Nanostructured iron oxyhydroxide（Fe OOH） thin films have been synthesized using an electrodeposition method on a nickel foam（NF） substrate and effect of air annealing temperature on the catalytic performance is st...Nanostructured iron oxyhydroxide（Fe OOH） thin films have been synthesized using an electrodeposition method on a nickel foam（NF） substrate and effect of air annealing temperature on the catalytic performance is studied. The as-deposited and annealed thin films were characterized by X-ray diffraction（XRD）,X-ray photoelectron spectroscopy（XPS）, field emission scanning electron microscopy（FE-SEM） and linear sweep voltammetry（LSV） to determine their structural, morphological, compositional and electrochemical properties, respectively. The as-deposited nanostructured amorphous Fe OOH thin film is converted into a polycrystalline Fe;O;with hematite crystal structure at a high temperature. The Fe OOH thin film acts as an efficient electrocatalyst for the oxygen evolution reaction（OER） in an alkaline 1 M KOH electrolyte. The film annealed at 200 °C shows high catalytic activity with an onset overpotential of 240 m V with a smaller Tafel slope of 48 m V/dec. Additionally, it needs an overpotential of 290 mV to the drive the current density of 10 m A/cm;and shows good stability in the 1 M KOH electrolyte solution.展开更多
In present work,the vertically aligned Ni S nano-flakes composed thin film is prepared by anionic exchange process in which hydrothermally prepared Ni（OH）2is used as a parent thin film and Na2S as a sulfide ion sour...In present work,the vertically aligned Ni S nano-flakes composed thin film is prepared by anionic exchange process in which hydrothermally prepared Ni（OH）2is used as a parent thin film and Na2S as a sulfide ion source.This synthesis process produced fully transformed and shape-controlled nano-flakes of Ni S from nano-flowers of Ni（OH）2.The electrochemical supercapacitor properties of Ni S electrode are studied with cyclic voltammetry（CV）,galvonostatic charge discharge（GCD）and electrochemical impedance spectroscopy（EIS）techniques.Highly porous surface area（85 m^2/g）of Ni S nano-flakes makes large material contribution in electrochemical reaction stretching specific capacitance（Cs）of 880 F/g at scan rate of 5 m V/s and 90%electrochemical stability up to 4000 CV cycles in 2 M KOH electrolyte.Further,the flexible solid-state symmetric supercapacitor device（Ni S/PVA–Li ClO4/Ni S）has been fabricated using Ni S electrodes with polyvinyl alcohol（PVA）–lithium perchlorate（Li ClO4）gel electrolyte.The Ni S/PVA–Li ClO4/Ni S device exhibits specific capacitance of 56 F/g with specific energy of 14.98 Wh/kg and excellent cycling stability after 2000 cycles.In addition,the Ni S/PVA–Li ClO4/Ni S device demonstrates illumination of red light emitting diode（LED）for 60 s,which confirms the practical applicability of Ni S/PVA–Li ClO4/Ni S device in energy storage.展开更多
基金supported by the Human Resources Development program(no.20124010203180) of the Korea Institute of Energy Technology Evaluation and Planning(KETEP)Grant funded by the Korea government Ministry of Trade,Industry and Energysupported by Basic Science Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Science,ICT and Future Planning(NRF-2015R1A2A2A01006856)
文摘Nanostructured iron oxyhydroxide（Fe OOH） thin films have been synthesized using an electrodeposition method on a nickel foam（NF） substrate and effect of air annealing temperature on the catalytic performance is studied. The as-deposited and annealed thin films were characterized by X-ray diffraction（XRD）,X-ray photoelectron spectroscopy（XPS）, field emission scanning electron microscopy（FE-SEM） and linear sweep voltammetry（LSV） to determine their structural, morphological, compositional and electrochemical properties, respectively. The as-deposited nanostructured amorphous Fe OOH thin film is converted into a polycrystalline Fe;O;with hematite crystal structure at a high temperature. The Fe OOH thin film acts as an efficient electrocatalyst for the oxygen evolution reaction（OER） in an alkaline 1 M KOH electrolyte. The film annealed at 200 °C shows high catalytic activity with an onset overpotential of 240 m V with a smaller Tafel slope of 48 m V/dec. Additionally, it needs an overpotential of 290 mV to the drive the current density of 10 m A/cm;and shows good stability in the 1 M KOH electrolyte solution.
基金the Human Resources Development program(No.20124010203180)of Korea Institute of Energy Technology EvaluationThe basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Science,ICT(NRF-2015R1A2A2A01006856)
文摘In present work,the vertically aligned Ni S nano-flakes composed thin film is prepared by anionic exchange process in which hydrothermally prepared Ni（OH）2is used as a parent thin film and Na2S as a sulfide ion source.This synthesis process produced fully transformed and shape-controlled nano-flakes of Ni S from nano-flowers of Ni（OH）2.The electrochemical supercapacitor properties of Ni S electrode are studied with cyclic voltammetry（CV）,galvonostatic charge discharge（GCD）and electrochemical impedance spectroscopy（EIS）techniques.Highly porous surface area（85 m^2/g）of Ni S nano-flakes makes large material contribution in electrochemical reaction stretching specific capacitance（Cs）of 880 F/g at scan rate of 5 m V/s and 90%electrochemical stability up to 4000 CV cycles in 2 M KOH electrolyte.Further,the flexible solid-state symmetric supercapacitor device（Ni S/PVA–Li ClO4/Ni S）has been fabricated using Ni S electrodes with polyvinyl alcohol（PVA）–lithium perchlorate（Li ClO4）gel electrolyte.The Ni S/PVA–Li ClO4/Ni S device exhibits specific capacitance of 56 F/g with specific energy of 14.98 Wh/kg and excellent cycling stability after 2000 cycles.In addition,the Ni S/PVA–Li ClO4/Ni S device demonstrates illumination of red light emitting diode（LED）for 60 s,which confirms the practical applicability of Ni S/PVA–Li ClO4/Ni S device in energy storage.
