Photocatalytic product-selective reduction of CO2, CO, and carbonates

Abstract

CO₂ conversion to value-added chemicals is a crucial technology toward carbon-neutral fuels. Photocatalysis using sunlight is an energy-efficient alternative to electrochemical and thermal CO₂ reduction. Photocatalysts usually yield either CO or formate with varying degrees of selectivity. Herein, a lanthanide-based photocatalytic platform producing CO with the highest turnover to date is reported. The catalyst consists of a pendant amine for CO₂ capture and a light-harvesting sensitizer that generates the reactive divalent lanthanide center. CO₂ reduction to CO was possible with high selectivity and reactivity by virtue of a distinct mechanistic pathway involving Sm(II), carbamate, and CO₂^⋅− as identified intermediates. Attractive (bi)carbonate CO₂ feedstocks were efficiently converted to CO. Depending on the conditions, the selective synthesis of formate, methane, and methanol was also possible, demonstrating the wide utility of the platform.