Effect of co-substitution on the electrocatalytic properties of Ni1.5Fe1.5O4 for oxygen evolution in alkaline solutions.

Singh, N.K.; Yadav, Ritu; Yadav, M.K.; Fernandez, Carlos

Abstract

Some ternary ferrites with composition CoxNi1.5-xFe1.5O4 (0.0 less than or equal to x les than or equal to 1.25) have been synthesized through NH4OH co-precipitation at 11.5 pH. Materials obtained in this way were tested for their electrocatalytic properties towards oxygen evolution reaction (OER), in the form of a film on Ni-support in alkaline solution. The study showed that the electrocatalytic properties of the material increased with partial substitution of Co for Ni in the base oxide (Ni1.5Fe1.5O4), the value being highest with 1.25 mol Co-substitution. At E = 850 mV vs Hg/HgO in 1M KOH at 25 degrees C, the electrode showed apparent current density 137.1 mA cm(-2), which is about 2.5 times higher than the base oxide. The Tafel slope values were ranged between 53-90 mV decade-1. A pair of redox peak, an anodic (E-Pa = 522 +/- 28 mV) and corresponding cathodic (E-Pc = 356 +/- 9 mV), was observed in the cyclic voltammetry (CV) study of the material. The thermodynamic parameters for the oxygen evolution reaction (OER) - namely the standard apparent electrochemical enthalpy of activation (Delta H-el degrees(not equal)), the standard enthalpy of activation (Delta H degrees(not equal)) and the standard entropy of activation (Delta s degrees(not equal)) - have also been determined by recording the anodic polarization curve in 1M KOH. The value of Delta H degrees(not equal) was observed to be almost similar with each oxide electrode. The Delta s degrees(not equal) values were highly negative and ranged between similar to -165 and similar to -207 J deg(-1) mol(-1). Phase and morphology of materials have been investigated by using physical techniques such as X-ray diffraction, infrared spectroscopy (IR) and scanning electron microscope (SEM).

Citation

SINGH, N.K., YADAV, R., YADAV, M.K. and FERNANDEZ, C. 2017. Effect of co-substitution on the electrocatalytic properties of Ni1.5Fe1.5O4 for oxygen evolution in alkaline solutions. Journal of new materials for electrochemical systems [online], 20(3), pages 115-121. Available from: https://doi.org/10.14447/jnmes.v20i3.317

• Journal Article Type: Article
• Acceptance Date: Jun 26, 2017
• Online Publication Date: Jul 27, 2017
• Publication Date: Sep 30, 2017
• Deposit Date: Sep 19, 2023
• Publicly Available Date: Sep 19, 2023
• Journal: Journal of new materials for electrochemical systems
• Print ISSN: 1480-2422
• Electronic ISSN: 2292-1168
• Publisher: International Information and Engineering Technology Association
• Peer Reviewed: Peer Reviewed
• Volume: 20
• Issue: 3
• Pages: 115-121
• DOI: https://doi.org/10.14447/jnmes.v20i3.317
• Keywords: Coprecipitation; XRD; SEM; Electrocatalysis; Oxygen evolution; Activation energy
• Public URL: https://rgu-repository.worktribe.com/output/247432
• Publisher URL: http://new-mat.org/ejournal/index.php/jnmes/article/view/317