Zinc oxide loaded indium monatomic material as well as preparation method and application thereof

Abstract

The invention provides a zinc oxide loaded indium monatomic material as well as a preparation method and application thereof. The preparation method comprises the following steps: (1) preparing a Zn < 2 + >-In < 3 + > mixed solution and a NaOH solution; (2) respectively pumping a Zn < 2 + >-In < 3 + > mixed solution and a NaOH solution into the micro-reaction cavity, and carrying out high-speed impact to generate a precipitation reaction; and (3) enabling the precipitate to flow into a stirring tank reactor, aging to obtain a precursor, washing, drying, and grinding into powder to obtain the ZnO-In-SAC material. The impinging stream technology is utilized to severely shear and crush the fluid to generate a huge and rapidly updated phase interface, so that the reaction is continuously and stably carried out, the reaction rate is increased, rapid induction of nucleation and crystal growth is realized in the subsequent process, and nanoparticles which are uniform in morphology and not easy to agglomerate are formed. The preparation method provided by the invention is simple and controllable, is convenient for macro synthesis, can produce 10kg-grade ZnO In-SAC material per day, and is expected to realize industrial application.

Description

Technical Field

[0001] The present invention relates to the field of electrocatalysis technology, and in particular to a zinc oxide-loaded indium single-atom material and a preparation method and application thereof. Background Art

[0002] The continuous generation of CO2 in industry and its impact on global warming have attracted widespread attention. At the same time, the continuous consumption of non-renewable energy (oil and coal) has also led to a global energy crisis. How to sustainably capture and reuse CO2 and achieve an efficient zero-carbon network cycle has become one of the major challenges that mankind urgently needs to solve. Therefore, the electrochemical conversion of CO2 to high-value-added chemicals has great application prospects. In recent years, the production of value-added chemicals by electrochemical carbon dioxide reduction reaction (eCO2RR) using green and sustainable electricity has become a research hotspot. Electrocatalytic reduction of CO2 can produce carbon monoxide (CO), formic acid and hydrocarbons, among which formic acid is considered to be an important industrial intermediate and an ideal candidate for hydrogen storage and fuel cells. From the perspective of technical and economic prospects, formic acid has the highest net present value and can be directly used in the petrochemical industry. Efficient electrocatalysts are the key to improving the performance of electrochemical reduction of CO2 to formic acid and comprehensively promoting the technology of electrochemical reduction of CO2 to formic acid. Single atom catalysts (SACs) have attracted widespread attention due to their unique catalytic activity and maximized atomic efficiency, as well as their good coordination structure and unique electronic structure. Although noble metal SACs have many advantages in CO2 reduction, their high cost and scarcity have deterred many researchers. Therefore, the research focus has now turned to inexpensive non-noble metals, which show better performance than some rare metals. Therefore, the electrocatalytic CO2 reduction technology of non-noble metal single atom-based catalysts is in line with the sustainable development strategy and has important ecological and environmental significance.

[0003] From the perspective of preparation technology, the large-scale preparation of single-atom catalytic materials is one of the long-sought and most challenging goals in this field. Currently, the preparation scale of single-atom catalysts mostly remains at the milligram-gram scale in the laboratory. There are problems such as scale-up effect, cumbersome preparation and serious pollution, which make it difficult to achieve industrial preparation and mass production. How to overcome the synthesis difficulties, realize batch and large-scale preparation of catalysts, and promote single-atom catalysts to truly move from the laboratory to industrialization is a major challenge in current research. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art and to provide a zinc oxide loaded indium single atom material and a preparation method and application thereof.

[0005] The technical solution adopted by the present invention is as follows: The first aspect of the present invention provides a method for preparing a zinc oxide-loaded indium single-atom material, comprising the following steps:

[0006] (1) Configuration of Zn 2+ -In 3+ Mix the solution and NaOH solution;

[0007] (2) Zn 2+ -In 3+ The mixed solution and NaOH solution are pumped into the micro-reaction chamber respectively to undergo high-speed collision and precipitation reaction;

[0008] (3) The precipitate is flowed into a stirred tank reactor for aging to obtain a precursor, which is then washed, dried and ground into powder to obtain a ZnO@In-SAC material. Specifically, the precursor is washed 3-5 times by centrifugation with deionized water and ethanol, and then dried in an oven at 60°C and ground into powder.

[0009] Preferably, in step (1), Zn 2+ -In 3+ The total concentration of the mixed solution (Zn 2+ andIn 3+ The sum of the concentrations of) is 0.15-0.85 mol / L, and the concentration of the NaOH solution is 0.55-1.25 mol / L.

[0010] Preferably, in step (1), Zn 2+ -In 3+ Zn in mixed solution 2+ WithIn 3+ The molar ratio is (0.1-200):1.

[0011] Preferably, in step (1), Zn 2+ -In 3+ Zn in mixed solution 2+ From Zn(NO3)2, Zn 2+ -In 3+ In mixed solution 3+ From In(NO3)3.

[0012] Preferably, in step (2), Zn 2+ -In 3+ The flow rate ratio of the mixed solution and the NaOH solution pumped into the micro-reaction chamber is (1-3):1, and the flow rate range is 50-150mL / min. Specifically, two horizontal flow pumps are used to pump Zn 2+ -In 3+ The mixed solution and NaOH solution are pumped into the micro-reaction chamber.

[0013] Preferably, in step (3), the aging time is 0.5-24h.

[0014] The second aspect of the present invention provides a zinc oxide-loaded indium single atom material prepared by the above preparation method, wherein the particle size of the zinc oxide-loaded indium single atom material is 20-500 nm.

[0015] The third aspect of the present invention provides the use of a zinc oxide-loaded indium single-atom material prepared by the above preparation method in electrocatalytic CO2 reduction.

[0016] The beneficial effects of the present invention are as follows:

[0017] 1. Since the reaction system is a heterogeneous system, this seriously hinders the reaction. The general preparation method has the disadvantages of long reaction time, low yield, high cost, etc. The present invention uses the impact flow technology to violently shear and crush the fluid, produce a huge and rapidly updated phase interface, so that the reaction is carried out continuously and stably, accelerates the reaction rate, and realizes rapid induction of nucleation and crystal growth in the subsequent process, forming nanoparticles with uniform morphology and not easy to agglomerate. The preparation method of the present invention is simple, controllable, and convenient for macro-scale synthesis. It can produce 10kg of ZnO@In-SAC materials per day, and is expected to achieve industrial application.

[0018] 2. The impinging flow enhanced reaction system constructed by the present invention is based on the mechanism of precisely controlling the ionic strength. It is difficult to achieve a uniform structure for the single atoms prepared in general, which hinders the study of structure-activity relationship. The reaction system can increase the ionic strength to increase the electrostatic repulsion between nanoparticles, thereby inhibiting the aggregation of nanoparticles and making the ZnO@In-SAC material present a uniform atomic-level dispersion.

[0019] 3. The present invention proposes a novel and simple Zn atomization method with warm operating conditions, easy to obtain raw materials, low cost, and compatible with large-scale industrial production.

[0020] 4. The ZnO@In-SAC material prepared by the present invention has excellent eCO2RR performance due to the synergistic effect between different metal components and internal structure. The prepared ZnO@In-SAC catalyst exhibits high selectivity and stability of eCO2RR and has good practical application value. In 1 mol / L KOH, 100 mA / cm 2 Up to 300mA / cm 2 Under a wide current density range of 1.5 Å, the selectivity of the ZnO@In-SAC catalyst prepared in the present invention for formic acid can be maintained at 85%, and the current density can reach up to 500 mA / cm 2 , at 100mA / cm 2 At a current density of 1.5 Ω / min, long-term stability of 40 h can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, without paying creative labor, other drawings obtained based on these drawings still belong to the scope of the present invention.

[0022] Figure 1 The schematic diagram of the T-type impact microreactor used in the present invention: in the figure, 1, liquid storage tanks A, B, 2, horizontal flow pump, 3, control system, 4, stainless steel capillary, 5, T-type micro mixing chamber, 6, stirring tank reactor.

[0023] Figure 2 X-ray diffraction patterns (XRD) of In(OH)3 prepared in Comparative Example 1 (a), ZnO prepared in Comparative Example 2 (b), and ZnO@In-SAC prepared in Example 1 (c).

[0024] Figure 3 This is the X-ray photoelectron spectrum (XPS) of In(OH)3 prepared in Comparative Example 1.

[0025] Figure 4 This is the X-ray photoelectron spectroscopy (XPS) of ZnO prepared in Comparative Example 2.

[0026] Figure 5 This is the X-ray photoelectron spectroscopy (XPS) of the ZnO@In-SAC prepared in Example 1.

[0027] Figure 6 Transmission electron microscopy (TEM) images of In(OH)3(ad) prepared in Comparative Example 1, ZnO(eh) prepared in Comparative Example 2, and ZnO@In-SAC(il) prepared in Example 1, as well as an elemental scanning map (Mapping) of ZnO@In-SAC(mp) prepared in Example 1.

[0028] Figure 7 This is the eCO2RR performance diagram of ZnO@In-SAC prepared in Example 1.

[0029] Figure 8 eCO2RR performance diagram of In(OH)3 (a) prepared in Comparative Example 1 and ZnO (b) prepared in Comparative Example 2.

[0030] Fig. 9 This is the eCO2RR stability diagram of ZnO@In-SAC prepared in Example 1. DETAILED DESCRIPTION

[0031] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings.

[0032] Example 1

[0033] (1) 12.05 g of Zn(NO3)2·6H2O and 0.128 g of In(NO3)3·6H2O powder were weighed on an analytical balance and dissolved in deionized water to prepare a total concentration of 0.48 mol / L Zn(NO3)2·6H2O. 2+ -In 3+ Mix solution A: weigh 3.42 g of NaOH powder and dissolve it in 100 mL of deionized water to prepare 0.85 mol / L NaOH solution B. Inject the prepared solutions into reservoirs A and B respectively for use.

[0034] (2) The flow rates of constant flow pumps A and B were set to 100 mL / min and 100 mL / min respectively, and the precursor was received by a stirred tank reactor at the outlet of the T-type micro-mixing chamber. Both constant flow pumps were turned on at the same time, allowing solutions A and B to undergo impact precipitation reaction in the T-type micro-mixing chamber and maintaining the precipitation pH at 9.5.

[0035] (3) The precursor was stirred and aged at room temperature for 12 h, then centrifuged, washed with water and ethanol 4 times each, dried and ground to obtain ZnO@In-SAC material with a particle size of 50-500 nm ( Figure 6 il). The prepared material has high eCO2RR activity. In 1 mol / L KOH, its selectivity for formic acid reaches 85%. 2 At a current density of 1.5 Ω / min, long-term stability of 40 h can be achieved.

[0036] Comparative Example 1

[0037] The total concentration of In was 0.48 mol / L. 3+ The solution and 0.85 mol / L NaOH solution were simultaneously introduced into a T-type micro-mixing chamber at a flow rate of 100 mL / min to undergo an impact precipitation reaction, and the precursor was flowed into a stirred tank reactor and stirred and aged at room temperature for 24 h. The remaining steps were the same as in Example 1, and finally In(OH)3( Figure 6 ad) materials.

[0038] Comparative Example 2

[0039] The total concentration of Zn was 0.48 mol / L. 2+The solution and 0.85 mol / L NaOH solution were simultaneously introduced into a T-type micro-mixing chamber at a flow rate of 100 mL / min to undergo an impact precipitation reaction, and the precursor was flowed into a stirred tank reactor and stirred and aged at room temperature for 24 h. The remaining steps were the same as in Example 1, and finally ZnO ( Figure 6 eh) materials.

[0040] Microscopic characterization

[0041] The ZnO@In-SAC prepared in Example 1 was microscopically characterized by a number of different methods, and the results are as follows:

[0042] (1) By Figure 2 It can be seen that it is confirmed that the phase of ZnO@In-SAC in Example 1 matches the phase of ZnO in Comparative Example 1, and no In(OH)3 phase appears.

[0043] (2) From 2, Figure 3 and Figure 4 It can be seen that the ZnO@In-SA in Example 1 contains Zn element, O element and In element.

[0044] (3) By Figure 5 It can be seen that the morphology of ZnO@In-SAC in Example 1 is consistent with that of ZnO in Comparative Example 1, and the In(OH)3 morphology of Comparative Example 1 does not appear. The mapping diagram of ZnO@In-SAC in Example 1 shows that Zn, O and In elements are evenly distributed and there are no clusters of In elements, confirming that In is dispersed on the ZnO carrier as single atoms.

[0045] The In(OH)3 material prepared in Comparative Example 1 and the ZnO( Figure 6 ) material and the data of Example 1 show that ZnO@In-SAC( Figure 7 ) shows better performance than ZnO materials and In(OH)3( Figure 8 ) materials have higher formic acid selectivity and stability. This is because under the synergistic effect of Zn, ZnO@In-SAC can reduce the overpotential of eCO2RR and inhibit the occurrence of hydrogen evolution reaction.

[0046] Application example: Preparation of working electrode

[0047] 25 mg of the ZnO@In-SAC material prepared in Example 1, 3 mL of multi-walled carbon nanotubes dispersed in tetrahydrofuran, and 20 uL of Nafion solution (5 wt%) were dispersed in 3 mL of isopropanol and ultrasonicated for 30 min to form a uniform dispersion slurry. 0.5 mg / cm 2The working electrode is obtained by preparing the dispersed slurry.

[0048] Electrochemical performance test

[0049] A three-electrode system was used for electrolysis. The gas diffusion electrode loaded with ZnO@In-SAC was assembled into a flow electrolyzer as the working electrode, nickel foam was used as the anode, saturated Ag / AgCl was used as the reference electrode, 1M KOH solution was used as the electrolyte, the CO2 flow rate was 15 sccm, and the gas products were detected by gas chromatography, and the liquid products were detected by nuclear magnetic resonance hydrogen spectroscopy.

[0050] like Figure 7 and 9 The results are as follows: 1mol / L KOH, 100mA / cm 2 Up to 300mA / cm 2 The selectivity of formic acid can be maintained at 85% under a wide current density of 500 mA / cm 2 At 100mA / cm 2 The long-term stability of 40 h can be achieved at a current density of 1.34 W. The prepared ZnO@In-SAC catalyst exhibits high selectivity and stability for eCO2RR and has good practical application value.

[0051] The above disclosure is only the preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A method for preparing a zinc oxide-loaded indium single-atom material, characterized in that: The steps include: (1) Configuration of Zn 2+ -In 3+ Mix the solution and NaOH solution; (2) Zn 2+ -In 3+ The mixed solution and NaOH solution are pumped into the micro-reaction chamber respectively to undergo high-speed collision and precipitation reaction; (3) The precipitate is flowed into a stirred tank reactor for aging to obtain a precursor, which is then washed, dried and ground into powder to obtain ZnO@In-SAC material.

2. The method for preparing a zinc oxide-loaded indium single atom material according to claim 1, characterized in that: In step (1), Zn 2+ -In 3+ The total concentration of the mixed solution is 0.15-0.85 mol / L, and the concentration of the NaOH solution is 0.55-1.25 mol / L.

3. The method for preparing a zinc oxide-loaded indium single atom material according to claim 1, characterized in that: In step (1), Zn 2+ -In 3+ Zn in mixed solution 2+ WithIn 3+ The molar ratio is (0.1-200):

1.

4. The method for preparing a zinc oxide-loaded indium single-atom material according to claim 1, characterized in that: In step (1), Zn 2+ -In 3+ Zn in mixed solution 2+ From Zn(NO3)2, Zn 2+ -In 3+ In mixed solution 3+ From In(NO3)3.

5. The method for preparing a zinc oxide-loaded indium single atom material according to claim 1, characterized in that: In step (2), Zn 2+ -In 3+ The flow rate ratio of the mixed solution and the NaOH solution pumped into the micro-reaction chamber is (1-3):1, and the flow rate range is 50-150mL / min.

6. The method for preparing a zinc oxide-loaded indium single atom material according to claim 1, characterized in that: In step (3), the aging time is 0.5-24h.

7. A zinc oxide-loaded indium single atom material prepared by the preparation method according to any one of claims 1 to 6, characterized in that: The particle size of the zinc oxide-loaded indium single-atom material is 20-500 nm.

8. Use of a zinc oxide-loaded indium single-atom material prepared by the preparation method according to any one of claims 1 to 6 in electrocatalytic CO2 reduction.

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