Vacuum ultraviolet (VUV)-based photocatalytic oxidation for toluene degradation over pure CeO2

Abstract

Volatile organic compounds (VOCs) are one of the biggest concerns in the ambient environment that have attracted a great number of studies related to its remediation. Vacuum ultraviolet (VUV)-based photocatalytic oxidation (PCO) is a promising technology in controlling VOCs. CeO2 is found to be a promising catalyst for the VUV-PCO technology possessing catalytic capacities in both the photocatalysis and ozonation processes. In this study, three typical kinds of pure CeO2 with various nanostructures were synthesized and creatively applied for VUV-photocatalytic oxidation of toluene. Material characterizations, including BET, SEM, TEM, XRD, Raman, XPS, H2-TPR and DRS, were conducted to characterize different CeO2 samples. Results indicated that synthetic CeO2 samples have a much more remarkable enhancement in degrading toluene compared to commercial ones. Higher COx generation and mineralization rates were obtained with the use of all the synthetic CeO2 samples. Compared to commercial CeO2, the synthetic samples have much better capacity towards removing ozone and the best activity in ozone decomposition was observed in CeO2 Nanorods catalysts. Both the effects of photocatalysis and catalytic ozonation exist in all the CeO2 catalysts. The amount of Ce3+ plays a critical role in both the catalytic activity of photocatalysis and ozonation that higher ratio of Ce3+ leads to better performance in toluene removal. The differences in photocatalytic activity were further explained by the results of electrochemical behaviors of different CeO2 samples which showed varying responses to UV irradiation.