Designing S-scheme Au/g-C3N4/BiO1.2I0.6 plasmonic heterojunction for efficient visible-light photocatalysis

Abstract

A novel S-scheme Au/g-C3N4/BiO1.2I0.6 plasmonic heterojunction was constructed by calcining a mixture of flower-like BiOI and Au/g-C3N4 nanosheets for the first time. This Au/g-C3N4/BiO1.2I0.6 heterojunction exhibited excellent photocatalytic activity in bisphenol AF (BPAF) degradation and Cr(VI) reduction with high cycle stability under visible light irradiation. In particular, the photocatalytic performance of the optimum material developed (4-Au/g-C3N4/BiO1.2I0.6) can reach 0.0174 min−1 (apparent rate of BPAF degradation) and 0.0204 min−1 (apparent rate of Cr(VI) reduction), which were 6.5 and 3.7 times that of pristine g-C3N4, respectively. The high photocatalytic performance was due to the high efficiency of charge separation, the excellent light absorption of localized surface plasmon resonance (LSPR) caused by the Au deposition, and the formation of S-scheme heterojunctions, which maintained strong photocatalytic reduction and oxidation activity. Noticeably, the charge density difference and band offsets of the g-C3N4/BiO1.2I0.6 were calculated. The results revealed that an internal electric field (IEF) was created, which further demonstrated the formation of an S-scheme photocatalytic mechanism.