NiSx modified Mn0.5Cd0.5S twinned homojunctions for efficient photocatalytic hydrogen evolution

Twinned Mn0.5Cd0.5S homojunction (T-MCS) was synthesized via a simple hydrothermal process, and then NiSx was precipitated on the surface of T-MCS by in situ precipitation process. The type-II staggered band alignment between zinc-blende (ZB) and wurtzite (WZ) Mn0.5Cd0.5S can form a homojunction in bulk T-MCS, and the introduction of NiSx nanoparticles can construct a heterojunction between NiSx and T-MCS. The synergistic of homojunction and heterojunction can effectively promote the separation of charge carriers in the bulk phase and surface of T-MCS, meanwhile, NiSx can reduce the H2 evolution overpotential and induce more active sites, leading to an increased H2 production efficiency. The 0.5 wt% NiSx/T-MCS shows a great H2 evolution rate of 111.5 mmol∙g−1∙h−1 in Na2S/Na2SO3 solution under visible light (λ ≥ 420 nm) irradiation, which is 2.3-fold higher than that of the pure T-MCS. Its apparent quantum efficiency (AQE) is 10.4% under 400 (±5) nm light irradiation. This research sheds light on the exploration of homo-heterojunction photocatalysts for efficient H2 evolution.