present invention will be further described below in conjunction with specific embodiments. These embodiments should be understood to be only used to illustrate the present invention and not to limit the scope of protection of the present invention. After reading the contents of the present invention, various changes or modifications made to the present invention based on the principles of the present invention also fall within the scope defined by the claims of the present invention.

[0020] Embodiment 1:

[0021] A nano-sheet Hf-Ni 2 P-Fe 2 P-FeNi 3 The preparation method of the / NF composite electrocatalytic material comprises the following specific steps:

[0022] (1) Pretreatment of nickel foam (NF)

[0023] NF (4.0 × 2.5 cm 2 ) was immersed in 1 mol / L hydrochloric acid solution for ultrasonic treatment for 15 minutes, and then washed with deionized water and anhydrous ethanol alternately for 3 times to make the surface completely clean. o C and vacuum-dried for 12 hours before use.

[0024] (2) Preparation of Hf-NiFe-LDH / NF precursor

[0025] 0.3729 g of nickel nitrate hexahydrate, 0.1727 g of iron nitrate nonahydrate, 0.0288 g of hafnium tetrachloride, 0.1111 g of ammonium fluoride and 0.3003 g of urea were dissolved in a mixed solution of 25 ml of deionized water and 5 ml of anhydrous ethanol and stirred at room temperature for 1 hour. 2 ) was transferred to a 50 ml polytetrafluoroethylene-lined autoclave and heated at 120 o C for 8 h, then cooled to room temperature, washed three times with deionized water and anhydrous ethanol alternately, and then o After vacuum drying for 12 h, yellow-green Hf-NiFe-LDH / NF was obtained.

[0026] (3) Hf-Ni 2 P-Fe 2 P-FeNi 3 Preparation of NF

[0027] Hf-NiFe-LDH / NF (loading amount: 4 mg / 2 × 2.5 cm -2) was placed downstream of the porcelain boat, and 80 mg of sodium hypophosphite was placed upstream of the porcelain boat. 2 Mixed atmosphere with 2 o The heating rate was increased to 350 o C, and keep warm for 2 hours, and collect the sample Hf-Ni after natural cooling 2 P-Fe 2 P-FeNi 3 / NF.

[0028] Embodiment 2:

[0029] A nano-sheet Hf-Ni 2 P-Fe 2 P-FeNi 3 The preparation method of the / NF composite electrocatalytic material comprises the following specific steps:

[0030] According to the preparation method described in Example 1 of the specification, it is characterized in that: Hf-NiFe-LDH / NF (loading amount: 4 mg / 2 × 2.5 cm -2 ) was placed downstream of the porcelain boat, and 40 mg of sodium hypophosphite was placed upstream of the porcelain boat. 2 Mixed atmosphere with 2 o The heating rate was increased to 350 o C, and keep warm for 2 hours, and collect the sample Hf-Ni after natural cooling 2 P-Fe 2 P-FeNi 3 / NF-1.

[0031] Embodiment three:

[0032] A nano-sheet Hf-Ni 2 P-Fe 2 P-FeNi 3 The preparation method of the / NF composite electrocatalytic material comprises the following specific steps:

[0033] According to the preparation method described in Example 1 of the specification, it is characterized in that: Hf-NiFe-LDH / NF (loading amount: 4 mg / 2 × 2.5 cm -2 ) was placed downstream of the porcelain boat, and 120 mg of sodium hypophosphite was placed upstream of the porcelain boat. 2 Mixed atmosphere with 2 o The heating rate was increased to 350 o C, and keep warm for 2 hours, and collect the sample Hf-Ni after natural cooling 2 P-Fe 2 P-FeNi 3 / NF-3.

[0034] Embodiment 4:

[0035] A nano-sheet Hf-Ni 2 P-Fe 2 P-FeNi 3 The preparation method of the / NF composite electrocatalytic material comprises the following specific steps:

[0036] According to the preparation method described in Example 1 of the specification, it is characterized in that: Hf-NiFe-LDH / NF (loading amount: 4 mg / 2 × 2.5 cm -2 ) was placed downstream of the porcelain boat, and 80 mg of sodium hypophosphite was placed upstream of the porcelain boat. 2 Mixed atmosphere with 2 o The heating rate was increased to 300 o C, and keep warm for 2 hours, and collect the sample Hf-Ni after natural cooling 2 P-Fe 2 P-FeNi 3 / NF-300.

[0037] Embodiment five:

[0038] A nano-sheet Hf-Ni 2 P-Fe 2 P-FeNi 3 The preparation method of the / NF composite electrocatalytic material comprises the following specific steps:

[0039] According to the preparation method described in Example 1 of the specification, it is characterized in that: Hf-NiFe-LDH / NF (loading amount: 4 mg / 2 × 2.5 cm -2 ) was placed downstream of the porcelain boat, and 80 mg of sodium hypophosphite was placed upstream of the porcelain boat. 2 Mixed atmosphere with 2 o The heating rate was increased to 400 o C, and keep warm for 2 hours, and collect the sample Hf-Ni after natural cooling 2 P-Fe 2 P-FeNi 3 / NF-400.

Claims

1. The present invention discloses a Hf-Ni2P-Fe2P-FeNi3 / NF electrocatalytic material prepared by a chemical vapor phase pyrolysis method, comprising the following steps: (1) Nickel foam (NF) was immersed in a hydrochloric acid solution for ultrasonic treatment, washed with deionized water and anhydrous ethanol, and vacuum dried to obtain NF. (2) Nickel nitrate hexahydrate, ferric nitrate nonahydrate, ammonium fluoride, urea and hafnium chloride were dissolved in a mixed solution of deionized water and anhydrous ethanol, and transferred to an autoclave together with the pretreated NF at 120 o C sealed reaction for 8 hours, then washed alternately with deionized water and anhydrous ethanol, and vacuum dried to obtain a yellow-green Hf-NiFe-LDH / NF precursor. (3) The precursor was placed in the downstream of the porcelain boat, and 80 mg of sodium hypophosphite was placed in the upstream of the porcelain boat. o The heating rate was increased to 350 o C, keep warm for 2 h, and collect the Hf-Ni2P-Fe2P-FeNi3 / NF nanocomposites after natural cooling.

2. The preparation method according to claim 1, characterized in that: (3) In the step, the ratio of the precursor to sodium hypophosphite is 1:10 (40 mg).

3. The preparation method according to claim 1, characterized in that: (3) In the step, the ratio of the precursor to sodium hypophosphite is 1:30 (120 mg).

4. The preparation method according to claim 1, characterized in that: (3) The reaction pyrolysis temperature in the step is 300 o C.

5. The preparation method according to claim 1, characterized in that: (3) The reaction pyrolysis temperature in the step is 400 o C.

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