Theory of electrochemical impedance of surface reactions: second-harmonic and large-amplitude response

1997 ◽  
Vol 75 (11) ◽  
pp. 1508-1517 ◽  
Author(s):  
David A. Harrington
Keyword(s):  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Electrochemical Impedance ◽  
Second Harmonic ◽  
Surface Reactions ◽  
Nonlinear Effects ◽  
Amplitude Dependence ◽  
Adsorbed Species ◽  
Amplitude Response ◽  
Potential Perturbation

The theory for the electrochemical impedance of surface reactions involving a single adsorbed species is presented. A new methodology is used, in which many harmonics are considered, and the differential equations are reduced to algebraic matrix equations. The amplitude of the ac potential perturbation is not assumed to be small, and nonlinear effects are taken into account. The amplitude dependence of the impedance and the second-harmonic response are investigated. The quasi-reversible electrosorption reaction and the hydrogen evolution reaction are considered in detail, assuming that the adsorbed species obeys the Langmuir isotherm. Keywords: electrochemistry, impedance, adsorption, hydrogen evolution reaction, second harmonic.

scholarly journals Amorphous Ni x Co y P-supported TiO2 nanotube arrays as an efficient hydrogen evolution reaction electrocatalyst in acidic solution

2019 ◽  
Vol 10 ◽  
pp. 62-70 ◽  
Author(s):  
Yong Li ◽  
Peng Yang ◽  
Bin Wang ◽  
Zhongqing Liu
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Photoelectron Spectroscopy ◽  
Electrochemical Impedance ◽  
Nanotube Arrays ◽  
Active Surface Area ◽  
X Ray ◽  
Transmission Electron

Bimetallic phosphides have been attracting increasing attention due to their synergistic effect for improving the hydrogen evolution reaction as compared to monometallic phosphides. In this work, NiCoP modified hybrid electrodes were fabricated by a one-step electrodeposition process with TiO2 nanotube arrays (TNAs) as a carrier. X-ray diffraction, transmission electron microscopy, UV–vis diffuse reflection spectroscopy, X-ray photoelectron spectroscopy and scanning transmission electron microscopy/energy-dispersive X-ray spectroscopy were used to characterize the physiochemical properties of the samples. The electrochemical performance was investigated by cyclic voltammetry, linear sweep voltammetry, and electrochemical impedance spectroscopy. We show that after incorporating Co into Ni–P, the resulting Ni x Co y P/TNAs present enhanced electrocatalytic activity due to the improved electron transfer and increased electrochemically active surface area (ECSA). In 0.5 mol L−1 H2SO4 electrolyte, the Ni x Co y P/TNAs (x = 3.84, y = 0.78) demonstrated an ECSA value of 52.1 mF cm−2, which is 3.8 times that of Ni–P/TNAs (13.7 mF cm−2). In a two-electrode system with a Pt sheet as the anode, the Ni x Co y P/TNAs presented a bath voltage of 1.92 V at 100 mA cm−2, which is an improvment of 79% over that of 1.07 V at 10 mA cm−2.

scholarly journals Electrodeposition and characterization of Ni-MoO2 composite coatings as cathodes for the hydrogen evolution reaction in alkaline solution

2013 ◽  
Vol 78 (4) ◽  
pp. 549-554 ◽  
Author(s):  
Uros Lacnjevac
Keyword(s):  
Catalytic Activity ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Alkaline Solution ◽  
Electrochemical Impedance ◽  
Composite Coatings ◽  
Theoretical Interpretation ◽  
X Ray ◽  
Polarization Measurements ◽  
Naoh Solution

Composite Ni-MoO2 coatings were prepared and characterized with respect to their possible application as electrocatalysts for the hydrogen evolution reaction (HER) in alkaline solution. The composites were electrodeposited onto Ni meshes from an ammonium chloride Ni solution with suspended MoO2 particles in simulated industrial conditions for production of commercial cathodes. The influence of the concentration of MoO2 particles in the solution and deposition current density on the morphology, chemical and phase composition of obtained coatings was investigated by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). Catalytic activity for the HER of the coatings was examined by polarization measurements in a 32 wt. % NaOH solution at 90?C and compared to the activity of the commercial De Nora?s cathode (DN). It was shown that the most active Ni-MoO2 coating exhibits better polarization characteristics for the HER than the DN cathode. The mechanism of the HER on the specified Ni-MoO2 coating was investigated in 8 mol dm-3 NaOH at 30?C by means of steady-state polarization measurements and an electrochemical impedance spectroscopy (EIS) method. Based on the theoretical interpretation of the experimental data, rate constants of the three individual steps of the HER were determined and the source of catalytic activity of the coating was elucidated.

scholarly journals Fabrication of Hybrid Catalyst ZnO Nanorod/α-Fe2O3 Composites for Hydrogen Evolution Reaction

Crystals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 356
Author(s):  
Kasimayan Uma ◽  
Elavarasan Muniranthinam ◽  
Siewhui Chong ◽  
Thomas C.-K Yang ◽  
Ja-Hon Lin
Keyword(s):  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Photoelectron Spectroscopy ◽  
Electrochemical Impedance ◽  
Nickel Foam ◽  
Zno Nanorods ◽  
Synergetic Effect ◽  
Zno Nanorod ◽  
Fe2o3 Nanoparticles ◽  
X Ray

This report presents the synthesis of ZnO nanorod/α-Fe2O3 composites by the hydrothermal method with different weight percentages of α-Fe2O3 nanoparticles. The as-synthesized nanorod composites were characterized by different techniques, such as X-ray diffraction (XRD), Fourier transform-infrared (FT-IR), field emission scanning electron microscopy (FE-SEM), electrochemical impedance spectroscopy (EIS), and X-ray photoelectron spectroscopy (XPS). From our results, it was found that the ZnO/α-Fe2O3 (3 wt%) nanorod composites exhibit a higher hydrogen evolution reaction (HER) activity when compared to other composites. The synergetic effect between ZnO and (3 wt%) of α-Fe2O3 nanocomposites resulted in a low onset potential of −125 mV, which can effectively produce more H2 than pure ZnO. The H2 production rate over the composite of ZnO/α-Fe2O3 (3 wt%) clearly shows a significant improvement in the photocatalytic activity in the heterojunction of the ZnO nanorods and α-Fe2O3 nanoparticles on nickel foam.

scholarly journals Silicon Nanowires with MoSxand Pt as Electrocatalysts for Hydrogen Evolution Reaction

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
S. H. Hsieh ◽  
S. T. Ho ◽  
W. J. Chen
Keyword(s):  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Silicon Nanowires ◽  
Electrochemical Impedance ◽  
Silicon Nanowire ◽  
Electrochemical Characterizations ◽  
Pt Nanoparticle ◽  
Transmission Electron ◽  
Acidic Electrolyte ◽  
Nanocomposite Catalysts

A convenient method was used for synthesizing Pt-nanoparticle/MoSx/silicon nanowires nanocomposites. Obtained Pt-MoSx/silicon nanowires electrocatalysts were characterized by transmission electron microscopy (TEM). The hydrogen evolution reaction efficiency of the Pt-MoSx/silicon nanowire nanocomposite catalysts was assessed by examining polarization and electrolysis measurements under solar light irradiations. The electrochemical characterizations demonstrate that Pt-MoSx/silicon nanowire electrodes exhibited an excellent catalytic activity for hydrogen evolution reaction in an acidic electrolyte. The hydrogen production capability of Pt-MoSx/silicon nanowires is also comparable toMoSx/silicon nanowires and Pt/silicon nanowires. Electrochemical impedance spectroscopy experiments suggest that the enhanced performance of Pt-MoSx/silicon nanowires can be attributed to the fast electron transfer between Pt-MoSx/silicon nanowire electrodes and electrolyte interfaces.

Visible-Light Illumination Enhanced Hydrogen Evolution on CuO Modified TiO2 Nanotube Arrays/Ti Electrocatalyst

2013 ◽  
Vol 772 ◽  
pp. 343-348
Author(s):  
Zhao Xiong Yan ◽  
Zhi Hua Xu ◽  
Li Hong Zhu
Keyword(s):  
Visible Light ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Electrocatalytic Activity ◽  
Electrochemical Impedance ◽  
Electrochemical Impedance Spectrum ◽  
Nanotube Arrays ◽  
Light Illumination ◽  
Current Time ◽  
Visible Light Illumination

TiO2nanotube arrays (TNAs) modified by CuO (CuO-TNAs) catalysts were prepared by an impregnating-calcinating method using the electrochemically prepared TNAs and Cu (NO3)2as precursors and were characterized by scanning electron microscope, transmission electron microscopy, X-ray diffraction spectroscopy and UV-visible spectroscopy. The electrocatalytic properties of the CuO-TNAs samples for hydrogen evolution reaction (HER) were investigated by linear sweep curves, electrochemical impedance spectrum and current-time curves. The results showed that the electrocatalytic activity of TNAs for hydrogen evolution reaction (HER) was significantly enhanced by CuO modification, and the electrocatalytic activity of CuO-TNAs catalysts could be further promoted by visible-light illumination. The combination of visible-light irradiation with applying a controlled potential may provide new insight into enhancing the performances of the cathode for hydrogen evolution reaction.

scholarly journals Prickly Nickel Nanowires Grown on Cu-Ni Substrate Surface as High Performance Cathodes for Hydrogen Evolution Reaction

2015 ◽  
Vol 18 (2) ◽  
pp. 095-102 ◽  
Author(s):  
Reza Karimi Shervedani ◽  
Akbar Amini ◽  
Motahareh Karevan
Keyword(s):  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
High Performance ◽  
Electrochemical Impedance ◽  
Substrate Surface ◽  
Electrochemical Characterizations ◽  
Equivalent Circuit Model ◽  
Model Parameters ◽  
Ni Substrate ◽  
Nickel Nanowires

A new and highly rough nickel electrode is fabricated based on in-situ assembling of prickly nickel nanowires, synthesized by electroless deposition method on a layer of nickel freshly preelectrodeposited on copper, constructing Cu-Ni-PNNWs. Then, the fabricated electrode is studied for Hydrogen Evolution Reaction (HER). Surface morphology of the electrodes is characterized by Field Emission Scanning Electron Microscopy (FESEM) and X-ray diffraction (XRD) microanalysis. Kinetics of the HER is studied in 0.5 M H2SO4 on Cu-Ni-PNNWs electrode in comparison with Ni and Cu-Ni electrodes. Evaluation of the electrode activities is carried out by steady-state polarization curves (Tafel plots) and electrochemical impedance spectroscopy (EIS). The results obtained by electrochemical characterizations have shown that the Cu-Ni-PNNWs electrode benefits of high electrocatalytic activity for the HER. The EIS data are approximated using appropriate equivalent circuit model, and values of the model parameters are extracted. Analysis of the EIS results has revealed that the double layer capacitance (Cdl) and exchange current density (j0) of the Cu-Ni-PNNWs electrode are increased by factors of ~ 47 and ~ 19 times, respectively, compared with Cu-Ni. Up to our knowledge, this is the first finding of this type, reporting synthesis and activity of the Cu-Ni-PNNWs electrode for the HER.

Effect of AC interference on hydrogen evolution reaction of x80 steel

2020 ◽  
Vol 67 (2) ◽  
pp. 197-204
Author(s):  
JiaYu Zhou ◽  
Zili Li ◽  
JianGuo Liu ◽  
Xiao Xing ◽  
Gan Cui ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Electrochemical Impedance ◽  
Ph Value ◽  
Electrode System ◽  
Oxygen Absorption ◽  
Content Type ◽  
Tafel Polarization ◽  
X80 Steel ◽  
Ac Interference

Purpose The purpose of this paper is to quantify the influence of alternating current (AC) interference on hydrogen evolution reaction of X80 steel. Design/methodology/approach The hydrogen evolution potential was obtained by cathodic potentiodynamic polarization curve. The instantaneous potential under AC interference was obtained by high-frequency acquisition with three-electrode system. Electrochemical impedance spectroscopy and Tafel polarization curves were used to study the influence mechanism of AC interference on instantaneous potential. Findings It was concluded that the hydrogen evolution reaction could occur on X80 steel under AC interference. There were critical AC current densities of about 100 to 200 A/m2, beyond which the cathode reaction of X80 steel changed from oxygen absorption to hydrogen evolution. Besides the pH value, the initial polarization potential EZ and impedance module of the steel/electrolyte interface under AC interference were also the factors that affected the critical AC densities in different solutions. Originality/value This research quantified the hydrogen evolution capacity of X80 steel under AC interference, which could be applied to clear the effect of AC interference on hydrogen evolution reaction.

scholarly journals Molybdenum Disulfide Nanosheets Decorated with Platinum Nanoparticle as a High Active Electrocatalyst in Hydrogen Evolution Reaction

2022 ◽  
Vol 17 (1) ◽  
Author(s):  
Mina Razavi ◽  
M. Sookhakian ◽  
Boon Tong Goh ◽  
Hadariah Bahron ◽  
Eyas Mahmoud ◽  
...  
Keyword(s):  
Molybdenum Disulfide ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Acidic Medium ◽  
High Performance ◽  
Hydrogen Adsorption ◽  
Electrochemical Impedance ◽  
Pt Nanoparticles ◽  
Platinum Nanoparticle ◽  
Molybdenum Disulfide Nanosheets

AbstractElectrochemical hydrogen evolution reaction (HER) refers to the process of generating hydrogen by splitting water molecules with applied external voltage on the active catalysts. HER reaction in the acidic medium can be studied by different mechanisms such as Volmer reaction (adsorption), Heyrovsky reaction (electrochemical desorption) or Tafel reaction (recombination). In this paper, facile hydrothermal methods are utilized to synthesis a high-performance metal-inorganic composite electrocatalyst, consisting of platinum nanoparticles (Pt) and molybdenum disulfide nanosheets (MoS2) with different platinum loading. The as-synthesized composite is further used as an electrocatalyst for HER. The as-synthesized Pt/Mo-90-modified glassy carbon electrode shows the best electrocatalytic performance than pure MoS2 nanosheets. It exhibits Pt-like performance with the lowest Tafel slope of 41 mV dec−1 and superior electrocatalytic stability in an acidic medium. According to this, the HER mechanism is related to the Volmer-Heyrovsky mechanism, where hydrogen adsorption and desorption occur in the two-step process. According to electrochemical impedance spectroscopy analysis, the presence of Pt nanoparticles enhanced the HER performance of the MoS2 nanosheets because of the increased number of charge carriers transport.

Sign in / Sign up

Export Citation Format

Share Document