MOF-based three-dimensional corn-cob-shaped Cu2O-Cu catalyst and application thereof

Abstract

The invention provides an MOF-based three-dimensional corn-shaped Cu2O-Cu catalyst and application thereof, the catalyst is composed of Cu2O and Cu nanoparticles, the size of the catalyst is 2-3 [mu] m, and the surface of the catalyst is of a corn-shaped structure formed by arranging nanospheres with the diameter of about 150 nm. The catalyst provided by the invention has high selectivity, under-1.39 V vs RHE, the faraday efficiency of a C2 + product reaches 63.6%, the ethylene selectivity is 50.5%, and the catalyst is significantly superior to a traditional copper-based catalyst. Besides, the catalyst can inhibit HER, H2 Faraday efficiency is stabilized below 20%, the three-dimensional corn-cob-shaped structure of the catalyst can provide a high specific surface area and rich active sites, and the catalyst is rich in Cu < + > / Cu0 heterogeneous interface and can promote C-C coupled complex kinetics.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrocatalytic materials, and specifically relates to a MOF-based three-dimensional corncob-shaped Cu2O-Cu catalyst and applications thereof. Background Art

[0002] As the global carbon emission problem becomes increasingly serious, electrocatalytic CO2 reduction (CO2RR) technology has attracted widespread attention due to its ability to convert CO2 into high value-added chemicals (such as ethylene, ethanol, etc.). 2+ Products (such as ethylene and ethanol) have become the focus of research due to their higher economic value and energy density.

[0003] Currently, copper-based catalysts are the only ones that can efficiently catalyze CO2RR to C 2+ The materials of the product, but there are still the following key problems: First, C1 product competition: traditional Cu catalysts tend to generate C1 products such as CO and formic acid instead of the target C 2+ products (such as ethylene and ethanol); second, the interference of hydrogen evolution reaction (HER): at the reduction potential, H + It is easy to be reduced to H2 on the Cu surface, competing with CO2RR and reducing C 2+ Product selectivity; Third, CC coupling efficiency is low: C 2+ Product formation relies on the adsorption and coupling of the CO intermediate, but conventional Cu catalysts lack sufficient CO adsorption strength and exhibit a high CC coupling energy barrier. Fourthly, the catalyst suffers from poor stability: Cu is susceptible to redox or structural remodeling during electrocatalysis, leading to deactivation of active sites. Therefore, the development of a novel catalyst is urgently needed to address the challenges of existing electrocatalytic CO2 reduction technologies, such as low selectivity for C2+ products, severe HER competition, and poor stability. Summary of the Invention

[0004] The object of the present invention is to provide a three-dimensional corncob-shaped Cu2O-Cu catalyst based on MOF.

[0005] The object of the present invention is to provide a method for preparing a three-dimensional corncob-shaped Cu2O-Cu catalyst based on MOF.

[0006] The present invention also aims to provide a MOF-based three-dimensional corncob-shaped Cu2O-Cu catalyst for electrocatalytic CO2 reduction to generate C 2+ Application in products.

[0007] In order to achieve the above technical objectives, the present invention adopts the following technical solutions: A three-dimensional corncob-shaped Cu2O-Cu composite catalyst based on MOF is composed of Cu2O and Cu nanoparticles. The composite catalyst has a size of 2-3 μm and a surface composed of nanospheres with a diameter of about 150 nm arranged to form a corncob-shaped structure.

[0008] Preferably, the composite catalyst has Cu + / Cu 0 Heterointerfaces and controllable oxygen defects.

[0009] Preferably, the preparation method of the composite catalyst comprises the following steps: S11. In a three-electrode system, pretreated carbon paper was fixed to the working electrode, with Ag / AgCl as the reference electrode, a platinum sheet as the counter electrode, and a copper-containing electrolyte. S12. at 4 mA cm -2 The electrodeposition was carried out stably for 1800 s under constant current conditions. After the deposition, the copper-coated carbon paper surface was rinsed with ultrapure water to obtain a Cu-CFP substrate. S13 was added 50mL of electroconversion solution, the Cu-CFP substrate obtained in step S12 was used as the working electrode, and under stirring, a working voltage of 4 V was applied for in situ conversion; S14. After 1800 s of reaction, the electrode surface was transformed into a uniformly covered blue coating of HKUST-1. The obtained electrode was dried in an oven at 80 °C for 8 h to obtain HKUST-1 II electrode; S15. Under CO2 reduction conditions, HKUST-1 II In situ conversion to Cu2O-Cu-II.

[0010] Preferably, the copper-containing electrolyte in step S11 is prepared by dissolving 0.01 M CuSO4·5H2O and 0.05 M C6H8O7 in 1 M H2SO4.

[0011] Preferably, in step S12, the surface of the Cu-CFP substrate exhibits Cu metallic red.

[0012] Preferably, the electroporation solution in step S13 is prepared by dissolving 0.08 M H3BTC and 0.01 M TEA TFB in a 4:1 ethanol / water mixture, stirring for 5 min, adding p-benzoquinone, and stirring for 30 min.

[0013] Preferably, the concentration of p-benzoquinone is 0.02-0.14 M.

[0014] Preferably, the potential range of the in-situ conversion in step S15 is -1.39 V vs RHE, and the electrolyte for the in-situ conversion is 0.1 M KCl.

[0015] Preferably, the catalyst is used to electrocatalyze the reduction of CO2 to generate C 2+ Application in products.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The MOF-based three-dimensional corncob-shaped Cu2O-Cu composite catalyst provided by the present invention has high selectivity. At -1.39 V vs RHE, C 2+ The product Faraday efficiency reached 63.6% and the ethylene selectivity was 50.5%, which was significantly better than that of traditional copper-based catalysts. In addition, the catalyst can inhibit HER, and the H2 Faraday efficiency is stable below 20%. Its three-dimensional corncob-like structure can provide a high specific surface area and abundant active sites. The catalyst is rich in Cu + / Cu 0 Heterogeneous interfaces can promote CC coupling kinetics. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings, which constitute part of the present invention, are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings: Figure 1 The diagram shows the conversion synthesis and electrocatalytic CO2 reduction process of the composite catalyst Cu2O-Cu; Figure 2 SEM images of deposition on carbon substrate, including (a) Cu, (b, c) HKUST-1; Figure 3 (a) is the XRD pattern of Cu and HKUST-1, Figure 3 (b) Raman spectrum of HKUST-1; Figure 4 SEM images of HKUST-III at conversion times of 0 min, 5 min, 10 min, and 15 min, where (a) is 0 min, (b) is 5 min, (c) is 10 min, and (d) is 15 min; Figure 5 XPS spectra of Cu 2p in HKUST-1 and Cu2O-Cu-II at the same electrolysis time, where (a) is the XRD pattern of HKUST-1 at electrolysis times of 5 min, 10 min, and 15 min, and (b) is the XRD pattern of Cu2O-Cu-II at electrolysis times of 5 min, 10 min, and 15 min; Figure 6(a) TEM image of Cu2O-Cu-II, Figure 6 (b, c) HR-TEM images of Cu2O-Cu-II after electroreduction for 15 min. Figure 6 (d) EDS element map; Figure 7 This is an element scanning analysis diagram of different parts of Cu2O-Cu-II; Figure 8 The infrared spectra of HKUST-1I, HKUST-1II and HKUST-1III are shown; Figure 9 (a) is the XRD pattern of the composite catalysts Cu2O-Cu-I, Cu2O-Cu-II and Cu2O-Cu-III. Figure 9 (b) Raman spectra of composite catalysts Cu2O-Cu-I, Cu2O-Cu-II and Cu2O-Cu-III; Figure 10 (a) Cu 2p, (b) Cu LMM Auger, (c) O 1s peak XPS spectra, (d) Cu + / Cu 0 The ratio of O in Cu2O-Cu-I, Cu2O-Cu-II and Cu2O-Cu-III, (e) O in Cu2O-Cu-I, Cu2O-Cu-II and Cu2O-Cu-III V / O Total The ratio of Cu on the catalyst surface is (f) + / (Cu + +Cu 0 ) ratio and O V / O Total correlation of ratios; Figure 11 Electrochemical CO2 reduction performance of (a) Cu2O-Cu-I, (b) Cu2O-Cu-II, and (c) Cu2O-Cu-III in an H-type electrolytic cell. Figure 12 The electrocatalytic CO2 reduction performance of Cu2O-Cu-I, Cu2O-Cu-II and Cu2O-Cu-III catalysts at different potentials, where (a) C1, (b) C 2+ , (c) C 2+ / C1 ratio; Figure 13 (a) LSV curves scanned in CO2-saturated 0.1 M KCl. Figure 13 (b) Double-layer capacitance obtained by cyclic voltammetry; Figure 14 A comparison chart of the CO2RR performance of different catalysts. DETAILED DESCRIPTION

[0018] The following specific descriptions are exemplary and are intended to provide further explanation of the present invention. It should be understood by those skilled in the art that the details and forms of the technical solutions of the present invention may be modified or replaced without departing from the spirit and scope of the present invention, and such modifications and replacements shall fall within the scope of protection of the present invention.

[0019] Unless otherwise specified, the test methods used in the following experimental examples are conventional methods.

[0020] Example 1: Preparation and structural characterization of Cu2O-Cu composite catalyst In a three-electrode system, the pretreated carbon paper was fixed on the working electrode, Ag / AgCl was used as the reference electrode, platinum sheet was used as the counter electrode, and the copper-containing electrolyte was made of 0.01 M CuSO4·5H2O and 0.05 M C6H8O7 dissolved in 1 M H2SO4. -2 The electrodeposition was carried out stably for 1800 s under constant current conditions. After the deposition, the surface of the copper-coated carbon paper was gently rinsed with ultrapure water to obtain a Cu-CFP substrate with a Cu metallic red surface.

[0021] Then 0.08 M H3BTC and 0.01 M TEA TFB were dissolved in a 4:1 ethanol / water mixture, stirred for 5 min, and then 0.08 M p-benzoquinone ( p -BQ), and continued stirring for 30 minutes to form an electroconversion solution. 50 mL of the above electroconversion solution was poured into the electrolytic cell, and the second step of conversion was carried out using the same three-electrode system as above, with the Cu-CFP substrate prepared in the first step as the working electrode. Under stirring, a working voltage of 4 V was applied for in-situ conversion. After 1800 seconds of reaction, the electrode surface was converted into a uniformly covered blue coating of HKUST-1. The obtained electrode was dried in an 80°C oven for 8 hours to obtain HKUST-1 II electrode.

[0022] Under CO2 reduction conditions, the potential range was -1.39 V vs RHE, the electrolyte was 0.1 M KCl, and the MOF precursor HKUST-1 II In situ conversion to Cu2O-Cu-II.

[0023] During the electroplating process of Cu-MOF precursor synthesis, p-benzoquinone (p-BQ) acts as an oxidant to trigger the in-situ oxidation of the Cu layer to generate Cu 2+ions, which reacted with deprotonated 1,3,5-benzenetricarboxylic acid (H3BTC) ligands to form a continuous HKUST-1 (Cu3(BTC)2) metal-organic framework film on a carbon substrate. The morphological evolution during the synthesis process was systematically observed by scanning electron microscopy (SEM). Figure 2 As shown. The electrodeposited copper layer exhibits a stacked structure of interconnected agglomerated nanoparticles, forming a uniform coating on the CFP surface and showing strong adhesion to the carbon fiber substrate. After coordination with H3BTC ligands, the resulting HKUST-1 film exhibits a unique blue color and atypical scaly morphology rather than traditional octahedral crystals. p The structural modification caused by the BQ-mediated oxidation process forms a rough surface structure compared to the standard HKUST-1 structure, which can enhance the specific surface area and increase the density of active sites. The XRD spectrum of the sample is shown in Figure 2. Figure 3 As shown in the figure, it can be seen that the first step of the deposition process successfully prepared a layer of metallic copper on the surface of the carbon paper. p The electrode after -BQ treatment showed obvious diffraction peaks at 6.2°, 8.9°, 11.1° and 12.9°, corresponding to the (200), (220), (222) and (400) crystal planes of HKUST-1, respectively, indicating that the metal Cu deposited in the first step was successfully converted into a MOF structure. No other impurity peaks were observed, indicating that the surface conversion synthesis was a pure HKUST-1 crystal structure. The Raman spectrum showed six characteristic peaks of HKUST-1, such as Figure 3 As shown, 826 cm -1 and 746 cm -1 The peaks at 1006 cm-1 are attributed to the out-of-plane ring (CH) bending vibration and the out-of-plane ring bending vibration, respectively. -1 and 1618 cm -1 The peak at 1541 cm is attributed to the C=C stretching vibration of the benzene ring. -1 and 1460 cm -1 The peaks at 3 and 4 correspond to the asymmetric and symmetric stretching vibrations of C=O, respectively. These results further demonstrate that HKUST-1 crystals were synthesized by in situ conversion of deposited Cu.

[0024] In the CO2 electroreduction environment, the HKUST-1 precursor undergoes in-situ transformation, and its structure and morphology change with treatment time. Figure 4After 5 minutes of electroreduction, the HKUST-1 crystal structure completely disappeared, and the scale-like structure on the carbon paper surface transformed into cauliflower-like three-dimensional clusters. After 10 minutes of reduction, the clusters gradually grew into a corncob-shaped catalyst with a single pointed end. After 15 minutes of electroreduction, the catalyst on the carbon paper surface completely transformed from a cluster into a corncob-shaped catalyst with two pointed ends, composed of four nanospheres arranged in a row. The nanospheres had a diameter of approximately 150 nm and a rough surface, and the size of a single catalyst strip ranged from 2 μm to 3 μm.

[0025] The valence state of the catalysts with different reduction degrees was analyzed by X-ray photon spectroscopy (XPS). Figure 5 As shown. During the electrolysis process, Cu 2+ Gradually reduced to Cu + / Cu 0 After 15 min of reduction, the sample was obtained. The catalyst surface was mainly composed of Cu + and Cu 0 XRD analysis results show that all samples exhibit weak diffraction peaks at 29.2°, 36.44°, and 43.3°, corresponding to the characteristic peaks of Cu2O (110), Cu2O (111), and Cu (111) crystal planes, respectively, further demonstrating that the MOF structure is transformed into a Cu2O and Cu composite structure. With the extension of reduction time, the diffraction peak intensity further weakens, indicating that the structural disorder increases, which is conducive to the formation of more catalytically active sites. Figure 6 Transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HR-TEM) images of the catalyst with an electroreduction time of 15 min are given. From the figure, lattice fringes of 0.209 nm and 0.180 nm can be clearly observed, which are attributed to the Cu (111) crystal plane and Cu (200) crystal plane, respectively; lattice fringes of 0.245 nm and 0.303 nm are attributed to the Cu2O (111) crystal plane and Cu2O (110) crystal plane. This shows that the formed Cu2O-Cu-II-15min sample is mainly composed of Cu and Cu2O components, and a clear grain boundary is formed between the two components, which makes the catalyst rich in Cu + / Cu 0 Heterogeneous interface. According to the literature, Cu + / Cu 0 The heterogeneous interface is the electrocatalytic reduction of CO2 to C 2+ The high active center of the product. In addition, EDS was used to analyze the distribution of catalyst elements, such as Figure 6 As shown in the figure, the catalyst is mainly composed of Cu and O and is evenly distributed, which further proves that the catalyst is composed of Cu and Cu2O.

[0026] Scanning the Cu2O-Cu-II-15 min corncob catalyst at different locations revealed that the Cu / O ratio at the catalyst tip was approximately 2:1, while the Cu / O ratio in the middle of the catalyst was slightly greater than 2:1, indicating that the interior of the corncob catalyst composed of four rows of nanospheres was composed of Cu and Cu2O, while the rough surface of each row of nanospheres was mainly composed of Cu2O. Another set of surface scan results further demonstrated that the Cu content in the gaps between the two rows of nanospheres was greater than the Cu content in the surface nanospheres. Based on this result, it can be inferred that Cu + species are mainly present at the tips and nanospheres of the catalyst, while the metallic Cu 0 They are mainly distributed in the internal area and interfacial gaps of the catalyst, thus forming a layered three-dimensional catalytic structure.

[0027] Example 2: Effect of the amount of benzoquinone added on the catalyst composition and structure Introduction of p-benzoquinone ( p -BQ) as an oxidant to in situ oxidize the deposited Cu into Cu 2+ ions, reacting with the deprotonated 1,3,5-benzenetricarboxylic acid (H3BTC) ligand in solution to form the MOF framework Cu 2+ ions. Therefore, the concentration of p-benzoquinone affects the oxidation rate. A higher concentration of p-benzoquinone can accelerate the dissolution of copper, thereby regulating the nucleation and growth dynamics of HKUST-1 crystals, and ultimately affecting the size and morphology of the crystals. While keeping the contents of other substances in the deposition solution unchanged, three Cu-MOF precursors were prepared by adjusting the amount of p-benzoquinone added: HKUST-1 I 、HKUST-1 II and HKUST-1 III The three MOF precursors synthesized were characterized by Fourier transform infrared spectroscopy (FT-IR). Figure 8 At 490 cm -1 and 730cm -1 The characteristic peaks at 1370 cm-1 correspond to the CuO and Cu centers in MOF, respectively; -1 、1450 cm -1 and 1642 cm -1 The characteristic peaks at correspond to the CH stretching, C=C stretching and C=O stretching vibration peaks related to the organic connection structure in MOF. The above characteristic peaks have similar intensities, which shows that HKUST-1 was successfully synthesized under the three addition amounts of benzoquinone, and the synthesized HKUST-1 has a similar structure. The three catalysts were treated under the in-situ conditions of electrocatalytic CO2 reduction to obtain Cu2O-Cu-I, Cu2O-Cu-II and Cu2O-Cu-III, respectively. The structures and compositions of the three metal catalysts after reduction were analyzed by XRD, Raman spectroscopy and XPS. Figure 4-9 As shown in (a), in addition to the strong CFP characteristic peak, characteristic peaks attributed to Cu2O and Cu were detected in the XRD spectrum, but these peaks were very weak, indicating that the catalytic coating formed on the carbon paper surface was relatively thin. The Cu2O-Cu-I and Cu2O-Cu-III samples mainly showed a weak diffraction peak (43.3°) attributed to the Cu (111) crystal plane, while the Cu2O-Cu-II mainly showed a weak diffraction peak (36.44°) attributed to the Cu (111) crystal plane. This indicates that the Cu in HKUST-III is 2+ It is not easy to be deeply reduced, so that the Cu2O component in Cu2O-Cu-II is relatively high. This may be because p-BQ can regulate the valence state transformation of Cu in the precursor during the coordination process of HKUST-1. With the increase of p-BQ addition, the oxidizability of Cu in HKUST-1 is stronger and it is more difficult to be deeply reduced. However, if the p-BQ concentration is too high, the structure of the synthesized MOF will be partially destroyed, which will cause the Cu 2+ Unstable.

[0028] In addition, Raman spectroscopy was used to further analyze the structure and composition of the Cu2O-Cu catalyst. Figure 9 As shown, in addition to the detection at 1358 cm -1 and 1585 cm -1 In addition to the characteristic peaks at 150 cm -1 、218cm -1 and 623 cm -1 The characteristic peak attributed to Cu2O was detected at 300 cm -1 The split double peaks on the left and right are attributed to the Raman peaks of the Cu2O / Cu interface strain effect, indicating the formation of a Cu2O / Cu heterojunction in the catalyst. The double peaks in Cu2O-Cu-II and Cu2O-Cu-III are more obvious than those in Cu2O-Cu-I, and the heterojunction structure is more prominent. This interface structure can optimize the adsorption of *CO intermediates and promote CC coupling. XPS was used to analyze the chemical valence of elements on the catalyst surface. Figure 10 It can be seen that Cu 2p Cu 2+ The satellite peak disappears, and the catalyst after in-situ conversion is Cu + and Cu 0 Species composition. Cu + and Cu 0 The Cu 2p binding energies of the metal catalysts are very similar, so Cu LMM Auger spectroscopy was used to determine the Cu + and Cu 0 The distribution of . Figure 10 As shown, the Cu Auger electron spectrum has peaks at 916.2 eV and 918.4 eV, which are respectively attributed to Cu + and Cu 0 species, while Cu at 916.2 eV + The peak is stronger, indicating that Cu + Species are the main species on the catalyst surface. Compared with Cu2O-Cu-I and Cu2O-Cu-III, Cu in Cu2O-Cu-II + The composition of oxygen species was also analyzed, such as Figure 10 The O 1s spectrum has three characteristic peaks at 530.8 eV, 532.3 eV and 533.2 eV, corresponding to copper oxide (O L ), oxygen-deficient species (O V ) and oxygen-containing species chemically adsorbed on the surface (such as hydroxyl anions or adsorbed O2 and water; O C ). With the increase of the dosage of p-benzoquinone, the oxygen defect content first decreases and then increases, and its concentration is similar to that of Cu + These results show that Cu2O-Cu-II has the highest Cu + / Cu 0 ratio, but the oxygen deficiency concentration is the lowest.

[0029] Example 3: Effect of the amount of benzoquinone added on the CO2RR performance of the catalyst The electrocatalytic performance of Cu2O-Cu-I, Cu2O-Cu-II and Cu2O-Cu-III electrodes at different potentials were tested, e.g. Figure 4-11 As shown. The main products obtained in the gas phase at different applied potentials are H2, CO, CH4 and C2H4, and the main products of liquid phase nuclear magnetic resonance (NMR) analysis are formic acid and ethanol. At the test potential, the H2 Faraday efficiency of the three composite catalysts is about 20%. In addition, at low potential, a large amount of HCOOH and CO are produced in the three composite catalysts, indicating that the catalyst does not have sufficient CC coupling ability at this time, and a large amount of CO2 is still converted into C1 products. With the increase of potential, the C2H4 generation trend of the three composite catalysts is different, but the Faraday efficiency of C2H5OH increases. Moreover, the higher the potential, the more CH4 is generated. Further analysis of the C1 and C 2+ The Faradaic efficiency and generation trend of the products were compared, such as Figure 12 As shown in Figure 2, the total Faraday efficiency of C1 of the three catalysts shows a downward trend with the increase of potential. Among them, the C1 product of Cu2O-Cu-II is the least. The C1 product of Cu2O-Cu-II and Cu2O-Cu-III is the least. 2+The Faraday efficiency of the product showed a trend of increasing first and then decreasing, and reached the maximum value at -1.39 V vs RHE, while the C 2+ The product Faraday efficiency first decreases and then increases. 2+ The product Faraday efficiency was significantly higher than that of the other two catalysts, reaching 63.6%, and the product was mainly ethylene, with a Faraday efficiency (FE) of 50.5%. The selectivity (C 2+ / C1 ratio), at the test potential, the C 2+ The / C1 ratio is greater than that of Cu2O-Cu-I and Cu2O-Cu-III, indicating that the Cu2O-Cu-II catalyst has the strongest CC coupling ability, which can promote the key C1 intermediate to be further converted into C 2+ product.

[0030] In order to explore the reasons for the excellent performance of Cu2O-Cu-II, the Cu2O-Cu-I, Cu2O-Cu-II and Cu2O-Cu-III electrodes were tested in CO2-saturated 0.1 M KCl electrolyte by linear sweep voltammetry (LSV). Figure 13 . Cu2O-Cu-II exhibits a higher current density than the other two catalysts, indicating that the Cu2O-Cu-II catalyst rich in active Cu2O and Cu2O-Cu interface has better CO2RR activity. The ECSA calculated by cyclic voltammetry shows that Cu2O-Cu-II has the highest roughness factor, indicating that the catalyst can provide abundant active sites. In addition, the catalyst also has suitable oxygen defects. These structural advantages enable the Cu2O-Cu-II catalyst to exhibit excellent catalytic activity and optimal C2 product selectivity. Cu + The site preferentially stabilizes the critical C2 intermediate *CO, thereby increasing the surface *CO coverage, and the active heterogeneous interface in the catalyst enhances the CC coupling ability, thereby promoting C 2+ In addition, the higher the Cu + / Cu 0 The appropriate oxygen vacancies can increase the coverage of *CO on the catalyst surface. Oxygen vacancies induce local charge rearrangement and optimize the adsorption strength of intermediates (such as *CO). + When coexisting with oxygen vacancies, it may form "electron-rich Cu + -oxygen vacancy” active sites, enhancing both CO adsorption and CC coupling kinetics.

[0031] Example 4: Interface Advantages of the Composite Catalyst Cu2O-Cu-II In order to explore the reasons for the enhanced performance of the Cu2O-Cu composite catalyst, commercial Cu-CFP, Cu2O-CFP and Cu2O-Cu-CFP catalysts were prepared by conventional spraying method, and the CO2RR performance of these catalysts was compared. Figure 14 As shown in the figure, the trend of the Faraday efficiency ratio of C2H4 to H2 of the three reference catalysts is: Cu2O>Cu2O / Cu>Cu, and the main product is H2. This shows that the physical mixing of Cu2O and Cu alone cannot improve the catalytic performance, probably because no Cu2O-Cu interface is formed in the catalyst. However, Cu2O-Cu-II shows better catalytic performance than Cu-CFP and Cu2O-CFP, and the C2H4 in the catalytic product is significantly higher than H2, and the ratio changes as Cu2O-Cu-CFP>Cu-CFP>Cu2O-CFP, indicating that Cu in the synthesized catalyst is + With Cu 0 The presence of an interaction does lead to the formation of a heterogeneous interface that improves the catalytic performance of the overall catalyst, highlighting the necessity of in situ derivatization of the interface structure. 0 / Cu + The interface sites can increase the adsorption density of *CO, Cu + and Cu 0 The synergistic effect breaks the thermodynamic and kinetic limitations of CO2RR and increases the chances of CC coupling reaction. In addition, the catalyst contains a large number of Cu2O (110) crystal planes, which have a lower CC coupling reaction energy barrier compared with Cu2O (111) crystal planes and (100) crystal planes. By comparing the electrode catalytic performance under different in situ conversion times, the three-dimensional structure of the catalyst has an advantage. The oxygen defects present in the three-dimensional structure also help to improve the selectivity of the catalyst for C2H4. The introduction of oxygen defects can improve the conductivity of the catalyst and generate a large number of activation sites and adsorption sites on these catalysts. The oxygen defects exposed on the catalyst surface can provide chemical adsorption sites to reduce the adsorption energy of carbon dioxide.

[0032] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A three-dimensional corncob-shaped Cu2O-Cu composite catalyst based on MOF, characterized in that: The composite catalyst is composed of Cu2O and Cu nanoparticles with a size of 2-3 μm, and the surface is arranged with nanospheres with a diameter of about 150 nm to form a corncob-like structure.

2. The MOF-based three-dimensional corncob-shaped Cu2O-Cu composite catalyst according to claim 1, characterized in that: The composite catalyst has Cu + / Cu 0 Heterointerfaces and controllable oxygen defects.

3. The MOF-based three-dimensional corncob-shaped Cu2O-Cu composite catalyst according to claim 1, characterized in that: The preparation method of the composite catalyst comprises the following steps: S11. In a three-electrode system, pretreated carbon paper was fixed to the working electrode, with Ag / AgCl as the reference electrode, a platinum sheet as the counter electrode, and a copper-containing electrolyte. S12. at 4 mA cm -2 The electrodeposition was carried out stably for 1800 s under constant current conditions. After the deposition, the copper-coated carbon paper surface was rinsed with ultrapure water to obtain a Cu-CFP substrate. S13 was added 50mL of electroconversion solution, the Cu-CFP substrate obtained in step S12 was used as the working electrode, and under stirring, a working voltage of 4V was applied for in situ conversion; S14. After 1800 s of reaction, the electrode surface was transformed into a uniformly covered blue coating of HKUST-1. The obtained electrode was dried in an oven at 80 °C for 8 h to obtain HKUST-1 II electrode; S15. Under CO2 reduction conditions, HKUST-1 II In situ conversion to Cu2O-Cu-II.

4. The MOF-based three-dimensional corncob-shaped Cu2O-Cu composite catalyst according to claim 3, characterized in that: The copper-containing electrolyte in step S11 is prepared by dissolving 0.01 M CuSO4·5H2O and 0.05 M C6H8O7 in 1 M H2SO4.

5. The MOF-based three-dimensional corncob-shaped Cu2O-Cu composite catalyst according to claim 3, characterized in that: In step S12, the surface of the Cu-CFP substrate exhibits Cu metallic red.

6. The MOF-based three-dimensional corncob-shaped Cu2O-Cu composite catalyst according to claim 3, characterized in that: The electroporation solution in step S13 is prepared by dissolving 0.08 M H3BTC and 0.01 M TEA TFB in a 4:1 ethanol / water mixture, stirring for 5 minutes, adding p-benzoquinone, and stirring for 30 minutes.

7. The MOF-based three-dimensional corncob-shaped Cu2O-Cu composite catalyst according to claim 6, characterized in that: The concentration of p-benzoquinone is 0.02-0.14 M.

8. The MOF-based three-dimensional corncob-shaped Cu2O-Cu composite catalyst according to claim 3, characterized in that: The potential range of the in-situ conversion in step S15 is -1.39 V vs RHE, and the electrolyte for the in-situ conversion is 0.1 M KCl.

9. A catalyst according to claim 1 for electrocatalytic reduction of CO2 to generate C 2+ Application in products.

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