CN110938831A

CN110938831A - Foam alloy-based iron-doped NiSe microsphere electrocatalytic material and preparation method thereof

Info

Publication number: CN110938831A
Application number: CN201911112571.3A
Authority: CN
Inventors: 张丽; 杨鹏; 杨海华; 黄杨; 阎建辉
Original assignee: Hunan Institute of Science and Technology
Current assignee: Hunan Institute of Science and Technology
Priority date: 2019-11-14
Filing date: 2019-11-14
Publication date: 2020-03-31
Anticipated expiration: 2039-11-14
Also published as: CN110938831B

Abstract

The invention discloses a three-dimensional porous iron-doped nickel selenide microsphere electrocatalytic oxygen evolution composite material generated by in-situ reaction on a foam iron-nickel alloy and a preparation method thereof, and the preparation method specifically comprises the following steps: (1) cleaning the foam FeNi strong acid dilute solution, then respectively ultrasonically cleaning and drying the foam FeNi strong acid dilute solution by using deionized water, acetone and absolute ethyl alcohol, and accurately weighing the foam FeNi strong acid dilute solution; (2) weighing selenium powder according to the weight ratio of selenium to foam FeNi (0.01-0.2):1, and ultrasonically dispersing the selenium powder in a mixed solution of amines, low molecular waxes and deionized water; (3) transferring the foam FeNi obtained in the step (1) and the mixed solution obtained in the step (2) into a high-pressure reaction kettle, carrying out solvothermal reaction, cooling, cleaning and drying; (4) and (4) placing the product obtained in the step (3) in a tubular furnace, carrying out temperature programming roasting under the protection of gas, and carrying out heat preservation in mixed protective gas containing reducibility to obtain the three-dimensional porous iron-doped nickel selenide microsphere electro-catalytic oxygen evolution composite material.

Description

Foam alloy-based iron-doped NiSe microsphere electrocatalytic material and preparation method thereof

Technical Field

The invention relates to a NiSe microsphere oxygen evolution material containing Fe and prepared by a foam iron-nickel alloy in-situ hydrothermal selenizing surface and a preparation method thereof, in particular to a material prepared by taking foam iron-nickel as a nickel source and selenium powder as a selenium source and roasting the nickel source and the selenium powder at a required temperature under a certain hydrothermal condition at a required atmosphere, wherein the prepared material shows excellent oxygen production performance by electrocatalytic decomposition of water.

Background

Energy has received a high degree of attention from countries around the world as a strategic resource. Along with the increasingly prominent global climate change and environmental pollution problems brought by traditional fossil energy represented by coal, petroleum and natural gas, the urgency of people to develop environment-friendly novel energy to replace fossil fuel is sharply increased, and more scientists have invested in basic research and application development of novel environment-friendly energy. Because of environmental pollution and energy crisis caused by rapid consumption of fossil fuels, development of clean renewable energy is receiving more and more attention from people. Among various novel energy sources, the hydrogen energy source is the cleanest, environment-friendly and high in conversion efficiency as the first choice. In recent years, with the rapid development of hydrogen storage technology, hydrogen energy sources have received increasing attention. Hydrogen is the most abundant element in the universe, however, most of hydrogen exists in a combined state, mainly in the form of water, except that the atmosphere contains a small amount of hydrogen in a free state. To realize the ambitious idea of "hydrogen economy", a series of problems such as the efficiency of hydrogen production, transportation, storage, and conversion to other energy sources (electrical energy) must be solved. Therefore, the industrial large-scale, efficient and sustainable production of hydrogen is the first step in the development and utilization of hydrogen energy.

As a carbon-free and abundant energy source, hydrogen is produced in large quantities in the process of electrocatalytic water decomposition. In addition to cathodic Hydrogen Evolution (HER), anodic Oxygen Evolution Reaction (OER) is a bottleneck in electrocatalytic water decomposition due to its slow reaction kinetics, requiring a high overpotential. The design of the high-performance OER catalyst provides a feasible way for reducing overpotential and improving the overall efficiency. Although noble metal oxides, including IrO₂And RuO₂Considered as the most effective OER reference catalyst, its high cost and scarcity hinderIt is applied in large scale.

Over the past few decades, there has been an effort to explore the earth's abundance of high performance OER catalysts. The earth's abundance of transition metals (e.g., iron, cobalt, copper, and particularly nickel) and their related compounds, including oxides, hydroxides, sulfides, selenides, phosphides, and the like, has proven to be a promising alternative to precious metals. It has recently been reported that Fe doping or incorporation can greatly improve the electrocatalytic properties of nickel oxides or hydroxides. The doping or doping of iron and the modification of the electronic structure of the nickel-related active center produce more catalytically active centers. In addition, the doping or doping of Fe can also improve the conductivity and synergistic effect between Fe and Ni metals. Inspired by this strategy, some Fe-Ni based sulfides, phosphides and selenides were designed and reported for electrocatalytic water decomposition. In general, various nanostructured metal selenides can be prepared with highly active surfaces by different methods, which contributes to the improvement of OER activity. These active catalysts are coupled with three-dimensional (3D) porous conductive current collectors (Ni foam, carbon fiber cloth, etc.) to construct integrated electrodes, further improving OER activity. The support of nickel iron selenide on these substrates is typically achieved by two steps, including hydrothermal treatment of externally added iron and nickel ions to grow iron-nickel hydroxide precursors on the substrates, which are then hydrothermally or solvothermally selenized to form Fe-Ni selenides. In addition to Ni foam, Fe-Ni alloy foam was also present. Good support and current collection for OER electrocatalyst. However, to our knowledge, few studies have reported nickel-iron selenides on Fe-Ni alloy foams.

Metal selenides on three-dimensional foam metal supports are considered to be a promising oxygen evolution reaction electrocatalyst. The porous iron-doped nickel selenide microsphere with the iron-nickel foam directly reacting with the selenium powder can be prepared by a simple hydrothermal method or other reactions. The iron-nickel alloy foam can be used as a matrix and Fe and Ni sources without adding exogenous Fe and Ni metal ions, and the selenium powder is directly used as a selenium source without forming any precursor. When the obtained material with the three-dimensional structure is used as an oxygen evolution anode, the material shows good electrocatalytic performance to OER in an alkaline medium (1.0M KOH), the overpotential is low, and the tafel slope is small. Under a certain over potential condition, the oxygen evolution performance has no obvious change after 24 hours of stability test, which shows that the catalyst has long-term stable electrocatalytic activity. The simple synthesis strategy provided by the idea can be conveniently applied to the preparation of the foam selenides with different compositions so as to construct the high-efficiency electrocatalyst.

Disclosure of Invention

The invention aims to solve the technical problem of providing a simple one-step hydrothermal method for preparing a three-dimensional porous iron-doped nickel selenide microsphere generated by directly reacting foamed iron nickel with selenium powder and synthesizing a Fe-based NiSe nano microsphere oxygen evolution composite anode material by in-situ selenization, so as to solve the problems of too high oxygen evolution overpotential and poor material circulation stability of the conventional electrocatalytic oxygen production material.

In order to solve the technical problems, the invention prepares the NiSe microspheres combined with Fe through simple one-step hydrothermal reaction, and the NiSe microspheres combined with Fe consist of a reaction kettle type hydrothermal reaction device. Compared with the reported preparation method, the synthesis process has the unique characteristics that the FeNi alloy foam is used as a substrate and a Fe-Ni source without adding external Fe and Ni metal ions, and the selenium powder is directly used as a Se source without forming any precursor. The obtained three-dimensional material as an OER anode shows high electrocatalytic activity to OER in a concentrated alkaline solution (1M-KOH), shows low overpotential, small tafel slope and obvious stability, and the excellent OER performance is mainly attributed to an active Fe-Ni-based 3D porous structure. The specific technical scheme comprises the following steps.

(1) Cutting the foam FeNi into strips of 1cm multiplied by 1.5cm, immersing the strips into strong acid dilute solution for 20-50min, then respectively placing the strips into deionized water, acetone and absolute ethyl alcohol for ultrasonic cleaning for several minutes, and drying the strips for later use.

(2) The amine and the deionized water are evenly mixed according to the volume ratio (0.1-10.0) to 1, the low molecular wax surfactant is added, the addition amount is 0.5-5.0 g/L, and the mixture is fully stirred to prepare the mixed solution.

(3) Accurately weighing the foamed FeNi obtained in the step (1), weighing selenium powder according to the weight ratio of selenium to the foamed FeNi of (0.01-0.2):1, and ultrasonically dispersing the selenium powder in the mixed solution in the step (2).

(4) Transferring the foam FeNi obtained in the step (1) and the selenium-containing mixed solution obtained in the step (3) to a stainless steel high-pressure reaction kettle with a polytetrafluoroethylene lining, sealing, and placing in a drying box at 160-^°And C, carrying out solvent thermal reaction for 6-18h, naturally cooling to room temperature, repeatedly washing with deionized water, then washing with absolute ethyl alcohol, and drying for later use.

(5) And (5) placing the product obtained in the step (4) in a tubular furnace, carrying out programmed heating and baking under the atmosphere protection to 500 ℃, then switching to inert gas containing a certain reducing atmosphere, carrying out heat preservation for 1-3h, and then naturally cooling to room temperature to obtain the Fe-bonded NiSe microsphere photoelectric composite material.

On the basis of the scheme, the strong acid dilute solution in the step (1) is a mixture of one or more of hydrochloric acid with the weight percentage concentration of 0.5-5%, nitric acid with the weight percentage concentration of 0.5-5%, sulfuric acid with the weight percentage concentration of 0.5-5% and phosphoric acid with the weight percentage concentration of 0.5-5%.

On the basis of the scheme, the amine in the mixed solution of the amine and the low-molecular wax in the step (2) is one or a mixture of more of methylamine, dimethylamine, ethylamine, aniline, benzylamine, ethylenediamine, diisopropylamine and triethylamine; the low molecular wax is polyethylene glycol (PEG), and is one or more of PEG200, PEG400, PEG600, PEG800 and PEG 1000.

On the basis of the scheme, the protective gas in the step (4) is one or a mixture of several of argon, helium, nitrogen and carbon dioxide; the reducing atmosphere is prepared by adding 0.5-5 vol% of H into protective gas₂CO and SO₂One or a mixture of several of them.

On the basis of the above scheme, in the sample obtained in step (4), newly added diffraction peaks belong to hexagonal NiSe (JCPDSNO 02-0892) and rhombohedral NiSe (JCPDS NO 18-0887), and NO other impurity peak (NO diffraction peak of iron-related compound is detected), indicating that the in-situ selenization of Ni in FeNi foam is successful (see FIG. 1). SEM pictures (see FIG. 2a, b) of the resulting material show that the surface of the FeNi foam is completely covered by porous Fe-NiSe microspheres with a diameter of about 3 μm. The 3d structure of the FeNi foam remains unchanged after in-situ selenization. HRTEM images of the microspheres (see FIG. 3) show clear lattice fringes with interplanar spacings of 0.24nm and 0.26nm, respectively, at the (220) and (021) planes of makinenite NiSe (JCPDS Nos. 18-0887), respectively, and a lattice spacing of 0.20nm, corresponding to the (102) plane of hexagonal NiSe (JCPDS Nos. 02-0892).

On the basis of the scheme, the Fe-NiSe composite material obtained in the step (4) is subjected to electrochemical performance test through an electrochemical workstation, the composite electrode material under the optimal condition shows good electrocatalytic oxygen evolution performance, and the oxygen evolution performance is 50 mA cm⁻²Overpotential at current density of 236mV, 100 mA cm⁻²Lower overpotential 266mV (see FIG. 4), tafel slope 53 mV dec^-1(see FIG. 5). During the stability test, the OER activity remained good despite the conversion of the partially crystalline Fe-NiSe to the amorphous worm-like NiOOH. The combination of the three-dimensional porous FeNi foam substrate and the high-activity Fe-NiSe microspheres or worm-like NiOOH is beneficial to providing larger pore volume and high specific surface area to expose more effective active sites and improving the oxidation resistance, electrolyte permeation and electron transport performance of the material. The invention not only provides an excellent OER catalyst for preparing selenide foam metal compounds with different components, but also paves the way for preparing environment-friendly and efficient electro-catalysts.

Drawings

Fig. 1 XRD patterns of FeNi foam samples before and after selenization.

FIG. 2 (a, b) SEM images of Fe-NiSe composite materials at different magnifications.

FIG. 3 HRTEM image of Fe-NiSe composite material.

FIG. 4 FeNi foam, Fe-NiSe @ FeNi foam and RuO₂LSV curve on glassy carbon electrode.

FIG. 5 FeNi foam, Fe-NiSe @ FeNi foam and RuO₂The tafel slope curve of (a).

Detailed Description

The present invention will be described in further detail with reference to the following examples, which are provided only for illustrating the present invention and are not to be construed as limiting the present invention.

Example 1

(1) Cutting foam FeNi into strips of 1cm multiplied by 1.5cm, immersing the strips into dilute hydrochloric acid solution with the weight percentage concentration of 2.0% for 25min, then respectively placing the strips into deionized water, acetone and absolute ethyl alcohol for ultrasonic cleaning for 5min, and drying the strips for later use; (2) accurately weighing the product obtained in the step (1) to 0.205g, weighing 25mL of ethylamine and 25mL of deionized water, fully mixing, adding 0.0500g of selenium powder and 0.100g of PEG4000.100g, and performing ultrasonic dispersion for 60min to obtain a mixed solution; (3) transferring the treated foam FeNi and the mixed solution obtained in the step (2) into a stainless steel high-pressure reaction kettle with a polytetrafluoroethylene lining, sealing, placing the sealed mixture into a drying box, carrying out solvent thermal reaction for 12 hours at 180 ℃, naturally cooling to room temperature, repeatedly washing with deionized water, then washing with absolute ethyl alcohol, and drying for later use; (4) placing the product obtained in the step (3) in a tubular furnace, heating and baking to 400 ℃ at a temperature of 3 ℃/min under the protection of argon, switching to a mixed gas containing 1% of CO and argon, preserving heat for 2h, and naturally cooling to room temperature to obtain the Fe-combined NiSe microsphere photoelectric composite material Fe-NiSe @ FeNi; (5) carrying out an electro-catalytic oxygen evolution performance test on the Fe-NiSe @ FeNi composite material obtained in the step (4) through an electrochemical workstation, wherein the current density is 10 mA-cm in alkaline electrolyte (1M KOH, pH is 13.7)^-2And then data such as overpotential, Tafel slope value and catalytic stability after CV circulation are obtained.

Example 2

(1) Cutting foamed cobalt into 2 × 2.5cm long blocks, respectively placing in acetone, anhydrous ethanol and distilled water, respectively cleaning and ultrasonically cleaning for 10 min, etching the surface of the cleaned foamed cobalt in 1% hydrochloric acid for 10 min, and cleaning with distilled water; (2) accurately weighing the product obtained in the step (1), and weighing thiourea according to the weight ratio of the cobalt source to the sulfur source of 3: 2; (3) dissolving the thiourea weighed in the step (2) into 140 mL of a mixed solution of deionized water and absolute ethyl alcohol (with the same volume), dropwise adding glucose with the molar weight of 1.0% of thiourea, and soaking the foamed cobalt obtained in the step (1) into the mixed solution after uniformly stirring; (4) transferring 200 mL of the mixture obtained in the step (3) into the containerIn a high-pressure reaction kettle lined with polytetrafluoroethylene at 160 DEG^°C, carrying out solvothermal reaction for 8 hours, naturally cooling to room temperature, repeatedly cleaning with deionized water, then cleaning with absolute ethyl alcohol, and drying for later use; (5) placing the vulcanized foam cobalt obtained in the step (4) into a tube furnace, baking the vulcanized foam cobalt to 350 ℃ at a temperature of 5 ℃/min under the protection of argon, and switching to the material containing 1% of H₂Preserving the temperature for 1h with the mixed gas of nitrogen, and naturally cooling to room temperature to obtain the composite material. Carrying out electrocatalysis hydrogen evolution performance on the composite material obtained in the step (5) through an electrochemical workstation, wherein the current density is 10 mA-cm^-2Thus, overpotential, Tafel slope value and catalytic stability after CV circulation are obtained.

Example 3

(1) Cutting foamed cobalt into 2 x 2.5cm long blocks, respectively placing in acetone, anhydrous alcohol and distilled water, respectively cleaning and ultrasonically cleaning for 10 min, etching the surface of the cleaned foamed cobalt in 2% sulfuric acid for 20 min, and cleaning with distilled water; (2) accurately weighing the product obtained in the step (1), and weighing thiourea dioxide according to the weight ratio of the cobalt source to the sulfur source of 1: 1; (3) dissolving the thiourea dioxide weighed in the step (2) into 140 mL of a mixed solution of deionized water and absolute ethyl alcohol (with the same volume), dropwise adding fructose in a molar amount of 2.0% of the thiourea dioxide, and soaking the foamed cobalt obtained in the step (1) into the mixture after uniformly stirring; (4) transferring the mixture obtained in the step (3) into a high-pressure reaction kettle with a polytetrafluoroethylene lining by 200 mL together, and performing reaction at 170 DEG C^°C, carrying out solvothermal reaction for 8 hours, naturally cooling to room temperature, repeatedly cleaning with deionized water, then cleaning with absolute ethyl alcohol, and drying for later use; (5) placing the vulcanized foam cobalt obtained in the step (4) in a tubular furnace in CO₂Under the protection, the mixture is heated and baked to 300 ℃ at the temperature of 7 ℃/min program, and then is switched to contain 1 percent of SO₂Preserving the temperature for 3h with the mixed gas of nitrogen, and naturally cooling to room temperature to obtain the composite material. Carrying out electrocatalysis hydrogen evolution performance on the composite material obtained in the step (5) through an electrochemical workstation, wherein the current density is 10 mA-cm^-2Thus, overpotential, Tafel slope value and catalytic stability after CV circulation are obtained.

Example 4

(1) Cutting foamed cobalt into 2 × 2.5cm long blocks, respectively placing in acetone, anhydrous ethanol and distilled water, respectively cleaning and ultrasonically cleaning for 10 min, etching the surface of the cleaned foamed cobalt in a mixed acid of 1% hydrochloric acid and 1% sulfuric acid for 18 min, and cleaning with distilled water; (2) accurately weighing the product obtained in the step (1), and weighing ethylene thiourea according to the weight ratio of the cobalt source to the sulfur source of 3: 1; (3) dissolving the ethylene thiourea weighed in the step (2) into 140 mL of a mixed solution of deionized water and absolute ethyl alcohol (with the same volume), dropwise adding lactose with the molar weight of 2.0% of the ethylene thiourea, and soaking the foamed cobalt obtained in the step (1) into the mixture after uniformly stirring; (4) transferring the mixture obtained in the step (3) into a high-pressure reaction kettle with a polytetrafluoroethylene lining by 200 mL together, and performing reaction at 180 DEG C^°C, carrying out solvent thermal reaction for 14 hours, naturally cooling to room temperature, repeatedly cleaning with deionized water, then cleaning with absolute ethyl alcohol, and drying for later use; (5) putting the vulcanized foam cobalt obtained in the step (4) into a tube furnace in N₂+CO₂(70% +30%) was baked at a programmed temperature of 4 ℃/min to 380 ℃ and switched to H₂+CO₂+N₂Keeping the temperature of the mixed gas (1% +1% +98%) for 2h, and naturally cooling to room temperature to obtain the composite material. Carrying out electrocatalysis hydrogen evolution performance on the composite material obtained in the step (5) through an electrochemical workstation, wherein the current density is 10 mA-cm^-2Thus, overpotential, Tafel slope value and catalytic stability after CV circulation are obtained.

Claims

1. The invention discloses a three-dimensional iron-doped nickel selenide microsphere electrocatalytic oxygen evolution composite material generated by foam iron-nickel alloy in-situ reaction and a preparation method thereof, and particularly relates to a composite material with strong electrocatalytic oxygen evolution capability, which is obtained by taking foam iron-nickel as a nickel source and iron and selenium powder as a selenium source, performing temperature programming roasting and heat preservation in a protective atmosphere through solvothermal reaction under the auxiliary action of a surfactant and an amine compound, and is characterized by comprising the following steps:

(1) cutting foam FeNi into long strips, immersing the long strips into strong acid dilute solution for 20-50min, then respectively placing the long strips into deionized water, acetone and absolute ethyl alcohol for ultrasonic cleaning for several minutes, and drying for later use;

(2) mixing amine and deionized water at volume ratio of 0.1-10.0: 1, adding low molecular wax surfactant at amount of 0.5-5.0 g/L, and stirring to obtain mixed solution;

(3) accurately weighing the processed foam FeNi obtained in the step (1), weighing selenium powder according to the weight ratio of selenium to foam FeNi of (0.01-0.2):1, and ultrasonically dispersing the selenium powder in the mixed solution in the step (2);

(4) transferring the foam FeNi obtained in the step (1) and the selenium-containing mixed solution obtained in the step (3) to a stainless steel high-pressure reaction kettle with a polytetrafluoroethylene lining, sealing, and placing in a drying box at 160-^°C, carrying out solvent thermal reaction for 6-18h, naturally cooling to room temperature, repeatedly washing with deionized water, then washing with absolute ethyl alcohol, and drying for later use;

(5) and (5) placing the product obtained in the step (4) in a tubular furnace, carrying out programmed heating and baking to 300-500 ℃ under the atmosphere protection, then switching to inert gas containing a certain reducing atmosphere, preserving the heat for 1-3h, and then naturally cooling to room temperature to obtain the Fe-doped NiSe microsphere electrocatalytic composite material.

2. The preparation method of the three-dimensional iron-doped nickel selenide microsphere electrocatalytic oxygen evolution composite material generated by the foam iron-nickel alloy in-situ reaction according to claim 1, which is characterized by comprising the following steps: on the basis of the scheme, the strong acid dilute solution in the step (1) is a mixture of one or more of hydrochloric acid with the weight percentage concentration of 0.5-5%, nitric acid with the weight percentage concentration of 0.5-5%, sulfuric acid with the weight percentage concentration of 0.5-5% and phosphoric acid with the weight percentage concentration of 0.5-5%.

3. The preparation method of the three-dimensional iron-doped nickel selenide microsphere electrocatalytic oxygen evolution composite material generated by the foam iron-nickel alloy in-situ reaction according to claim 1, on the basis of the scheme, the amine in the mixed solution of the amine and the low molecular wax in the step (2) is one or a mixture of more of methylamine, dimethylamine, ethylamine, aniline, benzylamine, ethylenediamine, diisopropylamine and triethylamine; the low molecular wax is polyethylene glycol (PEG), and is one or more of PEG200, PEG400, PEG600, PEG800 and PEG 1000.

4. The preparation method of the three-dimensional iron-doped nickel selenide microsphere electrocatalytic oxygen evolution composite material generated by the foam iron-nickel alloy in-situ reaction according to claim 1, wherein on the basis of the scheme, the protective gas in the step (4) is one or a mixture of argon, helium, nitrogen and carbon dioxide; the reducing atmosphere is prepared by adding 0.5-5 vol% of H into protective gas₂CO and SO₂One or more of the above gases.

5. On the basis of the claims 1-4, the three-dimensional iron-doped nickel selenide microsphere composite material generated in situ on the foam iron-nickel alloy by adopting the preparation method shows good electrocatalytic oxygen evolution performance and catalytic stability by carrying out electrochemical performance test on an electrochemical workstation.