The importance of intermediates ring-opening in preventing photocatalyst deactivation during toluene decomposition

The deactivation of photocatalysts is the main barrier that diminishes the commercial value of photocatalytic air-purification technology. It is essential to explore the intrinsic origins for the deactivation and develop effective strategy to address this key issue. This work investigates the intrinsic reasons for VOCs-decomposition induced intermediates accumulation on the surface of TiO2 (P25) based on the combined experiments and DFT calculations. The main culprit of deactivation is the accumulation of benzaldehyde intermediate on the surface of P25 because of its high reaction energy of aromatic ring opening. This will lead to the facilitated conversion of benzaldehyde to benzoic acid that will thus occupy the active sites on the surface of P25. However, the wide gap beta-Ga2O3 achieved the excellent deactivation resistance during prolonged VOCs degradation, which is derived from that the fact that the adsorbed intermediates will be activated on the surface of beta-Ga2O3 and strengthen the aromatic ring opening via center dot OH radicals, thus realizing efficient mineralization of the ring-containing intermediates into inorganic small molecules (CO2 and H2O). This work points out that the deactivation-resistant property of photocatalyst is closely related to the adsorption activation and the ring-opening characteristics of the intermediates, which could provide a new perspective in development of efficient and deactivation-resistant photocatalysts for practical applications.