Synthesis and Electrocatalytic Properties of LaSrCoO (0 ≤ x ≤ 0.8) Film Electrodes for Oxygen Evolution in Alkaline Solutions

Abstract

Perovskite-type oxides of lanthanum and cobalt with composition La 1-x Sr x CoO 3 (x = 0.0, 0.2, 0.4, 0.6 and 0.8) have been prepared by a low temperature sol-gel route. Electrodes of the material were formed on pretreated Ni-support by oxide slurry painting technique and studied their electrochemical behavior with regards to oxygen evolution reaction (OER) in aqueous KOH solution. The electrochemical characterization was done in three electrode single compartment glass cell using Gamry (Reference 600) Electrochemical Work Station. Techniques used for electrochemical studies were cyclic voltammetry and Tafel polarization. The data showed that the substitution of Sr (0.2 -0.8 mol) increased the electrocatalytic activity of the oxide. The value was found to be highest with 0.8 mol Sr. The Tafel slopes and reaction order with respect to OH -concentration for oxygen evolution reaction were found to be 65-77 mVdecade -1 and unity, respectively. The cyclic voltammogram recorded between 0.0 -0.7 V in 1M KOH at 25 0 C exhibited a pair of redox peaks prior to oxygen evolution reaction. The thermodynamic parameters for oxygen evolution reaction such as, standard electrochemical enthalpy of activation , standard enthalpy of activation , and standard entropy of activation have also been calculated by recording the Tafel polarization curve in 1 M KOH at different temperatures. Oxide samples were characterized physicochemically by scanning electron microscope (SEM) powder X-ray diffraction (XRD) techniques.

Partially substituted La for Sm in Sm 0.8 Sr 0.2 NiO 3 : An efficient electrocatalyst towards alkaline water splitting

“…However, it is not true in the case of every perovskite oxide. As described in in literature [31,[48][49][50][51][52][53]] some metal substituted LaMnO 3 and LaCoO 3 have higher OER electrocatalytic activity than the present system.…”

“…As the scan rate increased from 20-120 mVsec − 1 , the anodic peaks moved to the top and cathodic peaks to the bottom potential sides. The anodic as well as cathodic peaks on each side shifted as the scan rate increased implying that the redox process is quasi reversible [34][35][36][37][38]. With the anodic to cathodic peak current ratio surpassing one, it reveals an unmistakable sign of irreversibility in the redox process during the electrochemical reaction [39,40].…”

The Utilization of Iridium Nanoparticles Impregnated on Metal Oxides (Ceria, Titania, and Zirconia) with a Simple and Ecologically Safe Synthesis Approach in Oxygen Evolution Reactions

“…It is noteworthy that the observed E a value for OER on Ir@CeO 2 (37.476 kJ.mol −1 at E = 720 mV vs Hg/ HgO) is lower as compared to the E a values of the reported catalysts in the literature such as Fe 3 O 4 (E a = 109 kJ mol −1 ), 65 NiCoOx (E a = 71 kJ.mol −1 ), 66 CoFe 1.2 Cr 0.8 O 4 (E a = 67.3 kJ.mol −1 at E = 560 mV), 67 Adams-RuO 2 (E a = 49 ± 1 kJ.mol −1 ), 68 Cu 0.9 Co 2.1 O 4 (E a = 45.19 kJ.mol −1 ), 69 oxide coated Co 50 Ni 25 Si 15 B 10 amorphous alloy (E a = 40 kJ.mol −1 ), 70 La 0.6 Cu 0.4 CoO 3 (E a = 46 kJ.mol −1 ). 71 On the other hand, there are also a few reported catalysts such as NiFeOx/NF (25 ± 12 kJ mol -1 ), 72, and NiFe hydroxide (18.1 kJ mol −1 ) 73 which provide lower E a values. The electrochemical OER is a complicated process that includes a series of chemical reactions such as association or dissociation, as well as electron transfer steps.…”

Enhanced electrocatalytic oxygen evolution activity in geometrically designed SrRuO3 thin films

“…However, the origin and enhancement of their electrochemical energy conversion performance remains challenging due to the complex interplay between various parameters that hinders their practical implications. Matsumoto et al, proposed that OER takes place on the surface of perovskite oxides, when the B-site transition metal forms the σ* band within the lattice, thus attaining a high oxidation state which would lead to the enhanced catalytic activity [10]. Suntivich et al showed that intrinsic OER activity exhibits a volcanoshape dependence on the occupancy of the d-electron with an eg symmetry of surface transition metal cations [11].…”