Bismuth metal-organic framework for electroreduction of carbon dioxide

The electrocatalytic CO2 reduction (CO2R) to hydrocarbons is a carbon-neutral strategy to address the issues of the global greenhouse effect and depletion of fossil fuels. Bismuth (Bi) shows great potential as CO2R catalysts with high selectivity towards formic acid and low activity for hydrogen evolution. However, achieving high current density as well as high Faradaic efficiency (FE) during CO2R by using Bi-based catalysts remains a substantial challenge. Here, we investigate the catalytic performance of the bismuth metal-organic framework (Bi-MOF) for electrochemical CO2R. The FEHCOOH has been evaluated over a broad current density range, reaching 92% at 150 mA cm−2, and long time stability for 30 h with FEHCOOH above 80%, outperforming most Bi-based catalysts. X-ray photoelectron spectroscopy and operando Raman spectra demonstrate that Bi-MOF transfer into a mixture of metallic Bi and oxide Bi2O2.5 during the reduction process, and the hybrid Bi/Bi-O interface is the active site that enables the selective CO2R to HCOOH, while suppresses the hydrogen evolution. This work demonstrates that the Bi-MOF derived catalysts can introduce large surface area and abundant active metal/metal oxide interface, which can reach high selectivity and high current density, simultaneously. This finding and the understanding of the catalytic mechanism inspire future catalysts design.