Ionic liquids assist synthesis of Ag/AgX (X = Cl, Br, & F)-decorated rGO for visible light photocatalytic applications

Three different ionic liquids based on 1-butyl-3-methylimidazolium were prepared and used to synthesize Ag/AgX (X = Cl, Br, & F) nanoparticles-decorated reduced graphene oxide (rGO). The formation of the Ag/AgX-rGO composites were confirmed from the powder XRD patterns of the samples and the absorption peaks at 220 nm, 280 nm, and 352 nm in UV–visible spectroscopy. The functional groups in rGO and decoration of Ag/AgX on rGO sheets were established by the peaks in FT-IR at 1192 cm⁻¹, 1270 cm⁻¹, and 1569 cm⁻¹. The I_D/I_G ratios in micro-Raman analysis, and FE-SEM images witness the above observation. The endothermic peak at 956 °C in DSC analysis indicates the presence of silver in the samples. The natural visible light photocatalytic properties of these materials were studied with the degradation of methylene blue (MB) dye. The samples with Ag/AgX structures have better photocatalytic properties than AgX and rGO. This is due to the increased utilization of sunlight by the plasmonic Ag in the Ag/AgX-rGO samples and the fast charge separation by rGO. The samples GIA1 and GIA3 are showing better dye degradation efficiency, these samples degrade 97% and 97.5% of MB dye, respectively. The formation of AgX was dependent on the type of ionic liquids used in the synthesis which is highly reflected in the photocatalytic behavior.