Ternary NiTiO3@g-C3N4–Au nanofibers with a synergistic Z-scheme core@shell interface and dispersive Schottky contact surface for enhanced solar photocatalytic activity

Abstract

Z-scheme narrow bandgap heterojunctions can efficiently absorb solar light and provide high reduction and oxidation ability for photocatalysis. However, it is difficult to tune the Z-scheme interface charge transfer to achieve high charge separation. Here, we introduced a Schottky contact surface to promote Z-scheme interface charge separation. Thin g-C₃N₄ nanolayers of 50–60 nm were evenly grown on NiTiO₃ nanofibers forming a Z-scheme core@shell interface, and Au nanoparticles of ∼10 nm were dispersed in the g-C₃N₄ nanolayer developing an additional Schottky contact surface. The Z-scheme core@shell interface and dispersive Schottky contact surface could generate a uniform radial electric field, providing continuous charge transfer channels. Photocurrent and photoluminescence confirmed the improved charge separation in the NiTiO₃@g-C₃N₄–Au nanofibers. The ternary photocatalysts had enhanced photocatalytic activities under simulated solar light. Their hydrogen evolution rate was 212.50 μmol g⁻¹ h⁻¹, which was 4.22, 2.81 and 4.85 times higher than that of binary NiTiO₃@g-C₃N₄ nanofibers, g-C₃N₄–Au and g-C₃N₄. For water treatment, their first-order rate constant of Rhodamine B oxidation was 0.033 min⁻¹, which was 3.73, 3.83, 4.95 and 21.5 times higher than that of binary NiTiO₃@g-C₃N₄ nanofibers, g-C₃N₄–Au, g-C₃N₄, and NiTiO₃ nanofibers. The ternary photocatalysts also had relatively stable activity at various pH values, good separability, and recyclability. This work presents new insight into designing ternary photocatalysts with a synergistic interface and surface for photocatalysis.