Fabrication of heterostructured Pd-porphyrin MOFs/ZnIn2S4 composites to boost photocatalytic hydrogen evolution under visible light irradiation

Abstract

The purposeful and sensible fabrication of novel binary-shelled photocatalysts is highly attractive for photocatalytic hydrogen evolution. In this work, ZnIn₂S₄ (ZIS) nanosheets were induced to grow on a framework of Pd-porphyrin MOFs (Pd-PMOFs) to construct novel binary-shelled nanotubes (Pd-PMOFs@ZIS) via a multistep solvothermal process. On account of the abundant active sites, well-matched band gaps, strong visible light harvesting capability and outstanding charge migration efficiency, the assembled Pd-PMOFs@ZIS heterostructures exhibited prominently enhanced photocatalytic hydrogen generation activity. Concretely, the hydrogen evolution rate of the optimized sample was up to 8200.25 μmol g⁻¹ h⁻¹ under visible light irradiation, which was approximately 24.07 and 13.73 times larger than those of individual ZIS and Pd-PMOFs, respectively. More importantly, density functional theory (DFT) calculations demonstrated that the fabrication of the heterojunctions established electron transport channels with Pd and In ions showing strong covalent bonding, and the electrons were converged and consumed at the interfaces between Pd-PMOFs and ZIS. Specifically, the transfer pathway of electrons is from Pd-PMOFs to ZIS. Our work provides a convenient and advanced prototype for synthesizing binary heterojunction photocatalysts with superior charge separation and transfer efficiency.