Solar-Driven Production Of Hydrogen Peroxide And Benzaldehyde In Two-Phase System By An Interface-Engineered Co₉S₈-CoZnIn₂S₄ Heterostructure

Coupling the photoproduction of solar fuel and value-added chemicals is highly attractive, as it maximizes the utilization of incident sunlight and the economic value of photocatalytic reactions. Constructing intimate semiconductor heterojunction for these reactions is highly desirable due to accelerated charge separation at the interfacial contact, but is challenged by material synthesis. Here, an active heterostructure bearing intimate interface, consisting of discrete Co9S8 nanoparticles anchored on cobalt doped ZnIn2S4 using a facile in situ one-step strategy, can drive photocatalytic co-production of H2O2 and benzaldehyde from a two-phase water/benzyl alcohol system with spatial product separation is reported. The heterostructure yields a high production amount of 49.5 and 55.8 mmol L-1 for H2O2 and benzaldehyde under visible-light soaking, respectively. The synchronous elemental Co doping and intimate heterostructure establishment substantially improve the overall reaction kinetics. Mechanism studies reveal that H2O2 generated in the aqueous phase undergoes photodecomposition forming hydroxyl radical, which is subsequently transferred into the organic phase to oxidize benzyl alcohol into benzaldehyde. This study offers fertile guidelines for creating integrated semiconductors and broadens the avenue toward the coupled production of solar fuels and industrially important chemicals.