Abstract：
The hydroxide exchange membrane fuel cells (HEMFCs) are promising but lack of high-performance anode hydrogen oxidation reaction (HOR) electrocatalysts. The platinum group metals (PGMs) have the HOR activity in alkaline medium two to three orders of magnitude lower than those in acid, leading to the high required PGMs amount on anode to achieve high HEMFC performance. The mechanism study demonstrates the hydrogen binding energy of the catalyst determines the alkaline HOR kinetics, and the adsorbed OH and water on the catalyst surface promotes HOR. Iridium (Ir) has a unique advantage for alkaline HOR due to its similar hydrogen binding energy to Pt and enhanced adsorption of OH. However, the HOR activity of Ir/C is still unsatisfied in practical HEMFC applications. Further fine tuning the adsorption of the intermediate on Ir-based catalysts is of great significance to improve their alkaline HOR activity, which can be reasonably realized by structure design and composition regulation. In this concept, we address the current understanding about the alkaline HOR mechanism and summarize recent advances of Ir-based electrocatalysts with enhanced alkaline HOR activity. We also discuss the perspectives and challenges on Ir-based electrocatalysts in the future.
摘要：
氢氧化物交换膜燃料电池（HEMFCs）是有前途的，但缺乏高性能的阳极氢氧化反应（HOR）电催化剂。铂族金属（PGMs）在碱性介质中的HOR活性比酸中的HOR活性低2至3个数量级，导致阳极上所需的高PGM量以实现高HEMFC性能。机理研究表明，催化剂的氢结合能决定碱性HOR动力学，和吸附在催化剂表面的OH和水促进HOR。铱（Ir）由于其与Pt相似的氢结合能和增强的OH吸附而对碱性HOR具有独特的优势。然而,在HEMFC的实际应用中，Ir/C的HOR活性仍未得到满足。进一步微调中间体在Ir基催化剂上的吸附对提高其碱性HOR活性具有重要意义,这可以通过结构设计和组成调节来合理实现。在这个概念中,我们解决了当前对碱性HOR机理的理解，并总结了具有增强碱性HOR活性的基于Ir的电催化剂的最新进展。我们还讨论了未来基于Ir的电催化剂的前景和挑战。
