Additive-Free Ruthenium-Catalyzed Hydrogen Production from Aqueous Formaldehyde with High Efficiency and Selectivity

An efficient water-soluble ruthenium complex was developed for selective hydrogen production from aqueous formaldehyde under mild conditions with a high yield (∼95%). Hydrogen production by this catalytic system proceeds without using any additives or organic solvents, leading to a high turnover frequency (8300 h–1) and a record turnover number of 24 000. Moreover, based on mechanistic experiments and density functional theory (DFT) calculations, a step-by-step mechanism has been proposed for the catalytic cycle.