Photocatalytic CO2 reduction to C1–C5 hydrocarbons using K2Fe2O4/g-C3N4 as coupling photocatalyst

Abstract

A particularly interesting and difficult research topic is converting inexpensive and abundant single-carbon (C1) molecules to high-value multicarbon (C2+) molecules, especially to improve selectivity and conversion efficiency. Photocatalytic reduction offers a green technique for activating C1 molecules and controllable C–C coupling under mild and environmentally friendly conditions. This study synthesizes K2Fe2O4/g-C3N4 as a magnetic ferrite-containing photocatalyst for the C–C coupling of CO2 in the absence of a sacrificial agent. The findings significantly advance the photocatalytic conversion of CO2 into C2+ compounds, particularly CnH2n+2, CnH2n, and CnH2n−2 (n = 1–5), which are crucial in the chemical and energy industries. The photocatalyst, which has a remarkable selectivity to hydrocarbons (52% CH4, 48% C2+), was optimized to achieve the optimum progressive selective conversion from CO2 to CH4 and finally to C2+ hydrocarbons. The optimized K2Fe2O4/g-C3N4 shows an optimal CO2 to CH4 conversion rate of 130.96 μmol/g/h, which is 6.27 and 8.60 times the reaction rate constant of K2Fe2O4 and g-C3N4 as catalysts, respectively. It is speculated that this study will help understand the activation of CO2 in photocatalytic reduction and the highly selective production of hydrocarbons via the C–C coupling reaction.