Gamma-induced one-step synthesis of reduced graphene oxide–silver nanoparticles with enhanced properties†

Abstract

This study presents a novel gamma-induced one-pot synthesis of reduced graphene oxide–silver nanoparticle (rGO–Ag NPs) nanocomposites. Syntheses were conducted in a deoxygenated aqueous medium containing 0.2 g L⁻¹ graphene oxide (GO), silver ions (10⁻³ or 10⁻² mol L⁻¹), and 0.2 mol L⁻¹ isopropanol at ambient temperature and pressure. Multi-technique characterization confirmed the reduction of GO and silver ions, forming nanocomposites with significantly improved physicochemical and electrochemical properties compared to pristine GO, rGO alone, and rGO–Ag NPs prepared by other methods. UV-Vis absorption spectroscopy revealed tunable optical properties, while UPS measurements provided insights into the energy band structure, highlighting interactions between rGO and Ag NPs that enhance electronic properties. XPS and ATR-FTIR confirmed the successful reduction processes. SEM–EDX analyses demonstrated uniform silver nanoparticle distribution on rGO sheets. The C/O ratio significantly increased after irradiation, with values of 10.8 and 9.6 for composites synthesized with 10⁻³ and 10⁻² mol L⁻¹ in silver ions, respectively, compared to 11.2 for rGO alone. Raman spectroscopy showed a lower intensity ratio (I_D/I_G) between D and G bands (1.18 for nanocomposites vs. 1.40 for rGO), indicating fewer structural defects. Improved thermal stability was evidenced by reduced weight loss (10%) at 300–800 °C. Electrochemical studies revealed exceptional specific capacitance values of 218 F g⁻¹ (10⁻³ mol L⁻¹ Ag⁺ at 50 kGy) and 298 F g⁻¹ (10⁻² mol L⁻¹ Ag⁺ at 70 kGy), surpassing the 125.4 F g⁻¹ for rGO alone. These findings highlight the potential of gamma-induced synthesis for producing rGO–Ag NPs nanocomposites for high-performance supercapacitor applications.