An electrochemical flow cell system with catalyst-ionomer ink deposited on glassy carbon is used to investigate the aqueous stability of commercial PtCo alloys under cyclic potentials. An on-line inductively coupled plasma-mass spectrometer, capable of real-time measurements, is used to resolve the anodic and cathodic dissolution of Pt and Co during square-wave and triangle-wave potential cycles. We observe Co dissolution at all potentials, distinct peaks in anodic and cathodic Pt dissolution rates above 0.9 V, and potential-dependent Pt and Co dissolution rates. The amount of Pt that dissolves cathodically is smaller than the amount that dissolves anodically if the upper potential limit (UPL) is lower than 0.9 V. At the highest UPL investigated, 1.0 V, the cathodic dissolution greatly exceeds the anodic dissolution. A non-ideal solid solution model indicates that the anodic dissolution can be associated with the electrochemical oxidation of Pt and PtOH to Pt²⁺, and the cathodic dissolution to electrochemical reduction of a higher Pt oxide, PtO_x (x > 1), to Pt²⁺. Pt also dissolves oxidatively during the cathodic scans but in smaller amounts than due to the reductive dissolution of PtO_x. The relative amounts Pt dissolving oxidatively as Pt and PtOH depend on the potential cycle and UPL.

中文翻译：

---

铂钴合金PEFC催化剂中Pt和Co溶解度的时间依赖性测量

使用在玻璃碳上沉积有催化剂-离聚物墨水的电化学流通池系统来研究商用PtCo合金在循环电势下的水稳定性。能够进行实时测量的在线电感耦合等离子体质谱仪用于解决方波和三角波电势周期中Pt和Co的阳极和阴极溶解。我们观察到所有电位下的Co溶出，高于0.9 V的阳极和阴极Pt溶出速率的明显峰值以及与电位相关的Pt和Co溶出速率。如果上限电位（UPL）低于0.9 V，则阴极溶解的Pt量小于阳极溶解的量。在研究的最高UPL为1.0 V时，阴极溶解量大大超过了阳极溶解量。²⁺，并通过阴极溶解将较高的Pt氧化物PtO _x（x> 1）还原为Pt ²⁺。在阴极扫描期间，Pt也会氧化溶解，但溶解的量比PtO _x的还原溶解少。氧化溶解为Pt和PtOH的相对Pt量取决于电势循环和UPL。