Preparation method of single-atom modified 1t phase tmds / c superlattice structure electrocatalyst
By preparing a 1T-TMDs/C superlattice structure modified with a single atom of transition metal, the problem of poor electrocatalytic performance of two-dimensional 1T phase TMDs under alkaline conditions was solved, and high-efficiency electrocatalytic performance over a wide pH range was achieved, promoting its application in the field of electrocatalytic water splitting.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-09-19
- Publication Date
- 2026-03-20
AI Technical Summary
In the existing technology, two-dimensional 1T phase TMDs materials have good electrocatalytic performance under acidic conditions, but poor hydrogen or oxygen evolution performance under alkaline conditions. In addition, the preparation process is complicated, the product purity is low, and the phase stability is poor, which limits their large-scale application in the field of electrocatalytic water splitting.
A precursor was prepared by co-precipitation using a wet chemical method and reacted with a long-chain surfactant at high temperature to form a 1T-TMDs/C superlattice structure modified with a single atom of transition metal. The 1T-TMDs nanosheets with uniform size, no agglomeration, and easy dispersion were obtained by high-temperature calcination, thus realizing a superlattice heterostructure of 1T-TMDs and carbon stacked layer by layer.
The prepared catalyst exhibits excellent hydrogen evolution/oxygen evolution reaction activity under a wide pH range, and especially good stability under alkaline conditions, expanding the application potential of 1T-TMDs in the field of electrocatalytic water splitting.
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Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of material chemistry, and particularly relates to a preparation method of a 1T-TMDs / C superlattice structure electrocatalyst with high catalytic activity of transition metal single atom modification. BACKGROUND
[0002] Electrocatalytic overall water splitting is one of the important means in the field of clean energy conversion. At present, platinum / carbon catalyst is the standard commercial electrocatalyst in this field, but the high cost of platinum / carbon catalyst caused by the low abundance of platinum seriously limits its large-scale application. Therefore, seeking a material with large reserves and low cost to replace platinum / carbon catalyst is the goal of many researchers. Among them, transition metal dichalcogenides (TMDs) with a layered structure, such as MoS2 or WS2, are considered to be one of the most potential materials to replace commercial platinum / carbon catalysts due to their advantages of abundant reserves, high theoretical electrocatalytic activity, etc. TMDs materials are divided into semiconductor 2H phase and metal 1T phase according to the arrangement of transition metal elements and chalcogen elements. Among them, the semiconductor 2H phase has poor conductivity, which is not conducive to the electron transfer during electrocatalysis; while the metal 1T phase has good conductivity and more catalytic active sites, but the poor phase stability greatly limits its electrocatalytic performance.
[0003] At present, the main preparation method of two-dimensional 1T phase TMDs is the indirect method of phase transition of semiconductor 2H phase TMDs by physical or chemical methods. The main "driving force" of phase transition includes alkali metal intercalation, heteroatom doping, heat treatment, external induction (plasma, electron beam, laser), etc. However, these methods still have the disadvantages of low efficiency, low product purity (70%~80%), complex preparation process and poor phase stability of the final product. In addition, most of the TMDs materials currently only show good electrocatalytic hydrogen evolution performance under acidic conditions, and the hydrogen evolution or oxygen evolution performance under alkaline conditions is not satisfactory. This seriously hinders the large-scale application of two-dimensional 1T phase TMDs in the field of electrocatalytic overall water splitting. Therefore, it is very important to construct a universal and stable 1T-TMDs structure to activate its hydrogen evolution / oxygen evolution performance under alkaline conditions for the promotion of TMDs in the field of electrocatalytic overall water splitting. SUMMARY
[0004] In view of the above problems of the prior art, the purpose of the present application is to provide a preparation method of a 1T-TMDs / C superlattice structure electrocatalyst with transition metal single atom modification. The electrocatalyst prepared by the method has a superlattice structure of transition metal single atom modified 1T phase TMDs and C layers, and the synthesized sample has the advantages of high 1T-TMDs phase purity, uniform size, no agglomeration, easy dispersion in non-polar solvents, etc.
[0005] The above purpose of the present application is realized by the following technical scheme:
[0006] A preparation method of a single-atom modified 1T phase TMDs / C superlattice structure electrocatalyst, comprising the following steps:
[0007] Mixing and stirring molybdenum pentachloride or tungsten hexachloride and diethyldithiocarbamate (such as its sodium salt or potassium salt, etc.) with a molar ratio of 1:Y and an excess of ultrapure water, centrifuging and drying to obtain a precursor Mo(DDTC)5 or W(DDTC)6, wherein Y is the valence of Mo or W, and DDTC is diethyldithiocarbamate;
[0008] Mixing and stirring a transition metal salt and diethyldithiocarbamate with a molar ratio of 1:X and an excess of ultrapure water, centrifuging and drying to obtain a precursor M'(DDTC) X , wherein M' is a transition metal atom and is selected from Co, Fe, Ni, Cu or Mn, and X is the valence of the corresponding transition metal;
[0009] Mixing and stirring Mo(DDTC)5 or W(DDTC)6 and M'(DDTC) X with a molar ratio of 1:1, dispersing in an excess of a mixture of various long-chain carbon surfactants, heating to 100-120 DEG C under the protection of an inert gas (such as nitrogen or argon), removing oxygen and low-boiling-point solvents under vacuum, then reacting at 280-320 DEG C (the reaction time is preferably 1-3 hours), naturally cooling to room temperature after the reaction is completed, ultrasonic washing (a commonly used solvent can be used, and a mixture of hexane and ethanol in any ratio is preferably used) and drying to obtain a single-atom modified M'-1T-TMDs chain structure product;
[0010] Finally, calcining the M'-1T-TMDs chain structure product at 500 DEG C-700 DEG C under the protection of an inert gas to obtain a M'-1T-TMDs / C superlattice structure electrocatalyst, wherein the calcination temperature is preferably 500 DEG C-600 DEG C, and the time is preferably more than 1 hour.
[0011] The mixture of long-chain carbon surfactants is a mixture of any ratio of two or three of oleylamine, oleic acid, dodecylamine, hexadecylamine or octadecylamine.
[0012] The transition metal single-atom modified 1T-TMDs / C superlattice heterostructure prepared by the method has the advantages of high phase purity, uniform size, no agglomeration, and good dispersibility in non-polar solvents. BRIEF DESCRIPTION OF DRAWINGS
[0013] Figure 1 A Raman spectrum of Co-1T-MoS2 / C prepared in Example 1 of the present application.
[0014] Figure 2Transmission electron microscope image of Co-1T-MoS2 / C prepared in Example 1 of the present application.
[0015] Figure 3 High-resolution transmission electron microscope image of Co-1T-MoS2 / C prepared in Example 1 of the present application.
[0016] Figure 4 Electrocatalytic oxygen evolution stability of Co-1T-MoS2 / C prepared in Example 1 of the present application in 1 mol / L concentration of potassium hydroxide solution. DETAILED DESCRIPTION
[0017] In order to more clearly understand the objects, technical solutions and advantages of the present application, the present application will be further described in detail below with reference to the accompanying drawings and examples.
[0018] Example 1:
[0019] Mix 1 mmol of molybdenum pentachloride (MoCl5), 5 mmol of sodium diethyldithiocarbamate (NaDDTC) and 5 mol of ultrapure water, stir for 10 minutes, centrifuge and dry to obtain the precursor Mo(DDTC)5; mix 1 mmol of cobalt nitrate (Co(NO3)2), 2 mmol of NaDDTC and 5 mol of ultrapure water, stir for 10 minutes, centrifuge and dry to obtain the precursor Co(DDTC)2. Disperse 1 mmol of Mo(DDTC)5 and 1 mmol of Co(DDTC)2 in 10 mmol of oleylamine and 10 mmol of oleic acid, heat to 100°C under argon protection, vacuum remove oxygen and low boiling point solvents, then heat to 280°C and react for 1 hour, naturally cool to room temperature, add 5 mL of hexane and 20 mL of ethanol, ultrasonically wash and dry to obtain cobalt monatomic modified 1T phase molybdenum sulfide chain structure (Co-1T-MoS2). Finally, place the above chain structure product in a tube furnace, calcine at 500°C under argon gas protection for 1 hour, carbonize the long carbon chain surfactant, and obtain a superlattice heterostructure composed of cobalt monatomic modified 1T phase MoS2 and C (Co-1T-MoS2 / C) with high catalytic activity. The high catalytic activity described herein refers to the excellent performance of Co-1T-MoS2 / C as an electrocatalytic hydrogen production, oxygen production and overall water splitting catalyst under wide pH conditions, which is also applicable to each of the following examples.
[0020] Referring to Figure 1 , the product prepared is identified by Raman spectrum as metallic 1T phase MoS2.
[0021] Referring to Figure 2 , the product is observed by transmission electron microscope to be a superlattice heterostructure of MoS2 and carbon nanosheet layer-by-layer stacking.
[0022] Referring to Figure 3The TMDs nanosheets of the product were cobalt single-atom-modified 1T phase MoS2 nanosheets observed by a double spherical aberration corrected electron microscope.
[0023] Example 2:
[0024] 1 mmol of MoCl5, 5 mmol of NaDDTC and 5 mol of ultrapure water were mixed and stirred for 10 minutes, and then a precursor Mo(DDTC)5 was obtained after centrifugation and drying. 1 mmol of iron nitrate (Fe(NO3)3), 3 mmol of NaDDTC and 5 mol of ultrapure water were mixed and stirred for 10 minutes, and then a precursor Fe(DDTC)3 was obtained after centrifugation and drying. 1 mmol of Mo(DDTC)5 and 1 mmol of Fe(DDTC)3 were dispersed in 5 mmol of dodecylamine, 5 mmol of oleylamine and 10 mmol of oleic acid, heated to 110°C under argon protection, vacuumed to remove oxygen and water, then heated to 300°C for 1 hour, naturally cooled to room temperature, 5 mL of hexane and 30 mL of ethanol were added, and then ultrasonic washing, drying were performed to obtain a chain structure of iron single-atom-modified 1T phase molybdenum disulfide (Fe-1T-MoS2). Finally, the chain structure product was placed in a tube furnace and calcined at 500°C for 2 hours under argon gas protection, and the long carbon chain surfactant was carbonized to obtain a superlattice heterostructure of iron single-atom-modified 1T phase MoS2 and C with high catalytic activity (Fe-1T-MoS2 / C).
[0025] Example 3:
[0026] 1 mmol of tungsten hexachloride (WCl6), 6 mmol of NaDDTC and 10 mol of ultrapure water were mixed and stirred to obtain a precursor W(DDTC)6. 1 mmol of cobalt nitrate (Co(NO3)2), 2 mmol of NaDDTC and 5 mol of ultrapure water were mixed and stirred for 10 minutes, and then a precursor Co(DDTC)2 was obtained after centrifugation and drying. 1 mmol of W(DDTC)6 and 1 mmol of Co(DDTC)2 were dispersed in 10 mmol of octadecylamine and 10 mmol of oleic acid, heated to 100-120°C under argon protection, vacuumed to remove oxygen and low-boiling-point solvents, then heated to 320°C for 1 hour, naturally cooled to room temperature, 5 mL of hexane and 40 mL of ethanol were added, and then ultrasonic washing, drying were performed to obtain a chain structure of cobalt single-atom-modified 1T phase tungsten disulfide (Co-1T-WS2). Finally, the chain structure product was placed in a tube furnace and calcined at 600°C for 1 hour under argon gas protection, and the long carbon chain surfactant was carbonized to obtain a superlattice heterostructure of cobalt single-atom-modified 1T phase WS2 and C with high catalytic activity (Co-1T-WS2 / C).
[0027] Example 4:
[0028] Mix 1 mmol of MoCl5, 5 mmol of sodium diethyldithiocarbamate (NaDDTC) and 5 mol of ultrapure water, stir for 10 minutes, centrifuge and dry to obtain the precursor Mo(DDTC)5; mix 1 mmol of cobalt nitrate (Co(NO3)2), 2 mmol of NaDDTC and 5 mol of ultrapure water, stir for 10 minutes, centrifuge and dry to obtain the precursor Co(DDTC)2. Disperse 1 mmol of Mo(DDTC)5 and 1 mmol of Co(DDTC)2 in a mixed solution of 5 mmol of octadecylamine, 5 mmol of hexadecylamine and 10 mmol of oleic acid, heat to 100°C under argon protection, vacuum remove oxygen and water, then heat to 280°C and react for 1 hour, naturally cool to room temperature, add 5 mL of hexane and 50 mL of ethanol, ultrasonic, wash and dry to obtain cobalt monatomic modified 1T phase molybdenum sulfide chain structure (Co-1T-MoS2). Finally, place the above chain structure product in a tube furnace and calcine at 700°C under argon gas protection for 1 hour to carbonize the long carbon chain surfactant, thereby obtaining a superlattice heterostructure of cobalt monatomic modified 1T phase MoS2 and C (Co-1T-MoS2 / C).
[0029] The present application utilizes a wet chemical synthesis method, prepares a precursor by a coprecipitation method, and then co-reacts the relevant precursor and a long carbon chain surfactant at high temperature to realize self-assembly of transition metal monatomic modified 1T phase TMDs nanosheet into a chain structure. Finally, the chain structure is calcined at high temperature to obtain a superlattice heterostructure of transition metal monatomic modified 1T phase TMDs and carbon layers. The final product has the characteristics of uniform size, no agglomeration, easy dispersion in non-polar solvents, high 1T phase purity and high phase stability. Due to the ultra-high conductivity and rich catalytic active sites of 1T-TMDs, combined with the interface coupling effect between 1T-TMDs and carbon, the superlattice heterostructure of transition metal monatomic modified 1T phase TMDs and carbon layers exhibits excellent hydrogen evolution / oxygen evolution reaction activity as an electrocatalyst under wide pH conditions. The alkaline electrocatalytic test of the material proves that it has excellent alkaline oxygen evolution stability, which provides the possibility for the development of TMDs materials in the application of alkaline electrocatalysis.
[0030] Figure 4 It is shown that the current density still retains nearly 60% after 60h of oxygen evolution reaction at a static potential of 0.65V, indicating that the catalyst prepared by the present application has excellent stability.
Claims
1. A method for preparing a single-atom modified 1T phase TMDs / C superlattice structure electrocatalyst, characterized in that... Includes the following steps: Molybdenum pentachloride or tungsten hexachloride and diethyldithiocarbamate in a molar ratio of 1:Y were mixed with excess ultrapure water, stirred, centrifuged and dried to obtain the precursor Mo(DDTC)5 or W(DDTC)6, where Y is the valence state of Mo or W and DDTC is diethyldithiocarbamate. A transition metal salt and diethyldithiocarbamate in a molar ratio of 1:X were mixed with excess ultrapure water, stirred, centrifuged, and dried to obtain the precursor M'(DDTC). X , where M' is a transition metal atom selected from Co or Fe, and X is the valence state of the corresponding transition metal; Mix Mo(DDTC)5 or W(DDTC)6 and M'(DDTC) in a molar ratio of 1:
1. X The product was dispersed in a mixture of various long-chain surfactants and heated to 100–120°C under inert gas or nitrogen protection. Oxygen and low-boiling-point solvents were removed by vacuum. The product was then reacted at 280–320°C. After the reaction was completed, the product was naturally cooled to room temperature, ultrasonically washed and dried to obtain a single-atom modified M'-1T-TMDs chain structure product. Finally, the M'-1T-TMDs chain structure product was calcined at 500℃~700℃ under inert gas or nitrogen protection to obtain the M'-1T-TMDs / C superlattice structure electrocatalyst.
2. The preparation method according to claim 1, wherein the mixture of long-chain surfactants is a mixture of two or three of oleylamine, oleic acid, dodecylamine, hexadecylamine or octadecylamine in any proportion.
3. The preparation method according to claim 1, wherein the solvent used for ultrasonic washing is a mixture of hexane and ethanol in any proportion.
4. The preparation method according to claim 1, wherein the reaction time at 280-320°C is 1-3 hours.
5. The preparation method according to claim 1, wherein the calcination temperature is 500℃~600℃.
6. The preparation method according to claim 1 or 5, wherein the calcination time is more than 1 hour.
7. The preparation method according to claim 1, wherein the diethyldithiocarbamate is sodium diethyldithiocarbamate or potassium diethyldithiocarbamate.
8. The preparation method according to claim 1, wherein the molar ratio of molybdenum pentachloride or tungsten hexachloride, diethyl dithiocarbamate and ultrapure water is 1:Y:5000.
9. The preparation method according to claim 1, wherein the molar ratio of the transition metal salt, diethyldithiocarbamate and ultrapure water is 1:X:5000.