Co(dmgH) (2)pyCl as a noble-metal-free co-catalyst for highly efficient photocatalytic hydrogen evolution over hexagonal ZnIn2S4

摘要

Co(dmgH)(2)pyCl/ZnIn2S4 composites (dmgH - dimethylglyoxime and py - pyridine) with different amounts of Co(dmgH)(2)pyCl loaded were prepared from hexagonal ZnIn2S4 and Co(dmgH)(2)pyCl via an impregnation method. The photocatalytic activity for hydrogen evolution over the as-prepared Co(dmgH)(2)pyCl/ZnIn2S4 composites under visible light irradiation was investigated. It was found that the hydrogen evolution over hexagonal ZnIn2S4 can be significantly increased by loading Co(dmgH)(2)pyCl as a co-catalyst. An optimum activity was achieved over 3.0 wt% Co(dmgH)(2)pyCl/ZnIn2S4 composite, with 1438.5 mmol hydrogen generated and a turnover number of 387 (based on Co(dmgH)(2)pyCl)reached in 8 h visible light irradiation. This value is much higher than that obtained over Pt loaded ZnIn2S4 under similar conditions, indicating that Co(dmgH)(2)pyCl can be a highly efficient noble-metal-free co-catalyst for photocatalytic hydrogen evolution over hexagonal ZnIn2S4. The mechanism for the hydrogen evolution over the Co(dmgH)(2)pyCl/ZnIn2S4 composite was also proposed. This work paves a way to the development of highly efficient noble-metal-free photocatalytic systems for hydrogen evolution.