Tightly contacted heterojunction of ZnS/ZIS/In2S3: In situ construction from ZIF-8@MIL-68(In) and visible-light induced photocatalytic hydrogen generation

The construction of a tightly contacted heterojunction consisting of multi-components is proven to be one of the effective strategies to promote the photogenerated charges separation and to develop high-efficient photocatalysts in hydrogen evolution. Herein, a ternary hollow heterostructure of ZnS/ZIS/In2S3 has been fabricated by using a binary MOF@MOF (ZIF-8@MIL-68(In)) as the precursor, and an in-situ sulfurization of ZIF-8@MIL-68 (In) is controlled to optimize the photocatalytic performances. The resulting samples are signed as Z@M-t, where the t is pointed to the sulfurization time being varied from 4 h to 48 h. It's shown that the hierarchical and hollow architecture is formed for Z@M-t, and with the reinforced light harvest ability in both UV and visible light regions. In the subsequent visible-light-induced photocatalytic hydrogen generation, the optimized Z@M-24 manifests significantly improved hydrogen evolution rate of 607.34 & mu;mol g-1 h-1, which values are evidently higher than that by the single MOF and binary ZIF-8@MIL-68(In) heterostructure. The electrochemical analyses and the electron paramagnetic resonance (EPR) spectrum were analyzed to clarify the charge transfer routes and the enhanced photocatalytic mechanism, in which the contribution of each metal sulfide is also discussed. Finally, the good photocatalytic stability and reusability of Z@M-24 heterostructure are also represented, which define the structure superior brought by the effective heterojunction based on the in-situ sulfurization strategy of binary ZIF-8@MIL-68(In), and determine their prospect applications in the efficient H2 production under visible light irradiation.