Engineering Under-Coordinated Active Sites with Tailored Chemical Microenvironments over Mosaic Bismuth Nanosheets for Selective CO Electroreduction to Formate.

Selective electrochemical reduction of CO into fuels or chemical feedstocks is a promising avenue to achieve carbon-neutral goal, but its development is severely limited by the lack of highly efficient electrocatalysts. Herein, cation-exchange strategy is combined with electrochemical self-reconstruction strategy to successfully develop diethylenetriamine-functionalized mosaic Bi nanosheets (mBi-DETA NSs) for selective electrocatalytic CO reduction to formate, delivering a superior formate Faradaic efficiency of 96.87% at a low potential of -0.8 V . Mosaic nanosheet morphology of Bi can sufficiently expose the under-coordinated Bi active sites and promote the activation of CO molecules to form the OCHO * intermediate. Moreover, in situ attenuated total reflectance infrared spectra further corroborate that surface chemical microenvironment modulation of mosaic Bi nanosheets via DETA functionalization can improve CO adsorption on the catalyst surface and stabilize the key intermediate (OCHO *) due to the presence of amine groups, thus facilitate the CO -to-HCOO reaction kinetics and promote formate formation.