Programmable Vacancy Topology in High-Entropy-Alloy-Inspired Multiprincipal Alloys Directs Ru-Centered Alkaline Hydrogen Evolution
Huiyong Huang, Wenhui Zhong, Qiaoling Kang, Yinhe Wang, Chunyu Zhang, Hao Lei, Zhiyun Li, Qing Zhang, Wei Wei, Jinfeng Yang, Jingyuan Ma, Hao Liu, Li Li, Jun Jiang, Tingli Ma, Yi CuiAbstract
Vacancy topology in multiprincipal alloys provides a controllable handle to tune interfacial reaction pathways, yet practical routes to program vacancies in ultrasmall alloys remain scarce. Here, we report an H2-free, volatility-assisted MOF-to-alloy synthesis in an inert atmosphere that yields sub-4 nm MnFeRuCoNi-based multiprincipal alloy nanoparticles with a Ru-proximal vacancy environment. A closed set of mutually reinforcing measurements─PALS/EPR (defect generation), EXAFS/XPS/XANES (coordination/electronic states), multipressure NAP-XPS (Ru→O(H2O) interfacial charge transfer), REELS/TOF-SIMS (H* and H3O+ intermediates), and in situ Raman (Ru–H vibration)─establishes a causal sequence from programmed vacancy topology to local electron redistribution at Ru, accelerated water activation, and step-specific alkaline-HER kinetics. Density-functional theory with Bader analysis shows reduced electron density at Ru and enhanced Ru→O charge transfer upon H2O adsorption in vacancy-rich environments, consistent with experimental observables. In 1.0 M KOH, the catalyst delivers an overpotential of 13 mV at 10 mA cm–2, a 47 mV dec–1 Tafel slope, and ∼2600 h stability at 100 mA cm–2, rivaling Ru benchmarks and approaching Pt/C under matched protocols. The volatility-assisted MOF-to-alloy route may be extendable to other multiprincipal alloy families containing a sacrificial volatile component, thereby offering a promising strategy for encoding vacancy topology in complex alloys.