Potentiostatic and Potential Cycling Dissolution of Polycrystalline Platinum and Platinum Nano-Particle Fuel Cell Catalysts
Potentiostatic and Potential Cycling Dissolution of Polycrystalline Platinum and Platinum Nano-Particle Fuel Cell Catalysts
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DOI：
10.1149/2.0211806jes
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发表时间：
2018-03
影响因子：
3.9
通讯作者：
D. Myers;Xiaoping Wang;Matt C. Smith;K. More
中科院分区：
文献类型：
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作者：
D. Myers;Xiaoping Wang;Matt C. Smith;K. More
Pt在水性电解质中的溶解已经研究了四十多年，最近在理解聚合物电解质燃料电池中阴极电催化剂的电化学活性表面积（ECA）的观察到的损失的背景下。尽管进行了广泛的研究，但关于纳米颗粒Pt的溶解仍存在许多未解决的问题，例如所观察到的恒电位和电位循环溶解速率的电位依赖性的来源。为了帮助解决这些问题，在本文中，我们提出了碳支撑的铂纳米颗粒（Pt/C）在稀高氯酸中的溶解的Pt的浓度和Pt溶解速率的测量结果，作为PEFC阴极环境的模拟，作为电势和电势循环的电势上限的函数。为了比较，还介绍了多晶铂的类似研究结果。原位Pt L III的X-射线吸收光谱被用来确定氧化的程度，协调环境，和损失的Pt从Pt纳米粒子，以阐明Pt溶解的机制。基于这些研究与文献中提出的相关性，提出了恒电位和电位循环条件下Pt溶解的机制。- 非吸附性酸性电解质（稀高氯酸）中的颗粒，作为PEFC阴极催化剂层环境的模拟物，作为电势循环的电势和电势上限的函数。为了比较，我们还提出了多晶铂的类似研究结果。为了帮助阐明铂氧化和还原过程与Pt损失之间的联系，使用Pt L III吸收边处的原位X射线吸收光谱（XAFS）来确定氧化的程度和铂纳米颗粒的配位环境，并确定电位、氧化和Pt损失之间的关联。基于这些研究与文献中提出的相关性，提出了恒电位和电位循环条件下Pt溶解的机制和溶解的物种。
The dissolution of Pt in aqueous electrolytes has been studied for over forty years, most recently in the context of understanding the observed loss in electrochemically-active surface area (ECA) of cathode electrocatalysts in polymer electrolyte fuel cells. Despite extensive research, there are many unresolved issues regarding the dissolution of nano-particle Pt, such as the source of the observed potential dependence of potentiostatic and potential cycling dissolution rates. To help resolve these issues, in this paper we present results of measurements of the concentration of dissolved Pt and Pt dissolution rates for carbon-supported platinum nano - particles (Pt/C) in dilute perchloric acid, as a mimic of the PEFC cathode environment, as a function of potential and upper potential limit of potential cycling. Also presented, for comparison, are results of similar studies on polycrystalline platinum. In situ Pt L III X-ray absorption spectroscopy was used to determine the extent of oxidation, the coordination environment, and loss of Pt from the Pt nano-particles to elucidate the mechanism of Pt dissolution. Based on the correlation of these studies with those presented in the literature, mechanisms for Pt dissolution under potentiostatic and potential cycling conditions are proposed. - particles in non-adsorbing acidic electrolyte (dilute perchloric acid), as a mimic of the PEFC cathode catalyst layer environment, as a function of potential and upper potential limit of potential cycling. We also present, for comparison, the results of similar studies on polycrystalline platinum. To help elucidate the link between platinum oxidation and reduction processes and Pt loss, in situ X-ray absorption spectroscopy (XAFS) at the Pt L III absorption edge was used to determine the extent of oxidation and the coordination environment of the platinum nano-particles and to determine the association be- tween potential, oxidation, and Pt loss. Based on the correlation of these studies with those presented in the literature, mechanisms for Pt dissolution under potentiostatic and potential cycling conditions and the dissolved species are proposed.