Cadmium-based metal−organic frameworks for high-performance electrochemical CO2 reduction to CO over wide potential range

Electrochemical CO2 reduction (ECR) powered by renewable energy sources provides a sustainable avenue to producing carbon–neutral fuels and chemicals. The design and development of high performance, cost-effective, and stable catalysts for ECR remain a focus of intense research. Here, we report a novel electrocatalyst, two-dimensional cadmium-based 1,4-benzenedicarboxylate metal–organic frameworks (Cd-BDC MOFs) which can effectively convert CO2 to CO with a faradaic efficiency (FE) of more than 80.0% over the voltage range between −0.9 and −1.1 V (versus reversible hydrogen electrode, vs. RHE) in 0.1 mol·L−1 CO2-saturated KHCO3 solution with an H-type cell, reaching up to 88.9% at −1.0 V (vs. RHE). The performance outperforms commercial CdO and many other MOF-based materials demonstrated in prior literature. The catalytic property can be readily tuned by manipulating synthesis conditions as well as electrolyte type. Especially, high CO FEs exceeding 90.0% can be attained on the Cd-BDC electrode at potentials ranging from −0.16 to −1.06 V (vs. RHE) in 0.5 mol·L−1 KHCO3 solution by using a gas diffusion electrode cell system. The maximum CO FE approaches ∼97.6% at −0.26 V (vs. RHE) and the CO partial geometric current density is as high as about 108.1 mA · cm−2 at −1.1 V (vs. RHE). This work offers an efficient, low cost, and alternative electrocatalyst for CO2 transformation.