Metal-organic frameworks derived CeO2/Co3O4 nanocomposite as a new electrocatalyst for oxygen evolution reaction

Abstract

Although water splitting is an efficient method to synthesize H2, the development of new electrocatalysts is required to improve the economic viability of this process. In this way, the search for new methodologies to obtain new high-performance electrocatalysts based on Earth-abundant metals has gained urgent attention over the past decade. Thus, this work reports the synthesis of a new CeO2/Co3O4 nanocomposite obtained using Metal-Organic Frameworks (MOFs) as a sacrificial mold, applied as electrocatalyst for Oxygen Evolution Reaction (OER). CeO2/Co3O4 was obtained from the MOF-Ce@ZIF-67 composite (MOF-Ce = cerium succinate, ZIF-67 = Zeolitic-Imidazolate Framework-67) using calcination at 350 °C in air. The electrocatalyst was characterized by X-ray diffraction (XRD), confirming the crystalline phases and average crystallite size of 31 nm. The FT-IR spectrum indicates the main M−O vibration modes of cobaltite and ceria. UV–VIS results show charge transfer and d-d bands related to cobalt and cerium ions. SEM images reveal irregular morphology; however, a homogeneous elemental distribution was observed in the EDS maps. The electrocatalytic performance of the CeO2/Co3O4 for the OER was investigated by cyclic voltammetry, linear scanning voltammetry, chronopotentiometry, and electrochemical impedance spectroscopy, in an aqueous basic solution (KOH 1.0 mol/L). The electrochemical tests show an excellent overpotential of 366 mV (at J = 10 mA cm−2) and chemical stability until 15 h. The Tafel slope was 92.6 mV dec-1 and the double layer capacitance was found to be 3.19 mF. These results show similar or superior electrocatalytic performance compared to other ceria-based materials in the literature.