Efficient and durable photocatalytic degradation of benzene by interfacial electron redistribution induced by surface hydroxyl groups on PtOx/TiO2

Indoor benzene severely threatens air quality and human health. Photocatalytic oxidation (PCO) is a promising approach for benzene removal, yet TiO 2 suffered from rapid electron-hole recombination and easy carbon deposition. Decorating TiO 2 with Pt can promote charge separation via Schottky barriers, however, Pt species were easy to agglomerate and the roles of surface hydroxyls in benzene PCO were still unclear. Herein, I-PtO x /TiO 2 was synthesized via impregnation method, there were some Ti 3+ defects in the crystal structure of I-PtO x /TiO 2 , Pt 4+ and hydroxyls were highly dispersed on catalyst surface. Under UV light irradiation, 96.88% benzene (initial concentration, 30 ppm) was degraded within 120 min, and the related reaction rate constant (0.05 min −1 ) was 2.5 times that of P25 and 3.8 times that of PtO x , benzene removal efficiency maintained above 95% after 5 cycles. Highly dispersed Pt 4+ can form a strong electronic interaction with TiO 2 , which promoted the generation of hydroxyls on the surface of I-PtO x /TiO 2 . Surface hydroxyls can adsorb and activate benzene via hydrogen bonding, they can also induce Ti 3+ defects which can synergize with highly dispersed Pt 4+ to promote charge separation. The intermediate degradation products of benzene were detected, including alcohols such as 5-Hexyn-1-ol and 3-Cyclohexene-1-methanol, unsaturated hydrocarbons like 1,3-Hexadien-5-yne, ketones such as Methyl Isobutyl Ketone, and various esters and alkanes. Benzene ring-opening and deep oxidation achieved via • OH and • O 2 − as key reactive species. This study clarified how surface hydroxyls regulated Pt 4+ electronic structure and reaction processes, it provided a guidance for designing high-performance photocatalysts for VOCs purification.