Decoding the Hume-Rothery Rule in a Bifunctional Tetra-metallic Alloy for Alkaline Water Electrolysis

• Published in: Nano letters 2025-01
• Main Authors: Mondal, Surajit, Dutta, Supriti, Hazra, Vishwadeepa, Pati, Swapan K, Bhattacharyya, Sayan
• Format: Article
• Language: English
• ISSN: 1530-6984; 1530-6992; 1530-6992
• DOI: 10.1021/acs.nanolett.4c04412

The 90-year-old Hume-Rothery rule was adapted to design an outstanding bifunctional tetra-metallic alloy electrocatalyst for water electrolysis. Following the radius mismatch principles, Fe (131 pm) and Ni (124 pm) are selectively incorporated at the Pd (139 pm) site of Mo Pd nanosheets. Analogously, Cu (132 pm) alloys with only Pd, while Ag (145 pm) alloys with both Pd and Mo (154 pm). The face-centered cubic Mo Pd Ni Fe nanosheets with 10-12 atomic layers, featuring in-plane compressive strain along the {111} basal plane, show 1/3 (422) reflection from local hexagonal symmetry. The more electronegative Pd attracts electron density from Ni/Fe in Mo Pd Ni Fe , synergistically boosting the mass activities for hydrogen and oxygen evolution reactions to 89 ± 5 and 38.6 ± 3.1 A g at ±400 mV versus RHE, respectively. Full water electrolysis continues for ≥550 h, requiring cell voltages of 1.51 and 1.63 V at 10 and 100 mA cm , delivering 45 mL h green H .