A supported sulfur-doped nickel-based hydroxide nanomaterial, a preparation method and application thereof

Abstract

This invention provides a supported sulfur-doped nickel-based hydroxide nanoarray, its preparation method, and its application, belonging to the field of electrocatalysis technology. The preparation method first involves pretreating a carbonaceous conductive support by Joule heating in air to obtain a hydrophilic carbonaceous conductive support. Then, the hydrophilic carbonaceous conductive support is immersed in an aqueous solution of a reaction precursor composed of an organonitrile salt and an organic sulfur-containing compound. Joule heating is then applied to the conductive support in the liquid phase system. The precursor solution wetted and adsorbed on the surface of the conductive support reacts upon heating, and the product forms in situ on the surface of the conductive support, yielding the supported sulfur-doped nickel-based hydroxide nanoarray. This invention enables rapid synthesis of sulfur-doped nickel-based hydroxide nanoarrays with high preparation efficiency. The obtained supported sulfur-doped nickel-based hydroxide possesses a nanosheet array structure that is difficult to obtain using existing ultrafast synthesis techniques, exhibiting good catalytic activity, stability, and product selectivity.

Description

Technical Field

[0001] This invention relates to the field of catalysts, specifically to a supported sulfur-doped nickel-based hydroxide nanoarray, its preparation method, and its application. Background Technology

[0002] The oxidation of small-molecule organic compounds (such as methanol, formic acid, ethanol, and ethylene glycol) plays a crucial role in new energy conversion, including fuel cells and assisted water splitting for hydrogen production, as well as in the production of high-value-added chemicals. Because these oxidation reactions involve multiple electron transfer processes, numerous intermediates, and slow reaction kinetics, highly efficient catalysts are needed to accelerate the reaction and control the reaction pathway to obtain the target product. Platinum-based noble metals possess excellent catalytic performance in the oxidation of small-molecule organic compounds; however, they are easily poisoned by carbonaceous intermediates such as carbon monoxide, leading to their degradation. Their high cost has consistently limited their engineering applications in related energy, chemical, and other fields.

[0003] Nickel and its compounds exhibit potential for electrocatalytic oxidation of small organic molecules, but their performance still cannot truly rival that of noble metals. Compositional and structural regulation is a crucial method for optimizing the catalytic performance of these materials. Doping with heterogeneous elements such as sulfur helps adjust the electronic structure and other properties of the materials, thereby enhancing their catalytic performance. Currently, the synthesis of sulfur-doped metal compound nanomaterials with specific microstructures often employs thermodynamic near-equilibrium preparation techniques such as high-temperature liquid-phase chemical synthesis (e.g., hydrothermal, solvothermal methods). These techniques involve long synthesis cycles, difficulty in precise control, and stringent reaction conditions, hindering practical large-scale applications. Summary of the Invention

[0004] This invention provides a supported sulfur-doped nickel-based hydroxide nanoarray, its preparation method, and its application. The supported sulfur-doped nickel-based hydroxide nanoarray prepared by this invention has a regular morphology and good electrocatalytic performance. Moreover, the preparation method is simple to operate, has a short reaction time, and the morphology is controllable, which is conducive to large-scale application.

[0005] This invention provides a method for preparing a supported sulfur-doped nickel-based hydroxide nanoarray, comprising the following steps:

[0006] First, the carbonaceous conductive support is pretreated by Joule heating in air to obtain a hydrophilic carbonaceous conductive support.

[0007] Then, the hydrophilic carbonaceous conductive support is immersed in a liquid-phase reaction precursor composed of a mixed aqueous solution of organic nickel salt and organic sulfur-containing compound and subjected to Joule heating to complete the synthesis reaction, thereby obtaining the supported sulfur-doped nickel-based hydroxide nanoarray.

[0008] Preferably, the carbonaceous conductive carrier includes carbon cloth, carbon fiber membrane, or carbon felt.

[0009] Preferably, the loading voltage for the Joule heating pretreatment in air is 15~20V, the current is 15~20A, and the time is 0.5~1.0s.

[0010] Preferably, the organic nickel salt includes one or more of nickel carboxylate and nickel sulfonate salts.

[0011] Preferably, the organic sulfur-containing compound includes thiourea.

[0012] Preferably, the mixed aqueous solution of the organonickel salt and the organic sulfur-containing compound is obtained by mixing the aqueous solution of the organonickel salt and the aqueous solution of the organic sulfur-containing compound, wherein the concentration of the aqueous solution of the organonickel salt is 0.05~0.15 mol / L and the concentration of the aqueous solution of the organic sulfur-containing compound is 0.05~0.20 mol / L.

[0013] Preferably, the molar ratio of the organic nickel salt to the organic sulfur-containing compound is 1:0.25~4.

[0014] Preferably, the Joule heating is performed by passing a direct current through the hydrophilic carbonaceous conductive support immersed in the liquid-phase reaction precursor to heat it.

[0015] The Joule heating is applied at a voltage of 25-35V, a current of 25-35A, and a time of 1-12s.

[0016] This invention provides a supported sulfur-doped nickel-based hydroxide nanoarray prepared by the preparation method described above, comprising a hydrophilic carbon conductive support and sulfur-doped nickel-based hydroxide supported on the hydrophilic carbon conductive support;

[0017] The sulfur-doped nickel-based hydroxide has an array structure composed of nanosheets.

[0018] This invention provides the application of the supported sulfur-doped nickel-based hydroxide nanoarray described above as a self-supporting electrode in the oxidation reaction of small molecule organic compounds.

[0019] The hydrophilic carbonaceous conductive support of this invention is obtained by pretreating a carbonaceous conductive support in air with Joule heating. Then, the hydrophilic carbonaceous conductive support is immersed in a liquid-phase reaction precursor for Joule heating. Current is passed through the hydrophilic carbonaceous conductive support to instantly generate Joule heat, causing it to rapidly heat up within seconds and triggering a reaction in the precursor solution adsorbed on the surface of the hydrophilic carbonaceous conductive support. The reaction product forms in situ on the surface of the hydrophilic carbonaceous conductive support. Simultaneously, the high-temperature hydrophilic carbonaceous conductive support undergoes strong heat exchange with the contacting liquid system, inhibiting excessive heating of the hydrophilic carbonaceous conductive support and thus avoiding excessively high surface temperatures that could lead to rapid product growth and morphological deterioration. When the reaction is complete, the power is immediately cut off, heating is stopped, and the hydrophilic carbonaceous conductive support is removed and immediately air-cooled, completing the synthesis process. Under these extreme non-equilibrium reaction conditions of rapid heating and quenching, the material synthesis process and mechanism are completely different from existing synthesis methods under thermodynamic equilibrium or near-equilibrium conditions. These non-equilibrium conditions allow the growth and nucleation processes at the interface of the hydrophilic carbonaceous conductive support to be completed within seconds. Simultaneously, the dynamic changes in temperature and the physicochemical properties of the precursor in the liquid-phase reaction system affect the microstructure of the material, enabling the acquisition of sulfur-doped nickel hydroxide nanosheet arrays. Compared to conventional solid-phase Joule heating synthesis processes, the endothermic effect of the liquid-phase environment and the strong convection energy generated after heating effectively suppress overheating of the hydrophilic carbonaceous conductive support surface, providing a suitable reaction temperature environment for the synthesis of the target product. This also avoids abnormal product growth due to overheating, achieving effective control of product morphology and greatly improving the controllability of the reaction process and product morphology. Moreover, the products formed under ultrafast reaction conditions (extreme non-equilibrium conditions) are necessarily non-equilibrium products, possessing high energy and high reactivity, which is beneficial for catalytic reaction processes.

[0020] This invention enables the rapid preparation of sulfur-doped nickel-based hydroxide nanoarray materials directly in the liquid phase within tens of seconds, greatly shortening the reaction cycle and achieving high synthesis efficiency. The operation is simple, requiring no special additives; only organometallic salts and conventional organic sulfur-containing compounds are needed to obtain sulfur-doped nickel-based hydroxide nanoarray structures with regular morphology. It also has fewer restrictions on reaction conditions, and the control methods are flexible and universal.

[0021] The method provided by this invention can control the chemical composition, microstructure, and structure of sulfur-doped nickel-based hydroxides by adjusting the ratio of organonitrile salts and organosulfur compounds, the sulfidation method, and key parameters of Joule heating. For example, when nickel acetate and thiourea are used as reaction precursors, this invention can obtain sulfur-doped nickel-based hydroxide nanosheet arrays through a one-step liquid-phase Joule heating synthesis. However, the sulfur-doped nickel-based hydroxides obtained through a two-step liquid-phase Joule heating synthesis (i.e., first synthesizing nickel-based hydroxides, and then performing a second liquid-phase Joule heating to sulfide them) exhibit different morphologies. Sulfur-doped nickel-based hydroxides with different chemical compositions, morphologies, and microstructures exhibit different catalytic properties.

[0022] Moreover, the product obtained by the method of the present invention can be used as a highly efficient self-supporting working electrode for electrocatalytic alkaline methanol oxidation reaction. It has good catalytic activity, stability and formic acid selectivity, and has broad application prospects in the fields of new energy conversion and high value-added chemical product production. Attached Figure Description

[0023] Figure 1 The image shows the XRD pattern of the supported sulfur-doped nickel-based hydroxide nanoarray obtained in Example 1.

[0024] Figure 2 The energy spectrum of the supported sulfur-doped nickel-based hydroxide nanoarray obtained in Example 1;

[0025] Figure 3 This is a SEM image of the supported sulfur-doped nickel-based hydroxide nanoarray obtained in Example 1;

[0026] Figure 4 This is a SEM image of the supported sulfur-doped nickel-based hydroxide nanoarray obtained in Example 2;

[0027] Figure 5 The energy spectrum of the supported sulfur-doped nickel-based hydroxide nanoarray obtained in Example 2;

[0028] Figure 6 The image shows the infrared thermogram of the reaction system during liquid-phase Joule heating in Example 2 at 0s (before the reaction begins).

[0029] Figure 7 This is an infrared thermogram of the reaction system during liquid-phase Joule heating in Example 2, taken 3 seconds after the reaction.

[0030] Figure 8 This is an infrared thermogram of the reaction system during liquid-phase Joule heating in Example 2 at 6 seconds of reaction.

[0031] Figure 9 This is an infrared thermogram of the reaction system during liquid-phase Joule heating in Example 2 at 9 seconds of reaction.

[0032] Figure 10 This is an infrared thermogram of the reaction system during liquid-phase Joule heating in Example 2 at 12 s of reaction.

[0033] Figure 11 SEM image of the supported nickel-based hydroxide nanoarray material obtained in Comparative Example 1;

[0034] Figure 12 SEM image of the supported sulfur-doped nickel-based hydroxide nanomaterial obtained in Comparative Example 2;

[0035] Figure 13 The cyclic voltammetry curves of the products obtained in Example 2 and Comparative Example 1 in 1 mol / L KOH + 1 mol / L methanol electrolyte are shown. Detailed Implementation

[0036] This invention provides a method for preparing a supported sulfur-doped nickel-based hydroxide nanoarray, comprising the following steps:

[0037] First, the carbonaceous conductive support is pretreated by Joule heating in air to obtain a hydrophilic carbonaceous conductive support.

[0038] Then, the hydrophilic carbonaceous conductive support is immersed in a liquid-phase reaction precursor composed of a mixed aqueous solution of organic nickel salt and organic sulfur-containing compound and subjected to Joule heating to complete the synthesis reaction, thereby obtaining the supported sulfur-doped nickel-based hydroxide nanoarray.

[0039] This invention pretreats a carbonaceous conductive carrier by Joule heating in air to obtain a hydrophilic carbonaceous conductive carrier.

[0040] In this invention, the carbonaceous conductive carrier preferably comprises carbon cloth, carbon fiber membrane, or carbon felt. In an embodiment of this invention, carbon cloth is used as the carbonaceous conductive carrier.

[0041] The present invention improves the wettability of carbonaceous conductive carriers in liquid-phase reaction precursors by hydrophilic modification, enabling them to fully adsorb reaction solutions and thus facilitating the acquisition of well-shaped and uniformly distributed supported sulfur-doped nickel-based hydroxide nanoarrays.

[0042] This invention does not impose any special restrictions on the type, specifications, or source of the carbon cloth, as long as it has good electrical conductivity. For carbon cloths of different specifications, this invention preferably sets the Joule heating parameters according to the conductivity of the carbon cloth, the product loading requirements, and the physicochemical property requirements, thereby controlling the chemical composition, microstructure, and structure of the product, and thus preparing sulfur-doped nickel-based hydroxide nanoarray materials with good electrocatalytic performance.

[0043] In this invention, the Joule heating pretreatment involves applying direct current to the carbonaceous conductive carrier in an air environment for heating. The preferred loading voltage for the Joule heating pretreatment is 15-20V, and in specific embodiments, it can be 15V, 16V, 17V, 18V, 19V, or 20V. The preferred current for the Joule heating pretreatment is 15-20A, and in specific embodiments, it can be 15A, 16A, 17A, 18A, 19A, or 20A. The preferred time for the Joule heating pretreatment is 0.5-1s, and in specific embodiments, it can be 0.5s or 1s. The power supply is immediately cut off after the predetermined reaction time to terminate the pretreatment reaction.

[0044] After obtaining the hydrophilic carbonaceous conductive support, the present invention immerses the hydrophilic carbonaceous conductive support in the liquid phase reaction precursor (the liquid phase reaction precursor is a mixed aqueous solution of organic nickel salt and organic sulfur-containing compound) and performs Joule heating to obtain the supported sulfur-doped nickel-based hydroxide nanoarray.

[0045] In this invention, the mixed aqueous solution of the organonickel salt and the organic sulfur-containing compound is obtained by mixing the aqueous solution of the organonickel salt and the aqueous solution of the organic sulfur-containing compound. The concentration of the aqueous solution of the organonickel salt is preferably 0.05~0.15 mol / L, and in the examples it may be 0.05 mol / L, 0.1 mol / L or 0.15 mol / L. The organonickel salt preferably includes one or more of nickel carboxylate salt and nickel sulfonate salt. The nickel carboxylate salt preferably includes nickel acetate. The nickel sulfonate salt is preferably nickel aminosulfonate.

[0046] In this invention, the concentration of the aqueous solution of the organic sulfur-containing compound is preferably 0.05~0.20 mol / L, and in specific embodiments of this invention, it can be 0.05 mol / L, 0.06 mol / L, 0.07 mol / L, 0.08 mol / L, 0.09 mol / L, 0.10 mol / L, 0.11 mol / L, 0.12 mol / L, 0.13 mol / L, 0.14 mol / L, 0.15 mol / L, 0.16 mol / L, 0.17 mol / L, 0.18 mol / L, 0.19 mol / L, or 0.20 mol / L; the organic sulfur-containing compound preferably includes thiourea.

[0047] The method provided by this invention can regulate the chemical composition, microstructure and structure of sulfur-doped nickel-based hydroxides by changing the ratio of organic nickel salts to organic sulfur-containing compounds, the sulfidation method (using a one-step sulfidation method) and key parameters of Joule heating.

[0048] In this invention, the molar ratio of the organonitrile salt to the organic sulfur-containing compound is preferably 1:0.25~4, and in specific embodiments of this invention, it can be 1:0.25, 1:0.5, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, or 1:4. With the increase of the amount of organic sulfide added to the liquid-phase reaction precursor, the morphology of the product does not change significantly with the increase of sulfur content, but it will change the amount of sulfur doping in the product, thereby affecting the catalytic performance.

[0049] The present invention does not impose any special restrictions on the placement of the hydrophilic carbonaceous conductive carrier in the liquid-phase reaction precursor, as long as it can be immersed in the solution.

[0050] In this invention, Joule heating is achieved by applying direct current to the hydrophilic carbonaceous conductive carrier immersed in the liquid-phase reaction precursor. The preferred voltage for Joule heating is 25-35V, the preferred current is 25-35A, and the preferred time is 1-12s. In specific embodiments of this invention, the voltage for Joule heating can be 25V, 26V, 27V, 28V, 29V, 30V, 31V, 32V, 33V, 34V, or 35V; the preferred current can be 25A, 26A, 27A, 28A, 29A, 30A, 31A, 32A, 33A, 34A, or 35A; and the preferred time can be 1s, 2s, 3s, 4s, 5s, 6s, 7s, 8s, 9s, 10s, 11s, or 12s. The power supply is immediately cut off after the predetermined reaction time is reached, and the reaction stops, thus completing the Joule heating process.

[0051] After the Joule heating is completed, the hydrophilic carbonaceous conductive support loaded with sulfur-doped nickel-based hydroxide nanoarrays is immediately removed from the liquid-phase reaction precursor, air-cooled, washed, and dried to obtain the supported sulfur-doped nickel-based hydroxide nanoarrays. In this invention, the washing can specifically be repeated with deionized water to remove unreacted precursors; the drying can be isothermal drying. In this invention, the isothermal drying temperature is preferably 55~65℃, and in specific embodiments, it can be 55℃, 56℃, 57℃, 58℃, 59℃, 60℃, 61℃, 62℃, 63℃, 64℃, or 65℃; the isothermal drying time is preferably 8~15 min, and in specific embodiments, it can be 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min, or 15 min. In this invention, the supported sulfur-doped nickel-based hydroxide nanoarray material can be directly used as a working electrode.

[0052] The present invention also provides a supported sulfur-doped nickel-based hydroxide nanoarray prepared by the preparation method described in the above technical solution, comprising a hydrophilic carbon conductive support and sulfur-doped nickel-based hydroxide supported on the hydrophilic carbon conductive support;

[0053] The sulfur-doped nickel-based hydroxide has an array structure composed of nanosheets.

[0054] In this invention, the nickel-based hydroxide is mainly composed of nickel and nickel hydroxide crystals; the nanosheets are vertically grown on the surface of a hydrophilic carbonaceous conductive carrier.

[0055] This invention also provides the application of the supported sulfur-doped nickel-based hydroxide nanoarray described above as a self-supporting electrode in the oxidation reaction of small molecule organic compounds. In one embodiment of this invention, the oxidation reaction of the small molecule organic compound is an oxidation reaction under alkaline conditions, and the small molecule organic compound may specifically be methanol. A specific application can be as an anode catalyst for an alkaline direct methanol fuel cell.

[0056] The hydrophilic carbonaceous conductive support loaded with sulfur-doped nickel-based hydroxide nanoarray prepared by this invention can be directly used as an electrocatalytic working electrode, such as for catalyzing the oxidation of methanol under alkaline conditions.

[0057] The following detailed description, in conjunction with embodiments, illustrates the supported sulfur-doped nickel-based hydroxide nanoarrays, their preparation methods, and applications provided by the present invention. However, these descriptions should not be construed as limiting the scope of protection of the present invention.

[0058] The carbon cloth used in the following examples and comparative examples is conductive carbon fiber woven cloth with a thickness of 0.36 mm and a resistivity of <5 mΩ / cm. 2 The weight is 130g / m 2 The carbon cloth was not treated with PTFE.

[0059] The solvent used in the solutions of the following examples and comparative examples is water.

[0060] Example 1

[0061] In an air atmosphere, the two ends of the carbon cloth are connected to the electrodes of a DC power supply and DC current is applied to perform Joule heating pretreatment on the carbon cloth. The applied voltage is 20V, the current is 20A, and the treatment time is 0.5s to obtain hydrophilic carbon cloth.

[0062] A 0.1 mol / L aqueous solution of nickel acetate tetrahydrate and a 0.2 mol / L aqueous solution of thiourea were mixed at a nickel acetate to thiourea molar ratio of 1:0.25 to obtain 9 mL of liquid-phase reaction precursor; a 1×3 cm sample was then prepared. 2The hydrophilic carbon cloth was vertically immersed in the above-mentioned liquid-phase reaction precursor. The hydrophilic carbon cloth was subjected to Joule heating with a voltage of 30V and a current of 20A. The power was cut off immediately after 12s of reaction, and the synthesis reaction was stopped.

[0063] Carbon cloth was removed from the liquid-phase reaction precursor, air-cooled, and repeatedly rinsed with deionized water. After drying at a constant temperature of 60°C for 10 minutes, a supported sulfur-doped nickel-based hydroxide nanoarray was obtained.

[0064] The product obtained in Example 1 was characterized by X-ray diffraction, and the results are as follows: Figure 1 As shown, Figure 1 The image shows the XRD pattern of the supported sulfur-doped nickel-based hydroxide nanoarray obtained in Example 1. The results indicate that the product obtained in Example 1 mainly consists of nickel and nickel hydroxide crystals.

[0065] X-ray energy dispersive spectroscopy analysis was performed on the product obtained in Example 1, and the results are as follows: Figure 2 As shown, Figure 2 This is the energy spectrum of the supported sulfur-doped nickel-based hydroxide nanoarray obtained in Example 1. Figure 2 It can be seen that the product obtained in Example 1 mainly consists of nickel, oxygen, and sulfur elements. Figure 1 The results comprehensively prove that the product is a sulfur-doped nickel-based hydroxide nanomaterial.

[0066] The supported sulfur-doped nickel hydroxide nanoarray obtained in Example 1 was characterized by scanning electron microscopy, and the results are as follows: Figure 3 As shown, Figure 3 This is a SEM image of the supported sulfur-doped nickel-based hydroxide nanoarray obtained in Example 1. Figure 3 It can be seen that the sulfur-doped nickel-based hydroxide obtained in Example 1 forms a nanosheet array that grows vertically on the surface of carbon cloth.

[0067] Example 2

[0068] In an air atmosphere, the two ends of the carbon cloth are connected to the electrodes of a DC power supply and DC current is applied to perform Joule heating pretreatment on the carbon cloth. The applied voltage is 20V, the current is 20A, and the treatment time is 0.5s to obtain hydrophilic carbon cloth.

[0069] A 0.1 mol / L aqueous solution of nickel acetate tetrahydrate and a 0.2 mol / L aqueous solution of thiourea were mixed at a molar ratio of nickel acetate tetrahydrate to thiourea of ​​1:2 to obtain 10 mL of liquid-phase reaction precursor; a 1×3 cm... 2 The hydrophilic carbon cloth was vertically immersed in the above-mentioned liquid-phase reaction precursor and Joule heated. The applied voltage was 30V and the current was 20A. After 12 seconds of reaction, the power was cut off immediately, and the synthesis reaction was stopped.

[0070] Carbon cloth was removed from the liquid-phase reaction precursor, air-cooled, and repeatedly rinsed with deionized water. After drying at a constant temperature of 60°C for 10 minutes, a supported sulfur-doped nickel-based hydroxide nanoarray was obtained.

[0071] The product obtained in Example 2 was subjected to scanning electron microscopy, and the results are as follows: Figure 4 As shown, Figure 4 This is a SEM image of the supported sulfur-doped nickel-based hydroxide nanoarray obtained in Example 2. Figure 4 It can be seen that the product obtained in Example 2 still has a nanosheet array structure that grows vertically on the surface of carbon cloth.

[0072] X-ray energy dispersive spectroscopy analysis was performed on the product obtained in Example 2, and the results are as follows: Figure 5 As shown, Figure 5 This is the energy spectrum of the supported sulfur-doped nickel-based hydroxide nanoarray obtained in Example 2. Figure 5 It can be seen that the product obtained in Example 1 is also composed of nickel, oxygen and sulfur elements.

[0073] The temperature of the reaction system during Joule heating in Example 2 was characterized using an infrared thermal imager (overhead view). The infrared thermal images of the liquid-phase reaction system at different reaction time points are shown below. Figures 6-10 The diagram shows that under liquid-phase conditions, an electric current is applied to the conductive support, generating Joule heating that triggers a reaction in the precursors adsorbed on the support surface, leading to in-situ product formation. During synthesis, a three-dimensional, unstable temperature field exists between the support and the liquid phase. Due to the rapid heating and even boiling of the liquid phase, the resulting strong convection inhibits overheating of the support and excessive reaction rate, limiting the growth of the product from the support surface into the liquid phase, resulting in a size only at the nanometer scale. Figure 6 It can be seen that at 0s, the infrared thermogram of the liquid-phase reaction system shows that the temperature of the entire system before heating (when the reaction is about to begin) is room temperature (the red triangle indicates 25.7℃, and the blue triangle indicates 20.5℃). At 3s ( Figure 7 The highest temperature of the reaction system was 90.3℃ (marked by the red triangle), and the blue triangle marked 24.0℃. At 6 seconds... Figure 8 The highest temperature of the reaction system can reach 102.9℃ (marked by the red triangle), at which point the solution has boiled. The temperature at the blue triangle is 26.2℃, showing a large temperature difference between the central region and the surrounding edge region; at 9s ( Figure 9 The highest temperature of the reaction system can reach 106.2℃ (marked by the red triangle), and the temperature at the blue triangle is 32.4℃; when the reaction continues for 12 seconds ( Figure 10As the solution boiled violently (temperature indicated by the red triangle at 106.1℃) and overflowed the reaction tank, the infrared thermogram showed the reaction area gradually expanding, with the temperature indicated by the blue triangle at 34.0℃. After the reaction, the hydrophilic carbon cloth was immediately removed, and the carrier was removed from the hydrothermal environment and rapidly cooled in air. This demonstrates that a rapidly heating temperature field was formed at the interface between the hydrophilic carbon cloth and the solution, and the immediate air cooling after the reaction provided extremely non-equilibrium reaction conditions and processes.

[0074] The temperature change of the Joule heating reaction in the liquid-phase reaction precursor in Example 1 was similar to that in Example 2.

[0075] Comparative Example 1

[0076] In an air atmosphere, the two ends of the carbon cloth are connected to the electrodes of a DC power supply and DC current is applied to perform Joule heating pretreatment on the carbon cloth. The applied voltage is 20V, the current is 20A, and the treatment time is 0.5s to obtain hydrophilic carbon cloth.

[0077] The size is 1×3cm 2 The hydrophilic carbon cloth was vertically immersed in 10 mL of a 0.1 mol / L nickel acetate tetrahydrate solution. The hydrophilic carbon cloth was subjected to Joule heating in the above liquid-phase reaction precursor with a voltage of 30 V and a current of 20 A. The power was cut off immediately after 12 s of reaction, and the synthesis reaction was stopped.

[0078] Carbon cloth was removed from the liquid-phase reaction precursor, air-cooled, and repeatedly rinsed with deionized water. After drying at a constant temperature of 60°C for 10 minutes, the supported nickel-based hydroxide nanoarray material was obtained.

[0079] The product obtained in Comparative Example 1 was characterized by scanning electron microscopy, and the results are as follows: Figure 11 As shown, Figure 11 The image shows a SEM image of the supported nickel-based hydroxide nanoarray material in Comparative Example 1. The results indicate that the product obtained in Comparative Example 1 is a nanosheet array structure, demonstrating that the sulfidation process described in the examples does not affect the microstructure of the material.

[0080] Comparative Example 2

[0081] In an air atmosphere, the two ends of the carbon cloth are connected to the electrodes of a DC power supply and DC current is applied to perform Joule heating pretreatment on the carbon cloth. The applied voltage is 20V, the current is 20A, and the treatment time is 0.5s to obtain hydrophilic carbon cloth.

[0082] The size is 1×3cm 2Hydrophilic carbon cloth was vertically immersed in 10 mL of a 0.1 mol / L nickel acetate tetrahydrate solution. The hydrophilic carbon cloth was then Joule-heated at a voltage of 30 V and a current of 20 A for 12 seconds, after which the power was immediately cut off, and the synthesis reaction was stopped. Subsequently, the nickel-doped nickel hydroxide-loaded carbon cloth was vertically immersed in 10 mL of a 0.2 mol / L thiourea solution and Joule-heated again at a voltage of 20 V and a current of 20 A for 12 seconds. After the reaction, the carbon cloth was immediately removed, air-cooled, repeatedly rinsed with deionized water, and dried at 60 °C for 10 min to obtain the supported sulfur-doped nickel hydroxide nanoarray material.

[0083] The product obtained in Comparative Example 2 was characterized by scanning electron microscopy, and the results are as follows: Figure 12 As shown, Figure 12 The image shows a SEM image of the supported sulfur-doped nickel-based hydroxide nanomaterial obtained in Comparative Example 2.

[0084] Depend on Figure 12 It can be seen that, in addition to the nanosheet morphology, the sulfur-doped nickel-based hydroxide obtained by the two-step sulfidation method in Comparative Example 2 also contains obvious nanoparticles. Compared with the one-step sulfidation method in Examples 1 and 2, the morphological uniformity of the product in Comparative Example 2 is relatively poor.

[0085] Test case

[0086] Electrochemical tests were performed using a standard three-electrode system. The reference electrode was an Hg / HgO electrode, and the counter electrode was a carbon rod. The supported materials obtained in the embodiments and comparative examples of this invention were used as working electrodes (the geometric area of ​​each electrode was 1 cm²). 2 ).

[0087] Cyclic voltammetry tests were performed on the supported sulfur-doped nickel-based hydroxide nanoarrays prepared in Example 2 and the supported nickel-based hydroxide nanoarrays prepared in Comparative Example 1. The electrolyte used was a 1 mol / L KOH + 1 mol / L methanol solution. The test voltage was 0–1 V, and the scan rate was 50 mV / s. The results are as follows: Figure 13 As shown.

[0088] Figure 13 The figures show the cyclic voltammetry curves of the supported materials obtained in Example 2 and Comparative Example 1 in a 1 mol / L KOH + 1 mol / L methanol electrolyte. Figure 13 It can be seen that the products obtained in Example 2 and Comparative Example 1 both exhibit the ability to electrocatalyze the methanol oxidation reaction. In comparison, the sulfur-doped nickel-based hydroxide nanoarray has a higher catalytic current density, indicating that an appropriate amount of sulfur doping can enhance the catalytic activity of the nickel-based hydroxide nanoarray.

[0089] The technical solutions and embodiments for which protection is sought above are true and valid.

[0090] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a supported sulfur-doped nickel-based hydroxide nanomaterial array, characterized in that, Includes the following steps: A hydrophilic carbon conductive carrier is obtained by pretreating the carbon conductive carrier with air-assisted Joule heating. The hydrophilic carbonaceous conductive support was immersed in a liquid-phase reaction precursor provided by a mixed aqueous solution of organic nickel salt and organic sulfur-containing compound for Joule heating synthesis to obtain the supported sulfur-doped nickel-based hydroxide nanoarray. The molar ratio of the organonitrile salt to the organic sulfur-containing compound is 1:0.25~4; The organic nickel salt includes one or more of nickel carboxylate salts and nickel sulfonate salts; The organic sulfur-containing compounds include thiourea; The Joule heating synthesis process involves heating the hydrophilic carbonaceous conductive carrier immersed in the liquid-phase reaction precursor by passing a direct current through it. The Joule heating synthesis treatment is performed with a loading voltage of 25~35V, a current of 25~35A, and a time of 1~12s.

2. The preparation method according to claim 1, characterized in that, The carbonaceous conductive carrier includes carbon cloth, carbon fiber film, or carbon felt.

3. The preparation method according to claim 1 or 2, characterized in that, The loading voltage for the air-assisted Joule heating pretreatment is 15~20V, the current is 15~20A, and the time is 0.5~1.0s.

4. The preparation method according to claim 1, characterized in that, The mixed aqueous solution of the organonickel salt and the organic sulfur-containing compound is obtained by mixing the aqueous solution of the organonickel salt and the aqueous solution of the organic sulfur-containing compound, wherein the concentration of the aqueous solution of the organonickel salt is 0.05~0.15 mol / L and the concentration of the aqueous solution of the organic sulfur-containing compound is 0.05~0.20 mol / L.

5. The supported sulfur-doped nickel-based hydroxide nanoarray prepared by the preparation method according to any one of claims 1 to 4, characterized in that, It includes a hydrophilic carbonaceous conductive support and a sulfur-doped nickel-based hydroxide loaded on the hydrophilic carbonaceous conductive support; The sulfur-doped nickel-based hydroxide has an array structure composed of nanosheets.

6. The supported sulfur-doped nickel-based hydroxide nanoarray of claim 5 is used as a self-supporting electrode in the oxidation reaction of small molecule organic compounds.

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