One-step synthesis of non-equilibrium Pd-Ru alloys from Al-Pd-Ru quasicrystals and approximants

Abstract

Abstract Non-equilibrium Pd–Ru alloys were synthesized by leaching quasicrystal (icosahedral quasicrystal, IQC: Al71Pd19Ru10) and approximants (3/2 approximant, P40: Al72Pd16.4Ru11.6, 1/1 approximant, C1: Al70.4Pd14.7Ru14.9) of Al–Pd–Ru alloys with 20 wt% NaOH aqueous solution. The Pd-Ru alloys were investigated using XRD and HAADF-STEM, which showed that Pd and Ru were mixed and formed a non-equilibrium state (atomic ratio: 0.9 < Pd/Ru < 2). The Pd–Ru alloy obtained by leaching of P40 phase was found to exhibit high catalytic performance toward CO oxidation than Pd and Ru catalysts obtained by leaching of Al3Pd (decagonal quasicrystal) and Al13Ru4 (decagonal approximant), respectively (i.e., the alloying effect). Consequently, Al-Pd-Ru quasicrystals and approximant alloys are found to be useful precursors to obtain the non-equilibrium Pd-Ru alloys.