Sphere-like Co-doped Ni metal-organic framework for enhanced oxygen evolution reaction

Abstract

In recent years, economically viable multifunctional materials with large surface areas and exposed active metal sites, based on bimetallic metal-organic frameworks (MOFs), have emerged as excellent candidates for oxygen evolution reaction (OER). In this study, we synthesized sphere-like Co@Ni-MOF-X and Ni-MOF samples via a hydrothermal approach using 1,4-dicarboxylic acid as the organic source. Surface morphology and XRD patterns of the sphere-like Co@Ni-MOF-X and Ni-MOF samples were examined to confirm their crystallographic structure, phase purity, and morphology of as synthesized MOFs. Subsequently, modified electrodes using the sphere-like Co@Ni-MOF-X and Ni-MOF samples were subjected to electrochemical impedance spectroscopy (EIS) and linear sweep voltammetry (LSV) to assess their charge transfer resistance (R_ct) and OER performance in alkaline media. The Co@Ni-MOF-2 (317 mV) and Co@Ni-MOF-3 (293 mV) samples exhibited promising OER performance at a scan rate of 10 mV s⁻¹. Additionally, the Co@Ni-MOF-2 and Co@Ni-MOF-3 samples showed Tafel plot values of 140 and 168 mV dec⁻¹, respectively. Furthermore, Co@Ni-MOF-2 demonstrated good stability performance.