Dynamic Te-OH Proton Relay Enables Industrial-Level Acidic CO₂ Electroreduction on Single-Atom Catalysts.

Abstract

Electrochemical CO₂ reduction reaction (CO₂RR) in acidic media can suppress carbonate formation and boost CO₂ utilization efficiency. However, at high current densities, rapid proton consumption induces localized alkalization, causing insufficient proton supply and limiting reaction kinetics. Here we report a dynamic proton-relay strategy that enables rapid and selective CO₂RR by integrating atomically dispersed Ni-N sites on carbon with adjacent Te species (Ni-N/Te-C). The incorporated Te centers form reversible Te-OH/Te-O^- couples that simultaneously promote water activation and mediate controlled proton delivery, thereby synchronizing hydrogen supply with intermediate protonation while suppressing competitive hydrogen evolution. As a result, Ni-N/Te-C achieves a CO Faradaic efficiency above 94.8% across a wide potential window from -0.8 to -1.4 V versus the reversible hydrogen electrode. Ni-N/Te-C delivers an industrial CO current density of 562.5 mA cm^-2 and a turnover frequency of 16291.9 h^-1 at -1.4 V, significantly higher than that of Ni-N/C. The catalyst also demonstrates remarkable durability, maintaining 93.8% selectivity for 300 h at 100.0 mA cm^-2. In situ spectroscopic characterization and theoretical calculations reveal that the Te-OH-mediated proton relay modulates the reaction pathway of water dissociation and CO₂ protonation with significantly lower energy barriers, thus accelerating *COOH formation.