Method for application of tin dioxide doped cuprous oxide composite nanocatalyst in photoelectrocatalytic reduction of carbon dioxide

Abstract

The application belongs to the technical field of electrocatalysis application, and relates to a composite catalytic electrode, in particular to an application method of a tin dioxide doped cuprous oxide composite nano catalyst in carbon dioxide photoelectrocatalytic reduction, which comprises the following steps: taking a BiVO4 loaded FTO or platinum sheet electrode as a working electrode, taking a carbon paper loaded with Cu2O-SnO2 composite nanoparticles as a counter electrode, adding prepared CO2 saturated electrolyte solution to both sides of an H-shaped electrolytic cell, continuously introducing CO2 to remove oxygen, and then performing catalytic reduction of carbon dioxide under light or light conditions at a gas flow rate of 20-100 mL / min and at 20-30 DEG C. In the application, the small ball type SnO2 is compounded on the surface of the concave octahedral Cu2O, the electrochemical impedance of the catalyst is effectively reduced, the formation of CO2RR intermediates is accelerated, and the electrochemical active area of the catalyst is enhanced. After the anode is excited by light, the catalyst exhibits stronger catalytic activity, and has good application prospect in the fields of environment and energy.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalysis application technology, and relates to composite catalytic electrodes, particularly to a method for applying a tin dioxide-doped cuprous oxide composite nanocatalyst in the photoelectrocatalytic reduction of carbon dioxide. Background Technology

[0002] In recent decades, with the continuous increase in carbon dioxide concentration, CO2 reduction (CO2RR) has become an imperative solution. Although electrocatalysis and photocatalysis are relatively mature reduction methods, both face their limitations. For example, electrocatalysis heavily relies on electrical energy input, while photocatalysis still has unsatisfactory CO2 conversion efficiency and product selectivity. Photoelectrocatalytic reduction combines the advantages of electrocatalysis and photocatalysis, providing a promising approach to improve CO2 conversion efficiency and reduce energy input. To date, there are few published studies on photoelectrocatalytic CO2 reduction applications using photoanodes as working electrodes. Kim et al. achieved high selectivity for CO2 reduction on a copper cathode plate under different bias voltages by preparing the 040 crystal facet of BiVO4 in a photoanode (working electrode)-cathode system. Liu et al. achieved highly efficient photoelectrocatalytic reduction of carbon dioxide to liquid fuels in a photoanode-cathode (working electrode) system by preparing flower-shaped BiOBr photocatalysts and sheet-like CuO catalysts.

[0003] BiVO4 is a typical n-type semiconductor. Its O 2p and Bi 6s orbitals can promote electron transport from the valence band (VB) to the conduction band (CB), reducing the band gap energy and maintaining excellent stability in aqueous solutions, making it an excellent photoanode material. In aqueous electrolytes, many high-performance electrocatalysts often rely on the use of precious metals, and the high cost hinders their industrial application. Copper-based electrodes have been widely studied due to their non-toxicity, low cost, simple synthesis, and abundant resources. Inexpensive Sn doping and modification can significantly improve the Faradaic efficiency of copper-based electrocatalysts for CO. Density functional theory (DFT) calculations from relevant literature show that the presence of Sn greatly affects the adsorption capacity of Cu, significantly reducing the adsorption capacity of H, thereby leading to increased CO selectivity.

[0004] This invention utilizes a photoanode (working electrode) synthesized from BiVO4 via electrodeposition as the working electrode in a photoanode-cathode system to regulate the photoelectrocatalytic reduction of carbon dioxide by CSx nanocatalysts prepared on a carbon paper substrate in different electrolytes. Furthermore, comparative experiments were conducted using a platinum sheet-CS4 system and a BiVO4-Cu2O system. Summary of the Invention

[0005] The purpose of this invention is to disclose a method for applying a tin dioxide-doped cuprous oxide composite nanocatalyst (Cu2O-SnO2, abbreviated as CSx, x = 1, 2, 3, 4, 5) in the photoelectrochemical reduction of carbon dioxide.

[0006] Technical solution:

[0007] BiVO4 was first grown on the FTO surface using bismuth nitrate, potassium iodide, p-benzoquinone, ethanol, and FTO conductive glass as raw materials via electrodeposition and calcination. Concave octahedral Cu2O was first prepared by constant-temperature stirring using copper sulfate, oleic acid, sodium hydroxide, and sodium ascorbate as raw materials. Then, CSx was prepared by stirring and precipitation using sodium chloride, tin tetrachloride, ethanol, and conductive carbon paper as raw materials.

[0008] A method for applying a tin dioxide-doped cuprous oxide (Cu2O-SnO2) composite nanocatalyst in the photoelectrocatalytic reduction of carbon dioxide includes: using an FTO or platinum sheet electrode loaded with BiVO4 as the working electrode, and a carbon paper loaded with Cu2O-SnO2 composite nanoparticles as the counter electrode; adding a prepared CO2-saturated electrolyte solution to both sides of an H-type electrolytic cell; continuously introducing CO2 to remove oxygen; and then performing the catalytic reduction of carbon dioxide under light or light conditions at a gas flow rate of 20–100 mL / min and at 20–30 °C.

[0009] In a preferred embodiment of the present invention, the CO2-saturated electrolyte solution is prepared with a concentration of 0.1–0.5 mol·L⁻¹. -1 0.1 mol·L -1 Place the KHCO3, KOH, or NaCl solution in the dark and saturate it with CO2.

[0010] In a preferred embodiment of the present invention, the carbon paper supported on Cu2O-SnO2 composite nanoparticle catalyst is prepared by means of: preparing 50 mL of concave octahedral Cu2O ethanol solution, adding 5 mL of 0.1-0.3 M NaCl solution, and then preparing 50 mL of SnCl4 ethanol solution, wherein the molar ratio of Cu to Sn is 10-50:1; adding the SnCl4 ethanol solution dropwise to the concave octahedral Cu2O ethanol solution, reacting for 5-10 min, centrifuging, washing, and drying under vacuum at 50°C to obtain catalyst particles; finally, using carbon paper as a supporting substrate, ultrasonically homogenizing the catalyst particles and then drop-coating them onto the substrate surface, and drying to obtain the final product.

[0011] In a preferred embodiment of the present invention, the operating voltage of the electrolytic cell is 1.2 to 1.6V.

[0012] The preparation method of the BiVO4 FTO sheet described in this invention is detailed in CN110408951A; the preparation method of the concave octahedral Cu2O is detailed in CN107720803A.

[0013] Features of this invention:

[0014] (1) The introduction of tin element formed a nanoparticle catalyst of small spherical SnO2 supported by concave octahedral Cu2O, which effectively improved its electrochemical active area, thereby increasing the active sites. In addition, the reduction of impedance also made electron transfer faster.

[0015] (2) Using a photoanode (working electrode)-cathode system, the addition of the photoanode can improve CO selectivity and effectively suppress hydrogen evolution effect.

[0016] The CSx composite nanoparticle catalyst prepared in this invention was subjected to morphological, structural and compositional analysis using instruments such as X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The photocurrent density curve (JV) was measured using a standard three-electrode electrochemical workstation to evaluate its photoelectrocatalytic carbon dioxide reduction performance.

[0017] All reactants and reagents used in this invention are commercially available.

[0018] Beneficial effects

[0019] This invention synthesizes BiVO4 photoanode material via electrodeposition and calcination post-treatment, and synthesizes Cu2O-SnO2 cathode material via simple isothermal stirring deposition. The prepared small spherical SnO2 composites on the concave octahedral Cu2O surface effectively reduce the electrochemical impedance of the catalyst, accelerate the formation of CO2RR intermediates, and enhance the electrochemical active area of ​​the catalyst. At the same time, after the anode is photoexcited, the entire system exhibits stronger catalytic activity. The photoanode (working electrode)-cathode system and the prepared Cu2O-SnO2 catalyst have good application prospects in environmental, energy and other fields. Attached Figure Description

[0020] Figure 1 XRD pattern of the CS4 nanoparticle catalyst prepared in Example 4;

[0021] Figure 2 XPS spectrum of the CS4 nanoparticle catalyst prepared in Example 4;

[0022] Figure 3 SEM image of the CS4 nanoparticle catalyst prepared in Example 4;

[0023] Figure 4 TEM image of the CS4 nanoparticle catalyst prepared in Example 4;

[0024] Figure 5Example 4 shows the Faraday efficiency of the CS4 nanoparticle catalyst prepared as the counter electrode and the BiVO4 photoanode as the working electrode.

[0025] Figure 6 The Faraday efficiency diagrams of the CSx nanoparticle catalysts prepared in Examples 1-5 as counter electrodes and BiVO4 photoanodes as working electrodes;

[0026] Figure 7 The Faraday efficiency diagrams of Cu2O nanoparticle catalysts are shown in Examples 4, 6, and 7, where the BiVO4 photoanode and platinum sheet are the working electrodes, and the CS4 nanoparticle catalyst is the counter electrode and the BiVO4 photoanode is the working electrode. Detailed Implementation

[0027] The present invention will be described in detail below with reference to embodiments, so that those skilled in the art can better understand the present invention, but the present invention is not limited to the following embodiments.

[0028] Example 1

[0029] A method for applying a tin dioxide-doped cuprous oxide composite nanoparticle catalyst in photoelectrocatalytic carbon dioxide reduction includes the following steps:

[0030] A. Prepare 60 mL of a solution with a concentration of 0.1 mol·L⁻¹ -1 The KHCO3 solution was placed in the dark and CO2 was continuously bubbled through it for 30 minutes until the solution was saturated.

[0031] B. Using FTO loaded with BiVO4 as the working electrode and carbon paper loaded with CS1 composite nanoparticles as the counter electrode, a CO2-saturated KHCO3 solution was added to both sides of the H-type electrolytic cell, and CO2 was continuously introduced to remove oxygen. Then, carbon dioxide was catalytically reduced under light conditions at a gas flow rate of 50 mL / min and 25 °C.

[0032] The carbon paper supported on the CS1 composite nanoparticle catalyst is prepared by the following method: 50 mL of a 0.3 mM concave octahedral Cu₂O ethanol solution is prepared, followed by 5 mL of a 0.2 M NaCl solution, and then 50 mL of a 0.06 mM SnCl₄ ethanol solution. The molar ratio of Cu to Sn is 10:1 (abbreviated as CS₁). The SnCl₄ ethanol solution is added dropwise to the concave octahedral Cu₂O ethanol solution, and the reaction is allowed to proceed for 5–10 min. The resulting solution is centrifuged, washed, and dried under vacuum at 50 °C. Subsequently, carbon paper is used as the supporting substrate, and the catalyst particles are drop-coated onto its surface after ultrasonic homogenization.

[0033] Within the voltage range of 1.2–1.6 V, the Faraday efficiencies of the CS1 nanocatalyst for H2, CO, and HCOOH are 32%, 38%, and 19.6%, respectively, with an optimal voltage of 1.4 V.

[0034] Example 2

[0035] A method for applying a tin dioxide-doped cuprous oxide composite nanoparticle catalyst in photoelectrocatalytic carbon dioxide reduction includes the following steps:

[0036] A. Prepare 60 mL of a solution with a concentration of 0.1 mol·L⁻¹ -1 The KHCO3 solution was placed in the dark and CO2 was continuously bubbled through it for 30 minutes until the solution was saturated.

[0037] B. Using FTO loaded with BiVO4 as the working electrode and carbon paper loaded with CS1 composite nanoparticles as the counter electrode, a CO2-saturated KHCO3 solution was added to both sides of the H-type electrolytic cell, and CO2 was continuously introduced to remove oxygen. Then, carbon dioxide was catalytically reduced under light conditions at a gas flow rate of 50 mL / min and 25 °C.

[0038] The carbon paper supported on the CS2 composite nanoparticle catalyst is prepared by the following method: 50 mL of a 0.3 mM concave octahedral Cu2O ethanol solution is prepared, followed by 5 mL of a 0.2 M NaCl solution, and then 50 mL of a 0.03 mM SnCl4 ethanol solution. The molar ratio of Cu to Sn is 20:1 (abbreviated as CS2). The SnCl4 ethanol solution is added dropwise to the concave octahedral Cu2O ethanol solution, and the reaction is carried out for 5–10 min. The resulting solution is centrifuged, washed, and dried under vacuum at 50 °C. Subsequently, carbon paper is used as the supporting substrate, and the catalyst particles are drop-coated onto its surface after being ultrasonically homogenized.

[0039] Within the voltage range of 1.2–1.6 V, the optimal voltage for the CS2 nanocatalyst is 1.4 V, and the Faraday efficiencies for H2, CO, and HCOOH are 19%, 50%, and 14%, respectively.

[0040] Example 3

[0041] A method for applying a tin dioxide-doped cuprous oxide composite nanoparticle catalyst in photoelectrocatalytic carbon dioxide reduction includes the following steps:

[0042] A. Prepare 60 mL of a solution with a concentration of 0.1 mol·L⁻¹ -1 The KHCO3 solution was placed in the dark and CO2 was continuously bubbled through it for 30 minutes until the solution was saturated.

[0043] B. Using FTO loaded with BiVO4 as the working electrode and carbon paper loaded with CS3 composite nanoparticles as the counter electrode, a CO2-saturated KHCO3 solution was added to both sides of the H-type electrolytic cell, and CO2 was continuously introduced to remove oxygen. Then, carbon dioxide was catalytically reduced under light conditions at a gas flow rate of 50 mL / min and 25 °C.

[0044] The carbon paper supported on the CS3 composite nanoparticle catalyst is prepared by the following method: 50 mL of a 0.3 mM concave octahedral Cu₂O ethanol solution is prepared, followed by 5 mL of a 0.2 M NaCl solution, and then 50 mL of a 0.02 mM SnCl₄ ethanol solution. The molar ratio of Cu to Sn is 30:1 (abbreviated as CS₃). The SnCl₄ ethanol solution is added dropwise to the concave octahedral Cu₂O ethanol solution, and the reaction is allowed to proceed for 5–10 min. The resulting solution is centrifuged, washed, and dried under vacuum at 50 °C. Subsequently, carbon paper is used as the supporting substrate, and the catalyst particles are drop-coated onto its surface after ultrasonic homogenization.

[0045] Within the voltage range of 1.2–1.6 V, the Faraday efficiencies of CS3 nanocatalysts for H2, CO, and HCOOH are 16.8%, 40%, and 37%, respectively, with an optimal voltage of 1.4 V.

[0046] Example 4

[0047] A method for applying a tin dioxide-doped cuprous oxide composite nanoparticle catalyst in photoelectrocatalytic carbon dioxide reduction includes the following steps:

[0048] A. Prepare 60 mL of a solution with a concentration of 0.1 mol·L⁻¹ -1 The KHCO3 solution was placed in the dark and CO2 was continuously bubbled through it for 30 minutes until the solution was saturated.

[0049] B. Using FTO loaded with BiVO4 as the working electrode and carbon paper loaded with CS4 composite nanoparticles as the counter electrode, a CO2-saturated KHCO3 solution was added to both sides of the H-type electrolytic cell, and CO2 was continuously introduced to remove oxygen. Then, carbon dioxide was catalytically reduced under light conditions at a gas flow rate of 50 mL / min and 25 °C.

[0050] The carbon paper supported on the CS4 composite nanoparticle catalyst is prepared by the following method: 50 mL of a 0.3 mM concave octahedral Cu₂O ethanol solution is prepared, followed by 5 mL of a 0.2 M NaCl solution, and then 50 mL of a 0.015 mM SnCl₄ ethanol solution. The molar ratio of Cu to Sn is 40:1 (abbreviated as CS₄). The SnCl₄ ethanol solution is added dropwise to the concave octahedral Cu₂O ethanol solution, and the reaction is allowed to proceed for 5–10 min. The resulting solution is centrifuged, washed, and dried under vacuum at 50 °C. Subsequently, carbon paper is used as the supporting substrate, and the catalyst particles are drop-coated onto its surface after ultrasonic homogenization.

[0051] Within the voltage range of 1.2–1.6 V, the Faraday efficiencies of CS4 nanocatalysts for H2, CO, and HCOOH are 14%, 55%, and 25%, respectively, with an optimal voltage of 1.4 V.

[0052] from Figure 1 The XRD results clearly show the presence of cuprous oxide, but the characteristic peaks of Sn are not observed, which may be due to the low Sn content. Figure 2 The XPS results confirmed the existence of Sn, combined with Figure 3 Scanning electron microscope and Figure 4 Transmission electron microscopy (TEM) results further confirmed that Sn was successfully loaded onto the cuprous oxide surface. Subsequently, photoelectrochemical carbon dioxide reduction tests were conducted using CS4 catalyst as the cathode. It was clearly observed that the Faradaic efficiency of CO reached its maximum of 55% at 1.4 V, while the Faradaic efficiencies of H2 and HCOOH were 14% and 25%, respectively.

[0053] Example 5

[0054] A method for applying a tin dioxide-doped cuprous oxide composite nanoparticle catalyst in photoelectrocatalytic carbon dioxide reduction includes the following steps:

[0055] A. Prepare 60 mL of a solution with a concentration of 0.1 mol·L⁻¹ -1 The KHCO3 solution was placed in the dark and CO2 was continuously bubbled through it for 30 minutes until the solution was saturated.

[0056] B. Using FTO loaded with BiVO4 as the working electrode and carbon paper loaded with CS5 composite nanoparticles as the counter electrode, a CO2-saturated KHCO3 solution was added to both sides of the H-type electrolytic cell, and CO2 was continuously introduced to remove oxygen. Then, carbon dioxide was catalytically reduced under light conditions at a gas flow rate of 50 mL / min and 25 °C.

[0057] The carbon paper supported on the CS5 composite nanoparticle catalyst is prepared by the following method: 50 mL of a 0.3 mM concave octahedral Cu₂O ethanol solution is prepared, followed by 5 mL of a 0.2 M NaCl solution, and then 50 mL of a 0.012 mM SnCl₄ ethanol solution. The molar ratio of Cu to Sn is 50:1 (abbreviated as CS₅). The SnCl₄ ethanol solution is added dropwise to the concave octahedral Cu₂O ethanol solution, and the reaction is allowed to proceed for 5–10 min. The resulting solution is centrifuged, washed, and dried under vacuum at 50 °C. Subsequently, carbon paper is used as the supporting substrate, and the catalyst particles are drop-coated onto its surface after ultrasonic homogenization.

[0058] Within the range of 1.2–1.6 V, the Faraday efficiencies of CS5 nanocatalysts for H2, CO, and HCOOH at an optimal voltage of 1.4 V are 16.9%, 44%, and 30%, respectively.

[0059] Example 6

[0060] A method for applying a tin dioxide-doped cuprous oxide composite nanoparticle catalyst in photoelectrocatalytic carbon dioxide reduction includes the following steps:

[0061] A. Prepare 60 mL of a solution with a concentration of 0.1 mol·L⁻¹ -1 The KHCO3 solution was placed in the dark and CO2 was continuously bubbled through it for 30 minutes until the solution was saturated.

[0062] B. Using a platinum sheet as the working electrode and carbon paper loaded with CS4 composite nanoparticles as the counter electrode, a CO2-saturated KHCO3 solution was added to both sides of the H-type electrolytic cell. CO2 was continuously introduced to remove oxygen, and then carbon dioxide was catalytically reduced under no-light conditions at a gas flow rate of 50 mL / min and 25 °C.

[0063] The carbon paper supported on the CS4 composite nanoparticle catalyst is prepared by the following method: 50 mL of a 0.3 mM concave octahedral Cu₂O ethanol solution is prepared, followed by 5 mL of a 0.2 M NaCl solution, and then 50 mL of a 0.015 mM SnCl₄ ethanol solution. The molar ratio of Cu to Sn is 40:1 (abbreviated as CS₄). The SnCl₄ ethanol solution is added dropwise to the concave octahedral Cu₂O ethanol solution, and the reaction is allowed to proceed for 5–10 min. The resulting solution is centrifuged, washed, and dried under vacuum at 50 °C. Subsequently, carbon paper is used as the supporting substrate, and the catalyst particles are drop-coated onto its surface after ultrasonic homogenization.

[0064] Within the voltage range of 1.2V to 1.6V, the optimal voltage for the CS4 nanocatalyst is 1.4V, and the Faradaic efficiencies for H2, CO, and HCOOH are 60%, 4%, and 14%, respectively.

[0065] Example 7

[0066] A method for applying a tin dioxide-doped cuprous oxide composite nanoparticle catalyst in photoelectrocatalytic carbon dioxide reduction includes the following steps:

[0067] A. Prepare 60 mL of a solution with a concentration of 0.1 mol·L⁻¹ -1 The KHCO3 solution was placed in the dark and CO2 was continuously bubbled through it for 30 minutes until the solution was saturated.

[0068] B. Using FTO loaded with BiVO4 as the working electrode and carbon paper loaded with concave octahedral Cu2O as the counter electrode, a CO2-saturated KHCO3 solution was added to both sides of the H-type electrolytic cell, and CO2 was continuously introduced to remove oxygen. Then, carbon dioxide was catalytically reduced under light conditions at a gas flow rate of 50 mL / min and 25 °C.

[0069] The concave octahedral Cu2O uses carbon paper as a support substrate, and catalyst particles are drop-coated onto its surface after being ultrasonically homogenized.

[0070] Within the range of 1.2–1.6 V, the Faraday efficiencies of Cu2O nanocatalysts at an optimal voltage of 1.4 V for H2, CO, and HCOOH are 77%, 5.3%, and 13.7%, respectively.

[0071] Example 8

[0072] A method for applying a tin dioxide-doped cuprous oxide composite nanoparticle catalyst in photoelectrocatalytic carbon dioxide reduction includes the following steps:

[0073] A. Prepare 60 mL of a solution with a concentration of 0.1 mol·L⁻¹ -1 The KOH solution was placed in the dark and CO2 was continuously bubbled through it for 30 minutes until the solution was saturated.

[0074] B. Using FTO loaded with BiVO4 as the working electrode and carbon paper loaded with CS4 composite nanoparticles as the counter electrode, a CO2-saturated KHCO3 solution was added to both sides of the H-type electrolytic cell, and CO2 was continuously introduced to remove oxygen. Then, carbon dioxide was catalytically reduced under light conditions at a gas flow rate of 50 mL / min and 25 °C.

[0075] The carbon paper supported on the CS4 composite nanoparticle catalyst is prepared by the following method: 50 mL of a 0.3 mM concave octahedral Cu₂O ethanol solution is prepared, followed by 5 mL of a 0.2 M NaCl solution, and then 50 mL of a 0.015 mM SnCl₄ ethanol solution. The molar ratio of Cu to Sn is 40:1 (abbreviated as CS₄). The SnCl₄ ethanol solution is added dropwise to the concave octahedral Cu₂O ethanol solution, and the reaction is allowed to proceed for 5–10 min. The resulting solution is centrifuged, washed, and dried under vacuum at 50 °C. Subsequently, carbon paper is used as the supporting substrate, and the catalyst particles are drop-coated onto its surface after ultrasonic homogenization.

[0076] Within the voltage range of 1.2–1.6 V, the optimal voltage for the CS4 nanocatalyst is 1.4 V, and the Faraday efficiencies for H2, CO, and HCOOH are 35%, 30%, and 28%, respectively.

[0077] Example 9

[0078] A method for applying a tin dioxide-doped cuprous oxide composite nanoparticle catalyst in photoelectrocatalytic carbon dioxide reduction includes the following steps:

[0079] A. Prepare 60 mL of a solution with a concentration of 0.1 mol·L⁻¹ -1 The NaCl solution was placed in the dark and CO2 was continuously bubbled through it for 30 minutes until the solution was saturated.

[0080] B. Using FTO loaded with BiVO4 as the working electrode and carbon paper loaded with CS4 composite nanoparticles as the counter electrode, a CO2-saturated KHCO3 solution was added to both sides of the H-type electrolytic cell, and CO2 was continuously introduced to remove oxygen. Then, carbon dioxide was catalytically reduced under light conditions at a gas flow rate of 50 mL / min and 25 °C.

[0081] The carbon paper supported on the CS4 composite nanoparticle catalyst is prepared by the following method: 50 mL of a 0.3 mM concave octahedral Cu₂O ethanol solution is prepared, followed by 5 mL of a 0.2 M NaCl solution, and then 50 mL of a 0.015 mM SnCl₄ ethanol solution. The molar ratio of Cu to Sn is 40:1 (abbreviated as CS₄). The SnCl₄ ethanol solution is added dropwise to the concave octahedral Cu₂O ethanol solution, and the reaction is allowed to proceed for 5–10 min. The resulting solution is centrifuged, washed, and dried under vacuum at 50 °C. Subsequently, carbon paper is used as the supporting substrate, and the catalyst particles are drop-coated onto its surface after ultrasonic homogenization.

[0082] Within the voltage range of 1.2–1.6 V, the Faraday efficiencies of CS4 nanocatalysts for H2, CO, and HCOOH are 32%, 35%, and 25%, respectively, with an optimal voltage of 1.4 V.

[0083] like Figure 6 As shown, when the anode in the system becomes a platinum sheet and there is no longer the influence of light, the carbon dioxide conversion capacity is extremely low, specifically, the Faradaic efficiencies of CO and HCOOH are 4% and 14%, respectively. When unloaded cuprous oxide is used as the cathode in the system, the Faradaic efficiencies of CO and HCOOH are 5.3% and 13.7%, respectively. In comparison, it is clearly observed that the overall Faradaic efficiency of the gas is higher at this time than under the condition of no light. Meanwhile, from... Figure 7 It can be observed that the CS4 catalyst has the strongest ability to suppress hydrogen evolution and higher selectivity for CO at 1.4V.

[0084] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made using the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for applying a tin dioxide-doped cuprous oxide composite nanocatalyst in the photoelectrocatalytic reduction of carbon dioxide, characterized in that: Using BiVO4-loaded FTO as the working electrode (photoanode) and Cu2O-SnO2 composite nanoparticle-loaded carbon paper as the counter electrode (cathode), a prepared CO2-saturated electrolyte solution was added to both sides of an H-type electrolytic cell. CO2 was continuously introduced to remove oxygen, followed by catalytic reduction of carbon dioxide at a gas flow rate of 20–100 mL / min and a temperature of 20–30 °C. The preparation method of the BiVO4-loaded FTO includes the following steps: A. Mix KI solution and Bi(NO3)3 solution, adjust the pH to 1-2 with concentrated nitric acid to form solution A, and use an ethanol solution of p-benzoquinone as solution B. Mix the two solutions thoroughly to form a mixed solution, wherein the molar concentration ratio of KI, Bi(NO3)3 and p-benzoquinone is 100:10:15-30, and the volume ratio of solution A to solution B is 5:1-3. B. Using the mixed solution as the electrolyte, apply a bias voltage of -0.1V relative to Ag / AgCl, electrodeposit on the FTO substrate for 3-10 min, and then uniformly drop 0.2M vanadium acetylacetonate dimethyl sulfoxide (DMSO) solution onto the surface of the FTO substrate. C. Place the FTO substrate in a muffle furnace and heat it to 300-450℃ at a heating rate of 2℃ / min, and hold it at that temperature for 2-5 hours to obtain worm-like BiVO4 on the FTO substrate. After cooling to room temperature, immerse it in 1M NaOH solution to wash away the vanadium pentoxide produced after calcination, and you will get the product. The carbon paper supported on the Cu2O-SnO2 composite nanoparticle catalyst is prepared by the following steps: preparing 50 mL of concave octahedral Cu2O ethanol solution, adding 5 mL of 0.1-0.3 M NaCl solution, and then preparing 50 mL of SnCl4 ethanol solution, with a Cu to Sn molar ratio of 10-50:1; adding the SnCl4 ethanol solution dropwise to the concave octahedral Cu2O ethanol solution, reacting for 5-10 min, centrifuging, washing, and drying under vacuum at 50°C to obtain catalyst particles; finally, using carbon paper as a support substrate, ultrasonically homogenizing the catalyst particles and then drop-coating them onto the substrate surface, and drying to obtain the final product.

2. The method for applying the tin dioxide-doped cuprous oxide composite nanocatalyst according to claim 1 in the photoelectrocatalytic reduction of carbon dioxide, characterized in that: In step A, the molar concentration ratio of KI, Bi(NO3)3 to p-benzoquinone is 100:10:

23.

3. The method for applying the tin dioxide-doped cuprous oxide composite nanocatalyst according to claim 1 in the photoelectrocatalytic reduction of carbon dioxide, characterized in that: In step A, the volume ratio of liquid A to liquid B is 5:

2.

4. The method for applying the tin dioxide-doped cuprous oxide composite nanocatalyst according to claim 1 in the photoelectrocatalytic reduction of carbon dioxide, characterized in that: In step B, electrodeposition is performed on the FTO substrate for 5 minutes.

5. The method for applying the tin dioxide-doped cuprous oxide composite nanocatalyst according to claim 1 in the photoelectrocatalytic reduction of carbon dioxide, characterized in that: In step C, the FTO substrate is placed in a muffle furnace and heated to 450°C at a heating rate of 2°C / min and held at that temperature for 2 hours.

6. The method for applying the tin dioxide-doped cuprous oxide composite nanocatalyst according to claim 1 in the photoelectrocatalytic reduction of carbon dioxide, characterized in that: The CO2-saturated electrolyte solution is prepared with a concentration of 0.1–0.5 mol·L⁻¹. -1 Place the KHCO3, KOH, or NaCl solution in the dark and saturate it with CO2.

7. The method for applying the tin dioxide-doped cuprous oxide composite nanocatalyst according to claim 6 in the photoelectrocatalytic reduction of carbon dioxide, characterized in that: The CO2-saturated electrolyte solution is prepared with a concentration of 0.1 mol·L⁻¹. -1 Place the KHCO3, KOH, or NaCl solution in the dark and saturate it with CO2.

8. The method for applying the tin dioxide-doped cuprous oxide composite nanocatalyst according to claim 1 in the photoelectrocatalytic reduction of carbon dioxide, characterized in that: The working voltage of the electrolytic cell is 1.2 to 1.6 V.

9. The method for applying the tin dioxide-doped cuprous oxide composite nanocatalyst according to claim 1 in the photoelectrocatalytic reduction of carbon dioxide, characterized in that, The concave octahedral Cu₂O is prepared by the following steps:

1. Dissolve an aqueous solution of a copper salt in a mixed solution of water and oleic acid, wherein the aqueous solution of the copper salt is a divalent copper salt aqueous solution, including one or a combination of two of copper sulfate aqueous solution or copper acetate aqueous solution; 2. Add an alkaline solution to the solution obtained in step 1, stir evenly, and heat and keep warm. The alkaline solution includes one or a combination of sodium hydroxide aqueous solution or potassium hydroxide aqueous solution.

3. Add a reducing agent to the solution obtained in step 2 and continue stirring until the reaction yields crude cuprous oxide product. The reducing agent includes one or a combination of ascorbic acid or sodium ascorbate.

4. Wash the crude cuprous oxide product obtained in step 3 and vacuum dry it to obtain the final product.

10. The method for applying the tin dioxide-doped cuprous oxide composite nanocatalyst according to claim 9 in the photoelectrocatalytic reduction of carbon dioxide, characterized in that: In step one, the concentration of the divalent copper salt aqueous solution is 0.01–0.1 mol / L, and the volume is 1 mL.

11. The method for applying the tin dioxide-doped cuprous oxide composite nanocatalyst according to claim 9 in the photoelectrocatalytic reduction of carbon dioxide, characterized in that: In step one, the volume ratio of water to oleic acid is 20:

1.

12. The method for applying the tin dioxide-doped cuprous oxide composite nanocatalyst according to claim 9 in the photoelectrocatalytic reduction of carbon dioxide, characterized in that: In step two, the concentration of the alkaline aqueous solution is 0.1–1 mol / L, and the volume is 1 mL.

13. The method for applying the tin dioxide-doped cuprous oxide composite nanocatalyst according to claim 9 in the photoelectrocatalytic reduction of carbon dioxide, characterized in that: In step two, the heating and heat preservation temperature is 50-60℃.

14. The method for applying the tin dioxide-doped cuprous oxide composite nanocatalyst according to claim 9 in the photoelectrocatalytic reduction of carbon dioxide, characterized in that: In step three, the concentration of the reducing agent is 0.01–0.1 mol / L, and the volume is 1 mL.

15. The method for applying the tin dioxide-doped cuprous oxide composite nanocatalyst according to claim 9 in the photoelectrocatalytic reduction of carbon dioxide, characterized in that: In step four, the crude cuprous oxide product is washed with a mixed solvent of ethanol and cyclohexane, and the washing is repeated 2 to 3 times.

Images