Hierarchical architectures of wrinkle-like ZnFe2O4 nanosheet-enwrapped ZnO nanotube arrays for remarkably photoelectrochemical water splitting to produce hydrogen

In this study, we show for the first time a hierarchical ZnO/ZnFe2O4 nanotube array photoanode for water splitting to produce hydrogen. In this photoanode, the wrinkle-like ZnFe2O4 nanosheets (NSs) are grown onto ZnO nanotube arrays through adsorption and annealing reaction. The hierarchical ZnO/ZnFe2O4 nanotube array photoanode exhibits outstanding PEC water splitting to produce hydrogen due to the remarkable visible-light harvesting ability and the large surface area of wrinkle-like ZnFe2O4 NSs. Under simulated solar light irradiation, the hierarchical ZnO/ZnFe2O4 nanotube arrays (NTAs) achieve a remarkably enhanced photocurrent density of 1.3 mA/cm2, which is 2.2-fold higher than that of pristine ZnO NTAs at 0 V vs Ag/AgCl. Moreover, the hydrogen production rate of the hierarchical ZnO/ZnFe2O4 nanotube array photoanode is 3.6-fold higher than that of pristine ZnO nanotube array photoelectrode at 0.6 V vs Ag/AgCl.