Affiliation: | 1. Interdisciplinary Research Center for Catalytic Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki, 305-8565, Japan;2. Department of Chemical Science and Engineering, National Institute of Technology, Tokyo College, 1220-2 Kunugida, Hachioji, Tokyo, 193-0997, Japan |
Abstract: | High-entropy alloy (HEA) AlCoCrFeNiV nanoparticles were prepared from oxide precursors using a molten salt synthesis method without an electrical supply. The oxide precursor was directly reduced by CaH2 reducing agent in molten LiCl at 600°C-700°C or molten LiCl–CaCl2 at 500°C-550°C. When the reduction was conducted at 700°C, a face-centered cubic (FCC) structure produced, as identified by X-ray diffraction analysis. With lower reduction temperatures, the FCC structure was absent, replaced by a body-centered cubic (BCC) structure. With a reduction temperature of 550°C, the resulting sample was composed of highly pure HEA AlCoCrFeNiV nanoparticles with a BCC structure of 15 nm. Analyses by scanning electron microscopy/transmission electron microscopy with energy-dispersive X-ray spectroscopy confirmed the formation of homogeneous HEA AlCoCrFeNiV with a nanoscale morphology. In the hydrogenation reaction of p-nitrophenol by NaBH4, the AlCoCrFeNiV nanoparticles (produced at 550°C) exhibited a catalytic activity with ~90% conversion and 16 kJ/mol activation energy. |