▎ 摘　　要

Acid catalysts facilitate many chemical reactions. Sulfonated reduced grapheneoxide (rGOPhSO(3)H) has shown to be an encouraging solid acid catalyst because of its efficiency, cost-effectiveness and safety of use. In this study, we prepared the rGOPhSO(3)H nano acid catalyst, with the introduction of aromatic sulfonic acid radicals onto GO by fractional removal of oxygenated functions. It was thoroughly characterized by FT-IR, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, energy dispersive spectroscopy (EDS) and solid state C-13 MAS NMR (SSNMR). Here we report the conversion of CO2 (1.0 atm pressure, at = 50 degrees C, the source of C-1 carbon feed stock) with hydrazides and a catalytic amount rGOPhSO3H, which through a cyclization reaction results in a new strategy for the synthesis of 5-substituted-3H-[1,3,4]-oxadiazol-2-ones (SOxdOs) under ultrasonic irradiation. Hence this concept of cyclization opens up for new insights