We have demonstrated here that graphene quantum dots (GQD) bind to cobaltous ion giving it a flowery structure. As a result of this binding the cyclic voltammetric peak potential shows a cathodic shift with reference to unbound cobaltous ion. From the electrochemical data, it is estimated that Co2+ is hexa coordinated with GQD to form the bound species. The electrochemical reduction of cobaltous ion is carried out using four baths. A spectrophotometric examination of aquo cobaltic solution shows a characteristic maximum at 508 nm that is absent when cobaltous ion is in GQD bath. Co composite has been galvanostatically deposited on metal substrates. Fourier transform infrared spectroscopy (FTIR) of Co bound GQD shows distinct peaks at 3246(broad) cm–1, 2089 cm–1, 1639 cm–1, 1392 cm–1, 1274 cm–1, 1099 cm–1, 536 cm–1 that can be attributed to Co-C stretching and C-C stretching. The thermogravimetric analysis (TGA) of the composite shows that it is thermally stable from decomposition up to 600°C. The energy dispersion analysis (EDAX) of the deposited Co shows the presence of carbon and cobalt at 0.25 keV and 7.0 eV respectively. The electrochemically deposited graphene composite responds rapidly to a flowing hydrogen gas stream.
Published in: "Journal of the Electrochemical Society".