Oxygen-vacancy-rich hollow nanosphere indium hydroxide electrocatalyst as well as preparation method and application thereof

Abstract

The invention relates to an oxygen-vacancy-rich hollow nanosphere indium hydroxide electrocatalyst as well as a preparation method and application thereof, and belongs to the technical field of preparation of novel catalysts. The oxygen vacancy-rich hollow nanosphere indium hydroxide electrocatalyst is characterized in that the electrocatalyst VO-In (OH) 3 is an indium hydroxide hollow nanosphere of which the surface is rich in oxygen vacancy, and the indium hydroxide hollow nanosphere is formed by disorderly piling up In (OH) 3 nanocubes. The oxygen-vacancy-rich hollow nanosphere indium hydroxide VO-In (OH) 3 electrocatalyst prepared by the invention shows outstanding catalytic conversion performance when being used for preparing urea through CO2 and NO3-co-reduction C-N coupling, has excellent inhibition on side reactions such as hydrogen evolution and ammonia production, and still has relatively good stability and high yield and Faraday efficiency after being repeated for several times.

Description

Technical Field

[0001] The invention relates to an oxygen-vacancy-rich hollow nanosphere indium hydroxide electrocatalyst and a preparation method and application thereof, belonging to the technical field of novel catalyst preparation. Background Art

[0002] Urea is one of the most important nitrogen fertilizers in global agriculture. It has the advantages of high nitrogen content, ease of transportation and application, and is an indispensable raw material in global agricultural production. However, traditional urea industrial synthesis usually uses carbon dioxide (CO2) and ammonia (NH3) as carbon / nitrogen sources, and requires the Bosch-Meiser process under harsh conditions of high temperature and high pressure. This process consumes approximately 2% of the world's energy each year and produces a large amount of CO2, which has a huge negative impact on the environment. There is an urgent need to develop a more sustainable synthesis route. [1] . Using green electricity generated by renewable clean energy, develop low-temperature, low-pressure, low-energy consumption urea synthesis technology, especially through electrocatalysis to utilize CO2 and nitrate (NO3 - ) synthesizes urea, providing a new path for sustainable production of urea under mild conditions.

[0003] In CO2 and NO3 - In the reduction reaction, CN coupling reaction is the core step of urea synthesis. Electrocatalytic CN coupling reaction can improve the synthesis efficiency of urea by regulating the reaction conditions and catalyst design, while reducing CO2 emissions. Compared with the traditional urea synthesis process, electrocatalytic urea synthesis has significant advantages such as low energy consumption, low emissions, and green environmental protection. At present, many studies have focused on the development of efficient catalysts to promote the reduction of CO2 and NO3 - The electrocatalytic reduction reaction of . Catalysts based on metals (such as copper, iron, aluminum, zinc and indium) have been widely studied, among which indium-based catalysts show higher selectivity and activity.

[0004] Indium-based electrocatalysts exhibit excellent performance in electrocatalytic reactions, achieving ultra-low overpotential, high selectivity, and high activity. In addition, indium-based electrocatalysts exhibit good stability and corrosion resistance during the electrocatalytic process, and can maintain high catalytic performance for a long time. However, achieving efficient urea electrocatalytic synthesis still faces challenges such as poor catalyst selectivity, low reaction activity, and unstable reaction intermediates. Chen et al. [2] A sulfur-doped graphene oxide-supported In2S3 electrocatalyst (In2S3@S-RGO) was prepared for urea synthesis with an average Faradaic efficiency of 37.17% and a yield of 7.24 mmol h -1 g -1 , and maintain long-term stability. Mao et al. [3]The CuO / In2O3 heterojunction was designed and synthesized, and the interface formation induced the generation of a large number of oxygen vacancies. The study found that oxygen vacancies enhanced the material's NO3 - The heterogeneous interface enables the material to exhibit extraordinary capabilities in CO2 adsorption and activation, and promotes the CN coupling reaction. In the electrocatalytic synthesis of urea, the urea generation rate and Faradaic efficiency of CuO / In2O3 are 794.72 μg h -1 mg -1 Currently, the performance of many electrocatalysts for urea synthesis needs to be further improved. The key challenge is to find active sites that can promote CN coupling to improve urea selectivity while suppressing the competing hydrogen evolution reaction to increase yield and Faradaic efficiency.

[0005] References

[0006] [1] J.Cao, F.Zhao, C.Li, Q.Zhao, L.Gao, T.Ma, H.Xu, X.Ren, A.Liu, Electrocatalytic Synthesis of Urea: An In-depth Investigation from MaterialModification to Mechanism Analysis, Small, (2024).

[0007] [2]

[0008] [3] Y.Mao, Q.Gou, S.Lv, N.Zhao, Y.Jiang, W.Shen, M.Li, R.He, Synergistic effects of heterogeneous interfaces and induced oxygen vacancies enhance theCuO / In2O3performance in catalytic urea synthesis, Chemical Engineering Journal, 496 (2024). Summary of the Invention

[0009] The object of the present invention is to provide a method for treating CO2 and NO3 - A high-performance electrocatalyst for the co-reduction of CN coupled urea and its preparation method, wherein the electrocatalyst has the excellent properties of high catalytic activity, high stability, and high selectivity. The present invention utilizes a solvothermal method to synthesize hollow nanospheres of In(OH)3, using ethylene glycol solution as a crystal plane director to expose their {100} crystal planes. Plasma treatment technology is used to create oxygen vacancy defects on the surface of In(OH)3 in a hydrogen-argon mixed gas atmosphere, obtaining oxygen-rich hollow nanospheres V O -In(OH)3 electrocatalyst.

[0010] An oxygen vacancy-rich hollow nanosphere indium hydroxide electrocatalyst, the electrocatalyst V O -In(OH)3 is an indium hydroxide hollow nanosphere with rich oxygen vacancies on the surface, wherein the indium hydroxide hollow nanosphere is formed by disordered stacking of In(OH)3 nanocubes.

[0011] Preferably, the indium hydroxide hollow nanospheres are formed by disorderly stacking 2 to 4 layers of In(OH)3 cubes.

[0012] Preferably, the side length of the In(OH)3 nanocubes constituting the hollow nanospheres is 20 to 60 nm; and the size of the hollow nanospheres is 400 to 500 nm.

[0013] Preferably, the oxygen vacancies on the surface of the hollow indium hydroxide nanospheres are obtained by low-temperature plasma treatment in a hydrogen-argon mixed atmosphere. The oxygen vacancies described in the present invention are preferably produced by plasma treatment defect engineering. The low-temperature plasma device is a device disclosed in the prior art and can be purchased commercially or obtained by methods disclosed in the prior art.

[0014] Another object of the present invention is to provide a method for preparing the above-mentioned oxygen vacancy-rich hollow nanosphere indium hydroxide electrocatalyst.

[0015] A method for preparing oxygen-vacancy-rich hollow nanosphere indium hydroxide electrocatalyst comprises synthesizing indium hydroxide hollow nanospheres formed by disordered stacking of In(OH)3 nanocubes by a solvothermal method, and then treating the obtained indium hydroxide hollow nanospheres with low-temperature plasma to obtain indium hydroxide hollow nanospheres with oxygen vacancies rich on the surface.

[0016] Preferably, the solvent thermal method is specifically as follows: dissolving indium salt in ethylene glycol to obtain 0.01-0.5 mol / L In 3+ / EG solution; 10 mol / L NaOH solution and InO solution were mixed in a volume ratio of 1:1 to 1:5. 3+The method comprises the following steps: mixing the indium hydroxide / EG solution until the solution becomes homogeneous and transparent; transferring 8 to 12 mL of the obtained mixed solution to a 15 to 20 mL polytetrafluoroethylene-lined reactor, heating the mixture from room temperature to 120 to 200° C. at a heating rate of 1 to 10° C. / min, and reacting the mixture for 12 to 48 hours; and naturally cooling the mixture to room temperature after the reaction, washing the mixture, and drying the mixture to obtain indium hydroxide hollow nanospheres.

[0017] The present invention adopts a 15-20 mL reactor with a polytetrafluoroethylene lining, and the volume of the reaction liquid is 8-12 mL. Under this condition, hollow indium hydroxide nanospheres formed by disordered stacking of In(OH)3 nanocubes can be obtained.

[0018] Furthermore, a certain amount of indium salt was ultrasonically dissolved in ethylene glycol (EG) to obtain 0.01-0.5 mol / L In 3 + / EG solution. Mix 10mol / L NaOH solution with In 3+ The method involves mixing a NaOH solution with an InCl3 / EG solution in a volume ratio of 1:1 to 1:5. 8 to 12 mL of the mixed solution is stirred for 30 minutes until the solution becomes homogeneous and transparent, and then transferred to a 15 to 20 mL polytetrafluoroethylene-lined reactor. The mixture is then heated in an oven from room temperature to 120 to 200°C at a heating rate of 1 to 10°C / min, and the reaction is maintained for 12 to 48 hours. After the reaction is completed, the mixture is naturally cooled to room temperature, washed repeatedly with deionized water and ethanol, and dried at 60°C for 24 hours to obtain hollow nanospheres of In(OH)3.

[0019] Preferably, the ground indium hydroxide hollow nanospheres are placed in a low-temperature plasma device, a hydrogen-argon mixed gas is introduced to exhaust the air in the device, the plasma device power is turned on, the reaction voltage is adjusted to 10-60V, the reaction time is 5-25min, and the indium hydroxide hollow nanospheres with rich surface oxygen vacancies are obtained. O -In(OH)3, wherein the proportion of hydrogen in the hydrogen-argon mixed gas is 5-10%.

[0020] Furthermore, the obtained hollow nano-spherical In(OH)3 was placed in a quartz mortar and ground thoroughly. An appropriate amount (10-100 mg) of the sample was taken and placed in a quartz reactor and evenly spread. After the air in the device was exhausted by passing a hydrogen-argon mixture (hydrogen ratio 5-10%) for 30 minutes, the plasma device power was turned on, the reaction voltage was adjusted to 10-60V, the reaction time was 5-25 minutes, and different degrees of plasma surface oxygen vacancy defect treatment were performed. After the end, hollow nano-spherical V with rich oxygen vacancies was obtained. O -In(OH)3 electrocatalyst.

[0021] Preferably, the indium salt is one of InCl3, In(NO3)3 or In(C2H3O2)3.

[0022] Another object of the present invention is to provide the use of the above-mentioned oxygen vacancy-rich hollow nanosphere indium hydroxide electrocatalyst in the electrocatalytic synthesis of uric acid.

[0023] Furthermore, the oxygen-rich hollow nanosphere indium hydroxide electrocatalyst is provided as a CO2 and NO3 - Application of co-reduction CN coupling electrocatalyst for urea production.

[0024] A CO2 and NO3 - A method for preparing urea by co-reduction CN coupling, wherein the V O -In(OH)3 electrocatalyst is evenly mixed with ethanol, 5wt.% Nafion solution and ultrapure water, and ultrasonically dispersed for 30-60min. The resulting dispersion is evenly dropped on carbon paper, and after natural drying, the carbon paper is clamped with a glassy carbon electrode clamp as a working electrode; an Ag / AgCl electrode (saturated with KCl) is used as a reference electrode, a platinum electrode is used as a counter electrode, a Nafion 115 or 117 proton exchange membrane is used, and an H-type electrolytic cell is used as a reactor. Electrocatalytic carbon dioxide and nitrate solution are co-reduced to CN to produce urea in an electrochemical workstation.

[0025] The beneficial effects of the present invention are as follows: the present invention adopts a one-pot hydrothermal method to synthesize hollow indium hydroxide nanospheres, which is simple and feasible; the production cost of the raw materials is low; the synthesized V O -In(OH)3 electrocatalyst is composed of several layers of In(OH)3 nanocubes, exposing more {100} crystal faces; it has a hollow nanosphere structure to increase the contact area between the electrolyte and the catalyst; low-temperature plasma treatment creates oxygen vacancy defect engineering without changing the material morphology and other characteristics, and the degree of oxygen vacancy defect can be effectively controlled; the oxygen vacancy-rich hollow nanosphere V prepared by the present invention O -In(OH)3 electrocatalyst for CO2 and NO3 - The co-reduction CN coupling to produce urea exhibits outstanding catalytic conversion performance, excellent inhibition of side reactions such as hydrogen evolution and ammonia production, and still maintains good stability, high yield and Faradaic efficiency after several repetitions. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 V prepared in Example 3 of the present invention O -Scanning and transmission electron microscopy images of In(OH)3 electrocatalyst. Figure 1 The SEM, TEM and HRTEM images of ad show that the oxygen-rich hollow nanospheres V O-In(OH)3 electrocatalyst is composed of small nanocubes stacked into hollow nanospheres, exposing the {100} crystal face of In(OH)3.

[0027] Figure 2 V prepared in Example 3 of the present invention O -X-ray diffraction pattern of In(OH)3 electrocatalyst. Figure 2 XRD shows that the prepared hollow nano-spherical V O -In(OH)3 electrocatalyst is consistent with the standard card of indium hydroxide (PDF#85-1338), indicating that no impurities are generated.

[0028] Figure 3 V prepared in Example 3 of the present invention O -X-ray photoelectron spectroscopy (O 1s) of In(OH)3 electrocatalyst. Figure 3 It can be seen from the XPS O 1s that the peaks of lattice oxygen and adsorbed oxygen appear at the binding energy of 530.2eV and 533.9eV, and the characteristic peak of oxygen vacancy appears at the binding energy of 531.8eV. This shows that the oxygen vacancy defect engineering has been successfully introduced.

[0029] Figure 4 The yield and Faraday efficiency of urea produced by the electrocatalysts prepared in Examples 1 to 6 of the present invention and Comparative Example 1 in a 0.1 mol / L KNO3 solution saturated with CO2 for 60 min. Figure 4 It can be seen that the Faradaic efficiency of the electrocatalyst prepared in Example 3 for urea synthesis is as high as 81.03%, and its yield is as high as 2339.43 μg h -1 mg cat. -1 Compared with the solid cube and the oxygen-free vacancy, the hollow nano-spherical V O -In(OH)3 electrocatalyst performance is significantly improved.

[0030] Figure 5 TEM image of the electrocatalyst prepared in Comparative Example 2 of the present invention. Figure 5 It can be seen that when the volume of the reactor increases from 15 mL to 100 mL, the microscopic morphology of In(OH)3 changes from hollow nanospheres to solid cubes, and the performance of electrocatalytic synthesis of urea is poor. DETAILED DESCRIPTION

[0031] The following non-limiting examples may enable those skilled in the art to more fully understand the present invention, but are not intended to limit the present invention in any way.

[0032] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; the reagents and materials described are all commercially available unless otherwise specified.

[0033] One of the specific implementation methods:

[0034] A method for preparing an oxygen-vacancy-rich hollow nanosphere indium hydroxide electrocatalyst comprises the following steps:

[0035] (1) Preparation of hollow nanosphere In(OH)3 electrocatalyst: ultrasonically dissolve one of the indium salts among InCl3, In(NO3)3 and In(C2H3O2)3 in ethylene glycol (EG) to obtain any ratio of InCl3 to In(OH)3. 3+ / EG solution. Mix 10mol / L NaOH solution with In 3+ The indium hydroxide solution was mixed with EG solution in a volume ratio of 1:1 to 1:5. 8-12 mL of the mixed solution was stirred for 30 minutes until the solution became homogeneous and transparent. The mixture was then transferred to a 15-20 mL polytetrafluoroethylene-lined reactor. The mixture was heated in an oven at a rate of 1-10°C / min from room temperature to 150-200°C for 12-48 hours. After the reaction was completed, the mixture was naturally cooled to room temperature, washed repeatedly with deionized water and ethanol, and dried at 60°C for 24 hours to obtain hollow indium hydroxide nanospheres (In(OH)3).

[0036] (2) Preparation of indium hydroxide hollow nanospheres rich in oxygen vacancies V O -In(OH)3 electrocatalyst: The obtained hollow nano-sphere In(OH)3 was placed in a quartz mortar and ground thoroughly. An appropriate amount (10-100 mg) of sample was taken and placed in a quartz reactor and evenly spread. After the air in the device was exhausted by passing a hydrogen-argon mixture (H2 ratio 5-10%) for 30 minutes, the plasma device power was turned on, the reaction voltage was adjusted to 10-60V, the reaction time was 5-25 minutes, and different degrees of plasma-induced surface oxygen vacancy defect treatment were performed. After the end, hollow indium hydroxide nanospheres rich in oxygen vacancies were obtained. O -In(OH)3 electrocatalyst.

[0037] Take a small amount of indium hydroxide hollow nanospheres rich in oxygen vacancies V O-In(OH)3 electrocatalyst was added to a mixed solution of ethanol, Nafion and ultrapure water (the volume ratio of ethanol: Nafion: ultrapure water was 5:1:14), and ultrasonicated for 30 to 60 minutes to evenly disperse the electrocatalyst. A certain amount of the obtained dispersion was evenly dropped on a fixed area of carbon paper. After drying naturally, the carbon paper was clamped with a glassy carbon electrode clip as the working electrode; an Ag / AgCl electrode (saturated with KCl) was used as the reference electrode, a platinum electrode was used as the counter electrode, a Nafion 117 proton exchange membrane was used, and an H-type electrolytic cell was used as the reactor to electrocatalyze CO2 and NO3 on an electrochemical workstation. - The performance test of urea production by co-reduction CN coupling was carried out by using the diacetyl monoxime method to detect the urea concentration in the electrolyte using a UV-visible spectrophotometer, and using a gas chromatograph to detect the gas products. CO2 and NO3 were obtained by calculation. - Yield and Faradaic efficiency of co-reduction to urea and other products.

[0038] Another object of the present invention is to provide hollow nanospheres of indium hydroxide with oxygen vacancies prepared by the above method. O -In(OH)3 electrocatalyst, the hollow indium hydroxide nanospheres rich in oxygen vacancies V O -In(OH)3 electrocatalyst is composed of nanocubes stacked into hollow spheres.

[0039] The V synthesized by the preparation method provided by the present invention O -In(OH)3 electrocatalyst is composed of several layers of In(OH)3 nanocubes, exposing more {100} crystal faces; it has a hollow nanosphere structure to increase the contact area between the electrolyte and the catalyst; low-temperature plasma treatment creates oxygen vacancy defects without changing the material morphology and other characteristics, and the degree of oxygen vacancy defects can be effectively controlled. The hollow indium hydroxide nanospheres V rich in oxygen vacancies prepared by the present invention O -In(OH)3 electrocatalyst for CO2 and NO3 - The co-reduction CN coupling reaction for urea showed excellent catalytic conversion performance. Under constant potential electrolysis at -0.6 V (vs. RHE), the yield and Faradaic efficiency of urea synthesis reached 2339.43 μg h. -1 mg cat. -1 and 81.03%, is an efficient and stable electrocatalytic CO2 and NO3 - Co-reduction catalyst materials for urea production.

[0040] In the following embodiments, the In 3+ / EG solution was prepared according to 0.1 mol / L In 3+ / EG solution was prepared by ultrasonically dissolving indium salt to prepare 12 mL.

[0041] In the following examples, the 10 mol / L NaOH solution and In 3+ / EG solution were prepared by mixing 3 mL of 10 mol / L NaOH solution and 12 mL of 0.1 mol / L In solution in a volume ratio of 1:4. 3+ / EG solution was mixed and stirred for 30 min until the solution became homogeneous and transparent.

[0042] Example 1

[0043] (1) Weigh 0.235g of InCl3 and dissolve it in 8mL of ethylene glycol by ultrasonication. Weigh 0.8g of NaOH and dissolve it in 2mL of ultrapure water. Mix the NaOH solution with the InCl3 / EG solution, stir for 30min until the solution is homogeneous and transparent, and transfer it to a 15mL polytetrafluoroethylene-lined reactor. Use a heating oven to heat from room temperature to 200℃ at a heating rate of 5℃ / min, and maintain the reaction for 24h. After the reaction is completed, it is naturally cooled to room temperature, washed repeatedly with deionized water and ethanol, and dried at 60℃ for 24h to obtain indium hydroxide hollow nanospheres In(OH)3.

[0044] (2) The obtained indium hydroxide hollow nanospheres In(OH)3 were placed in a quartz mortar and ground thoroughly. 50 mg of the sample was placed in a quartz reactor and evenly spread. After the air in the device was exhausted by passing a hydrogen-argon mixture (H28%, Ar 92%) for 30 minutes, the plasma device power was turned on, the reaction voltage was adjusted to 30 V, the reaction time was 15 minutes, and the plasma was used to create surface oxygen vacancy defects to obtain oxygen-rich indium hydroxide hollow nanospheres V O(30V) -In(OH)3 electrocatalyst.

[0045] (3) Take 5mg V O(30V) -In(OH)3 electrocatalyst, 50μL 5wt.% Nafion solution and 250μL ultrapure water were added to 700μL ethanol and ultrasonicated for 60min to make ink solution. 20μL was dropped on a 1*1cm 2 On carbon paper (Toray TGP-H-090), dried naturally, with a loading of 0.1 mg cm -2 A glassy carbon electrode holder was used to hold the carbon paper as the working electrode. The electrocatalytic performance was tested in a CO₂-saturated 0.1 mol / L KNO₃ solution. The urea concentration in the electrolyte was measured using a UV-visible spectrophotometer. The catalyst showed a yield and Faradaic efficiency of 1006.1 μg h⁻¹ of urea synthesis under constant potential electrolysis at -0.6 V (vs. RHE). -1 mg cat. -1 and 44.16%.

[0046] Example 2

[0047] (1) Weigh 0.235g of InCl3 and dissolve it in 8mL of ethylene glycol by ultrasonication. Weigh 0.8g of NaOH and dissolve it in 2mL of ultrapure water. Mix the NaOH solution with the InCl3 / EG solution, stir for 30min until the solution is homogeneous and transparent, and transfer it to a 15mL polytetrafluoroethylene-lined reactor. Use a heating oven to heat from room temperature to 200℃ at a heating rate of 5℃ / min, and maintain the reaction for 24h. After the reaction is completed, it is naturally cooled to room temperature, washed repeatedly with deionized water and ethanol, and dried at 60℃ for 24h to obtain indium hydroxide hollow nanospheres In(OH)3.

[0048] (2) The obtained indium hydroxide hollow nanospheres In(OH)3 were placed in a quartz mortar and ground thoroughly. 50 mg of the sample was placed in a quartz reactor and evenly spread. After the air in the device was exhausted by passing a hydrogen-argon mixture (H28%, Ar 92%) for 30 minutes, the plasma device power was turned on, the reaction voltage was adjusted to 40 V, the reaction time was 15 minutes, and the plasma was used to create surface oxygen vacancy defects to obtain oxygen-rich indium hydroxide hollow nanospheres V O(40V) -In(OH)3 electrocatalyst.

[0049] (3) Take 5mg V O(40V) -In(OH)3 electrocatalyst, 50μL 5wt.% Nafion solution and 250μL ultrapure water were added to 700μL ethanol and ultrasonicated for 60min to make ink solution. 20μL was dropped on a 1*1cm 2 On carbon paper (Toray TGP-H-090), dried naturally, with a loading of 0.1 mg cm -2 A glassy carbon electrode holder was used to hold the carbon paper as the working electrode. The electrocatalytic performance was tested in a CO₂-saturated 0.1 mol / L KNO₃ solution. The urea concentration in the electrolyte was measured using a UV-visible spectrophotometer. The catalyst showed a yield and Faradaic efficiency of 1660.57 μg h⁻¹ of urea synthesis under constant potential electrolysis at -0.6 V (vs. RHE). -1 mg cat. -1 and 64.09%.

[0050] Example 3

[0051] (1) Weigh 0.235g of InCl3 and dissolve it in 8mL of ethylene glycol by ultrasonication. Weigh 0.8g of NaOH and dissolve it in 2mL of ultrapure water. Mix the NaOH solution with the InCl3 / EG solution, stir for 30min until the solution is homogeneous and transparent, and transfer it to a 15mL polytetrafluoroethylene-lined reactor. Use a heating oven to heat from room temperature to 200℃ at a heating rate of 5℃ / min, and maintain the reaction for 24h. After the reaction is completed, it is naturally cooled to room temperature, washed repeatedly with deionized water and ethanol, and dried at 60℃ for 24h to obtain indium hydroxide hollow nanospheres In(OH)3.

[0052] (2) The obtained indium hydroxide hollow nanospheres In(OH)3 were placed in a quartz mortar and ground thoroughly. 50 mg of the sample was placed in a quartz reactor and evenly spread. After the air in the device was exhausted by passing a hydrogen-argon mixture (H28%, Ar 92%) for 30 minutes, the plasma device power was turned on, the reaction voltage was adjusted to 50 V, the reaction time was 15 minutes, and the plasma was used to create surface oxygen vacancy defects to obtain oxygen-rich indium hydroxide hollow nanospheres V O(50V / 15min) -In(OH)3 electrocatalyst.

[0053] (3) Take 5mg V O(50V / 15min) -In(OH)3 electrocatalyst, 50μL 5wt.% Nafion solution and 250μL ultrapure water were added to 700μL ethanol and ultrasonicated for 60min to make ink solution. 20μL was dropped on a 1*1cm 2 On carbon paper (Toray TGP-H-090), dried naturally, with a loading of 0.1 mg cm -2 A glassy carbon electrode holder was used to hold the carbon paper as the working electrode. The electrocatalytic performance was tested in a CO₂-saturated 0.1 mol / L KNO₃ solution. The urea concentration in the electrolyte was measured using a UV-visible spectrophotometer. The catalyst showed a high yield and Faradaic efficiency of 2339.43 μg h⁻¹ in urea synthesis at a constant potential of -0.6 V (vs. RHE). -1 mg cat. -1 and 81.03%.

[0054] Example 4

[0055] (1) Weigh 0.235g of InCl3 and dissolve it in 8mL of ethylene glycol by ultrasonication. Weigh 0.8g of NaOH and dissolve it in 2mL of ultrapure water. Mix the NaOH solution with the InCl3 / EG solution, stir for 30min until the solution is homogeneous and transparent, and transfer it to a 15mL polytetrafluoroethylene-lined reactor. Use a heating oven to heat from room temperature to 200℃ at a heating rate of 5℃ / min, and maintain the reaction for 24h. After the reaction is completed, it is naturally cooled to room temperature, washed repeatedly with deionized water and ethanol, and dried at 60℃ for 24h to obtain indium hydroxide hollow nanospheres In(OH)3.

[0056] (2) The obtained indium hydroxide hollow nanospheres In(OH)3 were placed in a quartz mortar and ground thoroughly. 50 mg of the sample was placed in a quartz reactor and evenly spread. After the air in the device was exhausted by passing a hydrogen-argon mixture (H28%, Ar 92%) for 30 minutes, the plasma device power was turned on, the reaction voltage was adjusted to 60 V, the reaction time was 15 minutes, and the plasma was used to create surface oxygen vacancy defects to obtain oxygen-rich indium hydroxide hollow nanospheres V O(60V) -In(OH)3 electrocatalyst.

[0057] (3) Take 5mg V O(60V) -In(OH)3 electrocatalyst, 50μL 5wt.% Nafion solution and 250μL ultrapure water were added to 700μL ethanol and ultrasonicated for 60min to make ink solution. 20μL was dropped on a 1*1cm 2 On carbon paper (Toray TGP-H-090), dried naturally, with a loading of 0.1 mg cm -2 A glassy carbon electrode holder was used to hold the carbon paper as the working electrode. The electrocatalytic performance was tested in a CO₂-saturated 0.1 mol / L KNO₃ solution. The urea concentration in the electrolyte was measured using a UV-visible spectrophotometer. The catalyst showed a yield and Faradaic efficiency of 2042.68 μg h⁻¹ of urea synthesis under constant potential electrolysis at -0.6 V (vs. RHE). -1 mg cat. -1 and 66.6%.

[0058] Example 5

[0059] (1) Weigh 0.235g of InCl3 and dissolve it in 8mL of ethylene glycol by ultrasonication. Weigh 0.8g of NaOH and dissolve it in 2mL of ultrapure water. Mix the NaOH solution with the InCl3 / EG solution, stir for 30min until the solution is homogeneous and transparent, and transfer it to a 15mL polytetrafluoroethylene-lined reactor. Use a heating oven to heat from room temperature to 200℃ at a heating rate of 5℃ / min, and maintain the reaction for 24h. After the reaction is completed, it is naturally cooled to room temperature, washed repeatedly with deionized water and ethanol, and dried at 60℃ for 24h to obtain indium hydroxide hollow nanospheres In(OH)3.

[0060] (2) The obtained indium hydroxide hollow nanospheres In(OH)3 were placed in a quartz mortar and ground thoroughly. 50 mg of the sample was placed in a quartz reactor and evenly spread. After the air in the device was exhausted by passing a hydrogen-argon mixture (H28%, Ar 92%) for 30 minutes, the plasma device power was turned on, the reaction voltage was adjusted to 50 V, the reaction time was 5 minutes, and the plasma was used to create surface oxygen vacancy defects to obtain oxygen-rich indium hydroxide hollow nanospheres V O(5min) -In(OH)3 electrocatalyst.

[0061] (3) Take 5mg V O(5min) -In(OH)3 electrocatalyst, 50μL 5wt.% Nafion solution and 250μL ultrapure water were added to 700μL ethanol and ultrasonicated for 60min to make ink solution. 20μL was dropped on a 1*1cm 2 On carbon paper (Toray TGP-H-090), dried naturally, with a loading of 0.1 mg cm -2 A glassy carbon electrode holder was used to hold the carbon paper as the working electrode. The electrocatalytic performance was tested in a CO₂-saturated 0.1 mol / L KNO₃ solution. The urea concentration in the electrolyte was measured using a UV-visible spectrophotometer. The catalyst showed a high yield and Faradaic efficiency of 1733.74 μg h⁻¹ in urea synthesis at a constant potential of -0.6 V (vs. RHE). -1 mg cat. -1 and 70.52%.

[0062] Example 6

[0063] (1) Weigh 0.235g of InCl3 and dissolve it in 8mL of ethylene glycol by ultrasonication. Weigh 0.8g of NaOH and dissolve it in 2mL of ultrapure water. Mix the NaOH solution with the InCl3 / EG solution, stir for 30min until the solution is homogeneous and transparent, and transfer it to a 15mL polytetrafluoroethylene-lined reactor. Use a heating oven to heat from room temperature to 200℃ at a heating rate of 5℃ / min, and maintain the reaction for 24h. After the reaction is completed, it is naturally cooled to room temperature, washed repeatedly with deionized water and ethanol, and dried at 60℃ for 24h to obtain indium hydroxide hollow nanospheres In(OH)3.

[0064] (2) The obtained indium hydroxide hollow nanospheres In(OH)3 were placed in a quartz mortar and ground thoroughly. 50 mg of the sample was placed in a quartz reactor and evenly spread. After the air in the device was exhausted by passing a hydrogen-argon mixture (H28%, Ar 92%) for 30 minutes, the plasma device power was turned on, the reaction voltage was adjusted to 50 V, the reaction time was 25 minutes, and the plasma was used to create surface oxygen vacancy defects to obtain oxygen-rich indium hydroxide hollow nanospheres V O(25min) -In(OH)3 electrocatalyst.

[0065] (3) Take 5mg V O(25min) -In(OH)3 electrocatalyst, 50μL 5wt.% Nafion solution and 250μL ultrapure water were added to 700μL ethanol and ultrasonicated for 60min to make ink solution. 20μL was dropped on a 1*1cm 2 On carbon paper (Toray TGP-H-090), dried naturally, with a loading of 0.1 mg cm -2 A glassy carbon electrode holder was used to hold the carbon paper as the working electrode. The electrocatalytic performance was tested in a CO₂-saturated 0.1 mol / L KNO₃ solution. The urea concentration in the electrolyte was measured using a UV-visible spectrophotometer. The catalyst showed a yield and Faradaic efficiency of 2099.59 μg h⁻¹ of urea synthesis under constant potential electrolysis at -0.6 V (vs. RHE). -1 mg cat. -1 and 65.46%.

[0066] Comparative Example 1

[0067] (1) Weigh 0.235g of InCl3 and dissolve it in 8mL of ethylene glycol by ultrasonication. Weigh 0.8g of NaOH and dissolve it in 2mL of ultrapure water. Mix the NaOH solution with the InCl3 / EG solution, stir for 30min until the solution is homogeneous and transparent, and transfer it to a 15mL polytetrafluoroethylene-lined reactor. Use a heating oven to heat from room temperature to 200℃ at a heating rate of 5℃ / min, and maintain the reaction for 24h. After the reaction is completed, it is naturally cooled to room temperature, washed repeatedly with deionized water and ethanol, and dried at 60℃ for 24h to obtain indium hydroxide hollow nanospheres In(OH)3.

[0068] (2) Take 5mg In(OH)3 electrocatalyst, 50μL 5wt.% Nafion solution and 250μL ultrapure water and add them to 700μL ethanol. Ultrasonicate for 60min to make ink solution. Take 20μL dropwise and apply on 1*1cm 2 On carbon paper (Toray TGP-H-090), naturally dried, with a loading of 0.1 mg cm -2 A glassy carbon electrode holder was used to hold the carbon paper as the working electrode. The electrocatalytic performance was tested in a CO₂-saturated 0.1 mol / L KNO₃ solution. The urea concentration in the electrolyte was measured using a UV-visible spectrophotometer. The catalyst showed a high yield and Faradaic efficiency of 579.27 μg h⁻¹ in urea synthesis at a constant potential of -0.6 V (vs. RHE). -1 mg cat. -1 The electrocatalytic urea synthesis performance of the hollow indium hydroxide nanospheres In(OH)3 without oxygen vacancies is only as good as that of the hollow indium hydroxide nanospheres V with oxygen vacancies in Example 3. O(50V / 15min) -1 / 4 of the In(OH)3 electrocatalyst, indicating that oxygen vacancies significantly enhance the adsorption of CO2 and NO3 - molecules, which is beneficial to the protonation of *CO2NH2 and thus promotes urea production.

[0069] Comparative Example 2

[0070] (1) Weigh 1.173 g of InCl3 and dissolve it in 40 mL of ethylene glycol by ultrasonication. Weigh 4 g of NaOH and dissolve it in 10 mL of ultrapure water. Mix the NaOH solution with the InCl3 / EG solution, stir for 30 min until the solution is homogeneous and transparent, and transfer it to a 100 mL polytetrafluoroethylene-lined reactor. Use a heating oven to heat from room temperature to 200°C at a heating rate of 5°C / min, and maintain the reaction for 24 h. After the reaction is completed, naturally cool to room temperature, wash repeatedly with deionized water and ethanol, and dry at 60°C for 24 h to obtain solid cubic In(OH)3.

[0071] (2) Take 5 mg of solid cubic In(OH)3 electrocatalyst, 50 μL of 5 wt.% Nafion solution and 250 μL of ultrapure water and add them to 700 μL of ethanol. Ultrasonicate for 60 min to make ink solution. Take 20 μL and drop it on 1*1 cm 2 On carbon paper (Toray TGP-H-090), dried naturally, with a loading of 0.1 mg cm -2 A glassy carbon electrode holder was used to hold the carbon paper as the working electrode. The electrocatalytic performance was tested in a CO₂-saturated 0.1 mol / L KNO₃ solution. The urea concentration in the electrolyte was measured using a UV-visible spectrophotometer. The catalyst showed a high yield and Faradaic efficiency of 358.16 μg h⁻¹ in urea synthesis at a constant potential of -0.6 V (vs. RHE). -1 mg cat. -1 When the concentration and ratio of reactants are the same, the volume of the reactor is increased from 15 mL to 100 mL, the synthesized In(OH)3 is changed from hollow indium hydroxide nanospheres to solid cubes, and the electrocatalytic synthesis of urea performance is only as good as that of the oxygen-rich vacancy nano hollow spherical V in Example 3. O(50V / 15min) -3 / 20 of In(OH)3 electrocatalyst.

Claims

1. An oxygen vacancy-rich hollow nanosphere indium hydroxide electrocatalyst, the electrocatalyst V O -In(OH)3 is a hollow indium hydroxide nanosphere with rich oxygen vacancies on the surface, The indium hydroxide hollow nanospheres are formed by disorderly stacking of In(OH)3 nanocubes.

2. The electrocatalyst according to claim 1, characterized in that The indium hydroxide hollow nanospheres are formed by disorderly stacking 2 to 4 layers of In(OH)3 cubes.

3. The electrocatalyst according to claim 1, characterized in that The side length of the In(OH)3 nanocube constituting the hollow nanosphere is 20 to 60 nm; the size of the hollow nanosphere is 400 to 500 nm.

4. The electrocatalyst according to claim 1, characterized in that The oxygen vacancies on the surface of the hollow indium hydroxide nanospheres are obtained by low-temperature plasma treatment in a hydrogen-argon mixed atmosphere.

5. The method for preparing the oxygen vacancy-rich hollow nanosphere indium hydroxide electrocatalyst according to claim 1, characterized in that: Indium hydroxide hollow nanospheres composed of disordered stacking of In(OH)3 nanocubes were synthesized by a solvothermal method, and the obtained indium hydroxide hollow nanospheres were then treated with low-temperature plasma to obtain indium hydroxide hollow nanospheres with rich oxygen vacancies on the surface.

6. The method according to claim 5, characterized in that The solvent thermal method is specifically as follows: dissolving indium salt in ethylene glycol to obtain 0.01-0.5 mol / L In 3+ / EG solution; 10 mol / L NaOH solution and InO solution were mixed in a volume ratio of 1:1 to 1:

5. 3+ The method comprises the following steps: mixing the indium hydroxide / EG solution until the solution becomes homogeneous and transparent; transferring 8 to 12 mL of the obtained mixed solution to a 15 to 20 mL polytetrafluoroethylene-lined reactor, heating the mixture from room temperature to 120 to 200° C. at a heating rate of 1 to 10° C. / min, and reacting the mixture for 12 to 48 hours; and naturally cooling the mixture to room temperature after the reaction, washing the mixture, and drying the mixture to obtain indium hydroxide hollow nanospheres.

7. The method according to claim 5 or 6, characterized in that The ground indium hydroxide hollow nanospheres were placed in a low-temperature plasma device, and after the air in the device was exhausted by introducing a hydrogen-argon mixture, the plasma device power was turned on, and the reaction voltage was adjusted to 10-60V and the reaction time was 5-25min to obtain indium hydroxide hollow nanospheres V with rich surface oxygen vacancies. O -In(OH)3, wherein the proportion of hydrogen in the hydrogen-argon mixed gas is 5-10%.

8. The method according to claim 6, characterized in that The indium salt is one of InCl3, In(NO3)3 or In(C2H3O2)3.

9. Use of the oxygen-vacancy-rich hollow nanosphere indium hydroxide electrocatalyst according to any one of claims 1 to 4 in the electrocatalytic synthesis of urea.

10. Use according to claim 9, characterized in that The oxygen vacancy-rich hollow nanosphere indium hydroxide electrocatalyst is used as a CO2 and NO3 - Application of co-reduction CN coupling electrocatalyst for urea production.

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