Nanosilver-decorated reduced graphene oxide for catalytic carboxylation of phenylacetylene with CO₂

Nanosilver/reduced graphene oxide (AgNPs/rGO) nanocomposite by the green synthesis route was investigated using urea as a green reductor. The characterization of the AgNPs/rGO was confirmed by UV–Vis spectroscopy, FT-IR, XRD, Raman Spectroscopy, FE-SEM, Energy Dispersive X-ray (EDX), and TEM. The characterization result showed that the AgNPs/rGO was successfully synthesized by green reduction using urea, and the AgNPs were well-spread on the surface of the rGO. AgNPs/rGO nanocomposite was used as a catalyst towards the synthesize of phenylpropiolic acid from phenylacetylene carboxylation with CO₂. The difference in the base used and reaction temperature influenced the carboxylation of phenylacetylene with CO₂. The nanocomposite shows excellent selectivity towards phenylpropiolic acid. The highest conversion was obtained from the reaction using Na₂CO₃ at the temperature of 50 °C. Phenylpropiolic acid was formed as a major product with a high selectivity of 99.5%. The reusability of AgNPs/rGO nanocomposite as a carboxylation catalyst maintained an excellent selectivity above 99% even after third cycle.