Coupling photocatalytic overall water splitting with hydrogenation of organic molecules: a strategy for using water as a hydrogen source and an electron donor to enable hydrogenation

It is fascinating to use water as a hydrogen source to enable the hydrogenation of organic molecules in green chemistry. Nevertheless, current light-driven strategies suffer from an expense of reductants for proton reduction due to a high difficulty in overall water splitting. Herein, we have overcome this challenge and report that light-induced overall water splitting is coupled with hydrogenation of aryl bromides by cooperative catalysis between recyclable Pd/g-C3N4 and Fe species, which opens up a photocatalytic avenue to use water as both an electron donor and a hydrogen source to enable hydrogenation of aryl bromides, avoiding the use of additional reductants. Moreover, mild conditions, recyclable catalyst systems and the use of visible-light as the energy source make this process greener. The present method also allowed various high value-added deuterated arenes to be effectively synthesized. This work will guide chemists to use water as both an electron donor and a hydrogen source to develop green procedures for the hydrogenation of various organic compounds.