Mechanism, Performance, and Application of g-C3N5-Coupled TiO2 as an S-Scheme Heterojunction Photocatalyst for the Abatement of Gaseous Benzene

In this research, S-scheme heterojunction photocatalysts are prepared through the hybridization of nitrogen-rich g-C3N5 with TiO2 (coded as TCN5-(x): x as the weight ratio of TiO2:g-C3N5). The photocatalytic potential of TCN5-(x) is evaluated against benzene (1–5 ppm) across varying humidity levels using a dynamic flow packed-bed photocatalytic reactor. Among the prepared composites, TCN5-(10) exhibits the highest synergy between g-C3N5 and TiO2 at "x" ratio of 10%, showing superior best benzene degradation performance (e.g., 93.9% removal efficiency, specific clean air delivery rate of 1126.9 L g–1 h–1, kinetic reaction rate of 46.1 nmol mg–1 min–1, quantum yield of 6.0 × 10–4 molec. photon–1, and space-time yield of 1.2 × 10–4 molec. photon–1 mg–1). The formation of an S-scheme heterojunction with a built-in internal electric field is supported by both theoretical (through the density functional theory calculations) and photoelectrochemical bases (e.g., improvement in the band potential and electrochemistry along with surface characteristics (e.g., reactive sites and charge migrations at the interface)). The results of the in situ DRIFTS analysis confirm that the oxidation of benzene molecules is accompanied by many reaction intermediates (e.g., phenolate, maleate, acetate, and methylene). The outcomes of this work will help us pursue the development of a state-of-the-art photocatalytic system for air quality management.