Enhancing ROS generation and suppressing toxic intermediate production in photocatalytic NO oxidation on O/Ba co-functionalized amorphous carbon nitride

The generation of toxic intermediates during the photocatalytic reaction can result in the accumulation of secondary pollutants and lead to decreased performance. Here, we first designed an O/Ba co-functionalized amorphous carbon nitride (labeled as O-ACN-Ba) by conducting targeted density functional theory calculations for short-range and directional charge transfer in electronic transportation channels. Also, the O-ACN-Ba is synthesized via a one-step in situ co-pyrolysis of urea and BaCO₃. The unique electronic structure O-ACN-Ba enables highly enhanced photocatalytic NO removal rate and suppresses the generation of toxic intermediate (NO₂). The O and Ba are co-functionalized as a surface electronic trapping adjuster and an interlayer electronic trapping mediator to induce the convergence and localization of intralayer-delocalized electrons. Such internal electronic structure can facilitate the adsorption and activation of NO and O₂, elongate the lifetime of photogenerated carriers, and expedite the spatial charge separation to boost significantly the generation of reactive oxygen species, thus suppressing toxic NO₂ generation. In addition, the photocatalytic NO conversion pathway on O-ACN-Ba is characterized, and an important reaction intermediate—nitrosyl species Ba-NOδ⁽⁺⁾ is discovered and found to promote the selective conversion of NO to final products (nitrites or nitrates). This work proposes a novel strategy to advance the application of photocatalytic technology for efficient and safe air purification.