Preparation of double-shell Co9S8/Fe3O4 embedded in S/N co-decorated hollow carbon nanoellipsoid derived from Bi-Metal organic frameworks for oxygen evolution reaction

Metal organic frameworks (MOFs) based catalysts are the most promising candidates for electrocatalytic reaction. Herein, we describe a fast, cost-effective and efficient method to construct an oxygen evolution electrocatalyst with a “bivalve hollow nanoellipsoid” structure, namely three dimensional (3D) bi-shells Co9S8/Fe3O4 embedded in S/N co-decorated hollow carbon nanoellipsoid (H-Co9S8/Fe3O4@SNC). The bivalve metallic compounds hollow structure decreases the proton-electron transfer kinetics on carbon nanoellipsoid, and promoting the oxygen evolution reaction (OER). Specifically, the H- Co9S8/Fe3O4@SNC reveals an excellent catalytic activity with a low overpotential of 280 mV at the current density of 10 mA cm−2 and a small Tafel slope of 87 mV dec−1. Moreover, this H-Co9S8/Fe3O4@SNC electrode is applied to rotating ring-disk electrode (RRDE) and show remarkable catalytic stability and give ∼97.5% Faradic efficiency toward OER via chronoamperometric measurement at a rotation rate of 1600 rpm. Following that, the mechanism is investigated and reveal the excellent catalytic activity is mainly owed to the hollow structure and the catalytic synergistic effects of the double shell Co9S8/Fe3O4, simultaneously, the introduction of oxygen vacancy during the pyrolysis process to the formation of Fe3O4.