Ternary Hierarchical Cu7S4/TiO2/CoCr-LDH Heterostructured Nanorod Arrays with Multiphase Reaction Interfaces for More Efficient Photoelectrochemical Water Splitting

Fabricating hierarchical and highly matched heterostructure with large surface areas and multiple interfaces is an effective approach to enhancing the photo electrochemical performance. Here, well-aligned hierarchical Cu7S4/TiO2/CoCr-layered double hydroxide (LDH) nanorod arrays are reported, aiming at accelerating charge separation and transfer kinetics. The modifications of Cu7S4 and CoCr-LDH based on TiO2 have endowed the photoanode a surprising enhancement in both ultraviolet light absorption and charge separation efficiency due to highly matched band alignment. The formation of heterojunction is an effective strategy to prevent photocorrosion of Cu7S4 by attaching protective layers on Cu7S4. Moreover, other than the hierarchical morphology with enlarged active surface areas would provide sufficient active sites for the water oxidation processes and pore channels for the gas escaping, owing to the special band alignment of three components, multiple reaction interfaces are produced and involved in the water splitting process, since the photoinduced holes for water oxidation are simultaneously distributed in CoCr-LDH and Cu7S4. As expected, this synergistic effect in this ternary Cu7S4/TiO2/CoCr-LDH heterogeneous photoanode gives rise to a largely enhanced photoconversion efficiency (0.58% at 0.6 V) and photocurrent density (2.04 mA cm(-2) at 1.23 V).