1. School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022, China; 2. Key Laboratory of Gold Mineralization Processes and Resource Utilization, Shandong Provincial Key Laboratory of Metallogenic Geological Process and Resource Utilization, Shandong Institute and Laboratory of Geological Sciences, Jinan 250013, China
Abstract：Oxygen vacancy-enriched CeO2 catalyst with hierarchical structure was synthesized by impregnation of Ce-BTC (BTC=benzene-1,3,5-tricarboxylic acid) into urea solution, followed by a calcination step. The as-prepared catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy (Raman) and ultraviolet visible diffuse reflection (DRS). The results showed that, different from the reported papers in which the g-C3N4 could be obtained by calcining urea impregnated metal organic frameworks (MOFs) at high temperature, while in this study, there was no g-C3N4 detected in Ce-BTC/urea system after calcination. The absence of g-C3N4 may be related to the MOF-derived CeO2 that inhibited the thermal polycondensation of urea-decomposed species, and prevented the formation of g-C3N4. However, the addition of urea into the Ce-BTC induced the oxygen vacancy change within the formed CeO2, and more importantly, Ce-BTC impregnated urea system developed into hierarchical structure after thermal treatment. When the as-prepared oxygen vacancy-enriched CeO2-5 catalyst with hierarchical structure was used for photocatalytic CO2 reduction, the yield of CO could reach 2.06μmol/g after 4hours, and the yield of CH4 was 1.42μmol/g, which was more than 7 times higher than that of CeO2 prepared by direct thermal decomposition of Ce-BTC.
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