In Situ Reconstructed Hydroxyl-Rich Atomic-Thin Bi2O2CO3 Enables Ampere-Scale Synthesis of Formate from CO2 with Activated Water Dissociation

Renewable electricity-driven CO₂ electroreduction provides a promising route toward carbon neutrality and sustainable chemical production. Nevertheless, the viability of this route faces constraints of catalytic efficiency and durability in near-neutral electrolytes at industrial-scale current densities, mechanistically originating from unfavorable accommodation of ^*H species from water dissociation. Herein, a new strategy is reported to accelerate water dissociation by the rich surface hydroxyl on bismuth subcarbonate nanosheets in situ electrochemical transformed from bismuth hydroxide nanotube precursors. This catalyst enables the electrosynthesis of formate at current densities up to 1000 mA cm⁻² with >96% faradaic efficiencies in flow cells, and a 200 h durable membrane electrode assembly in a dilute near-neutral environment. Combined kinetic studies, in situ characterizations, and theoretical calculations reveal that the atomic thickness strengthens the hydroxyl adsorption, and with a highly localized electron configuration, the hydroxyl-functionalized surface is more affinitive to oxygenated species, thus lowering the barrier for water dissociation and the crucial hydrogenation step in the proton-coupled electron transfer from ^*OCHO to ^*HCOOH.