A sulfur-doped modified self-supporting electrode material and its preparation method and application

Abstract

The present invention discloses a method for preparing a sulfur-doped modified self-supporting electrode material, the preparation method comprising the following steps: step 1, using thiourea powder as a solid-phase gasification heat reagent and a conductive carbon material as a self-supporting electrode material, and obtaining a sulfur-containing carbon material by solid-phase gasification heat; step 2, calcining the sulfur-containing carbon material at a high temperature to obtain the sulfur-doped modified self-supporting electrode material. The present invention also discloses the sulfur-doped modified self-supporting electrode material obtained by the above preparation method and its application in oxygen evolution by proton exchange membrane water electrolysis. The present invention directly dopes sulfur elements onto the surface of the self-supporting conductive carbon material by a solid-phase gasification heat method, thereby solving the problem of catalytic materials falling off and becoming inactivated on the self-supporting base material, and adjusting the electronic configuration of the conductive carbon material by regulating sulfur atoms, thereby significantly improving the oxygen evolution activity of the conductive carbon material in the application of proton exchange membrane water electrolysis.

Description

Technical Field

[0001] The present invention relates to the field of electrochemical energy conversion, and in particular to a sulfur-doped modified self-supporting electrode material, a preparation method thereof, and applications thereof. Background Art

[0002] Hydrogen production through water electrolysis is a technology that can truly achieve zero-carbon emissions and zero pollution. Proton exchange membrane water electrolysis, with its hydrogen-ion-rich electrolyte environment, allows for high current density operation, and offers advantages such as high hydrogen purity and high electrolysis efficiency, making it a promising technology.

[0003] However, since the proton exchange membrane electrolysis water production hydrogen process requires a strong acid environment, transition metals such as iron, cobalt, and nickel are difficult to tolerate acid corrosion, so that the anode material is limited to precious metal catalysts such as iridium / ruthenium, and the high catalyst material cost limits its large-scale industrial application to a certain extent. The existing technology focuses on the reduction of iridium / ruthenium usage, such as CN116752187A discloses a nanoporous Ir / Ta2O5 composite material for acidic electrolysis water oxygen evolution, such as CN117285088A discloses an iridium oxide cluster assembly catalyst for acidic electrolysis water hydrogen production and its preparation method, such as CN 116949488 A discloses a carbon-supported ruthenium manganese oxide anode oxygen evolution reaction catalyst and its preparation method and application. These materials all adopt the strategy of improving iridium / ruthenium utilization rate in order to achieve reduction of iridium / ruthenium content. However, its material cost still cannot circumvent the precious metal iridium / ruthenium, and even due to being limited to iridium / ruthenium, causes the raw material cost to be further improved. Therefore, the development of a new acid-resistant and highly active catalytic material is expected to break through the situation where the anode material of the proton exchange membrane water electrolysis hydrogen production process is limited to iridium / ruthenium-based catalysts.

[0004] At present, new acid-resistant high-activity anode catalyst materials are still a huge challenge and opportunity, and only a small amount of work has been reported. As CN117904667A discloses a rare earth element doped cobalt manganese oxide based catalyst and its preparation and application, although the problem of non-precious metal cobalt maintaining activity and stability in acidic oxygen evolution reaction is solved to a certain extent by the doping of rare earth elements, the catalytic material is a metal oxide, and according to the lattice oxygen evolution reaction mechanism, it is inevitable that cobalt will be dissolved and separated, which eventually leads to material deactivation. According to published patents, proton exchange membrane electrolysis water anode materials have in-situ grown manganese ruthenium alloy catalyst (CN114250487A) on carbon paper and in-situ grown ruthenium manganese oxide catalyst (CN116949488A) on carbon paper, etc., all use carbon paper as self-supporting material, confirm that carbon paper this kind of conductive carbon material can be applied to acidic oxygen evolution reaction. However, in-situ growth catalyst on carbon paper can cause catalyst to fall off and deactivate due to its long-term operation.

[0005] Direct modification of conductive carbon materials is expected to simultaneously maintain high activity and stability, but there are almost no relevant research reports. Therefore, based on the direct modification of conductive carbon materials, a new non-metallic acid-resistant and highly active anode catalyst material has been developed, which is expected to overcome the shortcomings of existing technologies and promote the development of proton exchange membrane water electrolysis. Summary of the Invention

[0006] The purpose of the present invention is to provide a sulfur-doped modified self-supporting electrode material, a preparation method and application thereof. The present invention realizes direct doping of sulfur elements on the surface of a self-supporting conductive carbon material through a solid-phase gasification thermal method, thereby solving the problem of catalytic materials falling off and becoming inactivated on the self-supporting base material. The electronic configuration of the conductive carbon material is adjusted by regulating sulfur atoms, thereby significantly improving the oxygen evolution activity of the conductive carbon material in the application of proton exchange membrane water electrolysis.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] A method for preparing a sulfur-doped modified self-supporting electrode material, the method comprising the following steps:

[0009] Step 1, using thiourea powder as a solid-phase gasification heat reagent and a conductive carbon material as a self-supporting electrode material, to obtain a sulfur-containing carbon material by solid-phase gasification heat;

[0010] Step 2: calcining the sulfur-containing carbon material at a high temperature to obtain the sulfur-doped modified self-supporting electrode material.

[0011] Preferably, the amount of thiourea required for the solid phase gasification heat in step 1 is 2-4 mmol.

[0012] Preferably, the conductive carbon base material is selected from at least one of carbon paper, carbon cloth or graphite.

[0013] Preferably, the temperature of the solid phase gasification heat in step 1 is 180-200°C;

[0014] Preferably, the solid phase gasification heat time in step 1 is 12-18 hours.

[0015] Preferably, in step 2, the calcination temperature is 700-1100° C., the heating rate is 2-10° C. / min, and the calcination time is 1-5 h; and the calcination environment in step 2 is an inert atmosphere, such as nitrogen, argon, etc.

[0016] The present invention also provides a sulfur-doped modified self-supporting electrode material prepared according to the above preparation method.

[0017] The present invention also provides an application of a sulfur-doped modified self-supporting electrode material in a proton exchange membrane water electrolysis oxygen evolution reaction.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1) The sulfur-doped conductive carbon material (i.e., sulfur-doped modified self-supporting electrode material) prepared by the present invention greatly improves the catalytic activity of the conductive carbon material by regulating the sulfur element. This material also avoids the problem of easy shedding between the catalytic material and the substrate material by directly modifying the self-supporting conductive carbon material; at the same time, no metal is used as an active site, avoiding the problem of easy dissolution and precipitation of metal elements in an acidic environment. Therefore, the sulfur-doped modified self-supporting electrode material of the present invention can simultaneously exhibit electrocatalytic oxygen evolution activity and stability in the application of proton exchange membrane water electrolysis.

[0020] 2) The anode material prepared by this invention (i.e., a sulfur-doped self-supporting electrode material) utilizes a conductive carbon material as a self-supporting substrate and, through sulfur doping and modification, also serves as an oxygen evolution active site, significantly reducing raw material costs and simplifying the process. Compared with traditional processes, this anode material can be directly used in water electrolysis without the addition of auxiliary materials such as binders, simplifying the secondary preparation process, significantly reducing process costs, and broadening its commercial application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a scanning electron microscope image of the sulfur-doped modified self-supporting electrode material prepared in Example 1;

[0022] Figure 2 This is a scanning electron microscope image of the unmodified self-supporting electrode material carbon paper in Comparative Example 1;

[0023] Figure 3 This is an X-ray photoelectron spectroscopy image of the sulfur-doped modified self-supporting electrode material prepared in Example 1;

[0024] Figure 4 Linear voltammetric scans of the sulfur-doped modified self-supporting electrode materials prepared in Examples 1-4 and the unmodified self-supporting electrode material carbon paper in Comparative Example 1;

[0025] Figure 5 This is a stability diagram of the sulfur-doped modified self-supporting electrode material prepared in Example 1. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with embodiment. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Those skilled in the art will make modifications or equivalent substitutions based on understanding the technical solution of the present invention, without departing from the spirit and scope of the technical solution of the present invention, and all should be encompassed within the protection scope of the present invention.

[0027] The raw materials used in the following specific embodiments are all purchased from the market.

[0028] Example 1

[0029] The thiourea was pretreated and thoroughly ground; the carbon paper was pretreated, cut into 1 cm x 3 cm pieces, and washed and dried. The pretreated 4 mmol of thiourea and carbon paper were transferred to a sealed polytetrafluoroethylene stainless steel autoclave and placed in an oven for a solid-phase gasification reaction at 200°C for 12 hours. After the reaction was complete and the oven temperature cooled to room temperature, the material was removed and washed and dried to obtain a sulfur-containing carbon material. The sulfur-containing carbon material was then placed in a tubular furnace with a nitrogen atmosphere, heated at a rate of 5°C / min, and calcined at 1100°C for 1 hour. After calcination, the material was removed, washed, and dried to obtain sulfur-doped modified self-supporting electrode material-1.

[0030] Example 2

[0031] Referring to Example 1, 4 mmol of thiourea was replaced with 2 mmol of thiourea to obtain sulfur-doped modified self-supporting electrode material-2.

[0032] Example 3

[0033] Referring to Example 1, the solid-phase gasification thermal reaction time was changed to 18 h to obtain sulfur-doped modified self-supporting electrode material-3.

[0034] Example 4

[0035] Referring to Example 1, the calcination temperature was changed to 700° C. to obtain sulfur-doped modified self-supporting electrode material-4.

[0036] Comparative Example 1

[0037] The 1 cm×3 cm carbon paper was washed and dried to obtain unmodified self-supporting electrode material carbon paper.

[0038] Application Example 1

[0039] The material's oxygen evolution performance was evaluated using linear sweep voltammetry, while its stability was assessed using chronoamperometry and cyclic voltammetry. The specific testing system used a three-electrode system, with a graphite rod and an Ag / AgCl electrode serving as the counter and reference electrodes, respectively. The prepared catalytic electrode material served as the working electrode, and the electrolyte was 0.5M H2SO4.

[0040] Material structure and morphology analysis:

[0041] The sulfur-doped modified self-supporting electrode material prepared in Example 1 and the unmodified self-supporting electrode material carbon paper in Comparative Example 1 were characterized by scanning electron microscopy (SEM). Figure 1 This is the SEM image of the sulfur-doped modified self-supporting electrode material prepared in Example 1. Figure 2 This is the SEM image of the unmodified self-supporting electrode material carbon paper in Comparative Example 1. Figure 1 and Figure 2 As shown, compared with the unmodified carbon paper, the sulfur-doped modified self-supporting electrode material of the present invention does not undergo obvious changes in microscopic morphology, indicating that no other catalyst is in situ grown on the carbon paper. The material of the present invention can effectively avoid the problem of easy detachment between the catalytic material and the substrate material.

[0042] Furthermore, the sulfur-doped modified self-supporting electrode material prepared in Example 1 was characterized by X-ray photoelectron spectroscopy (XPS). Figure 3 As shown in the S2p spectrum, the presence of peaks can be clearly seen, and CSC (164.17 eV), C=S (165.37 eV) and SO (168.8 eV) can be obtained by peak separation, which proves the existence of sulfur and successful doping, and illustrates that the present invention can adjust the electronic configuration of the conductive carbon material to optimize the intrinsic activity of the conductive carbon material as a self-supporting electrode.

[0043] Oxygen evolution performance test and analysis:

[0044] Figure 4 The linear voltammetric scanning diagrams of the sulfur-doped modified self-supporting electrode materials prepared in Examples 1-4 and the unmodified self-supporting electrode material carbon paper in Comparative Example 1 are as follows: Figure 4 As shown, compared with the unmodified carbon paper, the performance of the sulfur-doped modified self-supporting electrode material of the present invention is significantly improved, showing excellent electrochemical performance. Figure 5 The stability diagram of the sulfur-doped modified self-supporting electrode material prepared in Example 1 is shown in FIG. Figure 5 As shown, the current of the sulfur-doped modified self-supporting electrode material of the present invention does not decay significantly over time, and even increases slightly, which shows that the material of the present invention has good stability. Figure 5 The illustration in FIG is a comparison diagram of the linear voltammetric scan of the sulfur-doped modified self-supporting electrode material prepared in Example 1 before and after 1000 cycles of cyclic voltammetry, as shown in FIG. Figure 5 As shown in the illustration, the sulfur-doped modified self-supporting electrode material of the present invention also showed a slight improvement in performance after 1000 cycles of cyclic voltammetry testing, which is consistent with the stability results tested by chronoamperometry. These results show that the material of the present invention effectively solves the problem of active material precipitation or deactivation during long-term operation in the prior art, and can even self-optimize and reconstruct sites with higher intrinsic activity to further improve material performance and demonstrate excellent stability.

[0045] In summary, the sulfur-doped modified self-supporting electrode material of the present invention has low raw material cost, simple process method, high electrocatalytic oxygen evolution activity and stability, and is a proton exchange membrane water electrolysis anode material with great application potential.

[0046] The above description is only a preferred specific embodiment of the present invention, and the protection scope of the present invention is not limited thereto. Any simple change or equivalent replacement of the technical solution that can be obviously obtained by any technician familiar with this technical field within the technical scope disclosed in the present invention falls within the protection scope of the present invention.

Claims

1. Application of a sulfur-doped modified self-supporting electrode material in proton exchange membrane water electrolysis and oxygen evolution, characterized in that: The method for preparing the sulfur-doped modified self-supporting electrode material comprises the following steps: Step 1, using thiourea powder as a solid-phase gasification heat reagent and a conductive carbon material as a self-supporting electrode material, to obtain a sulfur-containing carbon material by solid-phase gasification heat; Step 2: calcining the sulfur-containing carbon material at a high temperature to obtain the sulfur-doped modified self-supporting electrode material.

2. The use of the sulfur-doped modified self-supporting electrode material according to claim 1, characterized in that: The amount of thiourea required for the solid phase vaporization heat in step 1 is 2-4 mmol.

3. The use of the sulfur-doped modified self-supporting electrode material according to claim 1, characterized in that: The conductive carbon base material is selected from at least one of carbon paper, carbon cloth or graphite.

4. The use of the sulfur-doped modified self-supporting electrode material according to claim 1, characterized in that: The temperature of the solid phase gasification heat in step 1 is 180-200°C.

5. The use of the sulfur-doped modified self-supporting electrode material according to claim 1, characterized in that: The time of solid phase gasification heat in step 1 is 12-18 hours.

6. The use of the sulfur-doped modified self-supporting electrode material according to claim 1, characterized in that: In step 2, the calcination temperature is 700-1100° C., the heating rate is 2-10° C. / min, and the calcination time is 1-5 hours; the calcination environment is an inert atmosphere.

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