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首页> 外文期刊>Electrocatalysis >Analysis of the Corrosion Kinetic of Pt/C Catalysts Prepared on Different Carbon Supports Under the 'Start-Stop' Cycling
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Analysis of the Corrosion Kinetic of Pt/C Catalysts Prepared on Different Carbon Supports Under the 'Start-Stop' Cycling

机译：“起始-停止”循环下在不同碳载体上制备的Pt / C催化剂的腐蚀动力学分析

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摘要

A series of 50 wt% Pt/C catalysts based on carbon blacks with different specific surface areas and morphologies was synthesized and investigated using "start-stop" protocol (triangular scan in the 1.0-1.5 V vs. reversible hydrogen electrode (RHE) potential range with a scan rate of 500 mV s(-1)). The commercial 40 wt% Pt/Vulcan XC-72 and 50 wt% Pt/TEC were used for comparison. The oxygen reduction reaction (ORR) activities and electrochemically active surface area (ECSA) of Pt were obtained at 25 A degrees C in 0.1 M HClO4 electrolyte after every 4000 cycles. All synthesized Pt/C catalysts were characterized by X-ray powder diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), low-temperature nitrogen sorption, CO pulse chemisorption methods, and cycling voltammetry including a rotating disc electrode (RDE) method for analysis of the ORR kinetics. Dependences of the ORR activities, ECSA, and values of Tafel slopes on the number of oxidative cycles were obtained and analyzed in detail. It was shown that the initial values of Tafel slopes of the Pt/C catalysts decrease with increase of the surface area of carbon blacks. The increase in the values of Tafel slopes in the high-current density region with cycling was associated with the degradation of carbon support. The reciprocal ratios of the ECSA to initial values were found to grow linearly on the number of cycles. The ORR surface activity was significantly decreased in the first 8000-10,000 oxidation cycles as the result of changes of the active component and carbon support degradation. The following slight increase in the ORR surface activities with cycling was related to the increase in the Pt particle sizes in the Pt/C catalysts. Modification of Ketjen black EC 600 DJ through pyrocarbon deposition (KB600-C sample) led to appreciable increase of the stability of the Pt/KB600-C sample.
机译：合成了一系列基于碳黑的50 wt％Pt / C催化剂，这些炭黑具有不同的比表面积和形貌，并使用“启动-停止”规程（在1.0-1.5 V与可逆氢电极（RHE）势进行三角扫描）中进行了研究。扫描速率为500 mV s（-1）的范围）。用于比较的市售40重量％Pt / Vulcan XC-72和50重量％Pt / TEC。每4000个循环后，在0.1 A HClO4电解质中，于25 A摄氏度下获得Pt的氧还原反应（ORR）活性和电化学活性表面积（ECSA）。所有合成的Pt / C催化剂均通过X射线粉末衍射（XRD），高分辨率透射电子显微镜（HRTEM），低温氮吸附，CO脉冲化学吸附法以及包括旋转圆盘电极（RDE）的循环伏安法进行表征ORR动力学分析的方法。获得并详细分析了ORR活性，ECSA和Tafel斜率值与氧化循环数的关系。结果表明，Pt / C催化剂的Tafel斜率的初始值随着炭黑表面积的增加而减小。高电流密度区域中Tafel斜率值随循环的增加与碳载体的降解有关。发现ECSA与初始值的倒数比率随循环数线性增长。由于活性成分和碳载体降解的变化，在最初的8000-10,000个氧化循环中，ORR表面活性显着降低。随着循环，ORR表面活性的以下轻微增加与Pt / C催化剂中Pt粒径的增加有关。通过热碳沉积（KB600-C样品）对科琴黑EC 600 DJ的改性导致Pt / KB600-C样品的稳定性显着提高。

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