A sulfur-doped nickel single-atom catalyst and its preparation method and application
By doping sulfur atoms on the nickel single-atom catalyst and adjusting the adsorption of carbon dioxide reduction intermediates, a sulfur-doped nickel single-atom catalyst with specific structure and composition was prepared, which solved the stability problem of carbon dioxide electrical reduction under high current density, and achieved efficient carbon dioxide electrical reduction to carbon monoxide, with excellent catalytic performance and stability.
Patent Information
- Application Number
- CN202510518972.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-23
- Publication Date
- 2025-08-12
- Estimated Expiration
- 2045-04-23
AI Technical Summary
The existing nickel single-atom catalysts are difficult to achieve stable carbon dioxide electrical reduction to carbon monoxide under high current density, and the atomic utilization rate of the catalyst is low, resulting in metal waste.
A sulfur-doped nickel single-atom catalyst is designed. By doping sulfur atoms on the nickel single-atom material, the adsorption of carbon dioxide reduction intermediates is regulated. The catalyst is prepared by using a molecular sieve precursor supported by sulfur, nickel and carbon. The nickel, nitrogen and sulfur elements are evenly distributed on a carbon support with a large surface area, and a catalyst with specific structure and composition is used.
High-efficiency carbon dioxide electroreduction to carbon monoxide is achieved under high current density, with excellent catalytic performance and stability, achieving more than 99% of carbon monoxide Faraday efficiency at industrial-grade current density, and maintaining stability within 10 hours.
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Figure CN120037960B_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of metal single-atom catalyst preparation, and relates to a sulfur-doped nickel single-atom catalyst and a preparation method and application thereof. Background Art
[0002] Rapid social development has led to a substantial increase in greenhouse gas emissions, significantly impacting the global climate and causing frequent extreme weather events. The conflict between development and conservation is a major global challenge. To achieve sustainable development, carbon dioxide (CO2) emissions must be utilized as a valuable carbon resource and converted into chemicals using renewable energy, thereby establishing an artificial carbon cycle. While significant advances have been made in renewable energy technologies such as wind and hydropower over the past few decades, the intermittent generation of renewable energy sources such as wind, solar, and hydropower makes it difficult to directly integrate them into the power grid, resulting in significant electricity waste. Furthermore, mismatches between supply and demand can lead to excess electricity. Flexibly utilizing excess electricity to drive the catalytic conversion of CO2 would not only convert electrical energy into chemical energy and store it, but also enable CO2 resource utilization. This would also help streamline supply and demand, significantly improve the utilization rate of power equipment, and enhance grid stability.
[0003] Electrocatalytic carbon dioxide reduction (CO2) is an effective approach to addressing excessive CO2 emissions and balancing peak fluctuations in renewable electricity. Carbon monoxide (CO) is the most valuable product among the gaseous products of CO2 electrocatalysis and has attracted considerable attention. Metal nanocatalysts have been extensively studied in CO2 electroreduction reactions due to their easily tunable electronic states and diverse elemental combinations. Precious metal catalysts also offer exceptional performance, far exceeding that of common metals, and have been used in CO2 electroreduction research. However, because only surface atoms of the catalyst participate in the catalytic reaction, atomic utilization is low, resulting in metal waste. To address this challenge, single-atom catalysts have emerged as a new research hotspot in recent years. Compared to metal nanocatalysts, they can achieve comparable performance with fewer metal elements. Furthermore, due to their easily tunable coordination structures and simple active center composition, single-atom catalysts have been widely used in theoretical studies of CO2 electroreduction. However, studies have shown that while these single-atom catalysts, such as Ni-NC materials, exhibit excellent selectivity for catalyzing CO2 to CO, stable operation at high current densities is difficult to achieve due to limitations in the intrinsic activity or physical properties of the material.
[0004] Therefore, how to design a more suitable metal catalyst to solve the above-mentioned problems of existing catalysts has broad application prospects and is also one of the focuses of widespread attention of many researchers in the industry. Summary of the Invention
[0005] In view of this, the technical problem to be solved by the present invention is to provide a sulfur-doped nickel single-atom catalyst, its preparation method, and application. The catalyst provided by the present invention is a sulfur-doped mesoporous carbon material loaded with nickel atoms at varying concentrations. It has a large surface area and intrinsic activity, and can achieve highly selective and active conversion of carbon dioxide to carbon monoxide. Furthermore, the preparation method is simple, the conditions are mild, and the controllability is strong, making it more suitable for promotion and application in industrial production.
[0006] The present invention provides a sulfur-doped nickel single-atom catalyst. The sulfur-doped nickel single-atom catalyst is obtained by etching away the molecular sieve from a molecular sieve precursor loaded with sulfur, nickel and carbon.
[0007] Preferably, the molecular sieve precursor loaded with sulfur, nickel and carbon is obtained by calcining a molecular sieve precursor loaded with thiourea, a nickel source and o-phenanthroline;
[0008] In the molecular sieve precursor loaded with thiourea, nickel source and o-phenanthroline, nickel ions form a complex with o-phenanthroline;
[0009] The molecular sieve includes a mesoporous molecular sieve;
[0010] The mesoporous molecular sieve includes one or more of SBA-15 molecular sieve, SBA-16 molecular sieve, KIT-6 molecular sieve, MCM-41 molecular sieve and MCM-41 molecular sieve.
[0011] Preferably, the microstructure of the sulfur-doped nickel single-atom catalyst has a hexagonal columnar structure;
[0012] The mass content of nickel in the sulfur-doped nickel single-atom catalyst is 1.7% to 2.7%;
[0013] The sulfur-doped nickel single-atom catalyst has a sulfur content of 3.0% to 4.7% by mass;
[0014] The particle size of the sulfur-doped nickel single-atom catalyst is 0.2-1 μm.
[0015] The present invention provides a method for preparing a sulfur-doped nickel single-atom catalyst, comprising the following steps:
[0016] 1) Dissolving nickel salt in an organic solvent to obtain solution A;
[0017] Thiourea is dissolved in an organic solvent to obtain solution B, and o-phenanthroline is added to obtain solution C;
[0018] 2) Slowly adding solution A obtained in the above step to solution C while mixing to obtain a mixed solution D;
[0019] 3) The mixed solution D obtained in the above step is mixed again with the molecular sieve, and then calcined to obtain a powder, which is then placed in a hydrofluoric acid solution for etching reaction to obtain a sulfur-doped nickel single atom catalyst.
[0020] Preferably, the nickel salt comprises nickel nitrate hexahydrate;
[0021] The organic solvent includes ethanol;
[0022] In the solution A, the concentration of nickel salt is 1.2-2.1 g / L;
[0023] In the solution B, the concentration of thiourea is 10-40 g / L.
[0024] Preferably, the mass ratio of o-phenanthroline to thiourea is 4:(2-3);
[0025] The mass ratio of the nickel salt to thiourea is (0.16-0.2): (0.2-0.3);
[0026] The slow adding method includes injection;
[0027] The speed of the slow addition is 5-10 mL / h.
[0028] Preferably, the mixing method includes stirring;
[0029] The mixing speed is 500~1500rpm;
[0030] The molecular sieve includes mesoporous molecular sieve SBA-15;
[0031] The mass ratio of the molecular sieve to the nickel salt is (0.2-0.5): (0.15-0.21).
[0032] Preferably, the remixing time is 10 to 30 minutes;
[0033] After the re-mixing, the step of rotary evaporation and / or drying is also included;
[0034] The temperature of the rotary evaporation is 40-60°C;
[0035] The rotation speed of the rotary evaporation is 0.5~2rpm;
[0036] The calcination is specifically carried out under a protective atmosphere.
[0037] Preferably, the heating rate of the calcination is 5-10°C / min;
[0038] The calcination temperature is 600-1000°C;
[0039] The calcination time is 1 to 4 hours;
[0040] The mass concentration of the hydrofluoric acid solution is 5% to 15%;
[0041] The etching reaction time is 0.5 to 4 hours.
[0042] The present invention also provides the use of the sulfur-doped nickel single-atom catalyst described in any one of the above technical solutions or the sulfur-doped nickel single-atom catalyst prepared by the preparation method described in any one of the above technical solutions in electrocatalytic carbon dioxide reduction.
[0043] The present invention provides a sulfur-doped nickel single-atom catalyst, obtained by etching away the molecular sieve from a molecular sieve precursor loaded with sulfur, nickel, and carbon. Compared to the prior art, the present invention innovatively designs a sulfur-doped nickel single-atom catalyst with a specific structure and composition. By doping the nickel single-atom material with sulfur atoms, the adsorption of carbon dioxide reduction intermediates is modulated, enhancing the electroreduction of carbon dioxide to carbon monoxide. Furthermore, the nickel, nitrogen, and sulfur elements are evenly distributed on the carbon support with a large surface area, resulting in high catalytic efficiency and excellent stability at high current densities.
[0044] The present invention also provides a corresponding preparation method, which comprises injecting an ethanol solution of nickel nitrate into an ethanol solution of thiourea and o-phenanthroline in a certain proportion at a certain flow rate and ratio and stirring. After the stirring is completed, rotary evaporation is performed until the solvent is mostly volatilized, and then the mixture is placed in a vacuum drying oven for further drying. The dried solid is placed in a tubular furnace in an argon atmosphere and fully pyrolyzed to obtain a sulfur-doped nickel single-atom catalyst. The catalyst prepared by the present invention has excellent performance in catalyzing the electroreduction of carbon dioxide to carbon monoxide, and has an industrial-grade current density and an extremely excellent carbon monoxide Faraday efficiency.
[0045] Experimental results demonstrate that the sulfur-doped nickel single-atom catalyst prepared by this invention exhibits excellent electrochemical carbon dioxide reduction performance. Applied in a flow cell, it achieved a carbon monoxide Faradaic efficiency exceeding 99% at high current densities of 100 to 800 milliamperes per square centimeter. Furthermore, over a nearly 10-hour constant current electrolysis process, the electrocatalyst's selectivity, activity, and electrolysis potential showed no significant decrease, demonstrating excellent stability. BRIEF DESCRIPTION OF THE DRAWINGS
[0046] Figure 1 Transmission electron microscope images of different scales of the sulfur-doped nickel single-atom catalyst prepared in Example 1 of the present invention; (a) is a transmission electron microscope image at 200 nm, and (b) is a transmission electron microscope image at 100 nm.
[0047] Figure 2Scanning electron microscope images of nickel, sulfur, nitrogen and carbon elements of the sulfur-doped nickel single-atom catalyst prepared in Example 1 of the present invention; wherein (a) is a carbon element image, (b) is a nitrogen element image, (c) is a nickel element image, and (d) is a sulfur element image.
[0048] Figure 3 The electron diffraction pattern and high-resolution transmission electron microscopy image of the sulfur-doped nickel single-atom catalyst prepared in Example 1 of the present invention; wherein (a) is the electron diffraction pattern, and (b) is the high-resolution transmission electron microscopy image.
[0049] Figure 4 This is a high-angle annular dark field-scanning transmission electron microscope image of the sulfur-doped nickel single-atom catalyst prepared in Example 1 of the present invention;
[0050] Figure 5 The X-ray diffraction pattern of the sulfur-doped nickel single-atom catalyst prepared in Example 1 of the present invention;
[0051] Figure 6 This is a test curve of the specific surface area of the sulfur-doped nickel single-atom catalyst prepared in Example 1 of the present invention;
[0052] Figure 7 The results of the Faradaic efficiency and potential relative to the standard hydrogen electrode of each product at different current densities in the carbon dioxide electroreduction reaction catalyzed by the sulfur-doped nickel single-atom catalyst prepared in Example 1 of the present invention. DETAILED DESCRIPTION
[0053] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention rather than limiting the patent claims of the present invention.
[0054] All raw materials of the present invention are not particularly limited in their sources and can be purchased from the market or prepared according to conventional methods well known to those skilled in the art.
[0055] There is no particular limitation on the purity of all raw materials in the present invention. The present invention preferably uses analytically pure materials or materials with conventional purity in the field of single-atom catalyst preparation.
[0056] The present invention provides a sulfur-doped nickel single-atom catalyst. The sulfur-doped nickel single-atom catalyst is obtained by etching away the molecular sieve from a molecular sieve precursor loaded with sulfur, nickel and carbon.
[0057] In the present invention, the molecular sieve precursor loaded with sulfur, nickel and carbon is preferably obtained by calcining a molecular sieve precursor loaded with thiourea, a nickel source and o-phenanthroline.
[0058] In the present invention, in the molecular sieve precursor loaded with thiourea, nickel source and o-phenanthroline, it is preferred that nickel ions form a complex with o-phenanthroline.
[0059] In the present invention, the molecular sieve preferably includes a mesoporous molecular sieve.
[0060] In the present invention, the mesoporous molecular sieve preferably includes one or more of SBA-15 molecular sieve, SBA-16 molecular sieve, KIT-6 molecular sieve, MCM-41 molecular sieve and MCM-41 molecular sieve, more preferably SBA-15 molecular sieve, SBA-16 molecular sieve, KIT-6 molecular sieve, MCM-41 molecular sieve or MCM-41 molecular sieve.
[0061] In the present invention, the microstructure of the sulfur-doped nickel single-atom catalyst preferably has a hexagonal columnar structure.
[0062] In the present invention, the mass content of nickel in the sulfur-doped nickel single-atom catalyst is preferably 1.7% to 2.7%, more preferably 2.0% to 2.7%, more preferably 2.3% to 2.7%, and more preferably 2.5% to 2.7%.
[0063] In the present invention, the mass content of sulfur in the sulfur-doped nickel single-atom catalyst is preferably 3.0% to 4.7%, more preferably 3.4% to 4.3%, and even more preferably 3.8% to 3.9%.
[0064] In the present invention, the particle size of the sulfur-doped nickel single-atom catalyst is preferably 0.2 to 1 μm, more preferably 0.35 to 0.85 μm, and more preferably 0.5 to 0.7 μm.
[0065] The present invention provides a method for preparing a sulfur-doped nickel single-atom catalyst, comprising the following steps:
[0066] 1) Dissolving nickel salt in an organic solvent to obtain solution A;
[0067] Thiourea is dissolved in an organic solvent to obtain solution B, and o-phenanthroline is added to obtain solution C;
[0068] 2) Slowly adding solution A obtained in the above step to solution C while mixing to obtain a mixed solution D;
[0069] 3) The mixed solution D obtained in the above step is mixed again with the molecular sieve, and then calcined to obtain a powder, which is then placed in a hydrofluoric acid solution for etching reaction to obtain a sulfur-doped nickel single atom catalyst.
[0070] The present invention first dissolves nickel salt in an organic solvent to obtain solution A;
[0071] Thiourea is dissolved in an organic solvent to obtain solution B, and o-phenanthroline is added to obtain solution C.
[0072] In the present invention, the nickel salt preferably includes nickel nitrate hexahydrate.
[0073] In the present invention, the organic solvent preferably includes ethanol.
[0074] In the present invention, the concentration of the nickel salt in the solution A is preferably 1.2-2.1 g / L, more preferably 1.4-2.1 g / L, more preferably 1.5-2.1 g / L, and more preferably 1.6-2.0 g / L.
[0075] In the present invention, the concentration of thiourea in the solution B is preferably 10-40 g / L, more preferably 10-30 g / L, more preferably 10-20 g / L, and more preferably 10-15 g / L.
[0076] In the present invention, the mass ratio of o-phenanthroline to thiourea is preferably 4:(2-3), more preferably 4:(2.2-2.8), and even more preferably 4:(2.4-2.6).
[0077] In the present invention, the mass ratio of the nickel salt to thiourea is preferably (0.16-0.2): (0.2-0.3), more preferably (0.165-0.195): (0.22-0.28), and more preferably (0.17-0.19): (0.24-0.26).
[0078] In the present invention, the solution A obtained in the above step is slowly added to the solution C while mixing to obtain a mixed solution D.
[0079] In the present invention, mixed solution A is transferred into a syringe, slowly injected into mixed solution C, and stirred to obtain mixed solution D. The nickel ions in mixed solution A react with o-phenanthroline in C to form a stable complex; the thiourea molecules in mixed solution C promote the complexation process.
[0080] In the present invention, the slow adding method preferably includes injection.
[0081] In the present invention, the slow addition rate is preferably 5-10 mL / h, more preferably 6-9 mL / h, and even more preferably 7-8 mL / h.
[0082] In the present invention, the mixing method preferably includes stirring.
[0083] In the present invention, the mixing speed is preferably 500-1500 rpm, more preferably 700-1300 rpm, and even more preferably 900-1100 rpm.
[0084] Finally, the present invention mixes the mixed solution D obtained in the above steps with the molecular sieve again, and then calcines the mixed solution. The obtained powder is placed in a hydrofluoric acid solution for etching reaction to obtain a sulfur-doped nickel single-atom catalyst.
[0085] In the present invention, the molecular sieve preferably includes mesoporous molecular sieve SBA-15.
[0086] In the present invention, the mass ratio of the molecular sieve to the nickel salt is preferably (0.2-0.5): (0.15-0.21), more preferably (0.25-0.45): (0.16-0.20), and more preferably (0.3-0.4): (0.18-0.20).
[0087] In the present invention, the remixing time is preferably 10 to 30 minutes, more preferably 14 to 26 minutes, and even more preferably 18 to 22 minutes.
[0088] In the present invention, after the re-mixing, preferably, a rotary evaporation and / or drying step is further included, more preferably a rotary evaporation and drying step.
[0089] In the present invention, the rotary evaporation temperature is preferably 40-60°C, more preferably 40-55°C, and even more preferably 40-50°C.
[0090] In the present invention, the rotation speed of the rotary evaporation is preferably 0.5-2 rpm, more preferably 0.8-1.7 rpm, and more preferably 1.1-1.4 rpm.
[0091] In the present invention, the calcination is preferably carried out under a protective atmosphere.
[0092] In the present invention, the heating rate of the calcination is preferably 5-10° C. / min, more preferably 5-8° C. / min, and even more preferably 5-6° C. / min.
[0093] In the present invention, the calcination temperature is preferably 600-1000°C, more preferably 650-950°C, more preferably 700-900°C, and more preferably 750-850°C.
[0094] In the present invention, the calcination time is preferably 1 to 4 hours, more preferably 1.5 to 3.5 hours, and even more preferably 2 to 3 hours.
[0095] In the present invention, the mass concentration of the hydrofluoric acid solution is preferably 5% to 15%, more preferably 7% to 13%, more preferably 9% to 11%, and specifically can be 10%.
[0096] In the present invention, the etching reaction time is preferably 0.5 to 4 hours, more preferably 1 to 3.5 hours, more preferably 1.5 to 3 hours, and more preferably 2 to 2.5 hours.
[0097] The present invention provides the use of the sulfur-doped nickel single-atom catalyst described in any one of the above technical solutions or the sulfur-doped nickel single-atom catalyst prepared by the preparation method described in any one of the above technical solutions in electrocatalytic carbon dioxide reduction.
[0098] The present invention is a complete and detailed overall technical solution that better ensures the composition and structure of the sulfur-doped nickel single-atom catalyst and further improves the catalytic performance of the sulfur-doped nickel single-atom catalyst in electrocatalytic carbon dioxide reduction. The above-mentioned sulfur-doped nickel single-atom catalyst and its preparation method and application can specifically include the following contents:
[0099] The present invention provides a sulfur-doped nickel single-atom catalyst. The sulfur-doped nickel single-atom catalyst is a sulfur-doped mesoporous carbon material loaded with nickel atoms of different concentrations, and each nickel atom is isolated from each other.
[0100] Specifically, the mass proportion of the nickel atoms is 1.7% to 2.7%.
[0101] Preferably, when the mass atomic ratio of the nickel atoms is 2.7%, a carbon monoxide Faraday efficiency of more than 99% is achieved at a current density of 100 to 800 mA per square centimeter.
[0102] The present invention also provides a method for preparing a sulfur-doped nickel single-atom catalyst, comprising the following steps:
[0103] Step 1: dissolving nickel nitrate hexahydrate in anhydrous ethanol to obtain a mixed solution A;
[0104] Step 2: Dissolve thiourea in anhydrous ethanol and stir for 10 to 30 minutes to obtain a mixed solution B;
[0105] Step 3: adding o-phenanthroline to the mixed solution B and stirring thoroughly for 10 to 30 minutes to obtain a mixed solution C;
[0106] Step 4: Pour mixed solution A into a syringe, slowly inject mixed solution A into mixed solution C, and stir to obtain mixed solution D;
[0107] Step 5: Add 0.3 g of mesoporous molecular sieve SBA-15 to mixed solution D and stir for 10 to 30 minutes to obtain mixed solution E (filled skeleton)
[0108] Step 6: Transfer the mixed solution E into a single-necked flask and perform rotary evaporation until the ethanol is evaporated to dryness, and then further dry it in an oven for 6 to 12 hours to obtain solid powder F;
[0109] Step 7: calcining the solid powder F under an argon atmosphere to obtain a black powder G;
[0110] Step 8: Add the black powder G to a 10% hydrofluoric acid solution, let it stand for 0.5 to 4 hours, and centrifuge, wash, and dry to obtain a black powder, which is a sulfur-doped nickel single-atom catalyst.
[0111] Specifically, the amount of nickel sodium nitrate hexahydrate used in step 1 is 0.15-0.21 g, and the volume of ethanol is 100 ml.
[0112] Furthermore, the amount of nickel nitrate hexahydrate used in step 1 is 0.15-0.21 g, and the volume of ethanol is 100 ml. A higher amount of nickel nitrate hexahydrate does not increase the loading of nickel atoms, but instead causes nickel to agglomerate into particles.
[0113] Specifically, the concentration of the mixed solution B in step 2 is 10 to 40 grams per liter.
[0114] Specifically, in step 4, the injection speed is 5 to 10 ml per hour, and the stirring speed is 500 to 1500 revolutions per minute.
[0115] Furthermore, in the practice of the present invention, the aforementioned injection flow rate can yield a uniformly dispersed nickel single-atom catalyst. If the injection rate is too slow, the ethanol solvent in the mixed solution C will evaporate significantly. If the injection rate is too fast, the nickel atoms will not be able to fully react with the mixed solution C, resulting in the formation of nickel clusters.
[0116] Furthermore, in step 5, the mass of the mesoporous molecular sieve is 0.2-0.5 g.
[0117] Specifically, in step 6, the rotary evaporation temperature is 40-60 degrees Celsius and the rotation speed is 0.5-2 revolutions per minute.
[0118] Furthermore, a milder rotary evaporation temperature is not conducive to solvent volatilization, and a higher rotary evaporation temperature can easily cause explosive boiling and solid component precipitation, resulting in a decrease in uniformity.
[0119] Specifically, in step 7, the calcination temperature is 600-1000 degrees Celsius, the heating rate is 5-10 degrees Celsius per minute, and the calcination time is 1-4 hours.
[0120] The present invention also provides the use of the sulfur-doped nickel single-atom catalyst obtained by any of the above methods in the electrocatalytic reduction of carbon dioxide to produce carbon monoxide.
[0121] Specifically, in the application, the sulfur-doped nickel single-atom catalyst is dispersed in isopropanol, Nafion solution is added as a binder, and ultrasonic dispersion is performed to obtain a black mixed dispersion; the dispersion is sprayed onto carbon paper and dried on a heating table at 80 degrees Celsius to obtain a working electrode.
[0122] Specifically, in the application, the concentration of the sulfur-doped nickel single-atom catalyst in the black dispersion is 5 to 10 grams per liter, and the mass concentration of Nafion is 20 to 40 milligrams per liter.
[0123] The present invention also provides a use of the sulfur-doped nickel single-atom catalyst described in any of the above technical solutions or the sulfur-doped nickel single-atom catalyst obtained by the preparation method described in any of the above technical solutions in the electrocatalytic reduction of carbon dioxide to produce carbon monoxide.
[0124] The present invention provides a sulfur-doped nickel single-atom catalyst, its preparation method, and its application. The sulfur-doped nickel single-atom catalyst designed by the present invention has a specific structure and composition. By doping sulfur atoms onto the nickel single-atom material, the adsorption of carbon dioxide reduction intermediates is regulated, thereby enhancing the performance of the electroreduction of carbon dioxide to carbon monoxide. Furthermore, the nickel, nitrogen, and sulfur elements are evenly distributed on the carbon support with a large surface area, resulting in high catalytic efficiency and excellent stability at high current densities.
[0125] The present invention also provides a corresponding preparation method, which comprises injecting an ethanol solution of nickel nitrate into an ethanol solution of thiourea and o-phenanthroline in a certain proportion at a certain flow rate and ratio and stirring. After the stirring is completed, rotary evaporation is performed until the solvent is mostly volatilized, and then the mixture is placed in a vacuum drying oven for further drying. The dried solid is placed in a tubular furnace in an argon atmosphere and fully pyrolyzed to obtain a sulfur-doped nickel single-atom catalyst. The catalyst prepared by the present invention has excellent performance in catalyzing the electroreduction of carbon dioxide to carbon monoxide, and has an industrial-grade current density and an extremely excellent carbon monoxide Faraday efficiency.
[0126] Experimental results demonstrate that the sulfur-doped nickel single-atom catalyst prepared by this invention exhibits excellent electrochemical carbon dioxide reduction performance. Applied in a flow cell, it achieved a carbon monoxide Faradaic efficiency exceeding 99% at high current densities of 100 to 800 milliamperes per square centimeter. Furthermore, over a nearly 10-hour constant current electrolysis process, the electrocatalyst's selectivity, activity, and electrolysis potential showed no significant decrease, demonstrating excellent stability.
[0127] To further illustrate the present invention, a sulfur-doped nickel single-atom catalyst provided by the present invention, its preparation method, and application are described in detail below in conjunction with examples. However, it should be understood that these examples are implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operating processes are provided only to further illustrate the features and advantages of the present invention, rather than to limit the claims of the present invention. The scope of protection of the present invention is not limited to the following examples.
[0128] Example 1
[0129] This example prepares a sulfur-doped nickel single-atom catalyst, and the specific steps are as follows:
[0130] 200 mg of nickel nitrate hexahydrate was dissolved in 100 ml of anhydrous ethanol to obtain a mixed solution A; 0.2 g of thiourea was dissolved in 20 ml of anhydrous ethanol and stirred for 20 minutes to obtain a mixed solution B; 0.4 g of o-phenanthroline was added to the mixed solution B and stirred for 20 minutes to obtain a mixed solution C; 100 ml of the mixed solution A was transferred into a syringe and injected into the mixed solution C at a rate of 10 ml per hour and stirred to obtain a mixed solution D; 0.3 g of mesoporous molecular sieve SBA-15 was added to the mixed solution D and stirred for 10-30 minutes. minutes to obtain a mixed solution E; the mixed solution E was transferred into a single-necked flask and rotary evaporated at 40 degrees Celsius until the ethanol was dried, and further dried in an oven at 60 degrees Celsius for 12 hours to obtain a solid powder F; the solid powder F was calcined in an argon atmosphere at a calcination temperature of 900 degrees Celsius, a heating rate of 5 degrees Celsius per minute, and a calcination time of 3 hours to obtain a black powder G; the black powder G was added to a 10% hydrofluoric acid solution and allowed to stand for 0.5 hours, and then centrifuged, washed, and dried to obtain a black powder that is a sulfur-doped nickel single-atom catalyst.
[0131] The proportion of nickel atoms in the sulfur-doped nickel single-atom catalyst obtained in this example was determined by inductively coupled plasma atomic emission spectrometry to be 2.7%.
[0132] See also Figure 1 , Figure 1 Transmission electron microscope images of the sulfur-doped nickel single-atom catalyst prepared in Example 1 of the present invention at different scales. (a) is a transmission electron microscope image at 200 nm, and (b) is a transmission electron microscope image at 100 nm.
[0133] like Figure 1 As shown in the transmission electron microscope image, the stripes are the pores of the mesoporous carbon after the molecular sieve is etched away, and the catalyst particle size is about 0.2~1.0 microns.
[0134] See also Figure 2 , Figure 2Scanning electron microscope images of nickel, sulfur, nitrogen, and carbon elements of the sulfur-doped nickel single-atom catalyst prepared in Example 1 of the present invention. (a) is the carbon element image, (b) is the nitrogen element image, (c) is the nickel element image, and (d) is the sulfur element image.
[0135] like Figure 2 As shown in the scanning electron microscope element mapping, nickel and sulfur elements are evenly distributed on the carbon substrate.
[0136] See also Figure 3 , Figure 3 The electron diffraction pattern and high-resolution transmission electron microscopy image of the sulfur-doped nickel single-atom catalyst prepared in Example 1 of the present invention are shown in Figure 1. (a) is the electron diffraction pattern, and (b) is the high-resolution transmission electron microscopy image.
[0137] like Figure 3 The electron diffraction pattern and high-resolution transmission electron microscopy image show that no crystalline nickel is present.
[0138] See also Figure 4 , Figure 4 This is a high-angle annular dark field-scanning transmission electron microscope image of the sulfur-doped nickel single atom catalyst prepared in Example 1 of the present invention.
[0139] like Figure 4 As shown in the high-angle annular dark field-scanning transmission electron microscope image, the circles are isolated nickel atoms, proving that the nickel element in the sulfur-doped nickel single atom catalyst exists in the form of single atoms.
[0140] See also Figure 5 , Figure 5 This is the X-ray diffraction pattern of the sulfur-doped nickel single-atom catalyst prepared in Example 1 of the present invention.
[0141] like Figure 5 As shown in the X-ray diffraction pattern, there are no diffraction peaks of metallic nickel and its oxides.
[0142] See also Figure 6 , Figure 6 This is a specific surface area test curve of the sulfur-doped nickel single-atom catalyst prepared in Example 1 of the present invention.
[0143] like Figure 6 As shown in the specific surface area test curve, it has a large specific surface area of 751.986 square centimeters per gram, which can expose a larger active area.
[0144] The electrochemical carbon dioxide reduction catalytic performance of the sulfur-doped nickel single-atom catalyst obtained in this example was tested using a flow cell reactor. Specifically, 20 mg of the sulfur-doped nickel single-atom catalyst was dispersed in 2 mL of isopropanol. 40 μL of Nafion solution was added as a binder and ultrasonically dispersed to obtain a uniformly black mixed dispersion. The dispersion was sprayed onto a 3×3 cm² carbon paper sheet and dried on an 80°C heating plate to obtain a working electrode. The sulfur-doped nickel single-atom catalyst loading was approximately 1 mg / cm², serving as the gas diffusion electrode cathode. The working electrode had a working window area of 0.75 cm². The carbon dioxide gas flow rate was controlled at 30 mL / min. The catholyte was 1 M potassium hydroxide at a flow rate of 1.3 mL / min. The anolyte was 3 M potassium hydroxide, which was circulated by pump injection. Nickel foam was used as the counter electrode, and a mercury oxide electrode was used as the reference electrode.
[0145] This example uses a constant current method for testing. The resulting gaseous products (hydrogen, methane, carbon monoxide, and ethylene) are detected by gas chromatography, and the selectivity and activity of the catalytic reaction are then obtained based on the total coulombs recorded by the electrochemical workstation.
[0146] See also Figure 7 , Figure 7 The results of the Faradaic efficiency and potential relative to the standard hydrogen electrode of each product at different current densities in the carbon dioxide electroreduction reaction catalyzed by the sulfur-doped nickel single-atom catalyst prepared in Example 1 of the present invention.
[0147] like Figure 7 As shown in the Faraday efficiency of each gas product at different current densities, it can be seen that at a current density of 800 mA per square centimeter, the carbon monoxide Faraday efficiency is 99%, and there are no other reduction products except a small amount of hydrogen.
[0148] Example 2
[0149] This example prepares a sulfur-doped nickel single-atom catalyst, and the specific steps are as follows:
[0150] Dissolve 160 mg of nickel nitrate hexahydrate in 100 ml of anhydrous ethanol to obtain a mixed solution A; dissolve 0.25 g of thiourea in 20 ml of anhydrous ethanol and stir for 20 minutes to obtain a mixed solution B; add 0.4 g of o-phenanthroline to the mixed solution B and stir for 20 minutes to obtain a mixed solution C; transfer 100 ml of the mixed solution A into a syringe and inject it into the mixed solution C at a rate of 10 ml per hour while stirring to obtain a mixed solution D; add 0.3 g of mesoporous molecular sieve SBA-15 to the mixed solution D and stir for 10-30 minutes. minutes to obtain a mixed solution E; the mixed solution E was transferred into a single-necked flask and rotary evaporated at 40 degrees Celsius until the ethanol was dried, and further dried in an oven at 60 degrees Celsius for 12 hours to obtain a solid powder F; the solid powder F was calcined in an argon atmosphere at a calcination temperature of 900 degrees Celsius, a heating rate of 10 degrees Celsius per minute, and a calcination time of 3 hours to obtain a black powder G; the black powder G was added to a 10% hydrofluoric acid solution and allowed to stand for 0.5 hours, and then centrifuged, washed, and dried to obtain a black powder that is a sulfur-doped nickel single-atom catalyst.
[0151] The proportion of nickel atoms in the sulfur-doped nickel single-atom catalyst obtained in this example was determined by inductively coupled plasma atomic emission spectrometry to be 1.7%.
[0152] Example 3
[0153] This example prepares a sulfur-doped nickel single-atom catalyst, and the specific steps are as follows:
[0154] 180 mg of nickel nitrate hexahydrate was dissolved in 100 ml of anhydrous ethanol to obtain a mixed solution A; 0.3 g of thiourea was dissolved in 20 ml of anhydrous ethanol and stirred for 20 minutes to obtain a mixed solution B; 0.4 g of o-phenanthroline was added to the mixed solution B and stirred for 20 minutes to obtain a mixed solution C; 100 ml of the mixed solution A was transferred into a syringe and injected into the mixed solution C at a rate of 10 ml per hour and stirred to obtain a mixed solution D; 0.3 g of mesoporous molecular sieve SBA-15 was added to the mixed solution D and stirred for 10-30 minutes. minutes to obtain a mixed solution E; the mixed solution E was transferred into a single-necked flask and rotary evaporated at 40 degrees Celsius until the ethanol was dried, and further dried in an oven at 60 degrees Celsius for 12 hours to obtain a solid powder F; the solid powder F was calcined in an argon atmosphere at a calcination temperature of 900 degrees Celsius, a heating rate of 5 degrees Celsius per minute, and a calcination time of 3 hours to obtain a black powder G; the black powder G was added to a 10% hydrofluoric acid solution and allowed to stand for 0.5 hours, and then centrifuged, washed, and dried to obtain a black powder that is a sulfur-doped nickel single-atom catalyst.
[0155] The ratio of nickel atoms in the sulfur-doped nickel single-atom catalyst obtained in this example was determined by inductively coupled plasma atomic emission spectrometry to be 2.0%.
[0156] The above is a detailed introduction to a sulfur-doped nickel single-atom catalyst provided by the present invention, its preparation method, and application. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas, including the best mode, and also enables any technician in the field to practice the present invention, including the manufacture and use of any device or system, and the implementation of any combined method. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, the present invention can also be improved and modified in several ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention. The scope of patent protection of the present invention is defined by the claims and may include other embodiments that can be thought of by those skilled in the art. If these other embodiments have structural elements that are not different from the literal description of the claims, or if they include equivalent structural elements that are not substantially different from the literal description of the claims, then these other embodiments should also be included in the scope of the claims.
Claims
1. A sulfur-doped nickel single-atom catalyst, characterized in that: The sulfur-doped nickel single-atom catalyst is obtained by etching away the molecular sieve from a molecular sieve precursor loaded with sulfur, nickel and carbon; The molecular sieve precursor loaded with sulfur, nickel and carbon is obtained by calcining a molecular sieve precursor loaded with thiourea, a nickel source and o-phenanthroline; In the molecular sieve precursor loaded with thiourea, nickel source and o-phenanthroline, nickel ions form a complex with o-phenanthroline; The molecular sieve is a mesoporous molecular sieve; The mass content of nickel in the sulfur-doped nickel single-atom catalyst is 1.7% to 2.7%.
2. The sulfur-doped nickel single-atom catalyst according to claim 1, characterized in that The mesoporous molecular sieve includes one or more of SBA-15 molecular sieve, SBA-16 molecular sieve, KIT-6 molecular sieve, MCM-41 molecular sieve and MCM-41 molecular sieve.
3. The sulfur-doped nickel single-atom catalyst according to claim 1, characterized in that The sulfur-doped nickel single-atom catalyst has a hexagonal columnar structure in its microstructure; The sulfur-doped nickel single-atom catalyst has a sulfur content of 3.0% to 4.7% by mass; The particle size of the sulfur-doped nickel single-atom catalyst is 0.2-1 μm.
4. A method for preparing a sulfur-doped nickel single-atom catalyst, characterized in that: The following steps are involved: 1) dissolving a nickel salt in an organic solvent to obtain a solution A; Thiourea is dissolved in an organic solvent to obtain solution B, and o-phenanthroline is added to obtain solution C; 2) slowly adding solution A obtained in the above step to solution C while mixing to obtain a mixed solution D; 3) The mixed solution D obtained in the above step is mixed with the molecular sieve again, and then calcined to obtain a powder, which is placed in a hydrofluoric acid solution for etching reaction to obtain a sulfur-doped nickel single atom catalyst.
5. The preparation method according to claim 4, characterized in that The nickel salt includes nickel nitrate hexahydrate; The organic solvent includes ethanol; In the solution A, the concentration of nickel salt is 1.2-2.1 g / L; In the solution B, the concentration of thiourea is 10-40 g / L.
6. The preparation method according to claim 4, characterized in that The mass ratio of o-phenanthroline to thiourea is 4:(2-3); The mass ratio of the nickel salt to thiourea is (0.16-0.2): (0.2-0.3); The slow adding method includes injection; The speed of the slow addition is 5 to 10 mL / h.
7. The preparation method according to claim 4, characterized in that The mixing method includes stirring; The mixing speed is 500-1500 rpm; The molecular sieve includes mesoporous molecular sieve SBA-15; The mass ratio of the molecular sieve to the nickel salt is (0.2-0.5): (0.15-0.21).
8. The preparation method according to claim 4, characterized in that The remixing time is 10 to 30 minutes; After the re-mixing, the step of rotary evaporation and / or drying is also included; The temperature of the rotary evaporation is 40-60°C; The rotation speed of the rotary evaporation is 0.5-2 rpm; The calcination is specifically carried out under a protective atmosphere.
9. The preparation method according to claim 4, characterized in that The heating rate of the calcination is 5 to 10°C / min; The calcination temperature is 600-1000°C; The calcination time is 1 to 4 hours; The mass concentration of the hydrofluoric acid solution is 5% to 15%; The etching reaction time is 0.5 to 4 hours.
10. Use of the sulfur-doped nickel single-atom catalyst according to any one of claims 1 to 3 or the sulfur-doped nickel single-atom catalyst prepared by the preparation method according to any one of claims 4 to 9 in electrocatalytic carbon dioxide reduction.