电解质pH如何影响氧减少反应
Jay T Bender1, Rohan Yuri Sanspeur2, Nicolas Bueno Ponce3
1McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, United States.
Journal of the American Chemical Society
|October 1, 2025
概括
电解质的pH显著影响氧降解反应 (ORR) 速率,特别是对黄金和白银等弱结合催化剂. 这是由于电场改变了中间的结合能,影响了催化活性.
科学领域:
- 电化学
- 材料科学
- 催化剂
背景情况:
- 电解质pH是影响氧降解反应 (ORR) 动力学和选择性的关键因素.
- 在不同催化剂中,pH影响ORR率的确切机制尚不清楚.
- 了解这些依赖pH的效应对于设计高效的电催化剂至关重要.
研究的目的:
- 阐明不同金属催化剂ORR率pH敏感度的根本原因.
- 调查催化剂-电解质界面上的电场在调解pH效应中的作用.
- 将中间结合能量的变化与观察到的ORR速率变化相关联.
主要方法:
- 在各种金属电极 (Pt,Ir,Ru,Pd,Au,Ag) 上进行ORR的实验动力学研究.
- 原子模拟用于模拟电场效应和中间结合能.
- 分析ORR机制中的质子合电子转移 (PCET) 和非PCET步骤.
主要成果:
- 强结合金属 (Pt,Ir,Ru,Pd) 的ORR率表现出很弱的pH依赖性,因为中间结合能量受到电场的影响很小.
- 在性电解质中,由于被负电场稳定吸附的O2,弱结合金属 (Au,Ag) 的ORR率显著增加.
- ORR的速率决定步骤不受pH影响,但O2吸附的激活屏障在弱结合催化剂下降.
结论:
- 对ORR的pH影响主要是由电场诱导的中间结合能量的变化驱动的.
- 强结合的催化剂具有较低的pH敏感度,而弱结合的催化剂具有较高的pH敏感度.
- 调整电解质的pH值可以通过修改吸附屏障来调整ORR动力学,特别是对结合较弱的材料.
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