关于Fe-N-C催化剂活性位点的潜在依赖结构演变的第一原则分析
Ankita Morankar1, Siddharth Deshpande1, Zhenhua Zeng1
1Davidson School of Chemical Engineering, Purdue University, West Lafayette, IN 47907.
概括
铁--碳 (Fe-N-C) 催化剂对氧降解反应 (ORR) 是有前途的,但缺乏稳定性. 这项研究表明,边缘部位增强ORR活动,但容易降解,这表明燃料电池的催化剂设计优化.
科学领域:
- 材料科学 材料科学 材料科学
- 电化学 电化学 电化学
- 计算化学的计算化学
背景情况:
- 贵金属催化剂对于氧降解反应 (ORR) 是昂贵的.
- 铁--碳 (Fe-N-C) 材料提供了一个具有成本效益的替代品.
- 了解运行条件下的Fe-N-C结构及其稳定性对于燃料电池应用至关重要.
研究的目的:
- 在电化学条件下阐明Fe-N-C活性位点的现场结构.
- 将催化剂结构与活性和稳定性描述符联系起来.
- 为设计稳定和活性Fe-N-C电催化剂提供分子层面的见解.
主要方法:
- 周期密度函数理论 (DFT) 的计算.
- ORR中间体 (O,OH) 的共吸附和溶解效应.
- 构建电压依赖的初始热力学相图.
主要成果:
- 在曲的碳边缘的Pyridinic Fe位点表现出高的ORR活性.
- 边缘部位容易过氧化和活动丧失.
- 高ORR活动与特定的边缘站点配置相关.
结论:
- 在Fe-N-C催化剂设计中,应优先考虑小尺寸和大周边边长,以提高ORR活性.
- 尽量减少电压波动是防止活性站点碳腐蚀的必要条件.
- 分子层面的理解指导着用于燃料电池的耐用Fe-N-C电催化剂的开发.
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