Pd 2+ ‐Initiated Formic Acid Decomposition: Plausible Pathways for C‐H Activation of Formate

Formic acid (HCOOH, FA) has long been considered as a promising hydrogen‐storage material due to its efficient hydrogen release under mild conditions. In this work, FA decomposes to generate CO 2 and H 2 selectively in the presence of aqueous Pd 2+ complex solutions at 333 K. Pd(NO 3 ) 2 was the most effective in generating H 2 among various Pd 2+ complexes explored. Pd 2+ complexes were in situ reduced to Pd 0 species by the mixture of FA and sodium formate (SF) during the course of the reaction. Since C−H activation reaction of Pd 2+ ‐bound formate is occurred for both Pd 2+ reduction and H 2 /CO 2 gas generation, FA decomposition pathways using several Pd 2+ species were explored using density functional theory (DFT) calculations. Rotation of formate bound to Pd 2+ , β ‐hydride elimination, and subsequent CO 2 and H 2 elimination by formic acid were examined, providing different energies for rate determining step depending on the ligand electronics and geometries coordinated to the Pd 2+ complexes. Finally, Pd 2+ reduction toward Pd 0 pathways were explored computationally either by generated H 2 or reductive elimination of CO 2 and H 2 gas.