Plasmonic MoO2 as co-catalyst of MoS2 for enhanced photocatalytic hydrogen evolution

Generally, photocatalytic water splitting on MoS2 nanomaterials is restricted owing to the high carrier recombination and limited utilization of the visible light. This study describes the enhancement of the MoS2-catalysed hydrogen evolution by incorporating metallic MoO2 as a co-catalyst introduced by coupling with MoS2 nanosheets through a facile calcination strategy, forming a Schottky junction between MoO2 and MoS2. The localized surface plasmon resonance effect induced by the oxygen vacancies and favourable Fermi lever position of MoO2 lead to a broad spectral response and a significant improvement in the exciton generation and dissociation. The electron gets transferred from the conduction band (CB) of MoS2 to MoO2, wherein MoO2 acts as an 'electron pool' that gathers the photoexcited electrons, which are rapidly shuffled to the surface of MoO2, where the redox reaction occurs due to its great metallic conductivity. Resultantly, a 242% increment in the production of hydrogen gas by MoS2/MoO2 is achieved in comparison with that of the MoS2 nanosheets.