Cu Modified TiO₂ Catalyst for Electrochemical Reduction of Carbon Dioxide to Methane

Electrochemical reduction of CO₂ (ECO₂ R) is gaining attention as a promising approach to store excess or intermittent electricity generated from renewable energies in the form of valuable chemicals such as CO, HCOOH, CH₄, and so on. Selective ECO₂ R to CH₄ is a challenging target because the rate-determining step of CH₄ formation, namely CO* protonation, competes with hydrogen evolution reaction and the C–C coupling toward the production of longer-chain chemicals. Herein, a Cu-TiO₂ composite catalyst consisting of CuO_x clusters or Cu nanoparticles (CuNPs), which are isolated on the TiO₂ grain surface, was synthesized using a one-pot solvothermal method and subsequent thermal treatment. The Cu-TiO₂ catalyst exhibited high selectivity for CH₄, and the ratio of FE for CH₄ to total FE for all products in ECO₂ R reached 70%.