在酸性氧减少过程中,Fe-N-C电催化剂中的Fe溶解:局部pH值变化的影响
Angus Pedersen1,2,3, Kavita Kumar4, Yu-Ping Ku4,5
1Imperial College London, Department of Materials, Royal School of Mines London SW7 2AZ UK i.stephens@imperial.ac.uk.
概括
铁--碳 (Fe-N-C) 催化剂对燃料电池有希望,但耐用性是一个挑战. 这项研究表明,氧气减少过程中的局部pH值变化会导致铁的沉降,影响催化剂的稳定性.
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:
- 在N-化C (Fe-N-C) 催化剂中的原子Fe是引领质子交换膜燃料电池中O2减排的非贵金属催化剂.
- 耐久性有限,特别是Fe脱金属化,阻碍了Fe-N-C催化剂的广泛应用.
研究的目的:
- 在各种操作条件下研究Fe-N-C催化剂的Fe溶解和沉机制.
- 阐明当地pH在氧降解过程中Fe-N-C催化剂降解中的作用.
主要方法:
- 操作电化学测量与感应合等离子体质谱学 (ICP-MS) 相结合.
- 使用的流量电池和气体扩散电极 (GDE) 半电池配置.
- 结合了死前和死后分析和微动力学建模.
主要成果:
- 在没有氧气的情况下,Fe离子溶解并扩散到液态阶段.
- 在O2降低条件下 (≥-15 mA cm-2 geo),Fe离子在催化剂层内以Fe-氧化物形式呈现.
- 由于H+消耗,Fe-N-C层内的局部pH值增加 (至8-9) 会导致Fe-氧化物沉.
结论:
- 局部pH值是控制Fe-N-C催化剂在运行过程中的Fe稳定性的主要因素.
- 了解和控制当地的pH值对于提高燃料电池中Fe-N-C催化剂的耐用性至关重要.
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