Cuprous oxide nanorod array bifunctional catalyst wrapped by PdRh alloy as well as preparation method and application of cuprous oxide nanorod array bifunctional catalyst

Abstract

The invention provides a PdRh alloy coated cuprous oxide nanorod array bifunctional catalyst as well as a preparation method and application thereof. According to the preparation method disclosed by the invention, foamy copper is subjected to chemical oxidation treatment, then the foamy copper and a mixed solution of PdCl2 and RhCl3 are subjected to co-heating and redox reaction to obtain the cuprous oxide nanorod array bifunctional catalyst wrapped by the PdRh alloy, and the catalyst has a synergistic effect of PdRh alloy doping and Cu0 / Cu < + >; the catalyst can efficiently promote furfural molecular adsorption, C-H bond breakage and hydrogen desorption in furfural oxidation and hydrogen evolution reaction, can be used as an excellent bifunctional catalyst material for low-potential furfural oxidation and hydrogen evolution reaction, has excellent electrocatalytic activity and stability for low-potential furfural oxidation and hydrogen evolution reaction, and can be used as a catalyst for low-potential furfural oxidation and hydrogen evolution reaction. And a low-energy-consumption bipolar hydrogen production system can be constructed by coupling low-potential furfural oxidation and hydrogen evolution reaction. The preparation method disclosed by the invention is simple, convenient, feasible, economical, practical and suitable for large-scale industrial production.

Description

Technical Field

[0001] The invention relates to the technical field of catalysts, and in particular to a PdRh alloy-wrapped cuprous oxide nanorod array bifunctional catalyst and a preparation method and application thereof. Background Art

[0002] At present, due to the excessive dependence on fossil fuels, energy and environmental issues have always been the two key issues restricting the sustainable development of social economy. More and more researchers are committed to seeking sustainable energy, among which hydrogen energy has received widespread attention due to its advantages such as environmental protection, pollution-free and efficient utilization. In particular, the production of hydrogen by water electrolysis is becoming an increasingly popular research field. However, the slow kinetics of its anodic oxygen evolution reaction (OER) seriously inhibits the further development of hydrogen production by water electrolysis. Using the thermodynamically more favorable and inexpensive biomass oxidation reaction (BOR) instead of OER can effectively reduce the energy consumption of hydrogen production and obtain high value-added products. Among them, furfural (FF), as an important biomass platform molecule, is easily obtained from xylose and can be converted into a high value-added product furoic acid (FAC). However, the traditional furfural electrooxidation process is limited by high energy consumption (>1.0V RHE ), low conversion efficiency, and the product of the anode being water rather than hydrogen have hindered its further development.

[0003] The prior art discloses the use of Cu / Cu foam and Pt / C as anode and cathode catalysts respectively at near 0V. RHE Bipolar hydrogen production was achieved at a low potential, providing a new hydrogen production strategy. Studies have shown that the hydrogen production system strategy of coupling the low-potential furfural oxidation reaction at the anode and the hydrogen evolution reaction at the cathode can significantly improve the reaction efficiency and effectively reduce the power input required for hydrogen production. Given that the atomic utilization rate in monofunctional catalysts is still relatively low, there is an urgent need to further develop a bifunctional electrocatalyst to simultaneously achieve biomass oxidation and electrochemical hydrogen evolution. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects of the prior art and provide a method for preparing a PdRh alloy-wrapped cuprous oxide nanorod array bifunctional catalyst and its application in low-energy hydrogen evolution and furfural oxidation. The prepared catalyst has excellent catalytic activity and stability for hydrogen evolution reaction (HER) and furfural oxidation reaction (FFOR), and a low-energy bipolar hydrogen production system can be constructed by coupling anode low-potential furfural oxidation and cathode hydrogen evolution reaction.

[0005] The present invention is achieved through the following technical solutions:

[0006] In a first aspect, the present invention provides a method for preparing a PdRh alloy-wrapped cuprous oxide nanorod array bifunctional catalyst, comprising the following steps:

[0007] The copper foam was immersed in a solution containing NaOH and (NH 4 ) 2 S 2 O 8 The precursor Cu(OH) 2 NRAs / CFs;

[0008] The precursor Cu(OH) 2 NRAs / CF was placed in a PdCl 2 and RhCl 3 The mixed aqueous solution is heated for reaction, washed and dried to obtain a PdRh alloy-wrapped cuprous oxide nanorod array bifunctional catalyst.

[0009] Preferably, the 4 ) 2 S 2 O 8 The concentration of NaOH in the mixed aqueous solution is 2.5-3.0 M, (NH 4 ) 2 S 2 O 8 The concentration is 0.10~0.15M.

[0010] Preferably, the copper foam is immersed in a solution containing NaOH and (NH 4 ) 2 S 2 O 8 The soaking time in the mixed aqueous solution is 25 to 35 minutes.

[0011] Preferably, the PdCl 2 and RhCl 3 PdCl in a mixed aqueous solution 2 The concentration of RhCl is 3-7mM 3 The concentration is 8-12mM.

[0012] Preferably, the precursor Cu(OH) 2 NRAs / CF was placed in a PdCl 2 and RhCl 3 The mixed aqueous solution is heated at 80-100°C for 1-2h.

[0013] Preferably, the copper foam is immersed in a solution containing NaOH and (NH 4 ) 2 S 2 O 8 Before the copper foam is added into the mixed aqueous solution, the copper foam is also pretreated, and the pretreatment specifically includes:

[0014] The copper foam is placed in hydrochloric acid, ethanol and water for ultrasonic cleaning respectively to remove oxides on the surface of the copper foam;

[0015] The foam copper has a specification of 2.0 cm×2.0 cm.

[0016] In a second aspect, the present invention further provides a PdRh alloy-wrapped cuprous oxide nanorod array bifunctional catalyst, which is prepared by the preparation method.

[0017] In a third aspect, the present invention also provides an application of the PdRh alloy-wrapped cuprous oxide nanorod array bifunctional catalyst in bipolar hydrogen production.

[0018] Preferably, the bipolar hydrogen production is a low-power bipolar hydrogen production system constructed by coupling an anode furfural oxidation reaction and a cathode hydrogen evolution reaction.

[0019] Preferably, the PdRh alloy-wrapped cuprous oxide nanorod array bifunctional catalyst serves as both anode and cathode materials.

[0020] The preparation method of the PdRh alloy-wrapped cuprous oxide nanorod array bifunctional catalyst of the present invention has the following beneficial effects compared with the prior art:

[0021] 1. The present invention grows copper hydroxide nanorods on a foam copper substrate by chemical oxidation, and then converts Cu 2+ Partial reduction to Cu 0 / Cu + , and simultaneously introduce PdRh alloy doping to finally form a PdRh alloy-wrapped cuprous oxide nanorod array bifunctional catalyst. The preparation method of the present invention is simple, economical, and suitable for industrial large-scale production;

[0022] 2. The present invention introduces Pd and Cu 0 / Cu + The reconstruction of the catalysts promotes the adsorption of FF molecules and promotes the cleavage of the CH bonds. * GDA is converted to * FAC (furoic acid). Rh further reduced * H 2 The adsorption energy of H 2 The desorption capacity of PdRh is improved, which reduces the energy barrier of low-potential FFOR. In addition, PdRh synergistically promotes water dissociation and * H is recombined into H 2 , enhance HER performance, and can be used as an excellent low-potential furfural oxidation and hydrogen evolution dual-functional catalytic material;

[0023] 3. The catalyst prepared by the present invention can be used as a bifunctional catalyst to realize a low-energy consumption bipolar hydrogen production system that couples the anode low-potential furfural oxidation reaction and the cathode hydrogen evolution reaction, and simultaneously performs bipolar hydrogen production and obtains the high value-added product furoic acid. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0025] Figure 1 PdRh@Cu provided in Example 1 of the present invention 2 Characterization of O NRAs / CF catalysts: (a) PdRh@Cu 2 Schematic diagram of the synthesis of ONRAs / CF; (bd) PdRh@Cu 2 SEM image of O NRAs / CF; (e) PdRh@Cu 2 TEM image of O NRAs / CF; (e) PdRh@Cu 2 HRTEM image of O NRAs / CF; (f) PdRh@Cu 2 XRD patterns of O NRAs / CF; (h) PdRh@Cu 2 HAADF-STEM of ONRAs / CF and elemental mapping of (i) Pd, (j) Rh, (k) Cu and (l) O;

[0026] Figure 2 PdRh@Cu provided in Example 1 of the present invention 2 Characterization of O NRAs / CF catalysts: (a) PdRh@Cu 2 Schematic diagram of charge transfer calculated in ONRAs / CF; (b) PdRh@Cu 2 ONRAs / CF and control Cu 2 Cu 2pXPS spectrum of O NRAs / CF; (c) is the corresponding Cu LMM spectrum; (d) is PdRh@Cu 2 O NRAs / CF, Cu 2 UPS spectra of O NRAs / CF and CF; (e) PdRh@Cu 2 O NRAs / CF and control Pd@Cu 2 Pd 3d XPS spectrum of O NRAs / CF; (f) PdRh@Cu 2ONRAs / CF and control Rh@Cu 2 Rh 3d XPS spectrum of O NRAs / CF; (g) PdRh@Cu 2 Schematic diagram of multiple built-in electric fields in O NRAs / CF;

[0027] Figure 3 The PdRh@Cu provided in Example 1 of the present invention 2 O NRAs / CF catalysts for furfural oxidation reaction: (a) PdRh@Cu 2 O NRAs / CF, CF, Cu(OH) 2 NRAs / CF、Cu 2 O NRAs / CF, Pd@Cu 2 O NRAs / CF and Rh@Cu 2 LSV curves of ONRAs / CF in 1.0 M KOH solution with (solid line) and without (dashed line) 0.1 M FF; (b) is the corresponding Tafel slope in 0.1 M FF; (c) is the PdRh@Cu 2 OCP test of O NRAs / CF; (d) PdRh@Cu 2 O NRAs / CF at 0.1V RHE Nyquist curves with (red line) and without (blue line) 0.1M FF; PdRh@Cu 2 Bode curves of ONRAs / CF at different potentials (e) without and (f) with 0.1 M FF; (g) PdRh@Cu 2 LSV curves of O NRAs / CF in 1.0 M KOH + 0.1 M FF solution with (blue line) and without (red line) 20 mM NaSCN; (h) Stability test;

[0028] Figure 4 The PdRh@Cu provided in Example 1 of the present invention 2 Hydrogen evolution reaction test of O NRAs / CF catalyst: (a) PdRh@Cu 2 The reaction energy barrier diagram of O NRAs / CF and its control in water dissociation; (b) is the corresponding LSV curve in 1.0M KOH solution; (c) is the free energy change diagram of the HER process; (d) is the Tafel slope; (e) is the free energy change diagram at -0.4V RHE Nyquist curve when C dl ; (g) is PdRh@Cu 2 It curves of O NRAs / CF; (h) PdRh@Cu 2Cu LMM spectra of O NRAs / CF after HER test;

[0029] Figure 5 The PdRh@Cu provided in Example 1 of the present invention 2 O NRAs / CF catalyst bifunctional electrolysis cell performance: (a) is a real photo and schematic diagram of the coupled FFOR and HER flow electrolysis cell; (b) is PdRh@Cu 2 LSV curves of O NRAs / CF electrode pair in FFOR / / HER and OER / / HER; (c) PdRh@Cu 2 The concentration and carbon balance of the anodic products of O NRAs / CF in 1.0M KOH+0.15M FF change with time; (d) PdRh@Cu 2 O NRAs / CF in 1.0 M KOH catalysis cathode hydrogen volume change; (e) is the corresponding H 2 Image of variation and Faraday efficiency. DETAILED DESCRIPTION

[0030] To make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them.

[0031] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of the embodiments. In addition, in the description of the present application, the term "including" means "including but not limited to". Various embodiments of the present invention may be in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single values ​​within the range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the numbered ranges, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated in this article, it is meant to include any quoted numbers (fractions or integers) within the indicated range.

[0033] The present application provides a method for preparing a PdRh alloy-wrapped cuprous oxide nanorod array bifunctional catalyst, comprising the following steps:

[0034] S1. Soak the copper foam in a solution containing NaOH and (NH 4 ) 2 S 2 O 8 The precursor Cu(OH) 2 NRAs / CFs;

[0035] S2, the precursor Cu(OH) 2 NRAs / CF was placed in a PdCl 2 and RhCl 3 The mixed aqueous solution is heated for reaction, washed and dried to obtain a PdRh alloy-wrapped cuprous oxide nanorod array bifunctional catalyst.

[0036] The invention relates to a method for preparing a foam copper by chemically oxidizing the foam copper and then reacting the foam copper with PdCl 2 and RhCl 3 The mixed solution is heated together to undergo an oxidation-reduction reaction to obtain a PdRh alloy-wrapped cuprous oxide nanorod array bifunctional catalyst. The catalyst of the present invention has both PdRh alloy doping and Cu 0 / Cu + The synergistic effect can effectively promote the adsorption of furfural molecules, the breaking of CH bonds and the desorption of hydrogen in the furfural oxidation and hydrogen evolution reaction, and can be used as an excellent low-potential furfural oxidation and hydrogen evolution reaction bifunctional catalyst material. The catalyst has excellent electrocatalytic activity and stability for both low-potential furfural oxidation and hydrogen evolution reaction, and a low-energy consumption bipolar hydrogen production system can be constructed by coupling low-potential furfural oxidation and hydrogen evolution reaction. The preparation method of the present invention is simple, easy to operate, economical and affordable, and suitable for large-scale industrial production.

[0037] In some embodiments, the 4 ) 2 S 2 O 8 The concentration of NaOH in the mixed aqueous solution is 2.5-3.0 M, (NH 4 ) 2 S 2 O 8 The concentration is 0.10~0.15M.

[0038] In some embodiments, the copper foam is immersed in a solution containing NaOH and (NH 4 ) 2 S 2 O 8 The soaking time in the mixed aqueous solution is 25 to 35 minutes.

[0039] In some embodiments, the PdCl 2 and RhCl 3 PdCl in a mixed aqueous solution 2 The concentration of RhCl is 3-7mM 3 The concentration is 8-12mM.

[0040] In some embodiments, the precursor Cu(OH) 2 NRAs / CF was placed in a PdCl 2 and RhCl 3 The mixed aqueous solution is heated at 80-100°C for 1-2h.

[0041] In some embodiments, the copper foam is immersed in a solution containing NaOH and (NH 4 ) 2 S 2 O 8 Before the copper foam is added to the mixed aqueous solution, the copper foam is also pretreated, and the pretreatment specifically includes:

[0042] The foam copper is respectively placed in hydrochloric acid, ethanol and water for ultrasonic cleaning to remove oxides on the surface of the foam copper, wherein the concentration of the hydrochloric acid is 0.1-0.3M.

[0043] In some embodiments, the copper foam is in a rectangular shape with a length of 2.0 cm, a width of 2.0 cm, and a height of 1.0 mm.

[0044] Based on the same inventive concept, the present invention also provides a PdRh alloy-wrapped cuprous oxide nanorod array bifunctional catalyst, which is prepared by the above-mentioned preparation method.

[0045] The catalyst prepared by the present invention grows copper hydroxide nanorods on a foam copper substrate by chemical oxidation, and then converts Cu 2+ Partial reduction to Cu 0 / Cu + , and PdRh alloy doping was introduced at the same time, finally forming a PdRh alloy-wrapped cuprous oxide nanorod array bifunctional catalyst. 0 / Cu + The reconstruction of the catalysts promotes the adsorption of furfural (FF) molecules and promotes the cleavage of the CH bonds. * GDA is converted to * FAC (furoic acid). Rh further reduced * H 2 The adsorption energy of H 2 The desorption capacity of PdRh is improved, which reduces the energy barrier of low-potential FFOR. In addition, PdRh synergistically promotes water dissociation and * H is recombined into H 2 , enhance HER performance. The catalyst prepared by the present invention has both PdRh alloy and Cu 0 and Cu + The advantages of synergistic effect can be used as an excellent low-potential furfural oxidation and hydrogen evolution dual-functional catalytic material.

[0046] Based on the same inventive concept, the present invention also provides an application of the above-mentioned PdRh alloy-wrapped cuprous oxide nanorod array bifunctional catalyst in bipolar hydrogen production.

[0047] In some embodiments, the bipolar hydrogen production is a low-power bipolar hydrogen production system constructed by coupling an anode furfural oxidation reaction and a cathode hydrogen evolution reaction.

[0048] In some embodiments, the PdRh alloy-wrapped cuprous oxide nanorod array bifunctional catalyst serves as both anode and cathode materials.

[0049] The PdRh alloy-wrapped cuprous oxide nanorod array bifunctional catalyst prepared by the invention has excellent catalytic activity and stability for both electrochemical hydrogen evolution reaction and furfural oxidation reaction; the catalyst is used in low-energy hydrogen evolution and furfural oxidation; specifically, the bipolar hydrogen production is a low-energy bipolar hydrogen production system constructed by coupling a low-potential furfural oxidation reaction at the anode and a hydrogen evolution reaction at the cathode, the electrode materials of the anode and the cathode are both the catalyst, the anode electrolyte solution is a mixed solution of furfural and an alkaline solution, the cathode electrolyte solution is an alkaline solution, the cathode and the anode are separated by an anion exchange membrane, a certain potential is applied to the system for electrolysis, and low-energy bipolar hydrogen production and the generation of furoic acid (FAC), a high-value-added product at the anode, can be achieved.

[0050] The following further describes the PdRh alloy-wrapped cuprous oxide nanorod array bifunctional catalyst of the present application and its preparation method and application with specific examples. This section further describes the content of the present invention in conjunction with specific examples, but should not be construed as limiting the present invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0051] The foam copper in the following examples was purchased from Shenzhen Tianchenghe Technology Co., Ltd.

[0052] Example 1

[0053] The present application provides a method for preparing a PdRh alloy-wrapped cuprous oxide nanorod array bifunctional catalyst, comprising the following steps:

[0054] S1. Place the copper foam (the copper foam is in a rectangular shape with a length of 2.0 cm, a width of 2.0 cm, and a height of 2.0 cm) in 2.0 M hydrochloric acid, ethanol, and water for ultrasonic cleaning for 10 min to remove oxides on the surface of the copper foam;

[0055] S2, the copper foam pretreated in S1 was placed in a solution containing 2.67M NaOH and 0.13M (NH 4 ) 2 S 2 O 8 The precursor Cu(OH) was obtained by immersing the mixture in the aqueous solution for 30 min and then washing and drying. 2 NRAs / CFs;

[0056] S3, the precursor Cu(OH) in S2 2 NRAs / CF were placed in a solution containing 5 mM PdCl 2 and 10 mM RhCl 3 ·3H 2 O mixed aqueous solution, heated at 90 ° C for 1 h, and then washed and dried to obtain the PdRh alloy-wrapped cuprous oxide nanorod array bifunctional catalyst, denoted as PdRh@Cu 2 O NRAs / CFs.

[0057] Comparative Example 1

[0058] This comparative example provides a catalyst Cu(OH) 2 The preparation method of NRAs / CF is the same as that of Example 1, except that step S3 is omitted, and specifically comprises the following steps:

[0059] S1. Place the copper foam (the copper foam is in a rectangular shape with a length of 2.0 cm, a width of 2.0 cm, and a height of 1.0 mm) in 2.0 M hydrochloric acid, ethanol, and water for ultrasonic cleaning for 10 min to remove oxides on the surface of the copper foam;

[0060] S2, the copper foam pretreated in S1 was placed in a solution containing 2.67M NaOH and 0.13M (NH 4 ) 2 S 2 O 8 The precursor Cu(OH) was obtained by immersing the mixture in the aqueous solution for 30 min and then washing and drying. 2 NRAs / CF, that is, the catalyst Cu(OH) 2 NRAs / CFs.

[0061] Comparative Example 2

[0062] This comparative example provides a catalyst Cu 2 The preparation method of O NRAs / CF is the same as that of Example 1, except that in step S3, the step is heated in pure water at 90° C. for 1 h, and specifically comprises the following steps:

[0063] S1. Place the copper foam (the copper foam is in a rectangular shape with a length of 2.0 cm, a width of 2.0 cm, and a height of 1.0 mm) in 2.0 M hydrochloric acid, ethanol, and water for ultrasonic cleaning for 10 min to remove oxides on the surface of the copper foam;

[0064] S2, the copper foam pretreated in S1 was placed in a solution containing 2.67M NaOH and 0.13M (NH 4 ) 2 S 2 O 8 The precursor Cu(OH) was obtained by immersing the mixture in the aqueous solution for 30 min and then washing and drying. 2 NRAs / CFs;

[0065] S3, the precursor Cu(OH) in S2 2 NRAs / CF was placed in water and heated at 90 °C for 1 h, then washed and dried to obtain the catalyst Cu 2 O NRAs / CFs.

[0066] Comparative Example 3

[0067] This comparative example provides a catalyst Pd@Cu 2 The preparation method of O NRAs / CF is the same as that of Example 1, except that in step S3, 5 mM PdCl 2 The aqueous solution is heated at 90°C for 1 hour, specifically comprising the following steps:

[0068] S1. Place the copper foam (the copper foam is in a rectangular shape with a length of 2.0 cm, a width of 2.0 cm, and a height of 1.0 mm) in 2.0 M hydrochloric acid, ethanol, and water for ultrasonic cleaning for 10 min to remove oxides on the surface of the copper foam;

[0069] S2, the copper foam pretreated in S1 was placed in a solution containing 2.67M NaOH and 0.13M (NH 4 ) 2 S 2 O 8 The precursor Cu(OH) was obtained by immersing the mixture in the aqueous solution for 30 min and then washing and drying. 2 NRAs / CFs;

[0070] S3, the precursor Cu(OH) in S2 2 NRAs / CF were placed in a solution containing 5 mM PdCl 2 The catalyst Pd@Cu was obtained by heating the catalyst at 90 °C for 1 h and then washing and drying. 2 O NRAs / CFs.

[0071] Comparative Example 4

[0072] This comparative example provides a catalyst Rh@Cu 2 The preparation method of O NRAs / CF is the same as that of Example 1, except that in step S3, 10 mM RhCl 3 ·3H 2 O aqueous solution is heated at 90°C for 1h, specifically comprising the following steps:

[0073] S1. Place the copper foam (the copper foam is in a rectangular shape with a length of 2.0 cm, a width of 2.0 cm, and a height of 1.0 mm) in 2.0 M hydrochloric acid, ethanol, and water for ultrasonic cleaning for 10 min to remove oxides on the surface of the copper foam;

[0074] S2, the copper foam pretreated in S1 was placed in a solution containing 2.67M NaOH and 0.13M (NH 4 ) 2 S 2 O 8 The precursor Cu(OH) was obtained by immersing the mixture in the aqueous solution for 30 min and then washing and drying. 2 NRAs / CFs;

[0075] S3, the precursor Cu(OH) in S2 2 NRAs / CF were placed in a solution containing 10 mM RhCl 3 ·3H 2O aqueous solution, heated at 90 °C for 1 h, and then washed and dried to obtain the catalyst Rh@Cu 2 O NRAs / CFs.

[0076] Performance Testing

[0077] Figure 1 PdRh@Cu provided in Example 1 of the present invention 2 Characterization of O NRAs / CF catalysts, where (a) is PdRh@Cu 2 Schematic diagram of the synthesis of O NRAs / CF; (bd) PdRh@Cu 2 SEM image of O NRAs / CF; (e) PdRh@Cu 2 TEM image of ONRAs / CF; (f) PdRh@Cu 2 HRTEM image of ONRAs / CF; (g) PdRh@Cu 2 XRD patterns of O NRAs / CF; (h) PdRh@Cu 2 HAADF-STEM of O NRAs / CF and corresponding elemental mapping of (i) Pd, (j) Rh, (k) Cu and (l) O.

[0078] The catalyst PdRh@Cu prepared in Example 1 2 O NRAs / CF is taken as an example to characterize and analyze it: Figure 1 a shows that a dark yellow nanorod array was grown on the surface of copper foam (CF) by a two-step method of chemical oxidation and co-thermalization. Figure 1 b, 1c, and 1d show that nanorod arrays are uniformly grown on the surface of copper foam. Figure 1 e shows that in PdRh@Cu 2 O NRAs / CFs show a core-shell structure. Figure 1 f, the lattice fringe spacings of 0.19, 0.22, and 0.25 nm correspond to Pd(100), Rh(111), and Cu, respectively. 2 O(111) crystal plane. Figure 1 The diffraction peaks at 43.3°, 50.5°, and 74.2° in g correspond to the (111), (200), and (220) crystal planes of Cu, respectively, while the diffraction peaks at 36.8°, 42.7°, and 61.9° correspond to the (111), (200), and (220) crystal planes of Cu, respectively. 2 O (111), (200) and (220) crystal planes, indicating that Cu 0 and Cu + coexist. Figure 1hl shows that the Cu element is mainly concentrated in the inner part, while the Pd and Rh elements are evenly distributed in the outer layer of the nanorods, indicating that PdRh@Cu 2 Successful preparation of ONRAs / CF heterojunction.

[0079] Figure 2 PdRh@Cu provided in Example 1 of the present invention 2 Characterization of O NRAs / CF catalysts, where (a) is PdRh@Cu 2 Schematic diagram of charge transfer calculated in O NRAs / CF; (b) PdRh@Cu 2 ONRAs / CF and Cu in Comparative Example 2 2 Cu 2p XPS spectrum of O NRAs / CF; (c) is the corresponding Cu LMM spectrum; (d) is PdRh@Cu 2 O NRAs / CF, Cu in Comparative Example 2 2 UPS spectra of ONRAs / CF and copper foam (CF); (e) PdRh@Cu 2 O NRAs / CF and Pd@Cu in Comparative Example 3 2 Pd 3d XPS spectrum of O NRAs / CF; (f) PdRh@Cu 2 O NRAs / CF and Rh@Cu in Comparative Example 4 2 Rh 3d XPS spectrum of ONRAs / CF; (g) PdRh@Cu 2 Schematic diagram of multiple built-in electric fields in O NRAs / CF.

[0080] like Figure 2 As shown in a, PdRh@Cu 2 O NRAs / CF has 0.41 electrons from Cu 2 O / Cu transfers to PdRh. Figure 2 As shown in b, PdRh@Cu 2 The binding energies at 952.7 and 932.9 eV in O NRAs / CF correspond to the Cu 2p 1 / 2 and Cu 2p 3 / 2 Cu 0 / Cu + , while the peaks at 955.0 and 934.5 eV are attributed to Cu 2+ Compared with the control Cu 2 Compared with O NRAs / CF, the binding energy of O NRAs / CF has a positive shift of 0.3 eV, which indicates that the electrons in the catalyst are transferred from Cu 2 O / Cu flows to PdRh. Figure 2 c shows that PdRh@Cu 2The kinetic energies at 918.6 eV and 916.1 eV in O NRAs / CF correspond to Cu 0 and Cu + Compared with the control Cu 2 Compared with O NRAs / CF, the binding energy of O NRAs / CF shifted negatively by 0.3 eV, which once again indicates that the electrons in the catalyst shifted from Cu 2 O / Cu flows to PdRh.

[0081] Figure 2 As shown in d, PdRh@Cu 2 The work function of O NRAs / CF is 6.3 eV, which is significantly higher than that of Cu 2 ONRAs / CF(5.5eV) and CF((4.4eV), again confirming that the charge is from Cu 2 O NRAs / CF transfer to PdRh. Combined with Cu 2 The work functions of O NRAs / CF and CF can also explain the electron transfer from Cu to Cu 2 O transfer. Figure 2 As shown in e and f, PdRh@Cu 2 The peaks at 341.1 eV and 335.8 eV in O NRAs / CF belong to Pd3d 3 / 2 and 3D 5 / 2 Pd 0 , while the peaks at 312.3 eV and 307.6 eV belong to Rh 0 Compared with the control Pd@Cu 2 ONRAs / CF and Rh@Cu 2 Compared with O NRAs / CF, PdRh@Cu 2 The O NRAs / CF shifted positively and negatively by 0.1 eV, respectively, which together indicated that electrons were transferred from Pd to Rh. Figure 2 g, PdRh@Cu 2 There are three pairs of built-in electric fields in ONRAs / CF, namely Cu 2 O / Cu and PdRh, Cu 2 O / Cu and PdRh. The electrons are respectively 2 O / Cu moves to PdRh, Cu moves to Cu 2 O and Pd move toward Rh.

[0082] Using a three-electrode system, the PdRh@Cu prepared in Example 1 2O NRAs / CF is a bifunctional catalyst to test the performance of furfural oxidation at the anode and hydrogen evolution at the cathode. Specifically, the working electrode is the catalyst prepared in Example 1 or Comparative Examples 1 to 4, the reference electrode is a saturated calomel electrode, the counter electrode is a graphite electrode, and the electrolyte is a 1.0M KOH solution containing or not containing 0.1M FF. During the test, the voltage scan rate is 10mV / s.

[0083] The results are analyzed as follows:

[0084] Figure 3 The PdRh@Cu provided in Example 1 of the present invention 2 O NRAs / CF catalysts for furfural oxidation reaction, where (a) PdRh@Cu 2 O NRAs / CF, foam copper (CF), Cu(OH) in Comparative Example 1 2 NRAs / CF, Cu in Comparative Example 2 2 ONRAs / CF, Pd@Cu in Comparative Example 3 2 O NRAs / CF and Rh@Cu in Comparative Example 4 2 LSV curves of O NRAs / CF in 1.0 M KOH solution with (solid line) and without (dashed line) 0.1 M FF furfural (FF); (b) is the corresponding Tafel slope in 1.0 M KOH solution with 0.1 M FF; (c) is the PdRh@Cu 2 OCP test of O NRAs / CF in 1.0 M KOH solution with and without 0.1 M FF furfural (FF); (d) PdRh@Cu 2 O NRAs / CF at 0.1V RHE Nyquist curves with (red line) and without (blue line) 0.1 M furfural (FF); PdRh@Cu 2 Bode curves of O NRAs / CF at different potentials (e) without and (f) with 0.1 M furfural (FF); (g) PdRh@Cu 2 LSV curves of O NRAs / CF with (blue line) and without (red line) 20 mM NaSCN in 1.0 M KOH solution containing 0.1 M FF; (h) PdRh@Cu 2 The stability of ONRAs / CF was tested in 1.0 M KOH solution containing 0.1 M FF.

[0085] Figure 3 It is PdRh@Cu 2 O NRAs / CF catalysts for low potential furfural oxidation performance test, Figure 3 a shows that compared with the control Pd@Cu 2O NRAs / CF, Rh@Cu 2 O NRAs / CF, Cu 2 O NRAs / CF, Cu(OH) 2 Compared with CF and PdRh@Cu 2 ONRAs / CF has the lowest initial oxidation potential and the highest current density, which is attributed to the electronic regulation of its built-in electric field. -2 At the current density, PdRh@Cu 2 The furfural oxidation reaction (FFOR) potential of ONRAs / CF was reduced by 1.43 V compared with the oxygen evolution reaction (OER), indicating that it has great potential for FFOR to replace OER. Figure 3 b PdRh@Cu 2 The Tafel slope corresponding to O NRAs / CF was the smallest, indicating that it had the fastest reaction kinetics in FFOR.

[0086] Figure 3 c shows that after adding 0.1 M furfural (FF), PdRh@Cu 2 The OCP (open circuit potential) of O NRAs / CF decreased by 0.73 V, indicating that it has a strong adsorption capacity for furfural, thereby accelerating the FFOR activity. Figure 3 As shown in d, after adding FF, PdRh@Cu 2 O R of NRAs / CF ct Significantly reduced, indicating that FF is smaller than OH - More susceptible to electrochemical oxidation. Figure 3 As shown in Figures 3e and 3f, at the same potential, the phase angle decreases significantly after adding FF, indicating that FFOR is better than OER at this time. In addition, as the applied potential increases, the phase angle decreases further, indicating that PdRh@Cu 2 O Increase in FFOR rate on NRAs / CF. Figure 3 g is PdRh@Cu 2 NaSCN poisoning mechanism diagram of O NRAs / CF catalyst, the results show that its excellent FFOR catalytic performance is attributed to Cu 0 and Cu + synergistic effect. Figure 3 h, at 0.14V RHE Under a constant potential of 3000 seconds, one electrolysis cycle, PdRh@Cu 2 ONRAs / CF can always maintain 100 mA cm before 3 cycles. -2 The current density of 2.5 N·m is 0.17 W, which indicates its excellent cycling stability.

[0087] Figure 4The PdRh@Cu provided in Example 1 of the present invention 2 O NRAs / CF catalyst hydrogen evolution reaction test, specifically, the working electrode is the catalyst prepared in Example 1 or Comparative Examples 1 to 4, the reference electrode is a saturated calomel electrode, the counter electrode is a graphite electrode, the electrolyte is 1.0M KOH solution, and during the test, the voltage scan rate is 10mV / s.

[0088] Among them, (a) is PdRh@Cu 2 O NRAs / CF and Cu in Comparative Example 2 2 O NRAs / CF, Pd@Cu in Comparative Example 3 2 ONRAs / CF and Rh@Cu in Comparative Example 4 2 Reaction barrier diagram of O NRAs / CF in water dissociation; (b) is the corresponding LSV curve in 1.0M KOH solution; (c) is the free energy change diagram of the HER process; (d) is the corresponding Tafel slope; (e) is the free energy change diagram at -0.4V RHE Nyquist curve when ; (f) is the corresponding C dl ; (g) is PdRh@Cu 2 It curves of O NRAs / CF; (h) PdRh@Cu 2 Cu LMM spectra of O NRAs / CF after HER test.

[0089] Figure 4 It is PdRh@Cu 2 Electrochemical reaction hydrogen evolution test diagram of O NRAs / CF catalyst. Figure 4 a It can be seen that PdRh@Cu 2 O NRAs / CF has the lowest energy barrier (0.98 eV) compared to Cu 2 ONRAs / CF(1.29eV), Pd@Cu 2 ONRAs / CF (1.18 eV) and Rh@Cu 2 O NRAs / CF (1.15 eV), indicating its promoted water splitting energy. Figure 4 b, PdRh@Cu 2 ONRAs / CF exhibits excellent hydrogen evolution reaction (HER) activity, reaching -10 mA cm at only 32 mV. -2 The current density is much lower than CF (422mV) and Cu(OH) 2 NRAs / CF(358mV),Cu 2 O NRAs / CF (337mV), Pd@Cu 2 O NRAs / CF (221mV) and Rh@Cu2 O NRAs / CF (88mV). Figure 4 PdRh@Cu 2 The rate-determining step (RDS) of O NRAs / CF is * H recombination (0.16 eV), lower than Cu 2 ONRAs / CF(0.31eV) and Pd@Cu 2 O NRAs / CF (0.28eV). 2 O The RDS of NRAs / CF is * The formation of H (0.19 eV) indicates that the presence of Pd promotes * The formation of H, while Rh is beneficial * H recombine to form H 2 .

[0090] pass Figure 4 The Tafel slope of d can further clarify the HER reaction mechanism of the electrocatalyst. 2 The Tafel slope of ONRAs / CF catalyst (58 mV dec -1 ) is the smallest, compared to CF (100mV dec -1 )、Cu(OH) 2 NRAs / CF(98mV dec -1 ),Cu 2 O NRAs / CF(96mV dec -1 ), Pd@Cu 2 O NRAs / CF(97mV dec -1 ) and Rh@Cu 2 O NRAs / CF(95mV dec -1 ), indicating that it has fast HER kinetics. Figure 4 e, PdRh@Cu 2 O R of NRAs / CF ct The value is 3.49Ω, which is lower than CF (68.77Ω) and Cu(OH) 2 NRAs / CF(26.81Ω),Cu 2 O NRAs / CF(19.85Ω), Pd@Cu 2 O NRAs / CF (14.68Ω) and Rh@Cu 2 O NRAs / CF (6.20Ω), again indicating that PdRh@Cu 2 The IEFs in O NRAs / CFs promote the charge transfer ability. Figure 4 f is the double-layer capacitance (Cdl ), it can be seen from the double layer capacitance value that PdRh@Cu 2 C of ONRAs / CF dl (34mF cm -2 ) is significantly higher than CF (7mF cm -2 )、Cu(OH) 2 NRAs / CF(8mF cm -2 ),Cu 2 O NRAs / CF(13mF cm -2 ), Pd@Cu 2 O NRAs / CF(14mF cm -2 ) and Rh@Cu 2 O NRAs / CF(18mF cm -2 ), which is mainly due to the PdRh@Cu 2 The IEFs in O NRAs / CF provide more active sites.

[0091] Figure 4 g shows that PdRh@Cu 2 The O NRAs / CF catalyst also has good stability and can maintain a constant current density within 10 h. Figure 4 After long-term electrolysis, Cu 0 / Cu + The ratio is 0.15, which is almost the same as the initial ratio (0.14), indicating that PdRh@Cu 2 O Excellent stability of NRAs / CF.

[0092] In summary, the introduction of Pd and Cu 0 / Cu + The reconstruction of PdRh@Cu 2 O NRAs / CF has the ability to adsorb FF molecules and promotes the cleavage of CH bonds. * GDA is converted to * FAC. Rh further decreases * H 2 The adsorption energy of H 2 The desorption capacity of PdRh is improved, which reduces the energy barrier of low-potential FFOR. In addition, PdRh synergistically promotes water dissociation and * H is recombined into H 2 , enhance HER performance. The catalyst prepared by the present invention has both PdRh alloy and Cu 0 and Cu + The advantages of synergistic effect can be used as an excellent low-potential furfural oxidation and hydrogen evolution dual-functional catalytic material.

[0093] Application Examples

[0094] The PdRh@Cu prepared in Example 1 2 O NRAs / CF catalysts were used as anode and cathode materials of the bipolar hydrogen production system, respectively. The electrolyte solution of the anode was a 1.0 M KOH solution containing 0.1 M FF, and the electrolyte solution of the cathode was a 1.0 M KOH solution. The cathode and anode were separated by an anion exchange membrane, such as Figure 5 As shown in a. Figure 5 (a) is a real photo and schematic diagram of the coupled FFOR and HER flow electrolysis cell; (b) is a PdRh@Cu 2 LSV curves of O NRAs / CF electrode pair in FFOR / / HER and OER / / HER (scan rate was 10 mV / s during testing); (c) PdRh@Cu 2 The concentration and carbon balance of the anodic products of O NRAs / CF in 1.0M KOH+0.15MFF change with time; FAL represents furfuryl alcohol; (d) represents PdRh@Cu 2 O NRAs / CF in 1.0 M KOH catalysis cathode hydrogen volume change; (e) is the corresponding H 2 The graph of the change and Faraday efficiency, where theoretical in e represents the theoretical H 2 Output, measured means the actual measured H 2 Yield.

[0095] Figure 5 b PdRh@Cu 2 Compared with the conventional OER / / HER, the LSV of FFOR / / HER catalyzed by O NRAs / CF electrode pair can save 1.43 V of energy to achieve 100 mA cm -2 The current density shows that the FFOR / / HER system is expected to replace the traditional water electrolysis to produce hydrogen in a more energy-efficient way.

[0096] Figure 5 In c, as the electrolysis time increases, the concentration of the anode reactant furfural decreases to produce the product furoic acid, accompanied by a small amount of furfuryl alcohol (FAL) produced by the Cannizzaro disproportionation reaction. Finally, within 4 hours, the calculated furfural conversion rate is 94%, and the yield and selectivity of furoic acid are 70% and 74%, respectively. At the same time, the carbon balance is close to 100%, indicating that the reactants and products are conserved in this process. Figure 5 d reflects the change in the volume of hydrogen generated at the cathode with the amount of charge, and its corresponding amount of substance relationship is as follows Figure 5 As shown in e, a high Faradaic efficiency (≈100%) is exhibited.

[0097] The catalyst prepared by the present invention has excellent electrochemical hydrogen evolution and furfural oxidation bifunctional catalytic performance and good stability, and can construct a high-efficiency and low-energy bipolar hydrogen production system by coupling the anode low-potential furfural oxidation reaction with the cathode hydrogen evolution reaction.

[0098] 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 protection scope of the present invention.

Claims

1. A method for preparing a PdRh alloy-wrapped cuprous oxide nanorod array bifunctional catalyst, It is characterized in that The following steps are involved: The copper foam was immersed in a solution containing NaOH and (NH 4 ) 2 S 2 O 8 The precursor Cu(OH) 2 NRAs / CFs; The precursor Cu(OH) 2 NRAs / CF was placed in a PdCl 2 and RhCl 3 The mixture is placed in a mixed aqueous solution, heated for reaction, washed, and dried to obtain a PdRh alloy-wrapped cuprous oxide nanorod array bifunctional catalyst.

2. The method for preparing the PdRh alloy-wrapped cuprous oxide nanorod array bifunctional catalyst according to claim 1, It is characterized in that The containing NaOH and (NH 4 ) 2 S 2 O 8 The concentration of NaOH in the mixed aqueous solution is 2.5-3.0 M, (NH 4 ) 2 S 2 O 8 The concentration is 0.10~0.15M.

3. The method for preparing the PdRh alloy-wrapped cuprous oxide nanorod array bifunctional catalyst according to claim 1, It is characterized in that The copper foam was immersed in a solution containing NaOH and (NH 4 ) 2 S 2 O 8 The soaking time in the mixed aqueous solution is 25 to 35 minutes.

4. The method for preparing the PdRh alloy-wrapped cuprous oxide nanorod array bifunctional catalyst according to claim 1, It is characterized in that The PdCl 2 and RhCl 3 PdCl in a mixed aqueous solution 2 The concentration of RhCl is 3-7mM 3 The concentration is 8-12mM.

5. The method for preparing the PdRh alloy-wrapped cuprous oxide nanorod array bifunctional catalyst according to claim 1, It is characterized in that The precursor Cu(OH) 2 NRAs / CF was placed in a PdCl 2 and RhCl 3 The mixed aqueous solution is heated at 80-100°C for 1-2h.

6. The method for preparing the PdRh alloy-wrapped cuprous oxide nanorod array bifunctional catalyst according to claim 1, It is characterized in that The copper foam was immersed in a solution containing NaOH and (NH 4 ) 2 S 2 O 8 Before the copper foam is added into the mixed aqueous solution, the copper foam is also pretreated, and the pretreatment specifically includes: The copper foam was ultrasonically cleaned in hydrochloric acid, ethanol and water respectively to remove oxides on the surface of the copper foam.

7. A PdRh alloy-wrapped cuprous oxide nanorod array bifunctional catalyst. It is characterized in that The preparation is obtained by the preparation method according to any one of claims 1 to 6.

8. Use of the PdRh alloy-wrapped cuprous oxide nanorod array bifunctional catalyst as claimed in claim 7 in bipolar hydrogen production.

9. The use as claimed in claim 8, wherein the bipolar hydrogen production is a low-power bipolar hydrogen production system constructed by coupling the anode furfural oxidation reaction and the cathode hydrogen evolution reaction.

10. The use according to claim 8, wherein the PdRh alloy-wrapped cuprous oxide nanorod array bifunctional catalyst serves as both anode and cathode materials.

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