Insight into carbon corrosion of different carbon supports for Pt-based electrocatalysts using accelerated stress tests in polymer electrolyte fuel cells
Insight into carbon corrosion of different carbon supports for Pt-based electrocatalysts using accelerated stress tests in polymer electrolyte fuel cells
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DOI：
10.1016/j.jpowsour.2022.232209
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发表时间：
2022-12
影响因子：
9.2
通讯作者：
Yongzheng Qi;Ying Huang;Ziliang Gao;Celine H. Chen;A. Perego;H. Yildirim;M. Odgaard;T. Asset;P. Atanassov;I. Zenyuk
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文献类型：
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作者：
Yongzheng Qi;Ying Huang;Ziliang Gao;Celine H. Chen;A. Perego;H. Yildirim;M. Odgaard;T. Asset;P. Atanassov;I. Zenyuk
碳基催化剂载体和铂催化剂是聚合物电解质燃料电池（pefc）中常用的两种催化剂。在电池启动和关闭过程中，碳载体氧化会导致电化学性能的损失。通过碳腐蚀加速应力试验（ast），研究了高表面积碳（HSAC）和石墨化碳（GrC）支架的寿命。由于不同的碳腐蚀速率，在Pt/HSAC上进行了1000次AST循环，在Pt/GrC上进行了10000次AST循环，Pt/HSAC和Pt/GrC的性能在寿命结束时都出现了快速下降。并对Pt/HSAC和Pt/GrC的电化学特性进行了详细的比较。Pt/HSAC和Pt/GrC均存在不同程度的电化学表面积（ECSA）损失，这主要是由于Pt的损失、Pt的脱离和颗粒的聚并，这也导致了S O 3−基团覆盖的减少和H+的更曲折的运输，从而导致催化剂层离子电导率的降低。对于AST循环1000次后的Pt/HSAC， ECSA损失超过2倍，但粒径增长仅增加50%，类似的Pt损失强烈表明AST循环期间HSAC支架上发生了更大的Pt脱离。此外，经过1000次AST循环后，石墨化碳载体比HSAC载体具有更强的鲁棒性，其ECSA还原率降低了2倍，催化剂层离子电导率降低了2.5倍，S O 3−基团覆盖率降低了4倍。两种碳载体在其eol处AST后的双层电容均增加，因为形成了更多无序碳接触，从而在固体和离子材料之间产生了更多的接触。该研究表明，Pt/GrC催化剂有可能满足美国能源部（DOE） 5000 AST碳循环的目标，因为Pt/GrC电池达到了初始面积ECSA损失≤40%的目标。
Carbon-based catalyst support and Pt catalysts are commonly used in polymer electrolyte fuel cells (PEFCs). During cell start-up and shutdown processes, carbon support oxidation occurs, which leads to losses of electrochemical performance. In this work, carbon corrosion accelerated stress tests (ASTs) were performed and lifetimes of high surface area carbon (HSAC) and graphitized carbon (GrC) supports were investigated. 1000 AST cycles were conducted on Pt/HSAC while 10000 AST cycles were conducted on Pt/GrC due to different carbon corrosion rates, and both Pt/HSAC and Pt/GrC showed rapid decrease of performance at end of life (EOL). Detailed comparisons of electrochemical characterizations were also conducted between Pt/HSAC and Pt/GrC. Electrochemical surface area (ECSA) loss in different levels was found for both Pt/HSAC and Pt/GrC due to Pt loss, Pt detachment and particles coalescence, which also resulted in reduction of S O 3− group coverage and more tortuous H+ transportation, leading to decreased catalyst layer ionic conductivity. For Pt/HSAC after 1000 AST cycles, more than 2 times higher ECSA loss but with only 50% greater particle size growth and similar Pt loss strongly suggested that a greater Pt detachment occurred on HSAC support during the AST cycles. Apart from that, it was found that after 1000 AST cycles, graphitized carbon support was much more robust compared to HSAC support, and it showed 2 times less ECSA reduction, 2.5 times less catalyst layer ionic conductivity reduction and 4 times less S O 3− group coverage reduction. Double layer capacitances increased for both carbon supports after AST at their EOLs, as more disordered carbon contacts were formed, which created more contacts between solid and ionic materials. This study shows a possibility of Pt/GrC catalysts to meet the Department of Energy (DOE) target of 5000 AST carbon cycles, as the Pt/GrC cell met the target of≤ 40% ECSA loss of initial area.