Gram-scale rapid synthesis of BiO_2-x/Bi₂O₃ heterostructural nanotubes for highly efficient CO₂ electroreduction to...

Electrocatalytic CO₂ reduction to value-added chemicals is a promising strategy toward achieving carbon neutrality. Bismuth (Bi)-based materials have demonstrated significant potential for CO₂ electroreduction to formate; however, their large-scale and rapid synthesis remains a major challenge for industrial application. Herein, we propose a gram-scale rapid synthesis strategy to prepare Bi-based electrocatalysts with excellent catalytic performance. By precisely controlling the amount of ammonia added during synthesis, a BiO_2-x/Bi₂O₃ heterostructure with nanotube morphology was successfully fabricated and could be further reconstructed during CO₂ electroreduction into an active R-BiO_2-x/Bi₂O₃ phase. The catalyst delivers a high partial current density for formate production of 125 mA/cm² at -1.4 V vs. RHE and achieves a Faradaic efficiency of 98 % at -1.1 V vs. RHE. In situ spectroscopic analyses reveal that the R-BiO_2-x/Bi₂O₃ catalyst possesses enhanced intermediate stabilization and adsorption capability, which accelerates the reaction kinetics. Benefiting from these advantages, this catalyst also demonstrates promising applicability in both rechargeable Zn-CO₂ batteries and acidic CO₂-to-formate conversion systems. This work offers a new strategy for the scalable and efficient synthesis of high-performance Bi-based electrocatalysts for practical CO₂ reduction applications.