Lanthanum-doped and boron-modified ferronickel oxide (oxyhydrogen) self-supporting nano catalytic material and application thereof in electrolytic hydrogen production

Abstract

The invention relates to the technical field of hydrogen production through water electrolysis, and provides a lanthanum-doped and boron-modified ferronickel oxide (oxyhydrogen) self-supporting nano catalytic material and electro-catalysis application of the material by utilizing a simple, convenient and industrially compatible liquid-phase synthesis method and an electro-deposition strategy. According to the self-supporting material, commercial foam iron is used as a substrate, a sodium borohydride solution is used as a treatment solution, a sample is taken out after being soaked at low temperature, and the boron-modified ferrite (oxyhydrogen) self-supporting nano catalytic material is obtained after aftertreatment. Then, a mixed solution of nickel nitrate, ferric nitrate and lanthanum nitrate is used as an electrolyte, the boron-modified ferrite (oxyhydrogen) self-supporting nano catalytic material is used as an anode under the configuration of standard three electrodes, the boron-modified ferrite (oxyhydrogen) self-supporting nano catalytic material is treated through an i-t technology (the constant voltage is-1V vs.Hg / HgO), and a final sample is obtained through post-treatment. According to the innovative technology, the cheap commercial metal foam substrate can be quickly and simply converted into the high-activity and high-stability oxygen evolution catalyst. The self-supporting catalytic material not only has excellent oxygen evolution reaction (OER), but also is simple in preparation process (high temperature and high pressure are avoided, and complicated equipment is not needed), and is suitable for industrial large-scale preparation and application.

Description

Technical Field

[0001] This invention relates to the field of water electrolysis for hydrogen production technology, specifically to the preparation of lanthanum-doped and boron-modified nickel-iron oxide (hydroxide) self-supporting nanocatalytic materials by liquid-phase synthesis and electrodeposition strategies, and the application of the catalyst in water electrolysis for hydrogen production. Background Technology

[0002] Hydrogen gas has a high energy density (142 kJ / g). -1 Hydrogen, with its reducing power and pollution-free characteristics, plays a crucial role in industry. It can be converted into high-value-added products, used as a raw material for petroleum or metal refining, or as a clean energy carrier for sustainable energy systems. Currently, most hydrogen is produced through steam methane reforming (CH4 + 2H2O → 4H2 + CO2) or coal gasification (C + 2H2O → 2H2 + CO2), both of which rely on fossil fuel consumption and inevitably lead to greenhouse gas emissions. For example, producing 1 kg of hydrogen produces 5.5 kg and 11 kg of CO2, respectively. In contrast, water electrolysis (2H2O → 2H2 + O2) is a feasible, carbon-free method for producing high-purity, green hydrogen, and can be further combined with renewable energy power generation technologies.

[0003] However, water electrolysis is an uphill reaction, requiring additional energy (overpotential, η) to overcome the two half-reactions involved: the cathode hydrogen evolution reaction (HER) and the anodic oxygen evolution reaction (OER). The coupled OER, involving four electron transfers, is considered the bottleneck of the entire reaction due to its slow reaction kinetics. To achieve high energy efficiency and low cost in water electrolysis, various types of non-noble metal OER catalysts have been extensively studied as alternatives to noble metal catalysts, including transition metal layered hydrogen hydroxides (LDHs), oxides, phosphides, sulfides, and borides.

[0004] Typically, elemental doping can modulate the electronic structure of catalysts, activate surface active sites, and accelerate charge transfer. Lanthanum (La) doping can alter the electronic structure of nickel iron oxide (hydroxide), thereby lowering the Gibbs free energy of the reaction and enhancing electrocatalytic performance. Boron modification can fully activate the redox reaction of lattice oxygen in nickel iron oxide (hydroxide), thus significantly improving its intrinsic OER activity.

[0005] Therefore, this invention utilizes the optimization effect of lanthanum doping on the electronic structure of nickel iron oxide (hydroxide) compounds and the activation mechanism of boron modification on lattice oxygen to successfully prepare lanthanum-doped and boron-modified nickel iron oxide (hydroxide) compound self-supporting nanocatalytic materials. The materials exhibit excellent OER (oxygen evolution reaction) activity and stability at industrial-grade current densities. Summary of the Invention

[0006] The technical problem solved by this invention:

[0007] Lanthanum-doped and boron-modified nickel-iron oxide (hydroxyl) compound self-supporting nanocatalytic materials were prepared using liquid-phase synthesis and electrodeposition strategies. Their excellent OER (oxygen evolution reaction) performance solves the problems of low electrocatalytic activity and environmental unfriendliness in the past. Moreover, the preparation process of this material is simple, and the raw materials are inexpensive and readily available, which avoids the cumbersome and complicated steps in catalyst preparation and reduces the cost of catalyst preparation.

[0008] The technical solution adopted in this invention is as follows:

[0009] This invention is achieved through a two-step synthesis method. First, sodium borohydride solution is used as the treatment solution, and then commercial metallic iron foam is immersed in the above reaction solution. After removal, it is washed with pure water to obtain the initial sample (boron-modified iron oxide (hydroxide) self-supporting nanocatalytic material). Then, a mixed solution of nickel nitrate, iron nitrate, and lanthanum nitrate is used as the electrolyte. Under a standard three-electrode configuration, with the initial sample as the anode, it is treated using IT technology (constant voltage of -1V vs. Hg / HgO), and then post-processed to obtain the final sample.

[0010] The details are as follows:

[0011] First, the present invention provides a lanthanum-doped and boron-modified nickel iron oxide (hydroxide) self-supporting nanocatalytic material, wherein the lanthanum-doped and boron-modified nickel iron oxide (hydroxide) is uniformly anchored on the surface of a commercial metal foam iron substrate.

[0012] The catalyst was first treated with a commercial metal foam iron substrate using a sodium borohydride solution as the reaction liquid. Through the strong reducing effect of sodium borohydride, boron-modified iron oxide (hydroxide) self-supporting nanocatalytic materials were grown in situ on the catalyst surface. Then, through further electrodeposition of a mixed solution of nickel nitrate, iron nitrate, and lanthanum nitrate, a heterostructure of lanthanum-doped nickel iron oxide (hydroxide) / boron-modified iron oxide (hydroxide) was formed in situ on the foam iron surface, thus successfully obtaining a lanthanum-doped and boron-modified nickel iron oxide (hydroxide) self-supporting nanocatalytic material.

[0013] The reaction solution has the following characteristics: the molar concentration of sodium borohydride is 0.5 mol / L.

[0014] The electrolyte has the following characteristics: a nickel nitrate molar concentration of 0.1 mol / L, an iron nitrate molar concentration of 0.05 mol / L, and a lanthanum nitrate molar concentration of 0.03125 mol / L.

[0015] Second, the present invention provides the application of the aforementioned lanthanum-doped and boron-modified nickel-iron oxide (hydroxide) self-supporting nanocatalytic material in water electrolysis for hydrogen production.

[0016] Using a standard three-electrode system, with lanthanum-doped and boron-modified nickel-iron-oxygen (hydroxyl) compound self-supporting nanocatalytic material as the anode, a mercury / mercury oxide electrode as the reference electrode, and a platinum sheet as the counter electrode, OER tests were performed.

[0017] This invention yields a lanthanum-doped and boron-modified nickel-iron-oxygen (hydroxyl) compound self-supporting nanocatalytic material (NiFeLa / FFB), which, for OER, exhibits performance at 50 mA cm⁻¹. -2 and 500mA cm -2 At current densities of 227.87mV and 258.22mV, respectively, the overpotentials are 227.87mV and 258.22mV. Attached Figure Description

[0018] Figure 1 The graph shows the oxygen evolution reaction (OER) LSV test results for each experimental sample.

[0019] Figure 2 The overpotential of the oxygen evolution reaction (OER) for each experimental sample;

[0020] Figure 3 The stability test results for NiFeLa / FFB are shown in the figure. Detailed Implementation

[0021] To more clearly illustrate the purpose, technical solutions, and advantages of the embodiments of the present invention, the technical solutions in the embodiments will be described in detail below. Unless otherwise specified, operations will be performed under normal conditions or according to the manufacturer's recommendations. Unless otherwise specified, the manufacturers of reagents or instruments refer to conventional products that can be purchased on the market.

[0022] Example

[0023] The preparation method of lanthanum-doped and boron-modified nickel-iron-oxygen (hydroxide) self-supporting nanocatalytic materials includes the following steps: First, the sample is soaked in sodium borohydride solution at low temperature. After removal, commercial foamed iron is soaked in the treatment solution at room temperature for 30 min to obtain boron-modified iron-oxygen (hydroxide) self-supporting nanocatalytic materials. Then, using a mixed solution of nickel nitrate, iron nitrate, and lanthanum nitrate as the electrolyte, and under a standard three-electrode configuration, the boron-modified iron-oxygen (hydroxide) self-supporting nanocatalytic materials are electrodeposited for 250 s using IT technology (constant voltage of -1V vs. Hg / HgO). After removal, the sample is rinsed with deionized water and dried with filter paper. After air drying at room temperature, the final sample is obtained (labeled NiFeLa / FFB, where NiFeLa represents the electrodeposited nickel-iron-lanthanum element, and FFB represents the boronized foamed iron substrate).

[0024] Comparative Example 1

[0025] The preparation method of the self-supporting material (NiFe / FFB, where NiFe represents the nickel-iron element to be electrodeposited and FFB represents the boronized foamed iron substrate) without lanthanum nitrate treatment in the electrolyte of the electrodeposition step is different in that: after synthesizing boron-modified ferrooxide (hydroxide) self-supporting nanocatalyst material by liquid phase method, a mixed solution of nickel nitrate and iron nitrate is used as electrolyte. Under standard three-electrode configuration, the boron-modified ferrooxide (hydroxide) self-supporting nanocatalyst material is used as anode, and electrodeposition is performed on it for 250s by iterative electrochemical (IT) technology (constant voltage of -1V vs. Hg / HgO). After removal, it is rinsed with deionized water and the surface moisture is wiped dry with filter paper. Then, it is air-dried at room temperature to obtain the final sample.

[0026] Comparative Example 2

[0027] Boron-modified iron oxide (hydroxyl) compound self-supporting nanocatalytic materials (FFB) are synthesized by liquid phase without electrodeposition.

[0028] Comparative Example 3

[0029] Commercial foam iron base without any treatment.

[0030] The specific dosages of each reagent and the treatment times in the examples and comparative examples are shown in Tables 1 and 2.

[0031] Table 1. Parameter ratios and processing times in the liquid-phase synthesis method.

[0032]

[0033] Table 2. Parameter ratios and processing times for electrodeposition strategies.

[0034]

[0035] Test case

[0036] 1. CV, LSV, EIS and IT testing

[0037] The OER performance of the supporting catalysts in the examples and comparative examples was tested. The test conditions were as follows: In the OER test, a standard three-electrode system was used, with the self-supporting material as the anode, mercury / mercury oxide (Hg / HgO) as the reference electrode, and a platinum sheet as the cathode. The voltage window was set to 0-1V (vs. Hg / HgO) using a Corrtest Studio 6 electrochemical workstation from Wuhan.

[0038] The stability of materials was evaluated using potentiostatic techniques (with a capacitance of 1000 mA / cm). -2 (Assessment criteria). OER test results are shown in Table 2 and... Figure 1-3 .

[0039] Table 2. Results of Oxygen Evolution Reaction (OER) Overpotential Tests

[0040]

[0041] Figure 1 The figure shows the LSV polarization curves of the oxygen evolution reaction (OER) for each supporting catalytic material. As can be seen from the figure, the OER performance of the materials is significantly improved after treatment with liquid-phase synthesis and electrodeposition methods. NiFeLa / FFB exhibits the best OER performance, followed by NiFe / FFB, FFB, and FF, indicating that the presence of the heterostructure of lanthanum-doped nickel iron oxide (hydroxide) / boron-modified iron oxide (hydroxide) significantly enhances the OER catalytic performance of the materials.

[0042] Figure 2 For the OER overpotential diagrams of their respective supporting catalysts, from Figure 2 It can be seen that NiFeLa / FFB at 50 mA / cm -2 and 500mA cm -2 The overpotentials at the current densities were 227.87 mV and 258.22 mV, respectively (denoted as 227.87 mV @ 50 mA cm⁻¹). -2 and 258.22mV@500mA cm -2 Compared to other samples, its performance is significantly improved.

[0043] Figure 3 The image shows the OER stability test results for NiFeLa / FFB. The OER stability test was conducted at 1000 mA / cm². -2 As a benchmark, the catalyst must be able to operate stably for at least 200 hours to meet industrial application requirements.

[0044] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A lanthanum-doped and boron-modified nickel-iron oxide (hydroxyl) compound self-supporting nanocatalytic material, characterized in that, Lanthanum-doped and boron-modified nickel-iron oxide (hydroxide) compounds are uniformly anchored on the surface of a commercial metal foam iron substrate.

2. A lanthanum-doped and boron-modified nickel-iron oxide (hydroxyl) compound self-supporting nanocatalytic material, obtained by liquid-phase synthesis and electrodeposition, characterized in that... First, a preliminary sample (boron-modified iron oxide (hydroxide) self-supporting nanocatalytic material) is obtained through liquid-phase synthesis. The reaction solution is sodium borohydride solution. Clean commercial iron metal foam is placed in the above solution and allowed to stand. After being removed, the sample is post-processed to obtain the preliminary sample. Then, an electrodeposition strategy is used, characterized by using a mixed solution of nickel nitrate, iron nitrate and lanthanum nitrate as the electrolyte. Under a standard three-electrode configuration, the preliminary sample is used as the anode and treated with IT technology. Finally, the sample is post-processed to obtain the final sample. Further: (1) The area of ​​commercial iron metal foam is 1cm*1.5cm; (2) The molar concentration of sodium borohydride in the reaction solution is 0.5 mol / L; (3) Commercial iron metal foam was soaked in sodium borohydride solution for 30 minutes; (4) The molar concentration of nickel nitrate in the electrolyte is 0.1 mol / L, the molar concentration of iron nitrate is 0.05 mol / L, and the molar concentration of lanthanum nitrate is 0.03125 mol / L; (5) In the IT technique, a constant voltage of -1V vs. Hg / HgO is applied, and the electrodeposition time is 250s.

3. The lanthanum-doped and boron-modified nickel-iron oxide (hydroxyl) compound self-supporting nanocatalytic material according to claim 1, characterized in that, The surface exhibits a heterostructure of lanthanum-doped nickel ferrooxide (hydroxide) / boron-modified ferrooxide (hydroxide).

4. The application of the lanthanum-doped and boron-modified nickel-iron oxide (hydroxide) self-supporting nanocatalytic material according to claims 1-3 as an anode material in water electrolysis for hydrogen production.

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