Potential‐Driven In‐Situ Reconstruction of Layered Bismuth Oxychloride for Efficient Electrosynthesis of H ₂ O ₂ at Large Current Density

ABSTRACT

Bismuth‐based electro(pre)catalysts are emerging as promising systems for the selective two‐electron oxygen reduction reaction (2e ⁻ ORR), yet a clear understanding of their structure–property relationships remains limited. Here, we demonstrate that selective electrochemical potential control under alkaline conditions can deterministically direct the reconstruction of layered BiOCl precursors, establishing a direct link between applied bias and catalyst structure. Comprehensive in situ/ex situ characterization coupled with theoretical calculations reveal strong potential‐dependent behavior, where at 0 V versus reversible hydrogen electrode (RHE), BiOCl undergoes deep reconstruction to metallic Bi with surface Cl adsorption (BiOCl‐0 V), whereas at 0.5 V versus RHE, the structure is largely preserved (BiOCl‐0.5 V). The reconstructed BiOCl‐0 V exhibits significantly enhanced activity, H ₂ O ₂ selectivity, and a near‐ideal 2e ⁻ ORR pathway compared to BiOCl‐0.5 V and commercial Bi, achieving >95% selectivity over a wide potential range, with a peak value exceeding 99%. In a three‐electrode flow cell, BiOCl‐0 V sustains 150 mA·cm ⁻² over 160 h, with Faradaic efficiency above 90% and H ₂ O ₂ productivity of 5.56 mol·g _cat ⁻¹ ·h ⁻¹ . This superior performance stems from reconstruction‐induced porosity and an optimized electronic structure, which enhance mass transport and active‐site accessibility. These findings establish a direct link between Bi redox chemistry, potential‐driven reconstruction, and catalytic performance, offering a general strategy for designing efficient 2e ⁻ ORR catalysts.