Electrochemical kinetics of the hydrogen reaction on platinum in concentrated HCl(aq)

Hall, Derek M.; Beck, Justin; Lvov, Serguei N.

doi:10.1016/j.elecom.2015.05.012

Cited by 14 publications

(21 citation statements)

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“…Canada Nuclear Laboratories (formerly Atomic Energy of Canada Limited) demonstrated hydrogen production by a CuCl electrolyzer continuously for several days and reported that electrolysis is feasible at low potentials (0.6‐0.7 V) at a current density of 0.1 A cm −2 using inexpensive materials . The Pennsylvania State University has carried out comprehensive experiments and theoretical developments on the cycle . Balashov et al performed an experimental study on a CuCl/HCl electrolyzer and reported a voltage efficiency of 80% and a current efficiency of 98%, which is with a good agreement with Faraday law.…”

Section: Introductionmentioning

confidence: 83%

“…In addition, z r denotes number of electrons in each half‐reaction. For the anode, assuming a one‐step reaction, exchange current density can be determined as follows:

i_{normalo, anode} = F k_{normalo, anode} ((), c_{ox}^{1 - normalα} c_{red}^{α})

where c ox and c red denote molar concentrations of the oxidant and the reductant of the half‐cell reaction at the anode. In Equation , for example, the ion

{CuCl}_{3}^{-} ((), aq)

is the oxidant and

{CuCl}_{3}^{2 -} ((), aq)

is the reductant of the anode half‐reaction.…”

Section: Electrochemical Modeling and Kinetic Analysismentioning

confidence: 99%

“…For the cathode, Equation cannot be used because no data are reported in the literature, to the best of the authors' knowledge, regarding the k 0 value of the HER in concentrated acidic solution. Therefore, the i o,anode value from Hall et al is directly used. Hall et al apply the Koutecky‐Levich method with experimental results to determine i o,anode and α on a glassy carbon and platinum (Pt) electrode and determine k o,anode values resulting from Equation .…”

Section: Electrochemical Modeling and Kinetic Analysismentioning

confidence: 99%

“…Therefore, the i o,anode value from Hall et al is directly used. Hall et al apply the Koutecky‐Levich method with experimental results to determine i o,anode and α on a glassy carbon and platinum (Pt) electrode and determine k o,anode values resulting from Equation . However, i o,anode is not used directly in this study; rather, the k o,anode value is applied to obtain the i o,anode with Equation .…”

Section: Electrochemical Modeling and Kinetic Analysismentioning

confidence: 99%

“…Data regarding kinetics of the anode half‐reaction such as transfer coefficient, exchange current density, and symmetry factor of reaction have been determined by Hall et al These data are used in this study to develop the overpotential model of the cell. Furthermore, a kinetic study on the hydrogen evolution reaction (HER) at the cathode was conducted by Hall et al in concentrated HCl(aq) that provided some useful kinetic parameters.…”

Section: Introductionmentioning

confidence: 99%

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Kinetic and electrochemical analyses of a CuCI/HCl electrolyzer

2019

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Summary An electrochemical analysis is carried out from a kinetic electrochemistry perspective of a CuCl/HCl electrolysis cell, within the CuCl thermochemical water splitting process for hydrogen production. The anolyte is a solution of 2 mol L−1 CuCl(aq) and 10 mol L−1 HCl(aq) while the catholyte solution is 11 mol L−1 HCl(aq). The cell current density of 0.5 A cm−2 and voltage of 0.7 V are the desired working conditions for a CuCl/HCl electrolyzer. The current density of 0.5 A cm−2 is assumed to occur at a 5% anolyte conversion degree. At 25°C, the activation overpotential of the anode half‐reaction is found to be 53 mV for a current density of 0.5 A cm−2 while the activation overpotential of the cathode half‐reaction for the same condition is 87 mV. An increase in working temperature decreases the overpotential of the anode half‐reaction and increases the cathode half‐reaction activation overpotential. The ohmic overpotential of the cell membrane is almost 1000 times smaller than that of the activation overpotentials of the electrode half‐reactions for the same temperature and current density. A higher working temperature results in a lower membrane ohmic overpotential. The required voltage to trigger electrolysis for a current density of 0.5 A cm−2 is found to be 0.53 V at 25°C and 0.59 V at 80°C and a higher temperature results in a higher electrochemical efficiency. The cell electrochemical efficiency increases linearly with working temperature while the voltage efficiency peaks at 75% at 60°C.

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Section: Introductionmentioning

confidence: 83%

“…In addition, z r denotes number of electrons in each half‐reaction. For the anode, assuming a one‐step reaction, exchange current density can be determined as follows:

i_{normalo, anode} = F k_{normalo, anode} ((), c_{ox}^{1 - normalα} c_{red}^{α})

where c ox and c red denote molar concentrations of the oxidant and the reductant of the half‐cell reaction at the anode. In Equation , for example, the ion

{CuCl}_{3}^{-} ((), aq)

is the oxidant and

{CuCl}_{3}^{2 -} ((), aq)

is the reductant of the anode half‐reaction.…”

Section: Electrochemical Modeling and Kinetic Analysismentioning

confidence: 99%

Section: Electrochemical Modeling and Kinetic Analysismentioning

confidence: 99%

Section: Electrochemical Modeling and Kinetic Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Kinetic and electrochemical analyses of a CuCI/HCl electrolyzer

2019

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Modeling a CuCl(aq)/HCl(aq) Electrolyzer using Thermodynamics and Electrochemical Kinetics

Hall

Lvov

2016

Electrochimica Acta

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11Research efforts on the CuCl(aq)/HCl(aq) electrolyzer would greatly benefit from the ability to 12 quantify the dissipative processes that undesirably increase the cell's applied potential, E cell , 13 which decreases its efficiency. To date, little is known about what impact further improvements 14 to active surface area, extent of CuCl(aq) conversion and ohmic resistance would exactly have 15 on the electrolyzer performance. To better understand how this electrolyzer can be improved, a 16 model was developed to quantify and separate the effects of electrochemical kinetics, membrane 17 transport and open circuit potential, E OCP, on E cell for a given current density. By employing data 18 obtained from previous studies with electrochemical cells into the developed model, it was 19 possible to calculate E cell values that agreed with data collected from a lab scale electrolyzer 20 using just one adjustable parameter, the Nernst diffusion layer at limiting current. The model was 21 then used to identify the predicted E cell contributions as a function of CuCl(aq) conversion, active 22 electrode area and ohmic resistance. It was found that the extent of CuCl(aq) conversion can 23 © 2015. This manuscript version is made available under the Elsevier user license http://www.elsevier.com/open-access/userlicense/1.0/ 2 density. Overall, E cell could be most readily reduced by improving R ohm , whereas improvements 3 to electrode kinetics have limited impacts.4 5 Keywords 6 CuCl(aq)/HCl(aq) Electrolyzer, Electrochemical Kinetics, Thermodynamics, Current-Potential 7 Modeling, Conversion 8 9 12 continue. One option for storing harnessed thermal and electric energy is the hybrid Cu-Cl 13 thermochemical cycle to efficiently produce hydrogen [1,2]. When compared to other 14 thermochemical cycles under development, previous research found that the four-step Cu-Cl 15 hybrid thermochemical cycle had significantly lower temperature requirements [1]. For example, 16 while the hybrid-sulfur thermochemical cycle required operating temperatures above 800 °C [3], 17 the four-step Cu-Cl hybrid thermochemical cycle only needed temperatures up to 550 °C [4]. 18Given that much of the energy needed for this cycle to split the water is obtained from thermal 19 energy, the electric energy needed to split water by the Cu-Cl cycle has been shown to be 20 considerably less than an acid or alkaline electrolyzers [5]. After including the efficiency loss 21 from electricity production, the overall efficiency this cycle can be between 30-50 %, whereas 22 conventional water electrolysis is between 18-24 % [6]. Additionally, many studies were carried 23 16 transport limitations, and electrode overpotentials for the CuCl(aq)/HCl(aq) electrolyzer. The 17 advantage of this model over other models is that it uses fundamental thermodynamic, kinetic 18 and transport coefficients in non-equilibrium thermodynamic relations, making extrapolations 19 more reliable. The model parameters were obtained through experimental methods using single 20 cells wher...

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