Facile synthesis of Co3O4 nanoparticles from a novel tetranuclear cobalt(III) complex. Application as efficient electrocatalyst for oxygen evolution reaction in alkaline media

Abstract

A tetranuclear cobalt complex [Co4III(L′)6] was synthesized by the direct reaction of cobalt(II) acetate with a N2S2 Schiff base ligand H2L containing a disulfide bond under aerobic conditions {H2L = 2,2′-bis(2-hydroxynaphthyliminobenzyl)disulfide}. The X-ray crystal structure of [Co4III(L′)6] indicates reductive disulfide bond scission of H2L upon reaction with Co2+ to give [L′]2–. Furthermore, cobalt oxide nanoparticles of about 30 nm size were synthesized by thermal decomposition of [Co4III(L′)6] as a precursor. The Co3O4 nanoparticles were characterized by XRD, FE-SEM, TEM, and FT-IR spectroscopy. The electrocatalytic activity of the resulting oxide was examined in oxygen evolution reaction (OER) by cyclic voltammetry (CV) and linear sweep voltammetry (LSV) in 1.0 mol L−1 KOH. The NPs displays efficient electrocatalytic activity for oxygen evolution reaction with a current density of 10.0 mA cm−2 at 1.65 V, good onset potential of 1.52 V vs. RHE and small Tafel slope of 44 mV dec−1.