An exclusive CO2-to-CO converting single-stack electrolyzer driven by a biomass-derived N-doped carbon-based bimetallic electrocatalyst

Abstract

Effective carbon capture and its facile conversion into high-value chemicals is reckoned as a practical solution to mitigating the impending climate change effects. Electrochemical conversion of CO₂ to other compounds has emerged as one of the leading processes; however, it mostly lingers in the early stage of technology development with poor selectivity and high operational costs. Herein, we present a one-pot synthesis of a carbon-based bimetallic catalyst embedded in a carbon matrix derived from naturally abundant coconut fibers for the selective electrocatalytic reduction of CO₂. Incorporating bismuth and nickel as active metals within an N-doped carbon matrix, the catalyst demonstrates an impressive faradaic efficiency of approximately 95% to produce CO while operating at −0.9 V vs. RHE. Further testing of the N-doped carbon supported Bi₁₈Ni₈O₃₆ (Bi,Ni/N-C) composite catalyst in an electrolyzer revealed its capability to achieve a current density of 110 mA cm⁻² required for industrial-level applications and can produce ∼1.5 L (60.5 mmol) of CO in 6 hours. Density functional theory (DFT) calculations were conducted to gain deeper insights into the catalytic process, revealing that the nickel metal site exhibits greater activity in facilitating the CO₂ reduction reaction (CO₂RR). This approach not only enhances the selectivity and efficiency of CO₂ conversion processes but also underscores the potential of utilizing cost-effective and biodegradable materials for catalyst design, offering a sustainable pathway to mitigate rising CO₂ emissions and produce valuable industrial products.