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., C_nH_2n+2, C_nH_2n, and C_nH_2n-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.