基于数据挖掘对商业氧还原电催化剂Pt/C测试的综合分析

近几十年来,聚合物电解质膜燃料电池(PEMFC)因其在零排放汽车、固定式和便携式发电设备中的应用而得到迅速发展.燃料电池的阴极氧还原反应(ORR)和阳极氢氧化反应(HOR)常用的催化剂为Pt基催化剂,因此整个燃料电池系统的成本高昂.而ORR的反应速率比HOR慢得多,阴极上的Pt消耗量远高于阳极上.为了降低燃料电池Pt的用量,近年来,许多类型的非铂或低铂ORR电催化剂被报道作为传统Pt基催化剂的可能替代品,以降低成本促进燃料电池的大规模应用.为了评估新催化剂的ORR性能,一般来说,都是以最先进的商业Pt/C的ORR性能作为参考标准进行比较.最简单常用的方法是采用旋转盘电极测试技术,比较线性扫描曲线上极限扩散电流一半处的电位(半波电位E_1/2):半波电位越高,说明其ORR性能越好.众所周知,Pt/C催化剂的本征活性主要与其微观结构和组成有关,而不是与测试方案有关,理想情况下,不同实验室对相同类型的商用Pt/C的测量结果应该是相同的.然而,不同实验室采用的测试方案不同,所得的商业Pt/C的“表观”ORR性能差异巨大.显然,在不考虑不同实验室之间测试方案的微小差异的情况下,作为参比的Pt/C电催化剂的这种明显的性能差异使得来自不同实验室的不同催化剂之间的ORR性能的比较变得无序和不可靠.为解决此问题,需要一种标准的简单测试方案作为商业Pt/C甚至其他类型电催化剂的测试参考,以便在不同的实验室中获得易于重复的“表观”结果.本文通过对全球不同实验室的514篇参考文献进行数据挖掘并进行综合分析发现,同类型Pt/C参比的“表观”活性差异可能主要归因于测试方案的差异,如铂负载(μg/cm²)、玻碳电极的尺寸和线性扫描速率等.基于这些主要影响因素,本文重点分析了商业Pt/C的表观活性(E_1/2)与测试方案中各因素之间的相关性.经初步分析发现,大部分测试采用非欧姆补偿和负向扫描(从高电位向低电位扫描),在此前提下,本文深入分析了酸性和碱性电解质溶液中Pt载量、电极尺寸、扫描速率以及不同生产厂家对Pt/C的E1/2的影响.结果发现,在直径为4 mm、Pt负载量为20μg/cm²的玻碳工作电极上,以10 mV/s的扫描速率,在酸性和碱性电解质中都可以获得可靠的商业Pt/C最可重复的ORR催化性能(E_1/2=0.84±0.03 V),且在高氯酸中的E_1/2值比在硫酸中更高,并得到实验证实.本文结果可作为商业Pt/C的ORR半波电位的“黄金参考”,用于评估其他ORR催化剂在酸性和碱性电解液中的性能.这项工作为作为ORR性能参考标准的商业Pt/C的可靠测试提供了参考.

Meta-analysis of commercial Pt/C measurements for oxygen reduction reactions via data mining

The rotating disk electrode technique is commonly used for screening and characterizing the per-formance of electrocatalysts for the oxygen reduction reaction (ORR). However, a reliable perfor-mance comparison of different electrocatalysts from different labs remains a challenge because of the inconsistency in the measurement of commercial Pt/C. Commercial Pt/C has been adopted extensively as a reference for evaluating the ORR performance of a new electrocatalyst. However, the reported ORR performances of commercial Pt/C from different labs could be significantly dif-ferent because of multiple factors. Herein, we conducted a meta-analysis of the ORR performance of commercial Pt/C via data mining of the literature. This revealed the optimal testing conditions for the most repeatable ORR performance, with commercial Pt/C in both acid and alkaline electrolytes; the optimal Pt loading was 20 μg/cm2 on a 4 mm glassy carbon working electrode. The value of 0.84 ± 0.03 V was suggested as the "Golden reference" of the commercial Pt/C (with Pt 20 wt％) ORR half-wave potential for the performance evaluation of other ORR catalysts in both acid and alkaline electrolytes. The conclusion obtained through the meta-analysis was confirmed by experiments. This study provides general guidance for a reliable measurement of the ORR performance of com-mercial Pt/C as a reference.