Electroreduction of CO2 by Hybrid Cu-TiO2/rGO Catalyst: Qualitative Detection of Products using Rotating Ring Disc Electrode

Abstract

The electrochemical reduction of CO₂ (ERCO₂) to valuable chemicals such as acetic acid/acetate offers a promising route to revolutionize chemical production and enhance sustainability. Here, we report the hydrothermal preparation of an electrocatalyst consisting of copper/titanium dioxide/reduced graphene oxide (Cu-TiO₂/rGO) for ERCO₂ in aqueous medium. The metal-support (TiO₂/rGO) was pre-synthesized by combining an aqueous solution of TiO₂ and GO in an autoclave at 150 °C for 20 h. Then TiO₂/rGO was added to synthesized Cu colloid formed through the reduction of copper (II) nitrate trihydrate resulting in the formation of Cu-TiO₂/rGO. The Cu-TiO₂/rGO hybrid nanocomposite was fully characterized using spectroscopic and microscopic techniques. This study explored the versatility of the rotating ring-disc electrode (RRDE) as an in situ electroanalytical tool for the selective detection of products formed during ERCO₂. The well-designed hybrid electrocatalyst, containing Cu⁰/Cu⁺ active sites, facilitated the eight-electron transfer for acetic acid (AA) formation at low potentials. AA formation was detected on the RRDE and validated by conventional NMR and HPLC techniques. This work highlights and expands the scope of selective hydrogenation of CO₂ towards value-added products.