Metal-organic frameworks derived CeO 2 /Co 3 O 4 nanocomposite as a new electrocatalyst for oxygen evolution reaction

Although water splitting is an efficient method to synthesize H 2, 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 CeO 2 /Co 3 O 4 nanocomposite obtained using Metal-Organic Frameworks (MOFs) as a sacrificial mold, applied as electrocatalyst for Oxygen Evolution Reaction (OER). CeO 2 /Co 3 O 4 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 CeO 2 /Co 3 O 4 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.