Tuning dimensionality TiO2/g-C3N4 heterostructure for enhanced elemental mercury removal performance under visible-light

Highlights: • The dimensional transition from 3DBG to 2DGN improve the photocatalytic efficiency. • The effect of oxygen species and doping amount on photocatalytic oxidation was investigated. • The photocatalytic reaction mechanism of charge transfer was proposed. TiO₂/g-C₃N₄ (TCN) heterojunction photocatalysts with dimensionality tuning was prepared, g-C₃N₄ successfully shifted from 3D (3DBG) to 2D (2DGN). Compared with 2DGN and TiO₂, all the as-prepared heterostructure samples exhibited significantly enhanced photoactivities under light irradiation. Through the photocatalytic mercury removal experiment on samples with different doping ratios, the effect of oxygen species such as hydrocarbons or surface-adsorbing molecular H₂O and doping amount on the performance of photocatalytic oxidation were investigated. Finally, the photocatalytic reaction mechanism of charge transfer in the dimensional adjustable Z-scheme heterojunction was proposed. This work provides a new strategy for developing efficient photocatalysts to control mercury.