Waste to energy strategy: Graphene-supported Au-Ag2O polyIndole nanocomposites for antimony adsorption and their sequential utilization in supercapacitors device

A novel strategy for addressing industrial wastewater and energy storage issues has been introduced by constructing a symmetric supercapacitor device using the adsorption of antimony (Sb(III)) from wastewater, facilitated by RGO-Au-Ag2O/PIn NCs heralding a new era of efficiency and sustainability. The room temperature mediated synthesis of RGO-Au-Ag2O/PIn NCs demonstrates exceptional efficacy in Sb(III) removal. Moreover, we developed a sustainable approach by repurposing spent Sb(III) adsorbed RGO-Au-Ag2O/PIn NCs for energy storage, thereby reducing secondary pollution. The RGO-Au-Ag2O/PIn NCs presented the maximum removal efficiency of ∼ 90 % at 60 mg/L of initial Sb(III) concentration at pH 8 and 15 mg/25 mL. Experimental adsorption data of Sb(III) onto the RGO-Au-Ag2O/PIn NCs was well fitted with pseudo-second-order kinetic model and Langmuir adsorption isotherm model. Subsequently, the Sb-enriched waste adsorbent (RGO-Au-Ag2O/PIn@SbOx) was utilized to develop a symmetric supercapacitor device, which displayed an energy density of 40.66 Wh/kg alongside a power density of 1000 W/kg. Importantly, this device maintained 82 % capacitance retention even after 12,000 cycles. This research provides an effective method for repurposing exhausted adsorbents, potentially improving energy-efficient recycling of hazardous solid residues in an economical and environmentally friendly way.