Synthesis of Rh nanoparticles in alcohols: magnetic and electrocatalytic properties

The synthesis of Rh nanoparticles has been performed through an organometallic approach starting from the tris(allyl) rhodium complex, Rh(η³-C₃H₅)₃, as precursor and using an alcohol as both a solvent and a stabilizer, under mild reaction conditions (room temperature; 3 bar H₂). The influence of the alcohol used, among methanol, propanol or heptanol, on the morphological and structural characteristics as well as on the magnetic and electrocatalytic properties of the obtained Rh nanoparticles has been investigated. Assemblies of Rh nanoparticles of various sizes have been observed depending on the alkyl chain length of the alcohol used. A noticeable effect of the nanostructured character of these Rh nanoparticles is the appearance of a ferromagnetic ordering at room temperature due to a modified electronic structure. Magnetic moments per atom were determined as follows: 0.099, 0.073 and 0.036 µ_B for methanol, heptanol and propanol, respectively. The electrochemical evaluation of these Rh nanoparticles on the oxygen reduction reaction (ORR) showed that the electroactivity depends on the chain length of the alcohol; thus, Rh-heptanol system displayed the highest electroactivity for ORR.