Ultrafine Bi Nanoparticles Confined in Hydrothermal Carbon-Modified Carbon Nanotubes for Highly Efficient CO ₂ Electroreduction to Formate

Abstract

Electroreduction of carbon dioxide (CO 2 ) into formate is a sustainable and promising approach to solve the greenhouse effect. Herein, ultrafine Bi nanoparticles (Bi NPs) with a diameter of around 3.4 nm on hydrothermal carbons-modified carbon nanotubes were successfully obtained via dip-coating method, and could be used as an effective catalyst for electroreduction of CO 2 into formate. As a result, the as-prepared catalyst exhibited an outstanding CO 2 reduction performance with a faradaic efficiency of 94.8% and a higher current density of 17.8 mA cm −2 . The high selectivity could maintain over a wide potential range of 400 mV, together with satisfactory durability for more than 24 h. Electrochemical results and density functional theory (DFT) calculation showed that the rich intrinsic active sites of Bi could effectively adsorb CO 2 molecules and promote the CO 2 (ads) intermediate to form the CO 2 · − intermediate, and resulting in the higher intrinsic activity of the CO 2 reduction. Thus, our work demonstrated a synergistic effect between carbon supports and metal nanoparticles could broaden the activity and selectivity for CO 2 electroreduction and offer useful perspectives to design efficient and low-cost electrocatalysts.