Superior photoelectrochemical activity of self-assembled NiWO4-WO3 heteroepitaxy

Abstract Self-assembled nanocomposites with a high interface-to-volume ratio offer tremendous opportunities of tailoring functionalities by a proper combination of components. In this study, we report the first fabrication of self-assembled NiWO 4 –WO 3 heteroepitaxy and its excellent performance on photoelectrochemical water splitting. The heteroepitaxy is evidenced by a combination of x-ray diffraction and transmission electron microscopy. The energy band diagram of NiWO 4 –WO 3 heterostructure probed by x-ray photoelectron spectroscopy suggests an efficient charge separation at their interface by injecting photo-generated electrons from NiWO 4 to WO 3 and holes from WO 3 to NiWO 4 . Therefore, a great improvement in the photoelectrochemical activity of self-assembled NiWO 4 –WO 3 heteroepitaxy was achieved (1400 µA cm −2 at 0.7 V vs. Ag/AgCl). This work delivers a new category of composite materials for promising photoelectrode in photoelectrochemical cells.