Preparation method of Cu2O / Cu / Mn2O3 catalyst with enhanced hydrogen overflow effect for anode electrocatalytic hydrogen evolution

Abstract

A method for preparing a Cu2O / Cu / Mn2O3 catalyst with enhanced hydrogen spillover effect for anode electrocatalytic hydrogen evolution belongs to the technical field of anode electrocatalytic hydrogen evolution. The catalyst comprises a three-dimensional nanocomposite Cu2O / Cu / Mn2O3 heterostructure anode hydrogen evolution catalyst composed of approximately 20nm Cu2O / Cu and 30-70nm Mn2O3 nanoparticles. The Cu2O / Cu / Mn2O3 heterostructure catalyst with enhanced hydrogen spillover effect was prepared by a hydrothermal method and a photosensitive oxidation treatment technique. The catalyst obtained by this method achieves stable anode hydrogen evolution at low voltage and high current density in an alkaline formaldehyde solution environment, and as an anode, it reaches 100mA cm ‑2 Only a potential of 0.128V is required under the current density. By enhancing the hydrogen overflow effect, the barrier of electrocatalytic hydrogen evolution can be effectively lowered, energy consumption can be reduced, and hydrogen evolution efficiency and purity can be improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of anode electrocatalytic hydrogen evolution, and in particular relates to a method for preparing a Cu2O / Cu / Mn2O3 heterostructure catalyst with enhanced hydrogen overflow effect. Background Art

[0002] Hydrogen energy is not only a crucial component of the future global energy system but also crucial for building a green, low-carbon industrial system. Hydrogen evolution by water electrolysis, powered by wind or solar energy, is considered a sustainable green development strategy due to its simple process, high hydrogen purity, and zero carbon emissions. Water electrolysis involves the hydrogen evolution reaction (HER) at the cathode and the oxygen evolution reaction (OER) at the anode. The OER (oxygen evolution reaction) (OER) is a slow and complex four-electron kinetic process, significantly increasing the overall energy consumption of electrocatalytic hydrogen evolution (>1.23 V). Therefore, exploring superior oxidation reactions with lower energy input to replace the OER is of great significance. For example, the anodic OER reaction can be replaced by the oxidation of organic compounds such as urea, toluene, hydrazine, amines, and methylene blue. These molecules are more readily oxidized than water, enhancing the kinetics of the anodic oxidation reaction and further promoting hydrogen evolution at the cathode. Despite significant progress in this area, hydrogen is only produced at the cathode, and the required cell voltage for the entire system remains greater than 1 V, resulting in high energy consumption. A more ideal approach would be to produce higher value-added products, such as hydrogen, at the anode with lower energy input.

[0003] What is particularly interesting is that the oxidation reaction (FOR) of aldehyde organic matter at the anode can proceed at ultra-low potential and produce H2. Researchers have proposed a double-sided H2 production electrolyzer using biomass-derived aldehydes (such as furfural) and KOH as electrolyte solutions. However, biomass-derived aldehydes have a low hydrogen content, which will increase the raw material cost of hydrogen production. HCHO stands out among aldehydes because of its high hydrogen content and water solubility. In addition, formaldehyde has a small thermodynamic barrier to produce hydrogen at the anode (HCHO+2OH - →HCOO - +1 / 2H2+H2O+e - , E = -0.22V vs. RHE). Furthermore, HCHO is converted to formate, a more valuable chemical feedstock, while generating H2 at the anode. This method achieves multiple goals at one stroke. Cu-based catalysts have been shown to catalyze formaldehyde oxidation at ultra-low potentials. However, FOR catalysts are currently understudied and face key challenges such as low catalytic activity, high barriers to C-H bond cleavage and H-H bond formation, and unclear reaction mechanisms. Therefore, it is particularly important to design catalysts with appropriate electronic structures to address key issues such as high anode potentials and high energy barriers to C-H bond cleavage and H-H bond formation. Summary of the Invention

[0004] The present invention provides a strategy for electrocatalytic hydrogen evolution at the anode of a Cu2O / Cu / Mn2O3 heterostructure catalyst. By constructing a Cu2O / Cu / Mn2O3 heterostructure, the electronic structure of the active site is optimized, and the hydrogen overflow effect is promoted to reduce the transition potential barrier of C-H bond rupture and H-H bond formation, thereby reducing the FOR anode potential and improving the FOR performance.

[0005] A method for preparing a Cu2O / Cu / Mn2O3 catalyst with enhanced hydrogen spillover effect for anode electrocatalytic hydrogen evolution is characterized in that the Cu2O / Cu / Mn2O3 heterostructure catalyst is synthesized by a hydrothermal method and a photosensitive oxidation treatment technology, comprising the following steps:

[0006] (1) MnO was synthesized by hydrothermal method. x Nanoparticles.

[0007] (2) Through hydrothermal method, MnO x Cu nanoparticles were synthesized on the surface of the nanoparticles.

[0008] (3) The Cu2O / Cu / Mn2O3 heterostructure catalyst was finally prepared through photosensitive oxidation treatment technology. The photosensitive oxidation treatment process mainly removes organic matter on the catalyst surface and simultaneously generates a Cu2O active layer.

[0009] Furthermore, in step (1), MnO x During the nanoparticle preparation process, 0.3M ammonium oxalate solution and 0.05M potassium permanganate solution are preferred raw materials. The specific steps are to prepare 0.3M ammonium oxalate solution and 0.05M potassium permanganate solution, respectively, and add the ammonium oxalate solution dropwise to the potassium permanganate solution while stirring evenly, with 10mL of potassium permanganate solution for every 3mL of ammonium oxalate solution. The mixed solution is hydrothermally reacted at 90°C for 10 hours. The resulting solution is centrifuged, washed with deionized water, and dried at 105°C for 10 hours to obtain nano-manganese oxide particles.

[0010] In the further step (2), in MnO x In the process of synthesizing Cu nanoparticles on the surface of nanoparticles, oleylamine solution and copper acetylacetonate raw materials are preferred. The specific steps are as follows: x The nanoparticles were added to the oleylamine solution and stirred evenly, and then copper acetylacetonate powder was added. xThe nanoparticles are prepared by mixing 50 mL of oleylamine and 0.5 g of copper acetylacetonate powder. After stirring, the mixture is hydrothermally reacted at 230°C for 6 hours. The resulting solution is centrifuged, washed with anhydrous ethanol, and centrifuged three times. Subsequently, the mixture is dispersed in cyclohexane to obtain a Cu / Mn2O3 dispersion. The mass ratio of manganese oxide particles to copper is 1:0.5-1.5, preferably 1:1.

[0011] In the further step (3), during the Cu oxidation process, a photosensitive oxidation treatment technology is preferably used, and the specific steps are: adding the Cu / Mn2O3 dispersion dispersed in step (2) dropwise to a carbon cloth (CC, for example 1×1.5 cm 2 , 0.02 g), and then subjected to a photosensitive oxidation treatment in an ultraviolet ozone cleaning machine for 2 h. The photosensitive oxidation process mainly removes organic matter on the catalyst surface and simultaneously generates a cuprous oxide (Cu2O) active layer, ultimately obtaining a Cu2O / Cu / Mn2O3-CC catalyst with enhanced hydrogen spillover effect.

[0012] A method for preparing a Cu2O / Cu / Mn2O3 catalyst with enhanced hydrogen spillover effect for anode electrocatalytic hydrogen evolution is characterized by synthesizing a three-dimensional nanocomposite Cu2O / Cu / Mn2O3 heterostructure anode electrocatalytic hydrogen evolution catalyst composed of approximately 20nm Cu2O / Cu grown on 30-70nm Mn2O3 nanoparticles using a hydrothermal method and a photosensitive oxidation treatment technology, and can enhance the hydrogen spillover effect and promote electrocatalytic hydrogen evolution.

[0013] The Cu2O / Cu / Mn2O3-CC catalyst obtained by the present invention is used as an anode in a mixed solution of HCHO and KOH to improve the hydrogen production efficiency by enhancing the hydrogen overflow effect.

[0014] The electrochemical performance of different catalysts for FOR was further tested in a mixed solution of 0.45 M HCHO and 1.0 M KOH using an electrochemical test system. Graphite sheet and mercury oxide electrode were used as counter electrode and reference electrode, respectively, and the catalyst was used as working electrode. Linear sweep voltammetry (LSV) was used at 5 mV s -1 Polarization curves were measured at a scan rate of 100 nm and a compensation of 95% iR. The test area of ​​the electrocatalyst was 1×1 cm 2 The loading of different catalysts is 20 mg / cm 2 The test results show that Cu2O / Cu / Mn2O3 electrocatalyst has excellent FOR performance. -2 The anode potential at this current density is only 0.128 V, which is lower than that of Cu2O / Cu catalyst (0.25 V) and much lower than that of OER anode (1.73 V).

[0015] A Cu2OCuMn2O3 catalyst with enhanced hydrogen overflow effect for anode electrocatalytic hydrogen evolution, characterized in that in step (2), MnO x The best performance is achieved when the mass ratio of particles to Cu element is 1:1.

[0016] Further DFT theoretical calculations revealed that the Cu2O / Cu / Mn2O3 heterostructure catalyst promotes the hydrogen spillover effect, resulting in lower energy barriers for C-H bond rupture (0.48 eV) and H-H bond formation (-0.99 eV). During the anodic FOR process, HCHO and OH- first react on the Cu site of the Cu2O / Cu / Mn2O3 catalyst to generate H2C(OH)O*. Subsequently, H2C(OH)O* decomposes into H2CO2 and H* under the catalytic action of Cu at the active site. Driven by the potential, the H* on the Cu site spontaneously migrates to the Mn site through the hydrogen spillover effect. Finally, the two H* combine to generate H2 under the catalytic action of Mn at the active site. Ultimately, the Cu2O / Cu / Mn2O3 heterostructure catalyst promotes FOR by promoting the hydrogen spillover effect, achieving low-potential and efficient anodic electrocatalytic hydrogen evolution.

[0017] Advantages of the present invention:

[0018] 1. A three-dimensional nanocomposite Cu2O / Cu / Mn2O3 heterostructured anodic hydrogen evolution catalyst composed of approximately 20nm Cu2O / Cu and 30-70nm Mn2O3 nanoparticles was synthesized by hydrothermal method and photosensitive oxidation treatment technology.

[0019] 2. The Cu2O / Cu / Mn2O3 electrocatalyst has excellent FOR performance at 100 mA cm -2 The anode potential at this current density is only 0.128 V, which is lower than that of Cu2O / Cu catalyst (0.25 V) and much lower than that of OER anode (1.73 V).

[0020] 3. The Cu2O / Cu / Mn2O3 heterostructure catalyst formed by this method can promote the hydrogen overflow effect and reduce the energy barrier of CH bond breaking and HH bond formation. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the preparation process of Cu2O / Cu / Mn2O3 heterostructure catalyst;

[0022] Figure 2 (a)MnO x SEM images of the catalyst and (bc) Cu2O / Cu / Mn2O3 heterostructure catalyst;

[0023] Figure 3 MnO x , XRD patterns of Cu and Cu2O / Cu / Mn2O3 electrocatalysts;

[0024] Figure 4 Cu, MnO x , LSV curves of Cu2O / Cu, Cu / Mn2O3 and Cu2O / Cu / Mn2O3 electrocatalysts FOR;

[0025] Figure 5 Transition potential barriers for (a) C-H bond cleavage and (b) H-H bond formation of Cu, Cu2O, Mn2O3, and Cu2O / Cu / Mn2O3 catalysts. DETAILED DESCRIPTION

[0026] The following is a further description of a method for preparing a Cu2OCuMn2O3 catalyst with enhanced hydrogen overflow effect for anode electrocatalytic hydrogen evolution using an embodiment, but the present invention is not limited to the following embodiments.

[0027] Example 1

[0028] First, prepare 60 mL of 0.3 M ammonium oxalate solution and 200 mL of 0.05 M potassium permanganate solution. Add the ammonium oxalate solution dropwise to the potassium permanganate solution and stir evenly. The mixed solution is hydrothermally reacted at 90°C for 10 h. The solution after the redox reaction is centrifuged and then washed with deionized water and centrifuged three times. After drying at 105°C for 10 h, nano manganese oxide particles are obtained. 0.6-0.18 g of nano manganese oxide particles are added to 50 mL of oleylamine solution and stirred evenly. Then, 0.5 g of copper acetylacetonate powder is added. After stirring evenly, a hydrothermal reaction is carried out at 230°C for 6 h. The reaction solution is centrifuged and then washed with anhydrous ethanol and centrifuged three times. Subsequently, it is dispersed with cyclohexane solution to obtain a Cu / Mn2O3 dispersion. The dispersed solution is added dropwise to a carbon cloth (CC, 1×1.5 cm 2 , 0.02g) and then subjected to a photosensitive oxidation treatment in an ultraviolet ozone cleaning machine for 2 hours. The photosensitive oxidation treatment process mainly removes organic matter on the catalyst surface and simultaneously generates a cuprous oxide (Cu2O) active layer. Finally, a Cu2O / Cu / Mn2O3-CC catalyst with enhanced hydrogen overflow effect is obtained. Figure 1The figure shows the preparation process flow chart of Cu2O / Cu / Mn2O3-CC catalyst. The Cu2O / Cu / Mn2O3 catalysts with the mass ratio of manganese oxide particles to Cu element of 1:0.5, 1:0.75, 1:1, 1:1.25 and 1:1.5 prepared by adding 0.6, 0.9, 0.12, 0.15 and 0.18 g of nano manganese oxide particles are respectively marked as Cu2O / Cu / Mn2O3 (1:0.5), Cu2O / Cu / Mn2O3 (1:0.75), Cu2O / Cu / Mn2O3 (1:1), Cu2O / Cu / Mn2O3 (1:1.25) and Cu2O / Cu / Mn2O3 (1:1.5) samples. In order to better compare the electrocatalytic performance of Cu2O / Cu / Mn2O3-CC catalysts, Cu-CC, MnO x -CC, Cu2O / Cu-CC, and Cu / Mn2O3-CC catalysts were prepared.

[0029] like Figure 2 This is an SEM image of a Cu2O / Cu / Mn2O3 (1:1) heterostructured anode catalyst for electrocatalytic hydrogen evolution, showing enhanced hydrogen spillover. A three-dimensional nanocomposite Cu2O / Cu / Mn2O3 heterostructured anode catalyst composed of approximately 20nm Cu2O / Cu and 30-70nm Mn2O3 nanoparticles was synthesized using a hydrothermal method and photooxidation treatment.

[0030] like Figure 3 XRD pattern of Cu2O / Cu / Mn2O3 (1:1) heterostructure anode electrocatalytic hydrogen evolution catalyst with enhanced hydrogen overflow effect. x The crystal structures of Cu / Mn2O3 and Cu2O / Cu / Mn2O3 (1:1) catalysts were studied. x The catalyst has poor crystallinity, and its diffraction peak at 36.22° corresponds to the (110) crystal plane of δ-MnO2 (JCPDS No.80-1098). The three diffraction peaks of the Cu catalyst at 43.32°, 50.45° and 74.12° correspond to the (111), (200) and (220) crystal planes of the face-centered cubic structure of Cu (JCPDS No.85-1326), respectively. In addition to the three diffraction peaks of Cu, the Cu / Mn2O3 catalyst also contains three diffraction peaks of Mn2O3. The three diffraction peaks at 32.93°, 35.62° and 38.21° correspond to the (222), (321) and (400) crystal planes of the face-centered cubic structure of Mn2O3 (JCPDS No.71-0636), respectively. The increase of Mn2O3 is mainly due to the excessive amount of reducing oleylamine in the second step hydrothermal process. 4+ Reduced to Mn3+ . In addition to the three diffraction peaks of Cu and three diffraction peaks of Mn2O3, the Cu2O / Cu / Mn2O3 catalyst also has two diffraction peaks of Cu2O. The two diffraction peaks at 36.57° and 61.65° correspond to the (111) and (220) crystal planes of body-centered cubic Cu2O (JCPDS No.74-1230), respectively. In summary, the Cu2O / Cu / Mn2O3 catalyst with enhanced hydrogen spillover effect is composed of three substances: body-centered cubic Cu2O, face-centered cubic Cu, and face-centered cubic Mn2O3.

[0031] like Figure 4 FOR LSV performance diagram of Cu2O / Cu / Mn2O3 (1:1) heterostructure anode electrocatalytic hydrogen evolution catalyst with enhanced hydrogen overflow effect.

[0032] The electrochemical measurement system was obtained at room temperature by a CHI660E electrochemical workstation (CH Instruments, China) equipped with a fast digital signal generator and a dual-channel high-speed data acquisition system. The electrochemical test systems were all standard three-electrode systems, with graphite sheets and mercury oxide electrodes as counter electrodes and reference electrodes, respectively. The FOR electrochemical performance of different catalysts was tested in a mixed solution of 0.45 M HCHO and 1 M KOH. In order to obtain a more comprehensive electrochemical performance study, the HER and OER performance of the catalysts were tested in a 1 M KOH solution. The test area of ​​the electrocatalyst was 1 × 1 cm 2 The loading of different catalysts is 20 mg / cm 2 The measured potential was calibrated to the standard hydrogen electrode (RHE) potential. Linear sweep voltammetry (LSV) was used at 5 mVs -1 Polarization curves were tested at a scan rate of 100 nm and a compensation of 95% iR.

[0033] The Cu2O / Cu / Mn2O3 (1:1) electrocatalyst with enhanced hydrogen spillover effect exhibits the best FOR performance, achieving 100 mA cm at only 128 mV. -2 The current density is much lower than that of Cu2O / Cu (252mV), Cu / Mn2O3 (430mV), Cu and MnO x Electrocatalyst: MnO x The electrocatalyst reacts at a low potential with a current of 0 mA cm -2 , indicating that it has basically no FOR capability at low voltage. For different Cu2O / Cu / Mn2O3 electrocatalysts, as MO x With the increase of Cu ratio, the FOR performance of Cu2O / Cu / Mn2O3 electrocatalyst showed a trend of increasing first and then decreasing (e.g. Figure 4), Cu2O / Cu / Mn2O3(1:1) electrocatalyst has the best FOR performance. The first increase in the FOR performance of Cu2O / Cu / Mn2O3 electrocatalyst is mainly due to the synergistic promotion of Cu2O, Cu and Mn2O3.

[0034] like Figure 5 Theoretical calculation diagram of Cu2O / Cu / Mn2O3 heterostructure anode electrocatalytic hydrogen evolution catalyst with enhanced hydrogen overflow effect.

[0035] The CH bond breaking transition barriers of Cu, Cu2O, Mn2O3 and Cu2O / Cu / Mn2O3 catalysts are 0.84eV, 1.06eV, 2.09eV and 0.48eV, respectively. Figure 5 (a) The CH bond breaking barrier of Cu2O / Cu / Mn2O3 catalyst is the smallest and is the easiest to break, followed by Cu, Cu2O and Mn2O3. The HH bond formation transition barriers of Cu, Cu2O, Mn2O3 and Cu2O / Cu / Mn2O3 catalysts are 0.83eV, 1.00eV, 0.19eV and -0.99eV, respectively. Figure 5 (b) The Cu2O / Cu / Mn2O3 catalyst has the lowest barrier to HH bond formation, followed by Mn2O3, Cu, and Cu2O. DFT theoretical calculations indicate that the Cu2O / Cu / Mn2O3 heterostructure catalyst promotes hydrogen spillover, resulting in lower energy barriers for C-H bond rupture (0.48 eV) and HH bond formation (-0.99 eV). During the anodic FOR process, HCHO and OH- first react on the Cu site of the Cu2O / Cu / Mn2O3 catalyst to form H2C(OH)O*. Subsequently, H2C(OH)O* decomposes into H2CO2 and H* under the catalytic action of the active Cu site. Driven by the potential, the H* on the Cu site spontaneously migrates to the Mn site via the hydrogen spillover effect. Finally, the two H* combine to form H2 under the catalytic action of the Mn active site. Finally, the Cu2O / Cu / Mn2O3 heterostructure catalyst promotes FOR by promoting the hydrogen overflow effect, achieving low-potential and efficient anodic electrocatalytic hydrogen evolution.

Claims

1. A method for preparing a Cu2O / Cu / Mn2O3 catalyst with enhanced hydrogen overflow effect for anode electrocatalytic hydrogen evolution, characterized in that: A Cu2O / Cu / Mn2O3 heterostructure catalyst with enhanced hydrogen overflow effect was synthesized by hydrothermal method and photosensitive oxidation treatment technology, including the following steps: (1) MnO was synthesized by hydrothermal method. x Nanoparticles; (2) In MnO x Cu nanoparticles were synthesized on the surface of nanoparticles. The specific steps were to x The nanoparticles were added to an oleylamine solution and stirred evenly, followed by the addition of copper acetylacetonate powder for a solvothermal reaction. The resulting solution was centrifuged, washed with anhydrous ethanol, and centrifuged again. Subsequently, the solution was dispersed with a cyclohexane solution to obtain a Cu / Mn2O3 dispersion. (3) The Cu / Mn2O3 dispersion prepared in step (2) is added dropwise onto the carbon cloth, and then subjected to a photosensitive oxidation treatment in an ultraviolet ozone cleaning machine; the photosensitive oxidation treatment process removes organic matter on the catalyst surface and simultaneously generates a cuprous oxide (Cu2O) active layer, ultimately obtaining a Cu2O / Cu / Mn2O3-CC catalyst with enhanced hydrogen overflow effect; the mass ratio of manganese oxide particles to Cu element in the Cu2O / Cu / Mn2O3 catalyst is 1:0.75-1.

2. The method according to claim 1, characterized in that The mass ratio of manganese oxide particles to Cu element is 1:0.

75.

3. The method according to claim 1, characterized in that The mass ratio of manganese oxide particles to Cu element is 1:

1.

4. A Cu2O / Cu / Mn2O3 catalyst with enhanced hydrogen spillover effect is prepared according to the method described in any one of claims 1-3.

5. The Cu2O / Cu / Mn2O3 catalyst with enhanced hydrogen spillover effect prepared by the method described in any one of claims 1-3 is composed of 20 nm Cu2O / Cu grown on 30-70 nm Mn2O3 nanoparticles to form a three-dimensional nanocomposite Cu2O / Cu / Mn2O3 heterostructure anode electrocatalytic hydrogen evolution catalyst.

6. Use of the Cu2O / Cu / Mn2O3 catalyst prepared by the method described in any one of claims 1-3 as an anode for a mixed solution of HCHO and KOH to improve hydrogen production efficiency by enhancing the hydrogen overflow effect.

7. According to the use of claim 6, during the anodic electrochemical reaction (FOR) process, HCHO and OH- first react at the Cu site of the Cu2O / Cu / Mn2O3 catalyst to generate H2C(OH)O*, which is then decomposed into H2CO2 and H* under the catalytic action of Cu at the active site. Driven by the electric potential, the H* at the Cu site spontaneously migrates to the Mn site through a hydrogen spillover effect. Finally, the two H* combine to generate H2 under the catalytic action of Mn at the active site. Finally, the Cu2O / Cu / Mn2O3 heterostructure catalyst promotes FOR by promoting the hydrogen spillover effect, thereby achieving low-potential and high-efficiency anodic electrocatalytic hydrogen evolution.

8. The use according to claim 6, wherein the Cu2O / Cu / Mn2O3 catalyst with enhanced hydrogen spillover effect as an anode reaches 100 mA cm in a mixed solution of HCHO and KOH. -2 Only a potential of 0.128 V is required at this current density.

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