Highly efficient and autocatalytic H(2)O dissociation for CO(2) reduction into formic acid with zinc

Artificial photosynthesis, specifically H(2)O dissociation for CO(2) reduction with solar energy, is regarded as one of the most promising methods for sustainable energy and utilisation of environmental resources. However, a highly efficient conversion still remains extremely challenging. The hydrogenation of CO(2) is regarded as the most commercially feasible method, but this method requires either exotic catalysts or high-purity hydrogen and hydrogen storage, which are regarded as an energy-intensive process. Here we report a highly efficient method of H(2)O dissociation for reducing CO(2) into chemicals with Zn powder that produces formic acid with a high yield of approximately 80%, and this reaction is revealed for the first time as an autocatalytic process in which an active intermediate, ZnH(−) complex, serves as the active hydrogen. The proposed process can assist in developing a new concept for improving artificial photosynthetic efficiency by coupling geochemistry, specifically the metal-based reduction of H(2)O and CO(2), with solar-driven thermochemistry for reducing metal oxide into metal.