Preparation of SnO2/γ-Al2O3 Particle Electrode and Its Electrocatalytic Reduction of CO2 to Formic Acid

Abstract

Purposes Electrocatalytic reduction of CO2 (CO2RR) is a green and feasible solution to reduce the concentration of CO2 in the atmosphere. It is particularly important to prepare catalysts with high catalytic performance and stability. Methods The SnO2/γ-Al2O3 particle electrode was prepared by impregnation-calcination method with γ-Al2O3 particles as carriers for electrocatalytic reduction of CO2 to produce formic acid. The microstructure, phase composition, electrocatalytic activity, formic acid production performance, and stability of the particle electrodes were investigated by means of physical and chemical analyses, electrochemical workstation measurements, and long-term experiments. Findings The results of physical and chemical analyses illustrate that the morphology of the particles before and after loading SnO2 changes from pores and cracks to cracked layers and the specific surface area increases from 310.18 to 352.70 m2/g. Meanwhile, the Sn content is 48.32% in the prepared SnO2/γ-Al2O3 particle electrode. SnO2 is successfully dispersed on the surface of γ-Al2O3. According to the electrochemical test results, the voltammetric charge (scanning rate of 50 mV/s), exchange current density, and hydrogen evolution resistance of SnO2/γ-Al2O3 particle electrode are 40 mC, 20.02 μA/cm2, and 96.86 Ω, respectively, which are 37.93%, 75.46%, and 6.80% higher than those of γ-Al2O3, demonstrating the electrocatalytic activity of CO2 is greatly improved while the side reaction of hydrogen evolution is effectively inhibited. Furthermore, the SnO2/γ-Al2O3 particle electrode shows satisfactory CO2RR characteristics, the production rate of formic acid is 70.35 μmol·h-1·cm-2 and the current density is 4.94 mA/cm2 at the reaction time of 2 h, and the Faraday efficiency and energy efficiency are 79.05% and 24.51% respectively. After 12 h electrolysis experiment, the Faraday efficiency for formic acid production is still higher than 67.81%, indicating that the prepared SnO2/γ-Al2O3 particle electrode is strongly stable for long-term CO2 reduction.

Keywords

• co2 electrocatalytic reduction
• sno2/γ-al2o3 particle electrode
• formic acid production
• electrode stability