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铂单晶氧还原反应中的反向动力学同位素效应
作者:小柯机器人 发布时间:2022/11/12 14:04:49

美国耶鲁大学Abrua Hctor D.团队铂单晶氧还原反应中的反向动力学同位素效应。相关研究成果于2022年11月10日发表于国际一流学术期刊《自然—化学》。

尽管氧还原反应(ORR)涉及多个质子耦合电子转移过程,但早期研究报告了多晶铂没有动力学同位素效应(KIEs),这可能是由于使用了未纯化的D2O。

该文中,研究人员开发了一种制备超纯D2O的方法,这对于可靠地研究极其表面敏感的铂单晶是必不可少的。研究发现,Pt(111)在D2O中表现出比在H2O中高得多的ORR活性,与电位相关的反KIEs为~0.5,而Pt(100)和Pt(110)表现出与电位无关的反KIEs为~0.8。这种反向的KIEs与较低的*OD覆盖率和相对于*OH的减弱的*OD结合强度密切相关,根据理论计算,归因于它们的零点能量的差异。

研究表明,*OH/*OD和*O2之间的竞争吸附可能在ORR速率确定步骤中起重要作用,该步骤涉及电化学步骤之前的化学步骤(CE机制)。

附:英文原文

Title: Inverse kinetic isotope effects in the oxygen reduction reaction at platinum single crystals

Author: Yang, Yao, Agarwal, Rishi G., Hutchison, Phillips, Rizo, Rubn, Soudackov, Alexander V., Lu, Xinyao, Herrero, Enrique, Feliu, Juan M., Hammes-Schiffer, Sharon, Mayer, James M., Abrua, Hctor D.

Issue&Volume: 2022-11-10

Abstract: Although the oxygen reduction reaction (ORR) involves multiple proton-coupled electron transfer processes, early studies reported the absence of kinetic isotope effects (KIEs) on polycrystalline platinum, probably due to the use of unpurified D2O. Here we developed a methodology to prepare ultra-pure D2O, which is indispensable for reliably investigating extremely surface-sensitive platinum single crystals. We find that Pt(111) exhibits much higher ORR activity in D2O than in H2O, with potential-dependent inverse KIEs of ~0.5, whereas Pt(100) and Pt(110) exhibit potential-independent inverse KIEs of ~0.8. Such inverse KIEs are closely correlated to the lower *OD coverage and weakened *OD binding strength relative to *OH, which, based on theoretical calculations, are attributed to the differences in their zero-point energies. This study suggests that the competing adsorption between *OH/*OD and *O2 probably plays an important role in the ORR rate-determining steps that involve a chemical step preceding an electrochemical step (CE mechanism).

DOI: 10.1038/s41557-022-01084-y

Source: https://www.nature.com/articles/s41557-022-01084-y

期刊信息

Nature Chemistry:《自然—化学》,创刊于2009年。隶属于施普林格·自然出版集团,最新IF:21.687
官方网址:https://www.nature.com/nchem/
投稿链接:https://mts-nchem.nature.com/cgi-bin/main.plex