Preparation and Performance of Dandelion-shaped NiCo2O4/Carbon Quantum Dot Composites for Bifunctional Electrocatalysts
In this paper,using nickel cobalt oxide(NiCo2O4,NCO)and carbon quantum dots(CQDs),dandelion-shaped structures of NiCo2O4-CQDs(NCO-CQDs)composite bifunctional catalysts were prepared by the hydrothermal method and calcination.The microstructures of NCO-CQDs composites were studied by scanning electron microscopy(SEM),transmission electron microscopy(TEM)and X-ray diffraction(XRD).NCO-CQDs composites were composed of the stacked NCO nanorods and CQDs particles formed into dandelion flower spherical composite.In order to increase the oxygen vacancy of NCO-CQDs composite and improve the electrochemical performances,the NCO-CQDs composites were calcined in air to obtain excellent performances.The half wave potential reached 0.752 V during ORR.After 20000 seconds,NCO-CQDs composites maintained 92.2%of its initial current density,higher than that of Pt/C sample(68.6%),showing excellent stability.For OER,under the current density test of 10 mA/cm2,NCO-CQDs-air sample presented an onset potential of 1.874 V and a Tafel slope of 100.9 mV/dec,which is superior to Pt/C(2.007 V,312.9 mV/dec)and equivalent to IrO2(1.794 V,44.8 mV/dec).
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