Interfacial engineering of S-scheme ZnIn2S4/CoPPc for photoinduced H2 production coupled with benzyl alcohol valorization

Abstract

In response to inherent problems such as the hysteresis of hole consumption kinetics and the uncontrollable path of oxidation side reactions that are common in photocatalytic water splitting hydrogen production systems, we have innovatively constructed a ZnIn₂S₄ photocatalyst with a Zn vacancy defects/polyphthalocyanine cobalt (VDZIS/CoPPc) stacked S-scheme p–n heterojunction and an interfacial built-in polarization-enhanced electric field through an interface engineering strategy. Remarkably, the synergistic effects of the robust interfacial electric field and the heterostructure architecture achieve directional spatial separation and rapid transmission of the photogenerated carriers while retaining the intrinsic strong reduction capacity of CoPPc and the mild oxidation specificity of ZnIn₂S₄. Additionally, CoPPc contributes photothermal effects and Co–N₄ single-atom active sites, which collectively significantly reduce the activation energy barrier for redox reactions. Consequently, VDZIS/CoPPc enables highly efficient photocatalytic hydrogen production coupled with the selective oxidation of benzyl alcohol (BA) to benzaldehyde (BAD). Experimental results demonstrate that the VDZIS/CoPPc exhibits a high hydrogen production rate of 15.22 mmol h⁻¹ g⁻¹, along with 92% BA conversion and 94% BAD selectivity, which surpasses the corresponding values of both pristine ZnIn₂S₄ and previously reported active photocatalysts. This research provides a new strategy for developing integrated photocatalytic systems that simultaneously produce hydrogen fuel and enable valuable organic synthesis.