Arrays of ZnO/MoS2 nanocables and MoS2 nanotubes with phase engineering for bifunctional photoelectrochemical and electrochemical water splitting

The increasing exploration of clean energy sources has driven the development of advanced materials and nanostructures as electrodes for water splitting to generate hydrogen. In this work, arrays of ZnO/MoS2 nanocables and MoS2 nanotubes on F-doped SnO2 (FTO) glass substrates are synthesized and demonstrated as promising electrodes for photoelectrochemical (PEC) water splitting and electrochemical water splitting, respectively. Few-layered MoS2 nanosheets are deposited on surface of a ZnO nanorod array on FTO glass substrate by a solvothermal method to form a ZnO/MoS2 nanocable array. The ZnO/MoS2 nanocable array exhibits expanded light absorption up to 960 nm and a stepwise energy band alignment for fast charge carrier separation, consequently resulting in improved performance of PEC water splitting. The array of MoS2 nanotubes with mixed 1T and 2H phases is demonstrated as an efficient binder-free electrode for electrochemical water splitting, exhibiting a small Tafel slop of 45 mV per decade and a low onset potential of 103 mV. The superior electrochemical hydrogen evolution performance is considered to be attributed to synergistic effects of the 1T phase, the interlayer expansion, and the nanoarray structure.