Photo- and mechano-catalytic overall water splitting reactions to form hydrogen and oxygen on heterogeneous catalysts

Recent progress of overall water splitting by photocatalysts and mechanocat alysts is briefly reviewed. In photocatalytic reactions, several new materi als have been introduced, and the catalyst preparation has also been improv ed. As a result, a high quantum efficiency for overall water splitting of a bout 30% has been accomplished. In addition, recent progress in the underst anding of the reaction mechanism is briefly introduced. On the other hand, mechano-catalytic overall water splitting reaction has b een recently discovered by the authors. The phenomenological aspects of thi s novel reaction are summarized, and some implications of the reaction mech anism are also described.