A Spatially Separated Organic-Inorganic Hybrid Photoelectrochemical Cell for Unassisted Overall Water Splitting

The Z-scheme overall solar water splitting is a mimic of natural photosynthesis to convert solar energy into chemical fuels. Despite much effort, the available Z-scheme artificial systems are still rare, and most of them rely on inorganic semiconductors. In this study, inspired by the characteristics of p-type and higher unoccupied molecular orbital level of organic semiconductors, a spatially separated organic inorganic hybrid Z-schematic photoelectrochemical (PEC) cell for unassisted overall water splitting is developed by wiring inorganic ZnO nanorod arrays photoanode and organic poly(3-hexylthiophene):[6,6]-phenyl-C-61-butyric acid (P3HT:PCBM) photocathode in a tandem manner. In the short-circuit configuration, the photocurrent density reaches an initial value of similar to 78 mu A cm(-2) and an average value of similar to 95 mu A cm(-2) under continuous UV-vis light irradiation, giving rise to the solar-to-fuel conversion efficiency of similar to 0.12%. The average gas evolution rates are 1.59 mu mol h(-1) for H-2 and 0.75 mu mol h(-1) for O-2 under zero bias condition without sacrificial agents, corresponding to the faradic efficiency of similar to 90%. These results demonstrate a possibility of introducing organic semiconductor into a Z-schematic system to realize unassisted overall solar water splitting, which enriches the practical Z-schematic photocatalytic systems.