Deactivation and activation mechanism of TiO2 and rGO/Er3+-TiO2 during flowing gaseous VOCs photodegradation

The poor efficiency and stability of photocatalysts are the fundamental issues to be addressed for photodegrading VOCs in practical applications. Herein, 0.5 wt%rGO/0.5 mol%Er3+-TiO2 (0.5rGO/0.5 ET) exhibited the excellent performance and a remarkable durability towards gaseous VOC (o-xylene), while pure TiO2 (PT) and 0.5 mol%Er3+-TiO2 (0.5 ET) showed poor catalytic activity and deactivation after 60 min. The results suggested that intermediates accumulation was primarily responsible for the deactivation of PT and 0.5 ET. In contrast, the activity of 0.5rGO/0.5 ET was not decreased although more intermediates were generated compared with other samples. The experiments revealed that rGO provide more adsorption sites for the intermediates, which helped 0.5rGO/0.5 ET resist the deactivation even after photodegradation of 10 h and 4 cycles. Therefore, rGO played a vital role in keeping the stable activity of the composites. This study is helpful to understand the deactivation/activation mechanism of photocatalysts and provided a promising strategy to make catalyst in activation for industrial application.