▎ 摘　　要

ABS T R A C T The UV-Visible-NIR (250-1000 nm) light harvesting graphene based plasmonic nanocomposite was designed by precise choice and optimization of two ingredients of the nanocomposite. Our synthesized Ag hexagonal bi-pyramids show broad absorption comprising of two phenomena: d -> s interband transition and surface plasmon resonance (SPR). Suitable dispersion of Ag on the rGO sheet results in an enhanced absorption of the nano-composite. The optical phenomena of Ag and its composite were established by computing energy bands, density of states and optical properties of Ag, rGO and rGO/Ag by using dispersion-corrected density functional theory. A copious amount of photogenerated electrons caused by hot carrier assisted SPR under white light irradiation together with easy charge transfer between Ag and rGO make the nanocomposite an efficient solar photocatalyst. This degrades the safranin O dye under 40 min of light exposure. The degradation efficiency of our synthesized green plasmonic photocatalyst rGO/Ag was found to be maximum (100%) among the reported Ag and rGO/Ag photocatalysts in degradation of toxic dye within 40 min light exposure.