Accelerating Toluene Oxidation over Boron–Titanium–Oxygen Interface: Steric Hindrance of the Methyl Group Induced by the Plane-Adsorption Configuration
Wenqiang Qu, Zixiang Xu, Christoph Gruber, Hongmei Li, Xiaonan Hu, Limin Zhou, Haiyan Duan, Jin Zhang, Min Liu, Emiliano Cortés, Dengsong Zhang
Abstract
Elimination of dilute gaseous toluene is one of the critical concerns within the field of indoor air remediation. The typical degradation route on titanium-based catalysts, “toluene–benzaldehyde–carbon dioxide”, necessitates the oxidation of the methyl group as a prerequisite for photocatalytic toluene oxidation. However, the inherent planar adsorption configuration of toluene molecules, dominated by the benzene rings, leads to significant steric hindrance for the methyl group. This steric hindrance prevents the methyl group from contacting the active species on the catalyst surface, thereby limiting the removal of toluene under indoor conditions. To date, no effective strategy to control the steric hindrance of the methyl group has been identified. Herein, we showed a B–Ti–O interface that exhibits significantly enhanced toluene removal efficiency under indoor conditions. In-depth investigations revealed that, compared to typical Ti-based photocatalysts, the steric hindrance between the methyl group and the catalyst surface decreased from 3.42 to 3.03 Å on the designed interface. This reduction originates from the matching of orbital energy levels between Ti 3d z 2 and C 2p z of the benzene ring. The decreased steric hindrance improved the efficiency of toluene being attacked by surface active species, allowing for rapid conversion into benzaldehyde and benzoic acid species for subsequent reactions. Our work provides novel insights into the steric hindrance effect in the elimination of aromatic volatile organic compounds.