2D/3D S-scheme heterojunction of carbon nitride/iodine-deficient bismuth oxyiodide for photocatalytic hydrogen production and bisphenol A degradation

A novel 2D/3D S-scheme carbon nitride/iodine-deficient bismuth oxyiodide (g-C3N4/BiO1.2I0.6) heterojunction was constructed for the first time by calcining a mixture of g-C3N4 nanosheets and flower-like BiOI. Irradiated by visible light, this g-C3N4/BiO1.2I0.6 heterojunction exhibited excellent photocatalytic hydrogen production and BPA degradation activity with high cycle stability. In particular, the photocatalytic activity of 0.2-C3N4/BiO1.2I0.6 could reach 1402.7 μmol g-1 h-1 (hydrogen production rate) and 0.01155 min-1 (apparent rate of bisphenol A degradation), which were 3.5 and 3.2 times that of g-C3N4 respectively. The remarkable photocatalytic performance was due to the efficient charge separation of g-C3N4/BiO1.2I0.6 and the formation of S-scheme heterojunction, which maintained strong photocatalytic reduction and oxidation potentials. Noticeably, the charge density difference and band offsets of the g-C3N4/BiO1.2I0.6 were calculated. The results revealed that a built-in electric field (IEF) was created. The values of the valence band offset (ΔEVBO) and the conduction band offset (ΔECBO) were -0.84 and -1.27 eV, respectively, which further demonstrated the formation of S-scheme photocatalytic charge transfer mechanism.