Optimizing CO2 reduction conditions to increase carbon atom conversion using a Pt-RGO||Pt-TNT photoelectrochemical cell

This study aimed to determine the optimum conditions required to increase the carbon atom conversion rate in a Pt-RGO||Pt-TNT photoelectrochemical cell. The effects of Pt-RGO reduction time on CO2 conversion, voltage applied through the cell, catholyte pH, and pore size of nickel foam as a catalyst support were investigated. The conversion rate of C atoms initially increased and then decreased with increasing Pt-RGO reduction time, increasing electrolyte pH, and decreasing nickel foam pore size. Although carbon atom conversion showed sustainable growth as the applied voltage increased, the current efficiency of CO2 reduction products decreased because of enhanced proton interference when the voltage applied through the cell exceeds 2 V. A maximum carbon atom conversion rate of 1500 nmol/(cm2 h) was obtained by Pt-RGO reduction for 24 h when a 2 V voltage was applied through the cell, the catholyte pH was 8.8, and nickel foam with an average pore size of 160 μm was used as a support. Under optimum conditions, the liquid product selectivity of CO2 reduction reached 99%. The results of the study indicate that RGO-based catalysts have potential use as blueprints for CO2 reduction.