电化学 NH3 合成中 NRR-HER 竞争的操作扫描电化学显微研究和可视化,Journal of Materials Chemistry A

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电化学 NH3 合成中 NRR-HER 竞争的操作扫描电化学显微研究和可视化
Journal of Materials Chemistry A ( IF 10.7 ) Pub Date : 2023-10-26 , DOI: 10.1039/d3ta04976k
Divyani Gupta ₁ , Alankar Kafle ₁ , Man Singh ₁ , Devyani Dahare ₁ , Tharamani C. Nagaiah ₁

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电化学二氮还原（NRR）已成为能源密集型哈伯-博世工艺最有前途的潜在替代方案之一，用于清洁无碳氨（NH 3 _）生产。然而，这种电化学合成的主要障碍是 NRR 和竞争性析氢反应 (HER) 之间的选择性，导致法拉第效率较差。NRR和HER之间的竞争尚未得到充分研究，并且现有的非原位NH ₃和H ₂检测方法不能以高空间分辨率实时检测电极表面附近形成的产物。因此，使用扫描电化学显微镜（SECM）通过样品生成尖端收集（SG-TC）模式对电化学N ₂还原过程中NH ₄⁺的产生及其与HER的竞争进行了操作研究。_{在连续计时安培分析过程中，在金超微电极 (UME) 上观察到明显的净电流密度差异，并且在 Ar 和 N 2}饱和电解质中催化剂的局部催化活性可视化。因此，这项研究提供了有关 NRR 和 HER 在毫秒内施加电位下的竞争的宝贵信息，以及具有高空间分辨率和准确性的可视化。

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Operando scanning electrochemical microscopic investigation and visualization of NRR-HER competition in electrochemical NH3 synthesis

Electrochemical dinitrogen reduction (NRR) has emerged as one of the most promising potential alternatives to the energy-intensive Haber–Bosch process for clean and carbon-free ammonia (NH₃) production. However, the major setback in this electrochemical synthesis is the selectivity between NRR and the competing hydrogen evolution reaction (HER) that leads to poor faradaic efficiency. The competition between NRR and HER is underexplored, and the existing ex situ NH₃ and H₂ detection methods do not provide the real-time detection of products formed near the electrode surface with high spatial resolution. Therefore, the operando investigation of NH₄⁺ production during electrochemical N₂ reduction and its competition with HER was demonstrated using scanning electrochemical microscopy (SECM) via the sample generation-tip collection (SG-TC) mode. A distinct net current density difference was observed at an Au-ultramicroelectrode (UME) during sequential chronoamperometry and the visualization of local catalytic activity over the catalyst in Ar- and N₂-saturated electrolytes. Therefore, this study provides invaluable information on the competition between the NRR and the HER at applied potentials within milliseconds and also visualization with high spatial resolution and accuracy.

更新日期：2023-10-26

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