Loading PAN-PEG membranes with ZnIn2S4/Ni-MOF heterojunctions for visible-light photocatalytic water splitting

Abstract

One of the most promising paths for the scalable use of photocatalytic nanomaterials is their immobilization onto proper matrixes to enable catalyst reuse and separation. In this work, photocatalytic membranes (PZISNi-x) were prepared employing polyacrylonitrile and polyethylene glycol (PAN-PEG) precursors via non-solvent induced phase inversion, incorporating a pre-synthesized 2Dsingle bond2D ZnIn2S4 (ZIS)/Ni-MOF-74 heterojunction as a casting scaffold to enable visible-light-driven hydrogen production. The effect of photocatalyst loading (x = 0, 2, 5, 10, 15 and 20%) on membrane morphology, compositional, optical, electrochemical and photocatalytic properties was systematically investigated. The incorporated Ni-rich ZIS (ZIS@Ni) photocatalysts were homogenously immobilized within the membrane, while structural, surface and compositional analyses confirmed an ultra-low and controlled incorporation of active Ni sites in the PZISNi-x samples. The hydrogen evolution rate tops for the PZISNi-15 sample (0.77 ± 0.08 mmol g−1 h−1), representing a sixfold enhancement compared to the pure ZIS loaded membrane counterpart (PZIS-15). The PZISNi-15 membrane also shows an apparent quantum efficiency (AQE) of 2.1 ± 0.6% at 420 nm and excellent stability over repeated cycles. Optical and electrochemical analysis shows improved charge separation and favorable band alignment induced by Ni incorporation. These results demonstrate that PAN-PEG supported ZIS@Ni membranes constitute a robust and scalable platform for immobilized photocatalytic hydrogen generation.