Cuprous sulfide / tungsten sulfide composite titanium carbide material as well as preparation method and application thereof
By preparing Cu2S/WS2/Ti3C2Tx composite materials, the problems of insufficient activation and interlayer stacking of existing electrocatalysts were solved, the efficiency and selectivity of electrocatalytic nitrate reduction to ammonia synthesis were improved, and efficient electrocatalytic performance was achieved.
Patent Information
- Application Number
- CN202510904666.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-01
- Publication Date
- 2025-09-23
AI Technical Summary
Existing electrocatalytic nitrate reduction catalysts for ammonia synthesis have problems such as insufficient activation of the N≡O bond by transition metal catalysts, easy oxidation and deactivation of copper-based materials, and limited mass transfer caused by the stacking of two-dimensional material layers, which affect the reaction efficiency and selectivity.
A three-dimensional porous Ti3C2Tx-loaded phosphotungstic acid-based copper metal-organic framework was used as a precursor, and the Cu2S/WS2/Ti3C2Tx composite material was prepared by high-temperature calcination. The synergistic catalytic activity of Cu2S and WS2 was utilized to prevent the accumulation of Ti3C2Tx nanosheets and maintain good conductivity and stability.
The performance of electrocatalytic nitrate reduction to ammonia synthesis was significantly improved, the catalytic activity and selectivity were increased, and efficient electrocatalytic nitrate reduction was achieved.
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Abstract
Description
Technical Field
[0001] The invention relates to the technical field of catalyst materials for electrocatalytic nitrate reduction to synthesize ammonia, and is a cuprous sulfide / tungsten sulfide composite titanium carbide material and a preparation method and application thereof. Background Art
[0002] The traditional Haber-Bosch process for ammonia synthesis requires high temperature and high pressure (>400℃, 150-300bar), and its energy consumption accounts for 1-2% of global energy consumption. The emerging electrocatalytic nitrate reduction to ammonia (e-NO3RR) technology can use wastewater nitrate (NO3 – ) to achieve environmental remediation, where catalysts are crucial. However, current catalysts for e-NO≡RR still face the following technical bottlenecks: 1) Transition metal catalysts lack sufficient activation of the N≡O bond (204 kJ / mol), resulting in insufficient ammonia selectivity and Faradaic efficiency; 2) Copper-based materials (such as single-atom copper) are susceptible to oxidative deactivation at high potentials; and 3) The stacking of two-dimensional materials between layers limits mass transfer, severely restricting reaction efficiency.
[0003] Transition metal carbon / nitrogen / carbonitride (MXene, such as Ti3C2T x ) is a new type of nanomaterial, which has attracted much attention in the field of catalytic application research due to its unique two-dimensional layered structure, high density, excellent metal-like conductivity and controllable surface end group properties. Transition metal carbon / nitrogen / carbon nitrogen compound (MXene) materials have a wide range of applications in energy storage, sensing, catalysis, biology and other fields due to their unique morphology, metal-like conductivity and high chemical stability. Cuprous sulfide (Cu2S) is a narrow bandgap p-type semiconductor material with good chemical and thermal stability and is a good conductive material. Cu2S and WS2 (interlayer spacing 0.62nm) can construct a heterogeneous interface to form a built-in electric field and enhance NO3 – adsorption.
[0004] Polyoxometalates (POMOFs) are a type of crystalline porous hybrid material composed of polyoxometalates anions, metal ions or metal clusters, and organic ligands connected by coordination bonds. They cleverly combine the structural advantages of polyoxometalates (POMs, referred to as polyoxometalates) and metal-organic frameworks (MOFs). Using POMOFs as precursors, multi-component metal composites with heterogeneous structural interfaces can be prepared. x The loaded phosphotungstic acid-based copper metal organic framework was used as a precursor, and three-dimensional porous Ti3C2T was obtained by high-temperature calcination. xSupported copper tungsten sulfide composite material (Cu2S / WS2 / Ti3C2T x ), and applied it to electrocatalysis of NO3 - Reduction of synthetic ammonia to improve e-NO3RR performance. Summary of the Invention
[0005] The purpose of the present invention is to in situ grow a phosphotungstic acid-based copper metal organic framework on a porous Ti3C2T x On the synthetic PW 12 @Cu-BTC / Ti3C2T x The composite material was further calcined in a tube furnace under argon atmosphere to prepare Cu2S / WS2 / Ti3C2T x Composite materials. Cu2S and WS2 have synergistic catalytic activity. x The in-situ growth of the surface can prevent Ti3C2T x The accumulation of nanosheets increases the specific surface area of the composite material and maintains the x Good conductivity and stability. Using this material as a catalyst can improve the performance of electrocatalytic nitrate reduction to synthesize ammonia.
[0006] In order to achieve the above-mentioned purpose, the present invention provides the following technical solutions:
[0007] 1. Ti3C2T x Preparation of hydrogel: Take a single layer of Ti3C2T x Disperse in deionized water, dissolve copper nitrate hexahydrate (Cu(NO3)2·6H2O) in deionized water, mix the two quickly, and Ti3C2T x The hydrogel formed within seconds.
[0008] 2. PW 12 @Cu-BTC / Ti3C2T x Preparation: Solution A, Cu 2+ -Ti3C2T x Solution B, a mixed solution of copper acetate (Cu(Ac)2·H2O) and phosphotungstic acid (PW 12 ) a mixed solution. Solution A was slowly added to solution B, stirred thoroughly at room temperature and pressure, washed, centrifuged, freeze-dried, and the product PW was collected. 12 @Cu-BTC / Ti3C2T x Composite materials.
[0009] 3. Cu2S / WS2 / Ti3C2T x Preparation of composite materials: Take a certain amount of PW 12 @Cu-BTC / Ti3C2Tx The composite material and thiourea were mixed in a mass ratio of 1:20 and fully ground, placed in a porcelain boat, and calcined at a high temperature in a tube furnace under an argon atmosphere. The temperature was lowered and the product was collected.
[0010] 1. Cu as described in step 1 2+ -Ti3C2T x solution, in which Ti3C2T x The mass is 58-62 mg,
[0011] The mass of Cu(NO3)2·3H2O is 58~62mg.
[0012] 2. The mass of the trimesic acid described in step 2 is 0.14-0.15 g, and the solvent is anhydrous ethanol.
[0013] 3. The copper acetate described in step 2 has a mass of 0.18-0.24 g and the solvent is deionized water.
[0014] 4. The mass of the phosphotungstic acid described in step 2 is 0.3-0.4 g.
[0015] 5. The stirring time in step 2 is 30 min, and the mixture is washed several times with anhydrous ethanol and deionized water.
[0016] 6. PW described in step 3 12 @Cu-BTC / Ti3C2T x The composite material has a mass of 0.2 to 0.3 g.
[0017] 7. The mass of the thiourea described in step 3 is 4 to 5 g.
[0018] 8. The temperature of the tube furnace described in step 3 is 900°C, the heating rate is 7°C / min, and it is maintained for 2 hours. The cooling rate is the same as the heating rate.
[0019] Compared with the prior art, the present invention has the following beneficial effects:
[0020] The present invention successfully prepared Cu2S / WS2 / Ti3C2T with porous structure through high temperature calcination technology. x Composite electrode material. During the synthesis process, Ti3C2T x The reactivity and electronegativity of the abundant hydroxyl (-OH) and carboxyl (-COOH) functional groups on the surface can be used to convert Cu 2+ Anchored in Ti3C2T x Cu 2+ -Ti3C2T x On this basis, organic ligands are added to Ti3C2T x Surface in situ growth of PW12 @Cu-BTC, get PW 12 @Cu-BTC / Ti3C2T x The composite material was further synthesized by high temperature calcination to form Cu2S / WS2 / Ti3C2T x Composite materials. Porous Ti3C2T x With a larger specific surface area, it effectively avoids the x The interlayer stacking of two-dimensional nanosheets is more conducive to the loading of catalytic active substances. Cu2S and WS2 are evenly dispersed in porous Ti3C2T x The surface can not only effectively improve the conductivity and dispersibility of the material, but also optimize the electronic structure of the active site through the interface electronic effect and synergistic effect, promote electron transport, and thus significantly improve the catalytic activity and selectivity. Therefore, the bimetallic sulfide is modified on Ti3C2T by high temperature calcination technology. x This strategy provides new ideas and methods for developing efficient and stable e-NO3RR catalysts. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 Cu2S / WS2 / Ti3C2T prepared in Example 1 of the present invention x Scanning electron microscopy images of the composite material.
[0022] Figure 2 Cu2S / WS2 / Ti3C2T prepared in Example 1 of the present invention x Powder X-ray diffraction patterns of the composite materials.
[0023] Figure 3 Cu2S / WS2 / Ti3C2T prepared in Example 1 of the present invention x Composite materials with or without NO3 – Electrochemical linear sweep voltammogram in electrolyte.
[0024] Figure 4 Cu2S / WS2 / Ti3C2T prepared in Example 1 of the present invention x The composite material was subjected to nitrate reduction to synthesize ammonia in a neutral electrolyte (0.1 mol / L Na2SO4 and 0.1 mol / L NaNO3). After constant potential electrolysis for 1 h at different voltages, the ultraviolet-visible absorption spectra (UV-vis) of the electrolytes were measured.
[0025] Figure 5 Cu2S / WS2 / Ti3C2T prepared in Example 1 of the present invention xThe composite material undergoes nitrate reduction to synthesize ammonia in a neutral electrolyte (0.1 mol / L Na2SO4 and 0.1 mol / L NaNO3). The ammonia production and Faraday efficiency diagram after 1 h current-time test at different voltages. DETAILED DESCRIPTION
[0026] The present invention is further described in detail below with reference to implementation and comparative cases and accompanying drawings, but the embodiments of the present invention are not limited thereto.
[0027] Implementation Case 1
[0028] This embodiment provides a Cu2S / WS2 / Ti3C2T x The composite electrocatalyst is prepared according to the following method:
[0029] Ti3C2T x Preparation of hydrogel: Take a single layer of Ti3C2T x Disperse in deionized water, dissolve Cu(NO3)2·6H2O in deionized water, mix the two quickly, and Ti3C2T x The hydrogel formed within seconds.
[0030] PW 12 @Cu-BTC / Ti3C2T x Preparation: Solution A, Cu 2+ -Ti3C2T x Solution B, a mixed solution of copper acetate (Cu(Ac)2·H2O) and phosphotungstic acid (PW 12 ) a mixed solution. Solution A was slowly added to solution B, stirred thoroughly at room temperature and pressure, washed, centrifuged, freeze-dried, and the product PW was collected. 12 @Cu-BTC / Ti3C2T x Composite materials.
[0031] Cu2S / WS2 / Ti3C2T x Preparation of composite materials: Take a certain amount of PW 12 @Cu-BTC / Ti3C2T x The composite material and thiourea were mixed in a mass ratio of 1:20 and fully ground, placed in a porcelain boat, and calcined at a high temperature in a tube furnace under an argon atmosphere. The temperature was lowered and the product was collected.
[0032] The present invention will be further described below with reference to the accompanying drawings:
[0033] Figure 1 Cu2S / WS2 / Ti3C2T prepared in Example 1 of the present invention x Scanning electron microscope image of the composite material. As shown in Figure a, the substrate Ti3C2Tx The surface of the Ti3C2T substrate is rough and has a clear three-dimensional porous structure. In Figures b and c, it can be clearly observed that the nanoparticles are evenly dispersed on the substrate. x surface, indicating the successful loading of Cu2S and WS2.
[0034] Figure 2 Cu2S / WS2 / Ti3C2T prepared in Example 1 of the present invention x Powder X-ray diffraction pattern of the composite material. As shown in the figure, the diffraction peaks at 27.42°, 31.77°, 45.55°, 53.97° and 56.60° correspond to the (111), (200), (220), (311) and (222) crystal planes of the Cu2S standard card (JCPDS NO.84-1770); the diffraction peaks at 14.36°, 28.96°, 33.59°, 35.94°, 39.60° and 58.49° correspond to the (002), (004), (101), (102), (103) and (110) crystal planes of WS2 (JCPDS NO.84-1398); and in the composite material Cu2S / WS2 / Ti3C2T x In the Ti3C2T x The characteristic peaks of Ti3C2T x The structure of the Ti3C2T was not destroyed, and Cu2S and WS2 were successfully loaded on the Ti3C2T x On the Cu2S / WS2 / Ti3C2T x The composite material was successfully synthesized.
[0035] Figure 3 Cu2S / WS2 / Ti3C2T prepared in Example 1 of the present invention x Composite materials with or without NO3 - Electrochemical linear sweep voltammogram in electrolyte. As shown in the figure, in the voltage range of -0.3V vs.RHE to -0.7V vs.RHE, the composite material – The reduction current density in the electrolyte is higher than that in the NO3-free electrolyte. – The reduction current density in the electrolyte increases significantly, indicating that Cu2S / WS2 / Ti3C2T x The composite material has a certain ability of electrocatalytic reduction of nitrate.
[0036] Figure 4 Cu2S / WS2 / Ti3C2T prepared in Example 1 of the present invention xThe composite material was subjected to nitrate reduction to ammonia synthesis in a neutral electrolyte (0.1 mol / L Na2SO4 and 0.1 mol / L NaNO3). After 1 hour of potentiostatic electrolysis at different voltages, the resulting electrolytes were measured for UV-visible absorption spectra (UV-vis). As the applied voltage gradually increased, the absorbance of the electrolytes, which developed color after the electrocatalytic test, also gradually increased.
[0037] Figure 5 Cu2S / WS2 / Ti3C2T prepared in Example 1 of the present invention x The composite material was subjected to nitrate reduction to ammonia synthesis in a neutral electrolyte (0.1 mol / L Na2SO4 and 0.1 mol / L NaNO3). Ammonia production and Faradaic efficiency were plotted after a 1-hour current-time test at different voltages. As shown in the figure, the highest Faradaic efficiency of 74.87% was achieved at a potential of -0.5 V vs. RHE, corresponding to an NH3 yield of 13.46 mg h -1 mg cat. -1 Therefore, Cu2S / WS2 / Ti3C2T x The composite material can be used as a highly efficient catalyst for electrocatalytic nitrate synthesis of ammonia.
[0038] In summary, the Cu2S / WS2 / Ti3C2T x The composite material was successfully prepared by a synthesis method using stirring at room temperature and pressure and high-temperature calcination under an argon atmosphere, and was successfully applied to the electrocatalytic reduction of nitrates to synthesize ammonia. x The addition of Cu2S increases the specific surface area and electron transfer rate of the composite material. There is a certain synergistic effect between Cu2S and WS2, which is conducive to improving the electrocatalytic efficiency of the composite material. The composite material has good redox activity and has good application prospects in the electrocatalytic reduction of nitrates to synthesize ammonia.
Claims
1. A cuprous sulfide / tungsten sulfide composite titanium carbide material and its preparation method and application, characterized by: (1)Cu 2+ -Ti3C2T x Solution preparation: Take a single layer of Ti3C2T x Disperse in deionized water, dissolve copper nitrate trihydrate (Cu(NO3)2·3H2O) in deionized water, and mix the two quickly to form a porous three-dimensional network structure of Cu 2+ -Ti3C2T x solution. (2)PW 12 @Cu-BTC / Ti3C2T x Preparation: Solution A, Cu 2+ -Ti3C2T x Solution B, a mixed solution of copper acetate (Cu(Ac)2·H2O) and phosphotungstic acid (PW 12 ) a mixed solution. Solution A was slowly added to solution B, stirred thoroughly at room temperature and pressure, washed, centrifuged, freeze-dried, and the product PW was collected. 12 @Cu-BTC / Ti3C2T x Composite materials. (3) Preparation of Cu2S / WS2 / MXene composite materials: Take a certain amount of PW 12 @Cu-BTC / Ti3C2T x The composite material and thiourea were mixed in a mass ratio of 1:20 and fully ground, placed in a reaction porcelain boat, calcined at high temperature in a tube furnace under an argon atmosphere, cooled, and the product was collected.
2. Cu according to step (1) of claim 1 2+ -Ti3C2T x solution, in which Ti3C2T x The mass is 58~62mg, and the mass of Cu(NO3)2·3H2O is 58~62mg.
3. The trimesic acid according to step (2) of claim 1, wherein the mass is 0.14-0.15 g and the solvent is anhydrous ethanol.
4. The Cu(Ac)2·H2O according to step (2) of claim 1, wherein the mass thereof is 0.18 to 0.24 g and the solvent is deionized water.
5. The PW according to step (2) of claim 1 12 , its mass is 0.3~0.4g.
6. The stirring time according to step (2) of claim 1 is 30 min, and the product is washed several times with anhydrous ethanol and deionized water respectively.
7. The PW according to step (3) of claim 1 12 @Cu-BTC / Ti3C2T x The composite material has a mass of 0.2 to 0.3 g.
8. The thiourea according to step (3) of claim 1, having a mass of 4 to 5 g.
9. The temperature of the tube furnace according to step (3) of claim 1 is 900°C, the heating rate is 7°C / min, and the temperature is maintained for 2 hours, and the cooling rate is the same as the heating rate.
10. Cu2S / WS2 / Ti3C2T prepared by the method for preparing the composite material according to claims 1 to 9. x The composite material is used for electrocatalytic nitrate reduction to synthesize ammonia at room temperature and pressure.