Browsing by Author "A.N. Jain"

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Electrocatalytic activity of high specific surface area perovskite-type LaNiO3 via sol-gel route for electrolytic oxygen evolution in alkaline solution
(Elsevier Ltd, 1997) R.N. Singh; S.K. Tiwari; S.P. Singh; A.N. Jain; N.K. Singh
Lanthanum nickelate was synthesized by a sol-gel method at low temperature (500 °C) and its interfacial electrochemical and electrocatalytic properties in 1 M KOH were investigated in film form on Ni. The oxide film was obtained by painting a slurry of oxide powder and Triton X-100 and subsequent sintering at 400 °C. The cyclic voltammetry of the oxide electrode in 1 M KOH indicated the formation of the diffusion-controlled quasi-reversible Ni(II)-Ni(III) redox couple, prior to the onset of O2 evolution. The oxygen evolution reaction followed approximately first order kinetics in OH- concentration. The Tafel slope was 65 mV decade-1. The electrocatalytic activities of LaNiO3 prepared by different methods have been compared. ©1997 International Association for Hydrogen Energy.
Electrocatalytic properties of lanthanum manganite-based oxides obtained by a low temperature method
(1998) A.N. Jain; S.K. Tiwari; R.N. Singh
Pure and Sr-doped lanthanum manganites have been synthesized by a-non-conventional hydroxide solid solution precursor route at 500°C. Their electrochemical and electrocatatytic properties in relation to O2 evolution in KOH solutions have been investigated as film electrodes by cyclic voltammetry, AC impedance and Tafel polarization techniques. The oxide powders have been used to obtain catalytic films on the nickel supports by painting with a slurry of the oxide followed by sintering at 400°C. The electrochemically active area vis-a- vis the electrocatalytic activity of the oxides increases considerably with increasing Sr-content from 0.1 to 0.4 mole in the perovskite lattice. Both, the apparent as well as the true, catalytic activities of the oxide are found to be many times higher than those of the samples prepared by conventional ceramic methods. The electrolytic evolution of O2 follows approximately first order kinetics in OH- concentration. The Tafel slopes are in the range 90-140 mV decade-1.
Physicochemical and electrocatalytic properties of LaNiO3 prepared by a low-temperature route for anode application in alkaline water electrolysis
(Kluwer Academic Publishers, 1995) R.N. Singh; A.N. Jain; S.K. Tiwari; G. Poillerat; P. Chartier
LaNi1-xFexO3 (x = 0, 0.25, 0.5) has been synthesized by the hydroxide solid solution precursor method for electrochemical characterization as oxygen anode in strongly alkaline medium. Studies were made at the oxide film, which was obtained by the oxide-slurry painting technique. The cyclic voltammetric study showed the formation of a diffusion-controlled quasireversible redox couple, Ni(ii)/Ni(iii), (E0 ∼- 430 ± 10 mV) at the oxide surface in 1 m KOH. The reaction was observed to follow approximately first-order kinetics in OH- concentration. Values of the Tafel slope ranged between 59 and 86 mV decade-1 with all the oxide film electrodes. The electrocatalytic activity was found to be greatest with the Ni/LaNi0.75Fe0.25O3 electrode. A comparison was made between the electrocatalytic activities of LaNiO3 prepared by the hydroxide solid solution precursor and by the hydroxide coprecipitation technique. © 1995 Chapman & Hall.