Synthesis and thermal properties of the heterometallic nickel–ruthenium complex: a potential precursor for catalytically active nanosized Ni–Ru alloy

Abstract

The heterometallic complex [RuNO(NO₂)₄OHNi(En)₂] was prepared by the reaction of [RuNO(NO₂)₄OH]²⁻ with Ni²⁺ in the presence of a small excess of ethylenediamine. According to single-crystal XRD, the ruthenium fragment is coordinated to the nickel atom through μ-OH and the bidentate (N, O) nitro-ligand. Bidentate ethylenediamine ligands complete the coordination sphere of nickel. The thermal decomposition of the complex in reductive atmosphere with the heating rate of 1 K min⁻¹ allowed the preparation of a single-phase Ni_0.5Ru_0.5 solid solution. The crystallite size of the prepared nanoalloy varies in the range of 21–29 nm. The catalytic properties of the prepared nanoalloy in the CO methanation reaction closely resemble those of pure nickel. Yet, in the side reaction of CO to CO₂ oxidation, the Ni_0.5Ru_0.5 solid solution demonstrates greater activity in the low-temperature range.