Engineering lewis basic sites in S-scheme heterostructure to boost deep photocatalytic oxidation of nitric oxides in air

Photocatalytic oxidation of nitrogen oxides to harmless nitrate (NO₃^–) is an attractive approach for ambient air purification. However, its practicability is hindered by the accompanying release of highly toxic NO₂ byproduct. This study presents an effective strategy by coupling reduction and adsorption–oxidation processes to simultaneously eliminate NO and NO₂ over an S-scheme heterostructure with tailored Lewis basic sites. A defective B-doped polymeric carbon nitride/NH₂-MIL-125(Ti) (BCN/Ti-MOFs) S-scheme photocatalyst is delicately developed by integrating BCN with excellent O₂ reduction ability and Ti-MOFs with abundant Lewis basic sites for NO₂ adsorption. The catalyst achieves removal efficiencies of 78.8 % and 33.4 % for NO and NO₂, respectively. Ex/in situ experimental and density functional theory calculation results demonstrate the promoted carrier separation via TiO_x cluster electron shuttle channels and the robust NO₂ adsorption capacity. Consequently, the ·O₂^– species efficiently generates from O₂ reduction on electron-aggregated BCN to boost the removal of NO through the Eley–Rideal pathway. Simultaneously, NO₂ is captured by –NH₂ Lewis basic sites in Ti-MOFs and further converted to NO₃^– by the accumulated holes on ligands. This work provides a novel tandem-like catalysis approach by constructing S-scheme heterostructure with targeted reactive sites, offering a paradigm for the simultaneous conversion of multiple reactants. Copyright © 2026 Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.