Preparation of Lanthanum–Nickel Alloy Nanoparticles Through Low‐Temperation Electrolysis in Molten Chlorides

Growing global energy demands underscore the need for efficient, controllable synthesis of nanostructured hydrogen storage alloys. This work addresses the challenge of preparing composition‐ and morphology‐controlled La–Ni intermetallic nanoparticles via a one‐step electrochemical route in molten chlorides. We compared three electrochemical systems: La(III) reduction on an inert W electrode, co‐reduction of La(III) and Ni(II) on a W electrode, and La(III) reduction on a solid Ni electrode. Cyclic voltammetry, square wave voltammetry, and potentiostatic electrolysis at 647 K were employed to elucidate the deposition mechanisms. The results demonstrate that using a solid Ni cathode enables the direct formation of uniform LaNi ₅ nanoparticles with an average size of 100 nm and a well‐defined 1:5 La/Ni ratio, whereas the co‐deposition of La(III) and Ni(II) on a W electrode yields multiphase, agglomerated particles. The study reveals the critical role of the cathode material in directing phase selectivity and nanoparticle uniformity, providing a clean, one‐step alternative to conventional ball‐milling methods that yields LaNi ₅ nanoparticles with monodisperse distribution. This approach offers a practical pathway to synthesize high‐performance hydrogen‐storage nanomaterials with tailored compositions and morphologies.