Ramaswamy Nagappan, Mukerjee Sanjeev
Northeastern University Center for Renewable Energy Technology, Department of Chemistry and Chemical Biology , Northeastern University , 317 Egan Research Center, 360 Huntington Avenue , Boston , Massachusetts 02115 , United States.
Chem Rev. 2019 Dec 11;119(23):11945-11979. doi: 10.1021/acs.chemrev.9b00157. Epub 2019 Nov 8.
Alkaline anion-exchange membrane (AAEM) fuel cells have attracted significant interest in the past decade, thanks to the recent developments in hydroxide-anion conductive membranes. In this article, we compare the performance of current state of the art AAEM fuel cells to proton-exchange membrane (PEM) fuel cells and elucidate the sources of various overpotentials. While the continued development of highly conductive and thermally stable anion-exchange membranes is unambiguously a principal requirement, we attempt to put the focus on the challenges in electrocatalysis and interfacial charge transfer at an alkaline electrode/electrolyte interface. Specifically, a critical analysis presented here details the (i) fundamental causes for higher overpotential in hydrogen oxidation reaction, (ii) mechanistic aspects of oxygen reduction reaction, (iii) carbonate anion poisoning, (iv) unique challenges arising from the specific adsorption of alkaline ionomer cation-exchange head groups on electrocatalysts surfaces, and (v) the potential of alternative small molecule fuel oxidation. This review and analysis encompasses both the precious and nonprecious group metal based electrocatalysts from the perspective of various interfacial charge-transfer phenomena and reaction mechanisms. Finally, a research roadmap for further improvement in AAEM fuel cell performance is delineated here within the purview of electrocatalysis and interfacial charge transfer.
在过去十年中，碱性阴离子交换膜（AAEM）燃料电池因其在氢氧根离子传导膜方面的最新进展而备受关注。在本文中，我们将当前先进的AAEM燃料电池的性能与质子交换膜（PEM）燃料电池进行比较，并阐明各种过电位的来源。虽然持续开发高导电性和热稳定性的阴离子交换膜无疑是一项主要要求，但我们试图将重点放在碱性电极/电解质界面处的电催化和界面电荷转移方面的挑战上。具体而言，本文进行的批判性分析详细阐述了：（i）氢氧化反应中过电位较高的根本原因；（ii）氧还原反应的机理；（iii）碳酸根阴离子中毒；（iv）碱性离聚物阳离子交换头基团在电催化剂表面的特异性吸附所带来的独特挑战；以及（v）替代小分子燃料氧化的潜力。本综述和分析从各种界面电荷转移现象和反应机理的角度涵盖了基于贵金属和非贵金属的电催化剂。最后，在电催化和界面电荷转移的范围内，勾勒出了进一步提高AAEM燃料电池性能的研究路线图。
