Photothermal CO2 hydrogenation to hydrocarbons over trimetallic Co–Cu–Mn catalysts

Abstract

Photocatalytic CO₂ reduction is a highly vital process for converting CO₂ into valuable chemicals. However, the reaction always proceeds less efficaciously at low temperature. A combination of optical and thermal conditions is one of the feasible approaches to achieve the reaction with high efficiency and has gained much attention recently. In the present work, we prepared several Co–Cu–Mn trimetallic catalysts via a simple co-precipitation method, which were used in catalyzing photothermal CO₂ reduction to hydrocarbons. The metal composition and reduction temperature of the catalysts had important effects on their structural and photoelectrical characteristics and adsorption behaviors, further resulting in diverse catalytic performances. Among the prepared trimetallic catalysts, Co₇Cu₁Mn₁O_x(200), with a Co/Cu/Mn molar ratio of 7/1/1 and reduced at 200 °C in H₂ for 2 h, could produce CH₄ with an activity of 14.5 mmol g_cat⁻¹ h⁻¹ in 10% CO₂/30% H₂/60% N₂, and CH₄ and C₂₊ hydrocarbons with the activities of 15.9 and 7.5 mmol g_cat⁻¹ h⁻¹ in 25% CO₂/75% H₂, respectively. The present strategy for constructing trimetallic oxide catalysts for the photothermal reaction not only provides a highly active catalyst for CO₂ utilization, but also offers a potential possibility for reducing the high temperature of conventional thermal reactions.