Alkali metal ion-doped Bi2O2CO3 enhances ·OH generation via interfacial water activation for efficient toluene photodegradation

Abstract

The efficient removal of volatile organic compounds (VOCs) remains a significant challenge in air pollution control due to their high chemical stability and adverse health impacts. Among them, toluene is a representative aromatic VOC whose degradation requires effective generation of highly oxidative hydroxyl radicals (·OH) to achieve complete mineralization. In this study, we developed alkali metal ion-doped Bi₂O₂CO₃ (BOCO) photocatalysts via a one-step hydrothermal method. Alkali metal ions (Na⁺ and Rb⁺) were successfully incorporated into BOCO via substitutional doping. The doping process disrupts uniform surface charge distribution, creating active sites that facilitate interfacial water adsorption and activation. This leads to markedly increased hydroxyl radical (·OH) generation in doped catalysts, essential for ring-opening degradation of aromatic intermediates. Hence, Rb-BOCO achieved a toluene degradation efficiency of 60.7% and retained a stable mineralization rate (50.1%) over prolonged illumination, compared with 25.3% for pristine BOCO. These findings provide a mechanistic framework for designing durable photocatalysts by tuning surface chemistry to boost ·OH radical production for efficient VOC abatement.