Trivalent Metal Ions (Al, Ga, In)-Doped TiO2 for Enhanced Photocatalytic Desulfurization of H2S: Band Structure Regulation, Performance, and Mechanism

Rationally regulating the photogenerated carrier transfer behavior and band structure of TiO2 through metal doping is an effective strategy for enhancing the photocatalytic activity in the removal of malodorous gas hydrogen sulfide (H2S). In this study, TiO2 modified with the doping of Group IIIA metal ions (Al3+, Ga3+, and In3+) was utilized as an efficient photocatalytic desulfurizer under ultraviolet irradiation. Among these samples, the 4% In-TiO2 exhibited the best photocatalytic H2S removal efficiency of 100% for a duration of 120 min, nearly 3 times higher than that of commercial P25 TiO2. The UV–vis DRS and PL spectra demonstrated that the incorporation of Group-IIIA metal ions into TiO2 resulted in the formation of a shallow acceptor level above the valence band in the energy band structure, which induced a slight redshift at the edge of the visible light absorption band and reduced the electron–hole recombination rate. In situ DRIFTS and DFT calculations revealed that the adsorption and activation of H2S occurred simultaneously on In-TiO2, facilitated by its strong oxygen vacancy formation and adsorption capability. The ln3+ doping into TiO2 promoted photothermal-catalytic oxidation reaction on the surfaces of In-TiO2, thereby significantly enhancing the desulfurization efficiency of H2S. This study not only offers a deeper understanding of the regulated band structure of TiO2 by doping of Group IIIA metal ions, but also provides a promising and green photocatalytic desulfurizer of In-TiO2 for efficient removal of H2S.