Xie Xianxian, Briega-Martos Valentín, Alemany Pere, Mohandas Sandhya Athira Lekshmi, Skála Tomáš, Rodríguez Miquel Gamón, Nováková Jaroslava, Dopita Milan, Vorochta Michael, Bruix Albert, Cherevko Serhiy, Neyman Konstantin M, Matolínová Iva, Khalakhan Ivan
Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, 180 00 Prague 8, Czech Republic.
Helmholtz Institute Erlangen-Nürnberg for Renewable Energy (IET-2), Forschungszentrum Julich GmbH, Cauerstr. 1, 91058 Erlangen, Germany.
ACS Catal. 2024 Dec 16;15(1):234-245. doi: 10.1021/acscatal.4c05269. eCollection 2025 Jan 3.
Achieving the optimal balance between cost-efficiency and stability of oxygen reduction reaction (ORR) catalysts is currently among the key research focuses aiming at reaching a broader implementation of proton-exchange membrane fuel cells (PEMFCs). To address this challenge, we combine two well-established strategies to enhance both activity and stability of platinum-based ORR catalysts. Specifically, we prepare ternary PtNi-Au alloys, where each alloying element plays a distinct role: Ni reduces costs and boosts ORR activity, while Au enhances stability. A systematic comparative analysis of the activity-stability relationship for compositionally tuned PtNi-Au model layers, prepared by magnetron co-sputtering, was conducted using a diverse range of complementary characterization techniques and electrochemistry, supported by density functional theory calculations. Our study reveals that a progressive increase of the Au concentration in the PtNi alloy from 3 to 15 at % leads to opposing catalyst activity and stability trends. Specifically, we observe a decrease in the ORR activity accompanied by an increase in catalyst stability, manifested in the suppression of both Pt and Ni dissolution. Despite the reduced activity compared to PtNi, the PtNi-Au alloy with 15 at % Au still exhibits nearly three times the activity of monometallic Pt. It also demonstrates a significantly improved dissolution stability relative to that of the PtNi alloy and even monometallic Pt. These findings provide valuable insights into the intricate balance between activity and stability in multimetallic ORR catalysts, paving the way for the design of cost-effective and durable materials for PEMFCs.
在氧还原反应（ORR）催化剂的成本效益和稳定性之间实现最佳平衡，是目前旨在更广泛应用质子交换膜燃料电池（PEMFC）的关键研究重点之一。为应对这一挑战，我们结合了两种成熟的策略来提高铂基ORR催化剂的活性和稳定性。具体而言，我们制备了三元PtNi-Au合金，其中每种合金元素都发挥着独特作用：Ni降低成本并提高ORR活性，而Au增强稳定性。通过磁控共溅射制备了成分可调的PtNi-Au模型层，利用多种互补表征技术和电化学方法，并结合密度泛函理论计算，对其活性-稳定性关系进行了系统的对比分析。我们的研究表明，PtNi合金中Au浓度从3 at%逐渐增加到15 at%会导致催化剂活性和稳定性呈现相反趋势。具体来说，我们观察到ORR活性降低，同时催化剂稳定性增加，表现为Pt和Ni溶解的抑制。尽管与PtNi相比活性有所降低，但含15 at% Au的PtNi-Au合金的活性仍几乎是单金属Pt的三倍。它还显示出相对于PtNi合金甚至单金属Pt而言，溶解稳定性有显著提高。这些发现为多金属ORR催化剂活性和稳定性之间的复杂平衡提供了有价值的见解，为设计用于PEMFC的经济高效且耐用的材料铺平了道路。
