Z-Scheme in a Co-3(PO4)(2)/alpha-Fe2O3 photocatalysis system for overall water splitting under visible light

Overall water splitting under solar irradiation with a semiconductor has long been investigated as an attractive pathway to convert solar energy into chemical energy in the form of H-2. However, using only a single semiconductor as a photocatalyst remains a great challenge. Designing Z-scheme systems is the most common method used for photocatalysis. We report a Z-scheme Co-3(PO4)(2)/alpha-Fe2O3 structure as an efficient photocatalyst for overall water splitting under visible light. The as-prepared Co-3(PO4)(2)/alpha-Fe2O3 photocatalyst shows excellent improvement in visible light absorption and photocatalytic efficiency for overall water splitting, in which Co-3(PO4)(2) and Fe2O3 act as H-2-evolving and O-2-evolving photocatalysts, respectively. By varying the amount of alpha-Fe2O3 in the photocatalysts, we found that Co-3(PO4)(2)/alpha-Fe2O3-1.6% exhibited the optimal photocatalytic activity in hydrogen production (0.63 mu mol h(-1)) and oxygen evolution (0.32 mu mol h(-1)), which is almost 35-fold higher than that of a pure Co-3(PO4)(2) catalyst. In addition, the chemical stoichiometric ratio of H-2 and O-2 in the photocatalysis process is almost 2:1. The enhanced photocatalytic activity was attributed to the synergetic effects of Co-3(PO4)(2) and alpha-Fe2O3 in the Z-scheme structure, which resulted in highly efficient separation of photogenerated charge carriers.