质子传递吸附物诱导氧减少中的非纳尔斯特行为
Lulu Zhang1,2,3, Dongchen Zhao1, Weiqiang Tang2
1Hefei National Research Center for Physical Sciences at Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China.
概括
由于硫酸盐离子作为质子捐赠体而导致的氧降低反应中,质子合电子转移 (PCET) 显示出非纳斯蒂行为. 这一发现影响了电催化剂的理解和设计.
科学领域:
- 电化学
- 表面科学
- 计算化学
背景情况:
- 质子合电子转移 (PCET) 对于能量转换至关重要.
- 纳斯特方程预测PCET平衡潜力的-60 mV/pH转移.
- 在特定的电化学反应中观察到与Nernstian行为的偏差.
研究的目的:
- 在氧降解反应 (ORR) 中研究与Nernstian反应的偏差.
- 阐明阴离子和阴离子在pH依赖电催化中的作用.
- 了解局部反应环境对PCET的影响.
主要方法:
- 密度函数理论 (DFT) 的计算.
- 通过多步微动力模型.
- 包含质量传输和电双层效应的局部反应环境 (LRE) 模型
主要成果:
- 在H2SO4/M2SO4溶液中观察到与Nernstian行为的显著偏差,取决于离子标识 (Li,Cs).
- 确定了被吸附的硫酸盐离子作为质子转移的关键介质,形成二硫酸盐物种.
- 与酸盐相比,确定了硫酸盐中的减少质子反应序 (0.5-0.75) (1).
结论:
- 吸附的硫酸盐离子改变了ORR中的质子捐赠机制,解释了非尼恩斯的pH依赖性.
- 在电催化过程中,阳离子和阴离子身份显著调节LRE效应.
- 结合理论和计算方法可以解开复杂的电化学反应机制.
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