PtAu晶体缺陷处的化学分配作为电催化剂稳定化的途径
Chemical Partitioning at Crystalline Defects in PtAu as a Pathway to Stabilize Electrocatalysts
摘要：
电催化剂在长期和动态运行过程中的溶解是能量转换和存储装置如燃料电池和电解槽中的一个具有挑战性的问题。为了开发稳定的电催化剂，我们采用了偏析工程的设计理念，即在内部缺陷处使用易于电化学溶解的溶质偏析，晶界和位错。我们展示了这种方法的可行性，通过稳定的模型Pt催化剂，添加更贵的金（约5原子%）。我们表征了缺陷的纳米级结构和化学性质，并通过在线电感耦合等离子体质谱监测了Pt和PtAu合金的电化学溶解。一旦分离到缺陷，Au原子可以稳定并因此钝化最脆弱的位点以对抗电化学溶解，并将Pt电催化剂的稳定性和寿命提高一个数量级以上。这开辟了使用溶质偏析缺陷的发展更稳定的纳米级电催化剂，适用于广泛的催化体系的概念。
英文摘要：
Dissolution of electrocatalysts during long-term and dynamic operation is a challenging problem in energy conversion and storage devices such as fuel cells and electrolyzers. To develop stable electrocatalysts, we adopt the design concept of segregation engineering, which uses solute segregation prone to electrochemical dissolution at internal defects, i.e., grain boundaries and dislocations. We showcase the feasibility of this approach by stabilizing a model Pt catalyst with an addition of more noble Au (approximately 5 atomic percent). We characterized the defects' nanoscale structure and chemistry, and monitored the electrochemical dissolution of Pt and PtAu alloys by online inductively coupled plasma mass spectrometry. Once segregated to defects, Au atoms can stabilize and hence passivate the most vulnerable sites against electrochemical dissolution and improve the stability and longevity of the Pt electrocatalysts by more than an order of magnitude. This opens pathways to use solute segregation to defects for the development of more stable nanoscale electrocatalysts, a concept applicable for a wide range of catalytic systems.
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