Synthesis of Sn-based nanocomposites using waste polyethylene terephthalate (PET) for the electrochemical reduction of CO₂ to formate

Terephthalic acid (TPA) was recovered by alkaline hydrolysis of waste polyethylene terephthalate (PET) bottles. TPA recovered was used to prepare Sn-based catalyst by solvothermal method. For comparison, commercial TPA was also used to prepare Sn-based catalyst. The catalysts were used for the electrochemical reduction of CO₂ to formate. Both the catalysts were found to possess nanoflake morphology, and were highly porous in nature with Brunauer–Emmett–Teller (BET) surface area of 211.4 and 239.4 m²/g for commercial and PET derived TPA-based Sn catalysts, respectively. The catalyst made from the waste PET bottles derived TPA was found to be more effective than the one obtained from the commercial TPA. The Faradaic efficiency obtained for the formation of formate was 68.4% at potential − 1.8 V (vs Ag/AgCl) and current density of 13.5 mA/cm², when catalyst was synthesized using waste PET derived TPA. High activity of the electrocatalysts was attributed to higher capacitance, and lower resistance of the catalysts.