| Summary: | The oxygen evolution reaction (OER) is a crucial half-reaction in water splitting. However, this reaction is kinetically sluggish owing to the four-electron (4 e<sup>−</sup>) transfer process. Therefore, the development of low-cost, stable, highly efficient, and earth-abundant electrocatalysts for the OER is highly desirable. Metal oxides derived from metal–organic frameworks (MOFs) are among the most efficient electrocatalysts for the OER. Herein, Ce–MOF-derived CeO<sub>2</sub>/graphene oxide (GO) composites were successfully prepared using a facile method. The composites with 0, 25, 50, and 100 mg GO were named CeO<sub>2</sub>, CeO<sub>2</sub>–GO-1, CeO<sub>2</sub>–GO-2, and CeO<sub>2</sub>–GO-3, respectively. The physicochemical characteristics of the electrocatalysts were assessed using several analytical techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), and Brunauer–Emmett–Teller (BET) analysis. The TEM results revealed that the CeO<sub>2</sub> had a sheet-like morphology and that a GO layer was noticeable in the synthesized CeO<sub>2</sub>–GO-3 composite. The characterization results confirmed the formation of impurity-free CeO<sub>2</sub>–GO composites. The OER activity and stability were measured using cyclic voltammetry (CV), linear sweep voltammetry (LSV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS). The CeO<sub>2</sub>–GO-3 electrocatalyst has a smaller Tafel slope (176 mV·dec<sup>−1</sup>) and lower overpotential (240 mV) than the other electrocatalysts. In addition, it exhibited high cyclic stability for up to 10 h. Therefore, the inexpensive CeO<sub>2</sub>–GO-3 electrocatalyst is a promising OER candidate.
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