基于的氧气演变催化剂的核化,生长和修复
Yogesh Surendranath1, Daniel A Lutterman, Yi Liu
1Department of Chemistry, 6-335, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, USA.
Journal of the American Chemical Society
|March 8, 2012
概括
这项研究揭示了氧催化剂 (Co-OEC) 的电沉积机制,详细介绍了它们的核化,生长和修复过程. 在良性pH条件下对功能稳定性的洞察对于开发高效的氧化水阳极至关重要.
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
- 催化剂是一种催化剂.
背景情况:
- 氧进化反应 (OER) 对水的分裂至关重要.
- 在良好的条件下开发稳定和高效的OER催化剂是一个关键的挑战.
- 基于的催化剂对OER是有前途的,但需要机械学的理解.
研究的目的:
- 阐明核化,稳态增长和电沉积氧演化催化剂 (Co-OEC) 修复的机制.
- 调查电解质成分,特别是甲基酸盐度对催化剂形成和稳定性的影响.
- 为了确定催化剂功能和寿命的最佳pH条件.
主要方法:
- 潜在的步骤计时和原子力显微镜用于核和生长研究.
- 电化学动力学研究以确定速率定律和反应顺序.
- 用于催化剂结构分析的X射线吸收光谱学 (XAS).
- 核磁共振 (NMR) 光谱法用于量化催化剂溶解并评估不同pH值的稳定性.
主要成果:
- 同OEC核化是渐进的,在石墨基板上达到~70%的表面覆盖率.
- 稳定状态的电位沉积遵循一个Tafel斜率为~2.3 × RT/F.
- 电化学速率定律取决于CO2+),质子和甲基酸盐度,在不同的甲基酸盐度下观察到不同的顺序.
- 对于中间度的甲基酸盐,提出了一种涉及溶液和表面平衡的机制,其后是限制速率的Co (III) 合并步骤.
- 在较高的甲基酸盐度下,建议将MePO(3)(2-) 与Co(II) 的平衡结合.
- 催化剂在pH>6时表现出功能稳定性和修复性,而腐蚀在较低的pH时发生.
结论:
- 该研究提供了对Co-OEC形成和电催化活性的详细机制理解.
- 动力学见解使Co-OEC用于水氧化的合理设计和操作成为可能.
- 在良性pH条件下 (pH>6) 证明了功能稳定性和修复性,为在水氧化 (光) 阳极中的实际应用铺平了道路.
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