Er single atoms decorated TiO2 and Er3+ ions modified TiO2 for photocatalytic oxidation of mixed VOCs

Photocatalytic degradation of single volatile organic compounds (VOCs) has been widely discussed while that of VOCs mixture has been rarely mentioned. Herein, Erbium (Er) single atoms decorated TiO2 (Er1-TiO2) and Er3+ ions modified TiO2 (Er3+-TiO2) with more adsorption sites and stronger capacity for producing reactive oxygen species were chosen for the photocatalytic degradation of single VOC (ethylene, acetaldehyde and o-xylene) and VOCs mixture (o-xylene-acetaldehyde mixture and o-xylene-ethylene mixture). The adsorption capacity for oxylene was influenced by the introduction of acetaldehyde or ethylene. As for Er3+-TiO2, the calculated adsorption capacity for o-xylene was 4.44 mu mol/g while that for o-xylene in o-xylene-acetaldehyde mixture and o-xylene-ethylene mixture were 1.03 mu mol/g and 2.35 mu mol/g, respectively. The degradation efficiency for oxylene was also affected by the introduction of acetaldehyde or ethylene because of the competitive adsorption and the competitive availability of reactive oxygen species. As for Er3+-TiO2, the degradation efficiency for oxylene was 90% while that for o-xylene in o-xylene-acetaldehyde mixture and o-xylene-ethylene mixture were 85% and 80%, respectively. Furthermore, the degradation route of o-xylene was influenced by the introduction of acetaldehyde or ethylene. This study is beneficial to comprehend the interaction mechanism between different VOCs in the photocatalytic degradation process.