| dc.description.abstract |
Effective water splitting via the electrochemical technique is primarily restricted due to the high overpotential and stagnant kinetics of the oxygen evolution reaction (OER) at the anode. So, researchers are carefully working on this topic to reduce the overpotential and make the kinetics faster. Here, three metal-organic frameworks of the formulas [Co(OBA)(H2O)(2)] [OBA = 4,4 '-oxybis(benzoate)], [Ni0.20Co0.80(OBA)(H2O)(2)], and [Ni0.33Co0.66(OBA)(H2O)(2)], namely, 1-3, respectively, were synthesized. Confirmation of the phase purity of 1-3 was done using powder X-ray diffraction (PXRD). Compounds 2 and 3 were systematically characterized by IR spectroscopy. Compounds 1-3 were utilized as single-source precursors to prepare nanosized spinel-type oxides Co3O4, Ni0.6Co2.4O4, and NiCo2O4 through pyrolysis in the atmosphere. The obtained Co3O4, Ni0.6Co2.4O4, and NiCo2O4 nanoparticles with similar sizes were fully characterized by PXRD, IR and Raman spectroscopy, Brunauer-Emmett-Teller experiments, scanning electron microscopy, energy-dispersive X-ray (EDX) elemental mapping analysis, and X-ray photoelectron spectroscopy analysis. Transmission electron microscopy experiments were performed for Co3O4, Ni0.6Co2.4O4, and NiCo2O4 to get information about the closer structure of these materials. Co3O4, Ni0.6Co2.4O4, and NiCo2O4 were used for the electrocatalytic OER. The nickel content increases the OER activity of the oxides. For Co3O4, the overpotential (eta) required to reach a current density of 10 mA cm(-2) was 300 mV, while those for Ni0.6Co2.4O4 and NiCo2O4 were 277 and 256 mV, respectively. The determined values of the Tafel slope for Co3O4, Ni0.6Co2.4O4, and NiCo2O4 were 59, 48, and 45 mV dec(-1), respectively. Besides, the NiCo2O4 catalyst exhibited high electrocatalytic stability for up to 38 h. The reasons behind the greater catalytic activity of Ni0.6Co2.4O4 and NiCo2O4 compared to that of Co3O4 were also well explained by the experimental results. |
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