Although non-precious metal catalysts (NPMCs) have been extensively studied as low-cost catalyst alternatives to Pt, in particular for the oxygen reduction reaction (ORR) in polymer electrolyte membrane fuel cells (PEMFCs), the nature of the active ORR catalytic sites is still a subject of controversy. In this work, using carbon-supported copper phthalocyanine tetrasulfonic acid tetrasodium salt (CuTSPc/C) nanoparticles as the target catalyst, the effects of the transition metal Cu on the ORR active sites are systematically studied using both rotating disk electrode (RDE) and rotating ring disk electrode (RRDE) techniques in alkaline electrolyte. The results show that acid-leaching can significantly decrease the ORR activity of the CuTSPc/C catalyst, with the half-wave potential negatively shifted by more than 50 mV compared to the catalyst before acid-leaching. The electron transfer number of the ORR process catalyzed by the catalyst before acid-leaching remained at about 3.85 over the whole tested potential range from −0.6 to −0.1 V, while this number greatly decreased from 3.82 at −0.55 V to 3.53 at −0.1 V after acid-leaching. The H₂O₂ produced accordingly increased sharply from 7.8% to 22%. XRD and TEM results indicate that acid-leaching is an effective method to remove metal-Cu. XPS analysis reveals that metal-Cu is essential in the ORR active site structure, and also plays a key part in the stabilization of the active N and S species.

中文翻译：

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酸浸对碳载铜酞菁四磺酸四钠盐（CuTSPc / C）在碱性电解质中进行氧还原反应的影响：活性位点研究†

尽管已经广泛研究了非贵金属催化剂（NPMC）作为Pt的低成本替代品，特别是对于聚合物电解质膜燃料电池（PEMFC）中的氧还原反应（ORR），但活性ORR催化位的性质仍然是一个有争议的话题。在这项工作中，以碳载铜酞菁四磺酸四钠盐（CuTSPc / C）纳米粒子为目标催化剂，使用转盘电极（RDE）和旋转电极系统地研究了过渡金属Cu对ORR活性位的影响。碱性电解液中的环形盘电极（RRDE）技术。结果表明，酸浸可显着降低CuTSPc / C催化剂的ORR活性，与酸浸之前的催化剂相比，其半波电势负移超过50 mV。在-0.6至-0.1 V的整个测试电位范围内，酸浸之前催化剂催化的ORR过程的电子转移数保持在约3.85，而该值从-0.55 V的3.82大大降低至-0.1的3.53酸浸后的V。H_因此产生的₂ O ₂从7.8％急剧增加到22％。XRD和TEM结果表明，酸浸是去除金属铜的有效方法。XPS分析表明，金属铜在ORR活性位点结构中必不可少，并且在稳定活性N和S物种中也起着关键作用。