Photochemical CO2 Reduction Using a Lead-Free Cs2AgMCl6 (M= Bi, In, and Sb) Double Perovskite toward Selective Formic Acid Production

Perovskite materials have been identified as promising photocatalysts for CO2 reduction due to their unique physicochemical and optical characteristics. This study employs lead-free halide double perovskites based on Cs2AgMCl6 (M-Bi, In, and Sb or their mixed composition) as photocatalysts for carbon dioxide reduction. It was found that double perovskite materials are highly selective toward formic acid production, with more than 80% selectivity. The Cs2AgInCl6 material shows the best performance, with a formic acid conversion of 85.5 mu mol g-1 h-1. These materials show excellent structural stability over 24 h under photocatalytic conditions. Furthermore, the selectivity of the product was investigated using density functional theory calculations, and the results show a low free-energy barrier toward the formation of formic acid as compared to other reduction products, including carbon monoxide and methane. The Ag site of the [110] terminated surface is identified to be a favorable site for catalytic reduction.