Efficiency of CO2 photoreduction to hydrocarbons with K2Fe2O4/rGO heterojunction as a photocatalyst

Abstract

Conversion of CO2 into single-carbon (C1) or multi-carbon (C2+) compounds with high value-added chemicals is highly desirable but challenging. Under moderate, environmentally amiable conditions, photocatalysis may afford the deactivation and controllable C–C coupling of CO2. Here, we prepared K2Fe2O4/rGO, a photocatalyst containing magnetic ferrite, for CO2 photocatalytic reduction. The optimized K2Fe2O4/5 %rGO demonstrated the most efficient CO2-to-methane conversion performance of 23.35 µmol g−1 h−1, which is 3.24 and 2.49 times the conversion rate constant of K2Fe2O4 and rGO as photocatalytic catalysts, respectively. Therefore, the photocatalytic conversion of CO2 to hydrocarbons [e.g., CnH2n+2, CnH2n, and CnH2n-2 (n = 1–5)] with K2Fe2O4/rGO is an excellent method, with 100 % selectivity, for the production of multi-carbon hydrocarbons: 43 % CH4 and 57 % C2+. The time-varying concentrations of hydrocarbon profiles for the photocatalytic reduction of CO2 afford strong evidence for understanding the mechanisms underlying photoreduction. In an alkaline solution, K2Fe2O4/rGO can mediate CO2 photocatalytic reduction with simultaneous deoxygenation and C–C coupling.