Dual-function surface hydrogen bonds enable robust O2 activation for deep photocatalytic toluene oxidation

Abstract

Solar-driven molecular oxygen activation by semiconductor photocatalysts is a prototypical reaction manifesting complex interactions among photons, charge carriers, and reactants. In this study, we demonstrate that energetic O₂ activation towards volatile organic compound control can be realized via constructing a sophisticated surface hydrogen bond (HB) network having a dual-function. The extensive HBs established between the hydroxyl-rich BiOCl surface and phosphoric acid are first shown to significantly weaken surface Bi–O bonds, enabling facile oxygen vacancy (OV) generation. OVs, which act as reliable electron capture and static O₂ activation centers, reinforce the interaction between photons and excitons for rapid charge carrier separation. Moreover, dynamic O₂ activation with sluggish kinetics can be surmounted by another type of HB localized between hydroxyl groups of phosphoric acid and OV-adsorbed O₂. These unique localized HBs facilitate interfacial electron transfer from BiOCl to O₂, displaying a unique energy coupling route between charge carriers and reactants. For simulated indoor toluene oxidation, the substantially boosted O₂ activation is shown to accelerate the kinetic processes associated with the primary oxidation of toluene into benzaldehyde and benzoic acid, as well as aromatic ring opening towards deep oxidation. Undesirable intermediate accumulation and catalyst deactivation are thus avoided. The present work highlights the pivotal roles of HBs in robust photocatalytic O₂ activation. It will provide novel insights into the design of high-performance catalysts for efficient and safe control of indoor volatile organic compounds.