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

Abstract

Photocatalytic conversion of low-concentration NOx 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.