Method for preparing high-entropy alloy electrocatalyst by microbial corrosion

Abstract

This invention discloses a microbial corrosion method for preparing Al for hydrogen production by water electrolysis. 0.6 The method for developing a CrFe2Ni2 high-entropy alloy catalyst belongs to the field of electrochemical catalysis technology. This invention uses sulfate-reducing bacteria (SRB) as the experimental strain and bulk Al as the catalyst. 0.6 A CrFe2Ni2 high-entropy alloy was used as the matrix material. After SRB corrosion, the FeS corrosion product generated on the alloy surface promoted the catalytic activity of the material. The resulting catalyst was used as the working electrode for water electrolysis to produce hydrogen, exhibiting excellent OER activity and durability in alkaline solutions. Compared with existing technologies, this invention is the first to combine microbial corrosion with bulk alloys for industrial hydrogen production via water electrolysis. The preparation method is simple and mild, with potential application prospects, and provides theoretical guidance and technical support for the design and synthesis of other non-precious metal water electrolysis catalysts.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical catalysis technology, specifically relating to a method for preparing a high-efficiency high-entropy alloy catalyst for water electrolysis through microbial corrosion. Background Technology

[0002] Hydrogen is widely recognized as a green, economical, and recyclable fuel due to its cleanliness and emission-free energy conversion process. As a highly efficient and low-carbon secondary energy source, hydrogen energy is an important direction for future energy technology revolution and industrial development. Among various hydrogen production methods, water electrolysis is considered the most promising green hydrogen supply method, as it can store and utilize surplus green electricity. However, the oxygen evolution reaction (OER) at the anodic end of water electrolysis is a process requiring four electrons, and its slow kinetics limit the development of water electrolysis technology. Therefore, designing a highly active, low-cost, and durable OER electrocatalyst is crucial for hydrogen production via water electrolysis.

[0003] High-entropy alloys are alloys composed of multiple metals in a uniform molar ratio. The multi-metallic composition of high-entropy alloys can promote the formation of catalytic active sites, thereby increasing the reaction rate of OER (Optical Emission Reduction). However, the low specific surface area of ​​intrinsically high-entropy alloys limits the exposure conditions of active sites. Therefore, surface modification of high-entropy alloys is necessary to increase the exposure of active sites and improve catalytic performance. Many microorganisms in the natural environment spontaneously obtain electrons from metals to maintain their physiological activities, a process that leads to microbial corrosion of metallic materials. Among them, sulfate-reducing bacteria (SRB) are widely distributed and are among the most corrosive microorganisms. In an anaerobic environment, SRB use metallic iron as an electron donor to convert SO42- into sulfur dioxide. 2- Reduction to H2S further generates the characteristic corrosion product FeS, leading to the corrosion of metallic iron. In recent years, iron-based sulfides such as FeS have been proven to be excellent OER electrocatalysts. Therefore, some studies have utilized SRB corrosion to synthesize Ni-Fe composite oxygen evolution reaction catalysts composed of nickel-iron hydroxides, hydroxyl oxides, etc., on nickel foam, exhibiting excellent catalytic activity. However, there are currently no research cases on the preparation of bulk alloy catalysts using SRB corrosion. Summary of the Invention

[0004] This invention provides a microbial corrosion strategy for preparing Al for hydrogen production via water electrolysis using the SRB corrosion method. 0.6 A CrFe2Ni2 high-entropy alloy electrocatalyst for oxygen evolution reaction was developed. This preparation method involves in-situ construction of a catalytic layer on the alloy surface under mild conditions and low energy consumption, which aligns with the concept of green synthesis and opens up a new path for the preparation of high-entropy alloy electrocatalysts.

[0005] The preparation method includes the following steps: Step 1: Pre-culture SRB bacteria in ATCC 1249 medium for several generations.

[0006] Step 2: Immerse the polished alloys in ATCC 1249 medium containing and without SRB.

[0007] Step 3: Remove the alloy from the above culture medium, clean and dry it to obtain the high-entropy alloy electrocatalyst.

[0008] The “SRB-5 d” and “Sterile-5 d” mentioned in this invention refer to catalysts obtained by immersion and corrosion in ATCC 1249 medium containing / without SRB, respectively, where “5 d” is the immersion time.

[0009] The second technical solution of the present invention: The present invention also provides a high-entropy alloy catalyst prepared by the above preparation method.

[0010] The beneficial effects of this invention are as follows: This invention is the first to utilize SRB in Al 0.6 In-situ microbial corrosion is performed on the surface of a bulk high-entropy alloy CrFe2Ni2. Through the metabolic activities of microorganisms, the Fe element in the alloy is selectively converted into FeS with OER activity, while a FeOOH catalytic layer is formed on the surface, enhancing the intrinsic catalytic activity of the alloy. Furthermore, the experimental conditions of this invention are mild, requiring only common laboratory equipment, without the need for specialized equipment, and the preparation process is simple and easy to operate. The pharmaceuticals used in this invention are all non-toxic, harmless, and inexpensive. They are also simple to prepare and take little time. After preparation, no complicated or tedious steps are required, making them particularly suitable for batch and low-cost preparation, and suitable for industrial-scale production and commercial applications. The high-entropy alloy catalyst SRB-5d prepared by the method of this invention exhibits excellent performance in OER tests: when the current density reaches 10 mA·cm⁻¹ -2 At this time, the overpotential required for OER is only 306 mV; in addition, at a potential of 1.536 V vs. RHE, the material can operate stably for 12 h without performance degradation. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings will be briefly introduced in the description of the embodiments or the prior art below. However, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1The images shown are SEM images (Al) of the alloy catalysts SRB-5d and Sterile-5d of this invention. 0.6 SEM images of surface corrosion products of CrFe2Ni2 high-entropy alloy after immersion in sterile and sterile culture media for 5 days.

[0013] Figure 2 XPS plots (Al) of the alloy catalysts SRB-5d and Sterile-5d of this invention. 0.6 XPS spectra of surface corrosion products of CrFe2Ni2 high-entropy alloy after immersion in sterile and sterile culture media for 5 days.

[0014] Figure 3 The polarization curves (Al) of the alloy catalysts SRB-5d and Sterile-5d of this invention are shown below. 0.6 LSV curves of CrFe2Ni2 high-entropy alloy after immersion in sterile and sterile culture media for 5 days were measured in 1 M KOH solution.

[0015] Figure 4 This is a chronoamperometry curve of the alloy catalyst SRB-5d of the present invention (stability test curve of SRB-5d catalyst at 1.536 V). Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0017] Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention.

[0018] Unless otherwise specified, the experimental methods described in the following embodiments are conventional methods; unless otherwise specified, the reagents and materials are commercially available.

[0019] 1. Preparation of high-entropy alloy catalysts for efficient water electrolysis via microbial corrosion. The preparation method of this invention uses sterile and aseptic controls. 5 mL of SRB strain was added to 495 mL of ATCC1249 medium as the soaking solution for the sterile group, while the soaking solution for the aseptic group was 500 mL of ATCC 1249 medium. The polished Al... 0.6The CrFe2Ni2 high-entropy alloy samples were placed in sterile and sterile culture media, respectively, and then placed in a water bath at a temperature of 32 ± 0.5 °C. After soaking for 5 days, the samples were removed from the sterile and sterile solutions, and the resulting SRB-5 d and Sterile-5 d catalysts were dehydrated and dried with ethanol before being stored in a vacuum glove box for later use. To verify the feasibility of the preparation method of this invention, a polished sample without any subsequent treatment was set up as a control, i.e., Polished.

[0020] 2. Electrochemical performance of catalysts This experiment utilized a standard three-electrode system to test the catalyst's performance. A 1×1 cm⁻¹ electrode was used. 2 The prepared catalyst was used as the working electrode. A platinum sheet electrode and a Hg / HgO electrode were selected as the counter electrode and reference electrode of the three-electrode system, respectively. All electrochemically measured potentials were converted to the reversible hydrogen electrode (RHE) potential using the following equation: E RHE =E Hg / HgO +0.059×pH+0.098 Combined with SEM results (e.g.) Figure 1 As shown in the figure, the morphology of surface corrosion products differed between alloy samples after sterile and sterile immersion. In XPS testing (e.g....), the corrosion products... Figure 2 As shown in the figure, after 5 days of sterile corrosion, the O 1s and Fe 2p spectra of the alloy showed that the corrosion products on the surface of the Stereile-5 d catalyst were mainly iron-containing oxides. After 5 days of SRB corrosion, the S 2p spectra of the SRB-5 d catalyst showed that S ions appeared at 164.8 and 161.7 eV. n 2- S 2- The corresponding peaks; in its Fe 2p spectrum, FeS, FeOOH, Fe3O4 and other substances appear at 710.9, 713.9 and 725 eV, accompanied by two satellite peaks.

[0021] A 1M KOH electrolyte at room temperature was selected as the electrolyte for the alkaline OER experiment. At 2 mV·s -1 Linear scan voltammetric curves were obtained at a scan rate of [missing information]. For example... Figure 3 As shown, 10 mA·cm⁻¹ was measured in 1M KOH electrolyte. -2 At the specified current density, the overpotential of the polished sample was 329 mV. Based on this, after 5 days of aseptic etching, the overpotential of the alloy increased to 332 mV, indicating a decrease in the OER performance of the catalyst prepared by aseptic etching. After 5 days of SRB etching, the overpotential of the alloy decreased to 306 mV. This indicates that the Al prepared by microbial etching method... 0.6The CrFe2Ni2 high-entropy alloy catalyst exhibits significantly improved OER performance. Based on the above results and comparison with the Stellile-5-day catalyst, it can be concluded that after 5 days of SRB corrosion, FeS with certain catalytic activity is generated on the alloy surface, and the surface FeOOH further enhances its catalytic performance. Without the presence of microorganisms, simple aseptic corrosion is not only ineffective but also detrimental to improving the catalytic performance of the alloy.

[0022] The stability of the SRB-5 d catalyst at 1.536 V vs. RHE was evaluated using a chronoamperometry stability test. Figure 4 As shown, under 1.536 V vs. RHE, the current density change of SRB-5 d catalyst within 12 h showed a generally stable trend, exhibiting good stability.

[0023] 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 method for preparing high-entropy alloy electrocatalysts by microbial corrosion, characterized in that, Includes the following steps: Step 1: Pre-culture SRB bacteria in ATCC 1249 medium for several generations; Step 2: Polish the Al 0.6 CrFe2Ni2 high-entropy alloys were immersed in ATCC 1249 medium containing and without SRB, respectively; Step 3: After soaking, the alloy is removed from the above culture medium, cleaned and dried to obtain the high-entropy alloy electrocatalyst.

2. The preparation method according to claim 1, characterized in that, In step one: the SRB strain is Desulfovibrio vulgaris ( D. vulgaris The bacterium (CGMCC 1.5190) was selected for use at the China General Microbiological Culture Collection Center (CGMCC). The bacterium was cultured using ATCC 1249 medium, which consisted of the following components (g / L): K₂HPO₄·3H₂O 0.6552, CaSO₄·2H₂O 1.2647, NH₄Cl 1.0, (NH₄)₂Fe(SO₄)₂ 1.0, MgSO₄·7H₂O 4.1, yeast extract 1.0, Na₃C₆H₅O₇·2H₂O 5.6977, and NaC₃H₅O₃ 3.

5.

3. The preparation method according to claim 1, characterized in that, In step one: the pre-culture refers to culturing in a constant temperature water bath at 33℃, with each generation culturing for 12 to 24 hours.

4. The preparation method according to claim 1, characterized in that, In step two: the alloy is gradually sanded with alumina and silicon carbide sandpaper from 280 to 1200 grit, and then polished with 1.5 μm polishing paste.

5. The preparation method according to claim 1, characterized in that, In step two: the third-generation bacteria pre-cultured in step one are added to the culture medium as the sterile solution for the experiment; this step is omitted for sterile solutions.

6. The preparation method according to claim 1, characterized in that, In step two: the soaking time is 2-7 days, preferably 5 days. Therefore, the catalysts obtained by soaking in sterile / sterile culture medium for 5 days are respectively denoted as SRB-5d and Sterile-5d.

7. A high-entropy alloy catalyst prepared by microbial corrosion, characterized in that, The preparation method according to any one of claims 1 to 6 is used.

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