在中性pH的氧化水中产生的Co(IV) 种类的EPR证据
J Gregory McAlpin1, Yogesh Surendranath, Mircea Dinca
1Department of Chemistry, University of California, 1 Shields Avenue, Davis, California 95616-0935, USA.
Journal of the American Chemical Society
|May 4, 2010
概括
这项研究表明,酸 (Co-Pi) 水氧化催化剂在催化过程中形成活性-IV物种. 电子磁共振 (EPR) 光谱证实了水分裂过程中氧化状态的存在和变化.
科学领域:
- 电化学 电化学 电化学
- 材料科学 材料科学 材料科学
- 频谱学是一种光谱学.
背景情况:
- 薄膜酸 (Co-Pi) 材料是水氧化的有希望的电催化剂.
- 在催化过程中了解活性物种和氧化还原转化对于催化剂优化至关重要.
- 电子磁共振 (EPR) 光谱是一种强大的工具,用于表征磁共振金属离子.
研究的目的:
- 为了描述由电沉积制备的Co-Pi薄膜催化剂中的的氧化还原状态.
- 为了研究在中性pH的氧化水催化过程中的物种化变化.
- 提供光谱证据,证明特定的氧化状态在催化循环中的参与.
主要方法:
- 通过使用酸盐电解质和酸通过电沉积制备Co-Pi薄膜催化剂.
- 使用电子磁共振 (EPR) 光谱学对催化剂薄膜进行表征.
- EPR信号与不同沉积电压和催化活性的相关性.
主要成果:
- 在Co-Pi催化剂薄膜中显示出表明Co (II) 和Co (IV) 两种物种的EPR信号.
- 沉积电压向水氧化条件的增加导致Co (IV) 的增加和Co (II) 的减少.
- 长时间的氧化水催化也会诱导氧化还原物种化的变化,有利于更高的氧化状态.
结论:
- 谱学证据证实了在中性pH下由Co-Pi薄膜在水氧化催化过程中形成和存在Co(IV) 物种.
- 观察到的Co(II) 和Co(IV) 种群的变化与催化活性和沉积参数直接相关.
- 这些发现阐明了Co-Pi水氧化催化剂的氧化还原机制,突出了在更高氧化状态中的作用.
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