Nowadays, developing a simple, economical, and scalable approach for producing energy storage and harvesting devices remains challenging. Herein, we developed a mesoporous RGO-SiO₂-TiO₂ nanocomposite for the electroreduction of carbon dioxide through microbial electrosynthesis and high-performance supercapacitor device. An electrode containing Si/Ti oxide nanoparticles and a layer of RGO coated on carbon felt containing RGO-SiO₂-TiO₂ NCs demonstrated stable photocurrents 2.1 times higher than a bare carbon felt electrode and acetate production of 3.21 mM/d with a coulombic Efficiency of acetate 78% and a current density 2.7 A/m², which was metabolized into acetate from HCO₃^- by cultivated anaerobic bacteria. The RGO-SiO₂-TiO₂ NCs-based supercapacitor achieved a maximum energy density of 35 Wh/kg at 630 W/kg power density, and after 10,000 cycles, it retained 84% capacitance stability at 10 A/g with 180 F/g at 1.25 A/g. This method presents a straightforward, cost-effective approach for mitigating CO₂ emissions and generating energy harvesting devices.