Donor−π−Acceptor Conjugated Polymeric Photocatalyst for Efficient Deep Oxidation of NO Facilitated by Strong Asymmetric Local Electric Field

Photocatalytic conversion of low-concentration NO_x into NO₃ ^- is limited by strong exciton effects, rapid recombination of photogenerated charge carriers, and lack of localized bonding sites of oxygen species in catalysts. Directed enrichment of charge carriers and reactants (O₂ and NO) at active sites is essential for achieving high-performance photocatalytic NO removal. Herein, a donor-π-acceptor (D-π-A) conjugated polymeric catalyst was engineered by covalently incorporating ultrathin carbon nitride nanosheets with electron-donating π-pyrene-π molecules, which achieves an exceptional 82.2% NO elimination and 94.9% selectivity toward ionic products (NO₃ ^- sel. of 75.9%) with stable operation over 1000 mins, outperforming the previously reported carbon nitride photocatalysts. Rapidly reduces NO levels below safe concentration in a simulated environment chamber was also achieved. The generated asymmetric local electric field in D-π-A conjugated polymeric catalyst through intramolecular charge transfer between electron-accepting heptazine rings and electron-donating pyrene units facilitates exciton dissociation, accelerating charge transfer kinetics, and offer dual adsorption sites for capture O₂ and NO, thus favoring the O₂ activation for highly selective oxidization of NO to NO₃ ^-. This work highlights the pivotal role of asymmetric local electric fields in D-π-A architectures for advancing efficient photocatalytic NO oxidation.