Elevating dual-redox photocatalysis with p-n junction: Hydrangea-like Zn3In2S6 nanoflowers coupled hexagonal Co3O4 for cooperative hydrogen and benzaldehyde production

Despite advances in photocatalytic half-reduction reactions, challenges remain in effectively utilizing electron-hole pairs in concurrent redox processes. The present study involved the construction of a p-n junction Co₃O₄/Zn₃In₂S₆ (CoZ) hybrid with a complementary band edge potential. The photocatalyst formed by the 2D assembled-nanostructure portrayed an optimal yield of 13.8 (H₂) and 13.1 (benzaldehyde) mmol g⁻¹ h⁻¹ when exposed to light (λ ​> ​420 ​nm), surpassing 1 ​% Pt-added ZIS (12.4 (H₂) and 10.71 (benzaldehyde) mmol g⁻¹ h⁻¹). Around 95 ​% of the electron-hole utilization rate was achieved. The solar-to-hydrogen (STH) and apparent quantum yield (AQY) values of 0.466 ​% and 4.96 ​% (420 ​nm) achieved by this system in the absence of sacrificial agents exceeded those of previous works. The exceptional performance was mostly ascribed to the synergistic development of adjoining p-n heterojunctions and the built-in electric field for effective charge separation. Moreover, scavenger studies elucidated the intricate mechanistic enigma of the dual-redox process, in which benzaldehyde was produced via O-H activation and subsequent C-H cleavage of benzyl alcohol over CoZ hybrids. Furthermore, the widespread use of the optimal 1-CoZ composites was confirmed in multiple photoredox systems. This work presents an innovative perspective on the construction of dual-functioning p-n heterojunctions for practical photoredox applications.