CO₂ Electroreduction to Formate at a Partial Current Density up to 590 mA mg^-1 via Micrometer-Scale Lateral...

2D bismuth nanosheets are a promising layered material for formate-producing via electrocatalytic CO₂ conversion. However, the commercial interest of bismuth nanosheets in CO₂ electroreduction is still rare due to the undesirable current density for formate at moderate operation potentials (about 200 mA mg^-1 ) and harsh synthesis conditions (high temperature and/or high pressure). This work reports the preparation of Bi nanosheets with a lateral size in micrometer-scale via electrochemical cathodic exfoliation in aqueous solution at normal pressure and temperature. As-prepared Bi LNSs (L indicates large lateral size) possess high Faradaic efficiencies over 90% within a broad potential window from -0.44 to -1.10 V versus RHE and a superior partial current density about 590 mA mg^-1 for formate in comparison with state-of-the-art results. Structure analysis, electrochemical results, and density functional theory calculations demonstrate that the increasing tensile lattice strain observed in Bi LNSs leads to less overlap of d orbitals and a narrower d-band width, which tuning the intermediate binding energies, and therefore promotes the intrinsic activity.