Nat Mater. 2010 Dec;9(12):998-1003. doi: 10.1038/nmat2883. Epub 2010 Oct 31.
The design of new catalysts for polymer electrolyte membrane fuel cells must be guided by two equally important fundamental principles: optimization of their catalytic behaviour as well as the long-term stability of the metal catalysts and supports in hostile electrochemical environments. The methods used to improve catalytic activity are diverse, ranging from the alloying and de-alloying of platinum to the synthesis of platinum core-shell catalysts. However, methods to improve the stability of the carbon supports and catalyst nanoparticles are limited, especially during shutdown (when hydrogen is purged from the anode by air) and startup (when air is purged from the anode by hydrogen) conditions when the cathode potential can be pushed up to 1.5 V (ref. 11). Under the latter conditions, stability of the cathode materials is strongly affected (carbon oxidation reaction) by the undesired oxygen reduction reaction (ORR) on the anode side. This emphasizes the importance of designing selective anode catalysts that can efficiently suppress the ORR while fully preserving the Pt-like activity for the hydrogen oxidation reaction. Here, we demonstrate that chemically modified platinum with a self-assembled monolayer of calix[4]arene molecules meets this challenging requirement.
对于聚合物电解质膜燃料电池的新型催化剂的设计，必须遵循两个同样重要的基本原则：优化其催化性能以及金属催化剂和支撑体在恶劣电化学环境中的长期稳定性。用于提高催化活性的方法多种多样，从铂的合金化和脱合金化到铂核壳催化剂的合成。然而，提高碳载体和催化剂纳米粒子稳定性的方法有限，特别是在停机（通过空气从阳极吹扫氢气）和启动（通过氢气从阳极吹扫空气）条件下，阴极电势可被推高至 1.5 V（参考文献 11）。在后一种条件下，阴极材料的稳定性受到强烈影响（碳氧化反应），因为在阳极侧发生了不期望的氧还原反应（ORR）。这强调了设计具有选择性的阳极催化剂的重要性，该催化剂能够有效地抑制 ORR，同时充分保持对氢气氧化反应的类似铂的活性。在这里，我们证明了用杯[4]芳烃分子的自组装单层化学修饰的铂满足这一具有挑战性的要求。
