Xie Xiao-Qun, Shen Tao, Zhang Yi, Wei Di-Ye, Xing Guan-Nan, Bao Weichao, Sun Lan, Xu Qing-Chi, Zheng Qing-Na, Tian Jing-Hua, Zhang Hua, Li Jian-Feng
State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, College of Materials, College of Energy, College of Physical Science and Technology, iChEM, Fujian Key Laboratory of Advanced Materials, Xiamen University, Xiamen 361005, China.
State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Shanghai 200050, China.
J Colloid Interface Sci. 2024 Apr 15;660:916-922. doi: 10.1016/j.jcis.2024.01.108. Epub 2024 Jan 19.
Intermetallic compounds are emerging as promising oxygen reduction reaction (ORR) catalysts for fuel cells due to their typically higher activity and durability compared to disordered alloys. However, the preparation of intermetallic catalysts often requires high-temperature annealing, which unfortunately leads to adverse sintering of the metal nanoparticles. Herein, we develop a scalable site-selective sulfur anchoring strategy that effectively suppresses alloy sintering, ensuring the formation of efficient intermetallic electrocatalysts with small sizes and high ordering degrees. The alloy-support interactions are precisely modulated by selectively modifying the alloy-support interfaces with oxidized sulfur species, thus simultaneously blocking both the nanoparticle migration and Oswald ripening pathways for sintering. Using this strategy, sub-5 nm PtCo intermetallic electrocatalysts enclosed by two atomic layers of Pt shells have been successfully prepared even at a metal loading higher than 30 wt%. The intermetallic catalysts exhibit excellent ORR performances in both rotating disk electrode and membrane electrode assembly conditions with a mass activity of 1.28 A mg at 0.9 V (vs. RHE) and a power density of 1.0 W cm at a current density of 1.5 A cm. The improved performances result from the enhanced Pt-Co electronic interactions and compressive surface strain generated by the highly ordering structure, while the atomic Pt shells prevent the dissolution of Co under highly acidic conditions. This work provides new insights to inhibit the sintering of nanoalloys and would promote the scalable synthesis and applications of platinum-based intermetallic catalysts.
与无序合金相比，金属间化合物因其通常具有更高的活性和耐久性，正成为燃料电池中颇具前景的氧还原反应（ORR）催化剂。然而，金属间催化剂的制备通常需要高温退火，不幸的是，这会导致金属纳米颗粒发生不利的烧结。在此，我们开发了一种可扩展的位点选择性硫锚定策略，该策略能有效抑制合金烧结，确保形成尺寸小且有序度高的高效金属间电催化剂。通过用氧化硫物种选择性修饰合金 - 载体界面，精确调节合金与载体之间的相互作用，从而同时阻断纳米颗粒迁移和奥斯特瓦尔德熟化这两条烧结途径。使用该策略，即使在金属负载高于30 wt%的情况下，也成功制备出了被两层原子层的铂壳包裹的亚5纳米铂钴金属间电催化剂。这种金属间催化剂在旋转圆盘电极和膜电极组件条件下均表现出优异的ORR性能，在0.9 V（相对于可逆氢电极）时质量活性为1.28 A mg，在电流密度为1.5 A cm时功率密度为1.0 W cm。性能的提升源于高度有序结构产生的增强的铂 - 钴电子相互作用和压缩表面应变，而原子铂壳可防止钴在高酸性条件下溶解。这项工作为抑制纳米合金烧结提供了新的见解，并将推动铂基金属间催化剂的可扩展合成及应用。
