Mass Transport Modifies the Interfacial Electrolyte to Influence Electrochemical Nitrate Reduction
Mass Transport Modifies the Interfacial Electrolyte to Influence Electrochemical Nitrate Reduction
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DOI：
10.1021/acssuschemeng.3c01057
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发表时间：
2023-05-05
影响因子：
8.4
通讯作者：
Tarpeh, William A.
中科院分区：
文献类型：
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作者：
Guo, Jinyu;Brimley, Paige;Tarpeh, William A.
电化学硝酸盐还原反应（NO3 RR）可以促进硝酸盐污染废水的修复和氨的可持续生产。作为反应微环境的一个重要组成部分，界面电解质对NO3 RR的影响很大，但研究还不够深入。传质改变了界面电解质性质（例如，pH，溶质浓度），从而调节NO3 RR活性和选择性。在具有钛NO3 RR电极的代表性流动池配置中，我们系统地控制了传质条件，并证明了它们对NO3 RR性能的影响。采用连续介质模型模拟和原位红外吸收光谱，研究了不同传质条件下的界面电解质环境。此外，我们策略性地调整了界面电解质的性质，并通过实验去卷积了它们对NO3 RR活性和选择性的影响。我们发现，扩散层厚度和背景电解质浓度控制NO3 RR活性，而界面pH值转向NO3 RR选择性。受这些发现的启发，我们应用脉冲电位定期刷新界面电解质环境并降低局部pH值，成功地将相对氨-亚硝酸盐选择性提高了两倍。与专注于反应动力学的NO3 RR研究不同，这项研究是在常见的质量传输限制下进行的，以促进对质量传输效应背后的机理理解，并帮助确定优化氨生产的工程机会。
The electrochemical nitrate reduction reaction (NO3RR) can facilitate remediation of nitrate-polluted wastewater and sustainable production of ammonia. As an important component of the reaction microenvironment, the interfacial electrolyte substantially influences NO3RR but remains underexplored. Mass transport modifies the interfacial electrolyte properties (e.g., pH, solute concentrations) and thus regulates NO3RR activity and selectivity. In a representative flow-cell configuration with a titanium NO3RR electrode, we systematically controlled mass transport conditions and demonstrated their impacts on NO3RR performance. With continuum model simulation and in situ infrared absorption spectroscopy, we characterized the interfacial electrolyte environment under varied mass transport conditions. Furthermore, we strategically tuned the interfacial electrolyte properties and experimentally deconvoluted their impacts on NO3RR activity and selectivity. We found that diffusion layer thickness and background electrolyte concentration govern NO3RR activity, while interfacial pH steers NO3RR selectivity. Inspired by these findings, we applied pulsed potential to periodically refresh the interfacial electrolyte environment and lower the local pH, successfully tripling the relative ammonia-to-nitrite selectivity. Distinct from NO3RR studies that focus on reaction kinetics, this study was conducted under commonly observed mass transport limitations to advance mechanistic understanding behind mass transport effects and to help identify engineering opportunities that optimize ammonia production.