▎ 摘　　要

The present study is focused on the synthesis and characterization of ceria loaded graphene oxide (GO) and investigates their catalytic activity on vapor phase selective oxidation of cyclohexane. In this regards, we have synthesized various loading of CeO2 on GO with two different morphology includes nanocrystals and flower-like, which designated as CeO2(x)/GO (where x= 0, 0.2, 0.4, 0.6, 0.8 and 1.0wt.%). The physico-chemical properties of the materials were extensively studied with help of XRD, N-2 adsorption desorption (BET), DRUV-Vis, HRSEM, HRTEM, H-2-TPR and XPS techniques. The crystalline nature of materials were analyzed by XRD, pure ceria shows high crystalline size about 15. 3nm compared to others. Surface area of synthesized materials has been obtained with help of N-2 adsorption desorption analysis, pure ceria and graphene oxide shows surface area about 93 and 574m(2)/g, respectively. XPS and DRUV-Vis spectra were confirms the presence of enormous Ce3+ ions in the lattice. The presence of nanocrystals and flower-like morphology of CeO2(x)/GO were confirmed by HRSEM images. HRTEM images were clearly illustrated that the presence of dominant active {1 0 0} facets in flower-like CeO2/GO than that of nanocrystalline morphology. The catalytic activity of materials has been evaluated on selective oxidation of cyclohexane using air as a green oxidant. The key reaction parameters were varied to study the stability, activity and selectivity of the catalysts. The activity of the catalysts is correlated with their physico-chemical properties, and these results concluded that suitable amount of ceria and it's flower-like morphology on GO is essential for selective oxidation of cyclohexane at low temperature (180 degrees C) compared to nanocrystalline morphology. Hence, flower-like CeO2(0.4)/GO is a most suitable catalyst for high conversion (90%) of cyclohexane into cyclohexanone with 74% selectivity due to occurrence of enormous {1 0 0} facet and Ce3+.