Fe3+-Induced surface hole generation for selective •OH formation and efficient NO2 Suppression in photocatalytic NO oxidation

Selective photocatalytic oxidation of NO to nitrate (NO 3 – ) over toxic NO 2 remains challenging due to low selectivity and inefficient charge migration in existing systems. This study introduces Fe 3+ as an electron acceptor beneath a Bi 4 TaO 8 Cl/Bi 2 O 2 CO 3 heterojunction to precisely regulate electron pathways and promote targeted hydroxyl radical ( • OH) generation. Combined experimental and DFT analyses reveal Fe 3+ ’s dual role: enhancing interfacial electron transfer and activating H 2 O at surface sites to form • OH. The optimized heterojunction achieves 68.19 % NO conversion with minimal NO 2 selectivity (10.98 %). ESR and ROS quenching confirm Fe 3+ -driven electron migration enriches surface holes, boosting H 2 O adsorption and • OH production (2.76-fold increase). The strong oxidation capacity of • OH suppresses NO 2 formation, favoring complete NO oxidation to NO 3 – . This work provides a strategic approach for selective NO removal by electron-pathway engineering, advancing the design of eco-friendly photocatalysts for air pollution control.