Dose-dependent gamma irradiation effects on Ni nanoparticle size in rGO–Ni nanocomposites for enhanced electrochemical performance

This study introduces an environmentally friendly method for synthesizing reduced graphene oxide/nickel (rGO-Ni) nanocomposites for electrochemical applications using gamma irradiation. This approach eliminates the need for toxic chemical reductants and mitigates the generation of hazardous residues and undesirable by-products. The effect of the gamma irradiation dose on the size of nickel nanoparticles supported on graphene oxide was also investigated. The graphene oxide (GO) dispersion was subjected to gamma irradiation in the presence of the (Ni[(NH₃)₆]Cl₂) complex at doses of 20, 40 and 80 kGy and a dose rate of 10 kGy h^-1. X-ray diffraction confirmed the formation of metallic Ni and the simultaneous reduction of graphene oxide (GO) induced by gamma irradiation, while X-ray photoelectron spectroscopy indicated the oxidation of the Ni metal on the GO surface. These findings were further corroborated by thermogravimetric analysis. To evaluate the electrochemical properties, screen-printed electrodes were modified with rGO and rGO-Ni. Cyclic voltammetry measurements in the presence of K₃[Fe(CN)₆] demonstrated reversible redox behavior for all samples. It is noteworthy that rGO-Ni/SPE exhibited a significant enhancement in the anodic peak currents (<i>I</i>_pa) and electroactive surface area compared to the unmodified SPE. Furthermore, a direct correlation was observed between the <i>I</i>_pa value and the gamma radiation dose applied during the nanocomposite synthesis. These results point out the potential applications of rGO-Ni nanocomposites in electrochemical devices.