Dynamics of Particle Growth and Electrochemical Surface Area Loss due to Platinum Dissolution
Dynamics of Particle Growth and Electrochemical Surface Area Loss due to Platinum Dissolution
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DOI：
10.1149/2.051403jes
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发表时间：
2014-01-01
影响因子：
3.9
通讯作者：
Polevaya, Olga
中科院分区：
文献类型：
--
作者：
Ahluwalia, Rajesh K.;Arisetty, Srikanth;Polevaya, Olga
建立了铂纳米粒子聚结/烧结模型，用于分析在水测试和含催化剂涂层膜和气体扩散电极的单一燃料电池中测量的颗粒生长和电化学表面积（ECSA）损失。该模型结合了Pt溶解的非理想固溶体理论和考虑颗粒生长的奥斯特瓦尔德成熟和聚结/烧结的粒度演化动力学。模型的结果表明，加速试验中观察到的ECSA颗粒尺寸的增大和损失主要是由于Pt在颗粒之间的溶解和再沉积引起的聚结/烧结。溶解焓为49.3 kJ。mol(-1)，有效聚变热28.2 kJ。通过测量颗粒生长对温度的依赖性，经验地确定了颗粒聚结/烧结的Mol（-1）。该模型表明，与H-2/N-2相比，在H-2/空气中加速试验中，更高的铂在氧气存在下的溶解度是促进颗粒生长和ECSA损失的原因。该模型还表明，溶解速率常数必须降低两个数量级，才能解释在80℃下，当相对湿度从100%降低到30%时，铂阴极催化剂在10,000平方电位循环后ECSA损失的下降。(C) 2014电化学学会。版权所有。
A model for coalescence/sintering of Pt nanoparticles is developed to analyze particle growth and electrochemical surface area (ECSA) loss measured in aqueous tests and in catalyst-coated membrane and gas diffusion electrode-containing single fuel cells. The model combines a non-ideal solid solution theory for Pt dissolution with the dynamics of particle size evolution considering particle growth by Ostwald ripening and coalescence/sintering. Results from the model indicate that the observed growth in particle size and loss in ECSA in accelerated tests are primarily due to coalescence/sintering resulting from Pt dissolution and redeposition between particles. An enthalpy of dissolution of 49.3 kJ.mol(-1) and an effective heat of fusion of 28.2 kJ.mol(-1) for particle coalescence/sintering have been empirically determined from the measured temperature dependence of particle growth. The model suggests that higher Pt solubility in the presence of oxygen is responsible for enhanced particle growth and ECSA loss in accelerated tests in H-2/air as compared to H-2/N-2. The model also indicates that the dissolution rate constant must be reduced by two orders of magnitude to explain the measured decrease in ECSA loss of the Pt cathode catalyst after 10,000 square potential cycles at 80 degrees C when the relative humidity is decreased from 100% to 30%. (C) 2014 The Electrochemical Society. All rights reserved.