2D/2D layered BiOIO3/g-C3N4 S-scheme heterojunction for photocatalytic NO oxidation

It is essential to promote interfacial separation and migration of charge in heterojunctions for effectively driving surface photocatalytic reaction. In this work, we construct a 2D/2D layered BiOIO3/g-C3N4 (BIO/CN) heterojunction for photocatalytic NO removal. The BIO/CN heterojunction exhibits a remarkably higher NO photo-oxidation removal rate (46.9%) than that of pristine BIO (20.1%) and CN (25.9%) under visible-light irradiation. Additionally, it effectively suppresses the formation of toxic NO2 intermediates during photocatalytic reaction. The improved photocatalytic performance of BIO/CN composite is caused by its S-scheme charge carrier transport mechanism, which is supported by DFT simulations of work function and electron density difference, along with in-situ irradiated XPS and EPR analyses. This S-scheme structure improves the interfacial carrier separation efficiency and retains the strong photo-redox ability. Our study demonstrates that construction of S-scheme heterojunction is of significance in the design and preparation of highly efficient photocatalysts for air purification.