Decorating {0 0 1} TiO2 nanosheets on hydrophobic NaY zeolite: An efficient deactivation-resistant photocatalyst for gaseous toluene removal

Abstract

Photocatalysis is regarded as a promising in situ air purification technology for the removal of volatile organic compounds. However, the deactivation of photocatalysts remains a serious issue that needs to be addressed. Herein, we report a novel dual-functional photocatalyst (TiO2@HYZ) with spatially separated catalytic sites and adsorption sites, which has been obtained by combining hydrophilic {001} TiO2 nanosheets with hydrophobic NaY zeolite. TiO2@HYZ showed excellent photocatalytic activity for the degradation of gaseous toluene under UV irradiation in humid air. The optimized TiO2@HYZ-2 (containing 45.7 wt% TiO2) achieved 96.6% toluene removal and 87.4% mineralization within 120 min. The specific reaction rate constant of TiO2@HYZ-2, pristine TiO2 and P25 normalized by the unit amount of TiO2 during the photocatalytic degradation process were calculated to be 0.481, 0.230 and 0.250 min−1 g−1, respectively. Moreover, TiO2@HYZ-2 showed superior durability, maintaining stable performance over repeated toluene degradation processes, even at high toluene concentration, whereas pristine TiO2 incurred severe deactivation with increasing number of photocatalysis cycles. The significantly enhanced activity and anti-deactivation property was attributed to a synergistic effect between HYZ and TiO2 in the catalyst structure, which strengthened the adsorption of toluene on HYZ and facilitated effective separation of photoexcited charge carriers on TiO2, thus avoiding the deposition of degradation intermediates on the active sites and simultaneously improving mineralization. This work provided a new perspective for the design of efficient and deactivation-resistant photocatalysts for air pollution remediation.