Construction and performance of CdS/MoO₂@Mo₂C-MXene photocatalyst for H₂ production

Nowadays, photocatalytic technologies are regarded as promising strategies to solve energy problems, and various photocatalysts have been synthesized and explored. In this paper, a novel CdS/MoO₂@Mo₂C-MXene photocatalyst for H₂ production was constructed by a two-step hydrothermal method, where MoO₂@Mo₂C-MXene acted as a binary co-catalyst. In the first hydrothermal step, MoO₂ crystals with an egged shape grew on the surface of two-dimensional (2D) Mo₂C MXene via an oxidation process in HCl aqueous solution. In the second hydrothermal step, CdS nanorods were uniformly assembled on the surface of MoO₂@Mo₂C-MXene in ethylenediamine with an inorganic cadmium source and organic sulfur source. The CdS/MoO₂@Mo₂C-MXene composite with MoO₂@Mo₂C-MXene of 5 wt% exhibits an ultrahigh visible-light photocatalytic H₂ production activity of 22,672 μmol/(g·h), which is ~21% higher than that of CdS/Mo₂C-MXene. In the CdS/MoO₂@Mo₂C-MXene composite, the MoO₂ with metallic nature separates CdS and Mo₂C MXene, which acts as an electron-transport bridge between CdS and Mo₂C MXene to accelerate the photoinduced electron transferring. Moreover, the energy band structure of CdS was changed by MoO₂@Mo₂C-MXene to suppress the recombination of photogenerated carriers. This novel compound delivers upgraded photocatalytic H₂ evolution performance and a new pathway of preparing the low-cost photocatalyst to solve energy problems in the future.