S-scheme Sb2WO6/g-C3N4 photocatalysts with enhanced visible-light-induced photocatalytic NO oxidation performance

Normal photocatalysts cannot effectively remove low-concentration NO because of the high recombination rate of the photogenerated carriers. To overcome this problem, S-scheme composites have been developed to fabricate photocatalysts. Herein, a novel S-scheme Sb2WO6/g-C3N4 nanocomposite was fabricated by an ultrasound-assisted method, which exhibited excellent performance for photocatalytic ppb-level NO removal. Compared with the pure constituents of the nanocomposite, the as-prepared 15%-Sb2WO6/g-C3N4 photocatalyst could remove more than 68% continuous-flowing NO (initial concentration: 400 ppb) under visible-light irradiation in 30 min. The findings of the trapping experiments confirmed that •O2− and h+ were the important active species in the NO oxidation reaction. Meanwhile, the transient photocurrent response and PL spectroscopy analyses proved that the unique S-scheme structure of the samples could enhance the charge separation efficiency. In situ DRIFTS revealed that the photocatalytic reaction pathway of NO removal over the Sb2WO6/g-C3N4 nanocomposite occurred via an oxygen-induced route. The present work proposes a new concept for fabricating efficient photocatalysts for photocatalytic ppb-level NO oxidation and provides deeper insights into the mechanism of photocatalytic NO oxidation.