A heterostructured WO₃-SnO₂ nanocomposite for the efficient photocatalytic production of H₂O₂ under visible light

Hydrogen peroxide (H2O2) is a versatile oxidant that is clean, environmentally friendly and typically produced industrially via the anthraquinone oxidation (AO) method. As opposed to the highly polluting conventional ways, the visible light photocatalytic reaction is a viable method for achieving sustainable H2O2 generation. Herein, visible light active WO3-SnO2 nanocomposites (WSN) were synthesized through a facile process for H2O2 production. The nanoscale particles of WO3 and SnO2 exhibit crystalline and mesocrystalline states, respectively, in the composites and, which are uniformly dispersed and tightly bound, forming the unique heterostructures, providing strong visible light absorption and abundant substrate adsorption and reaction sites. The composite exhibited the highest apparent catalytic activity with a WO3 : SnO2 molar ratio of 1 : 1. Under visible light irradiation, the catalytic production of H2O2 by the composite is 30 times more efficient than that by its individual components. The n-n heterojunction formed by the combination of WO3 and SnO2 allows for the directional transfer of photogenerated electrons and holes, while SnO2 promotes the migration of electrons from the bulk to the surface of the catalyst, further enabling the spatial separation of the charge carriers and higher oxygen reduction efficiency of the catalyst. This work provides a new research idea for improving WO3-based photocatalysts for H2O2 production and also presents a new pathway for effective visible light-driven generation of H2O2.