Preparation and Photocatalytic Performance of MoS/MoO Composite Catalyst.

Solar energy is an inexhaustible clean energy providing a key solution to the dual challenges of energy and environmental crises. Graphite-like layered molybdenum disulfide (MoS) is a promising photocatalytic material with three different crystal structures, 1T, 2H and 3R, each with distinct photoelectric properties. In this paper, 1T-MoS and 2H-MoS, which are widely used in photocatalytic hydrogen evolution, were combined with MoO to form composite catalysts using a bottom-up one-step hydrothermal method. The microstructure and morphology of the composite catalysts were studied by XRD, SEM, BET, XPS and EIS. The prepared catalysts were used in the photocatalytic hydrogen evolution of formic acid. The results show that MoS/MoO composite catalysts have an excellent catalytic effect on hydrogen evolution from formic acid. By analyzing the photocatalytic hydrogen production performance of composite catalysts, it suggests that the properties of MoS composite catalysts with different polymorphs are distinct, and different content of MoO also bring differences. Among the composite catalysts, 2H-MoS/MoO composite catalysts with 48% MoO content show the best performance. The hydrogen yield is 960 µmol/h, which is 1.2 times pure 2H-MoS and two times pure MoO. The hydrogen selectivity reaches 75%, which is 22% times higher than that of pure 2H-MoS and 30% higher than that of MoO. The excellent performance of the 2H-MoS/MoO composite catalyst is mainly due to the formation of the heterogeneous structure between MoS and MoO, which improves the migration of photogenerated carriers and reduces the possibilities of recombination through the internal electric field. MoS/MoO composite catalyst provides a cheap and efficient solution for photocatalytic hydrogen production from formic acid.