通过电化学氧降解选择性生产过氧的起源
1Texas Materials Institute, The University of Texas at Austin, Austin, Texas 78712, United States.
Journal of the American Chemical Society
|June 16, 2021
概括
研究人员发现了催化剂为什么在氧降解反应 (ORR) 中有利于过氧化的产生. 他们发现质子亲和力受电位和pH的影响,决定了选择性,解释了实验观测.
科学领域:
- 电化学
- 材料科学
- 计算化学
背景情况:
- 氧降解反应 (ORR) 在电化学中至关重要,从*-O-OH中间体有两个途径:过氧化 (H2O2) 或水形成.
- 现有的催化剂通常显示出高的H2O2选择性,与热力学预测相反,这种选择性随着电位和pH值的变化而变化,缺乏明确的解释.
研究的目的:
- 开发一个先进的第一原理模型来计算固体水界面的电化学反应动力学.
- 阐明控制ORR中的H2O2选择性的基本机制,特别是电位和pH的影响.
主要方法:
- 开发并应用先进的第一原理计算模型来模拟电化学反应动力学.
- 在代表性催化剂上研究了H2O生产的反应途径和能量障碍.
主要成果:
- 鉴定O-OH键断裂可以比*-O键断裂具有更高的能量屏障,这是由于键的刚性.
- 发现*-O-OH中间体中质子对氧原子的亲和力是决定选择性依赖电位和pH的关键因素.
- 单个原子和碳催化剂的不同质子吸附行为,解释了它们在不同条件下的不同H2O2选择性.
结论:
- 质子亲和力是控制ORR选择性的关键,以前未知的因素.
- 开发的模型准确地解释了实验性的H2O2选择性及其对外部因素的依赖性.
- 这项工作促进了ORR动学的理解,并为异质电化学提供了新的计算工具.
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