Amphipathic Surfactant on Reconstructed Bismuth Enables Industrial-Level Electroreduction of CO 2 to Formate.

Developing efficient electrocatalysts for selective formate production via the electrochemical CO 2 reduction reaction (CO 2 RR) is challenged by high overpotential, a narrow potential window of high Faradaic efficiency (FE formate ), and limited current density ( J formate ). Herein, we report a hierarchical BiOBr (CT/h-BiOBr) with surface-anchored cetyltrimethylammonium bromide (CTAB) for formate-selective large-scale CO 2 RR electrocatalysis. CT/h-BiOBr achieves over 90% FE formate across a wide potential range (-0.5 to -1.1 V) and an industrial-level J formate surpassing 100 mA·cm -2 at -0.7 V. In situ investigations uncover the reconstructed Bi(110) surface as the active phase, with CTAB playing a dual role: its hydrophobic alkyl chains create a CO 2 -enriching microenvironment, while its polar head groups fine-tune the electronic structure, fostering a highly active phase. This work provides valuable insights into the role of surfactants in electrocatalysis and guides the design of electrocatalysts for the large-scale CO 2 RR.