Controlled Synthesis and Electrocatalytic Performance of Porous Nickel Cobaltite Rods

doi:10.15541/jim20160140

Abstract

Abstract:

Porous rod-like NiCo₂O₄ powders were synthesized by coordination precipitation-thermal decomposition using NiCl₂·6H₂O, CoCl₂·6H₂O and oxalate as starting materials, and ammonia as coordination agent and pH adjustor. Morphology and structure of the precursor and as-prepared porous NiCo₂O₄ rods were characterized by X-ray diffraction, scanning electron microscope, transmission electron microscope, and N₂ adsorption/desorption analysis. Influence of solution pH on the morphology of the precurosr was investigated. Cyclic voltammetry and chronoamperometry were applied to investigate the electrochemical oxidation of ethanol on porous NiCo₂O₄ rods modified glassy carbon electrode in alkaline medium. The results show that morphology of the precursor depends on pH of the solution. The as-prepared NiCo₂O₄ rod inherits the morphology of the precursor and shows porous structures consisting of mesopores with a significantly high specific surface area of 89 m²/g and average pore diameter of 12.56 nm. Porous rod-like NiCo₂O₄ powders exhibit high electrocatalytic activity in cyclic voltammetry measurement. The linear relationships between oxidation peak current and ethanol concentration, and square root of scan rate indicate that ethanol diffusion is a rate-determining step in its oxidation on as-prepared porous NiCo₂O₄ rods.

Key words: direct ethanol fuel cell, electrocatalysis, ethanol oxidation, NiCo2O4 rod, coordination co-precipitation

CLC Number:

O614

ZHAN Jing, LU Er-Ju, CAI Meng, MA Ya-Lin, ZHANG Chuan-Fu. Controlled Synthesis and Electrocatalytic Performance of Porous Nickel Cobaltite Rods[J]. Journal of Inorganic Materials, 2017, 32(1): 11-17.

Figures/Tables 10

Fig. 1 SEM images of NiCo2O4 precursors prepared in solution with different Ph(a) 3.0; (b) 5.0; (c) 7.0; (d) 8.0

Fig. 2 XRD patterns of NiCo2O4 precursor prepared in solution with different pH

Fig. 3 XRD pattern of NiCo2O4 rods powders

Fig. 4 (a) SEM, (b) TEM, (c) HRTEM images and (d) SAED pattern of NiCo2O4 rods powders

Fig. 5 N2 adsorption/desorption isotherms and pore size distribution of NiCo2O4 rods

Fig. 6 CVs of NiCo2O4/GCE in 0 and 0.1 mol/L ethanol in 1 mol/L NaOH solution at scan rate of 10 mV/sInset is the zoomed main panel of line b

Fig. 7 CV curves of NiCo2O4/GCE in 1 mol/L NaOH solution in the presence of ethanol with various concentrations at scan rate of 10 mV/sInset is peak current versus the ethanol concentration

Fig. 8 CV curves of NiCo2O4/GCE in 1 mol/L NaOH solution contained 0.1 mol/L ethanol at different scan rates (10 mV/s to 50 mV/s)Inset is proportionality of anodic peak currents to the square root of the scan rates

Fig. 9 Polarization curves of NiCo2O4/GCE in 1 mol/L NaOH solution in the presence of ethanol with various concentrationsInset is anodic current versus the ethanol concentration at t = 15 s

Fig. 10 CV curves of NiCo2O4/GCE in the presence of 0.1 mol/L ethanol in 1 mol/L NaOH solution at different scans the 1st (line a), 500th (line b) scan from continuous cycling and the 501st scan (line c) using a new electrolyte at the scan rate of 10 mV/s

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