Unraveling the importance between electronic intensity and oxygen vacancy on photothermocatalytic toluene oxidation over CeO2

Developing low-temperature, high-efficiency and anti-poisoning catalysts is crucial for VOCs removal. CeO2 materials with different electron density are prepared via regulation on facets and oxygen vacancies. It reveals that high electron density of materials plays a decisive role in the production of reactive oxygen species, reducibility of surface lattice oxygen and improvement of photothermocatalytic activity for toluene oxidation compared with highly concentrated oxygen vacancies and large special surface area. Photothermocatalytic conversion rate for 1500 ppm of toluene over the optimized defective CeO2 could reach 93 % at 145 °C under the gas hourly space velocity of 60,000 mL·g−1·h−1. H2-TPR result shows that excessive oxygen vacancies are detrimental to the appearance of mobile reactive oxygen species due to the strong chemical interaction and the escape probability of surface lattice oxygen of CeO2. It is also found that the decrement of electron density of the recovered sample can account for the slight catalyst deactivation, accompanied by the increasement of bulk oxygen vacancies in the recovered sample, exclusive of disappearance of surface oxygen vacancies, aggregations and deposition of organic carbon. This work provides an insight into the design of high-efficiency non-noble catalysts applied to VOCs removal.