The high selectivity for benzoic acid formation on Ca2Sb2O7 enables efficient and stable toluene mineralization

The selectivity for different intermediates in VOCs degradation process may lead to different reaction paths, which determines the overall pollutant degradation efficiency. In this work, Ca2Sb2O7 shows a superior photocatalytic activity and stability in gaseous toluene degradation as compared to P25. To shed light on the mechanism of efficient and stable toluene degradation, particularly the role of selectivity for intermediates during the reaction process, the theoretical and experimental approaches were closely combined. Owing to the promoted charge transfer between the absorbents (such as O-2, H2O, toluene and other intermediates) and Ca2Sb2O7, both the ROS generation and principal intermediates adsorption are significantly enhanced, which leads to a high selectivity for benzoic acid formation. That is confirmed by in suit DRIFTS and theoretical calculations. Enhanced generation of benzoic acid on Ca2Sb2O7 surface could improve the efficiency of toluene ring-opening and over-all degradation due to lower energy barrier for toluene transformation into benzoic acid. Thus, this could enable efficient and stable degradation of toluene and prevent the catalyst from deactivation. This work provides new insight into the mechanistic understanding of photocatalytic VOCs degradation reaction.