• Yang, Shuang
• Arnouts, Sven
• An, Hongyu
• Yu, Xiang
• Wang, Hui
• Altantzis, Thomas
• Ruiter, Jim De
• Bals, Sara
• Weckhuysen, Bm Bert

Abstract

<jats:title>Abstract</jats:title><jats:p>It remains a challenge to identify the active sites of bismuth catalysts in the electrochemical CO<jats:sub>2</jats:sub> reduction reaction. Here we show through in situ characterization that the activation of bismuth oxyhalide electrocatalysts to metallic bismuth is guided by the halides. In situ X-ray diffraction results show that bromide promotes the selective exposure of planar bismuth surfaces, whereas chloride and iodide result in more disordered active sites. Furthermore, we find that bromide-activated bismuth catalysts outperform the chloride and iodide counterparts, achieving high current density (&gt;100 mA cm<jats:sup>–2</jats:sup>) and formic acid selectivity (&gt;90%), suggesting that planar bismuth surfaces are more active for the electrochemical CO<jats:sub>2</jats:sub> reduction reaction. In addition, in situ X-ray absorption spectroscopy measurements reveal that the reconstruction proceeds rapidly in chloride-activated bismuth and gradually when bromide is present, facilitating the formation of ordered planar surfaces. These findings show the pivotal role of halogens on selective facet exposure in activated bismuth-based electrocatalysts during the electrochemical CO<jats:sub>2</jats:sub> reduction reaction.</jats:p>

Topics

• density
• impedance spectroscopy
• surface
• x-ray diffraction
• activation
• current density
• x-ray absorption spectroscopy
• Bismuth