The superiority of Pd 2+ in CO 2 hydrogenation to formic acid.

The hydrogenation of CO 2 to formic acid is an essential subject since formic acid is a promising hydrogen storage material and a valuable commodity chemical. In this study, we report for the first time the hydrogenation of CO 2 to formic acid catalyzed by a Pd 2+ catalyst, Pd-V/AC-air. The catalyst exhibited extraordinary catalytic activity toward the hydrogenation of CO 2 to formic acid. The TON and TOF are up to 4790 and 2825 h -1 , respectively, representing the top level among reported heterogeneous Pd catalysts. By combining a study of first-principles density functional theory with experimental results, the superiority of Pd 2+ over Pd 0 was confirmed. Furthermore, the presence of V modified the electronic state of Pd 2+ , thus promoting the reaction. This study reports the effect of metal valence and electronic state on the catalytic performance for the first time and provides a new prospect for the design of an efficient heterogeneous catalyst for the hydrogenation of CO 2 to formic acid.