Joint density functional theory of the electrode-electrolyte interface: Application to fixed electrode potentials, interfacial capacitances, and potentials of zero charge

Letchworth‐Weaver, Kendra; Arias, T. A.

doi:10.1103/physrevb.86.075140

Cited by 294 publications

(417 citation statements)

References 47 publications

(86 reference statements)

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“…Several methods [5][6][7][8][9][10][11][12][13] have been proposed for correcting quantum chemical calculations to constant electrode potential. The most elegant solution would be to treat electrons in the grand canonical ensemble, that is, to allow the number of electrons to change during the electronic structure self-consistency loop, which is equivalent to connecting the system to a fictitious potentiostat.…”

Section: Introductionmentioning

confidence: 99%

“…7 Alternatively, a combination of explicit water molecules and a continuum description of the electrochemical double-layer could be employed in the spirit of the modified Poisson-Boltzmann equation approach. [11][12][13] Having corrected the charged system absolute energies, the potential dependence of the grand canonical energies is obtained by fitting a parabola to the graph energy vs absolute potential. This quadratic relationship arises because the combined system of atoms and background charge can be interpreted as a capacitor.…”

Section: Construction Of Grand Canonical Energiesmentioning

confidence: 99%

“…Recently, the method has also been extended to grand canonical simulations in the framework of joint-density functional theory. 13 For a detailed overview of the presented methods including suggestions for further improvements, we refer the interested reader to ref. 14.…”

Section: Introductionmentioning

confidence: 99%

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Ab Initio Electrochemistry: Exploring the Hydrogen Evolution Reaction on Carbon Nanotubes

Holmberg

Laasonen

2015

J. Phys. Chem. C

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Density functional theory (DFT) was employed to investigate the hydrogen evolution reaction (HER) on pristine and nitrogen doped carbon nanotubes (CNTs) in acidic solution. As the reaction is an electrocatalytic surface reaction, an accurate description of HER requires performing simulations under constant electrode potential conditions. To this end, we examined HER at several electrode charges allowing us to determine grand canonical activation energies as a continuous function of electrode potential. By studying the elementary steps of HER -the Volmer, Tafel and Heyrovsky reactions -and by considering hydrogen coverage effects, we found that the Volmer-Heyrovsky mechanism is the predominant HER mechanism on CNTs with the Heyrovsky step being rate-determining. Our results indicated that CNTs are electrochemically active towards HER, which seen as a decrease in activation energies with growing electrode potential, but that the activity is lower than on platinum matching experimental data.Substitutional nitrogen doping did not improve HER activity, and further research is required to determine which nitrogen configurations contribute to the enhanced catalytic activity observed for experimental NCNTs.

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Section: Introductionmentioning

confidence: 99%

Section: Construction Of Grand Canonical Energiesmentioning

confidence: 99%

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Ab Initio Electrochemistry: Exploring the Hydrogen Evolution Reaction on Carbon Nanotubes

Holmberg

Laasonen

2015

J. Phys. Chem. C

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“…Here we carry out quantum mechanics (QM) calculations at constant potential by using our grand canonical methodology (17,18) that uses the chargeasymmetric nonlocally determined local-electric (CANDLE) implicit solvation model (19) to achieve constant electrochemical potential (not constant number of electrons) within the framework of joint density functional theory (JDFT) (20,21) (details in Computational Details). The three key steps we focus on are (i) CO2 activation, which we previously showed to be the ratedetermining step (RDS) for CO production on pure Cu (22); (ii) CO dimerization, which we previously showed to be the RDS for forming C2 products from CO on pure Cu (17,18); and (iii) C1 product formation, which we find to compete with C2 products for pure Cu.…”

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confidence: 99%

Cu metal embedded in oxidized matrix catalyst to promote CO ₂ activation and CO dimerization for electrochemical reduction of CO ₂

Xiao

Goddard

Cheng

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

464

429

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We propose and validate with quantum mechanics methods a unique catalyst for electrochemical reduction of CO 2 (CO 2 RR) in which selectivity and activity of CO and C 2 products are both enhanced at the borders of oxidized and metallic surface regions. This Cu metal embedded in oxidized matrix (MEOM) catalyst is consistent with observations that Cu 2 O-based electrodes improve performance. However, we show that a fully oxidized matrix (FOM) model would not explain the experimentally observed performance boost, and we show that the FOM is not stable under CO 2 reduction conditions. This electrostatic tension between the Cu + and Cu 0 surface sites responsible for the MEOM mechanism suggests a unique strategy for designing more efficient and selective electrocatalysts for CO 2 RR to valuable chemicals (HCOx), a critical need for practical environmental and energy applications.electrochemical reduction of CO 2 | Cu metal embedded in oxidized matrix | density functional theory | CO 2 activation | CO dimerization E lectrochemical reduction of CO2 (CO2RR) to valuable chemicals is an essential strategy to achieve industrial-scale reduction of the carbon footprint under mild conditions and to provide a means of storing electrical power from intermittent renewable sources into stable chemical forms (1). Cu is the prototype electrocatalyst for CO2RR, because it is the only pure metal that delivers appreciable amounts of methane and ethylene plus minor alcohol products (2-7), but it suffers from high overpotentials and very significant hydrogen evolution reactions (HERs). Consequently, tremendous efforts are being made to develop more efficient and selective electrocatalysts, for example by surface modification (8) and by nanoparticle (9, 10) and nanowire (11) engineering.We examine here the mechanism by which Cu2O-based electrodes are observed to improve both efficiency and selectivity for C2 products (12-15), which also suppresses HERs by severalfold. Because Cu2O is subject to reduction (back to Cu metal) under CO2RR conditions, the improved performance was initially attributed to Cu metal surface morphology (8,16). But a more recent experiment (15) showed that Cu + sites can survive on the Cu surface for the course of CO2RR. Importantly, a Cu sample that is first oxidized and then reduced using an H2 plasma leads to performance substantially worse than that of the oxidized sample, despite both having similarly roughened surfaces. This provides solid evidence that surface Cu + plays an essential role in promoting the efficiency and selectivity of CO2RR. However, experiments have provided no clue about how surface Cu + affects the mechanisms of CO2RR. Moreover, no previous theoretical efforts have elucidated its role.To understand the promising results achieved with Cu2O-based electrodes, we investigated three distinct models aimed at unraveling the role of surface Cu + in shaping the free energy profiles of two key steps for CO2RR. Here we carry out quantum mechanics (QM) calculations at constant potential by using our ...

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“…Notably, these dynamical effects are not apparent in the thermodynamics and are thus difficult to predict without a model that explicitly describes the interplay between ions, their solvation shell, and the aqueous dynamics at the electrode interface. Traditional continuum models (40) are thus insufficient to predict these significant interfacial effects.…”

Section: Implications For Electrochemistrymentioning

confidence: 99%

Microscopic dynamics of charge separation at the aqueous electrochemical interface

Kattirtzi

Limmer

Willard

2017

Proc. Natl. Acad. Sci. U.S.A.

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We have used molecular simulation and methods of importance sampling to study the thermodynamics and kinetics of ionic charge separation at a liquid water-metal interface. We have considered this process using canonical examples of two different classes of ions: a simple alkali-halide pair, Na + I − , or classical ions, and the products of water autoionization, H 3 O + OH − , or water ions. We find that for both ion classes, the microscopic mechanism of charge separation, including water's collective role in the process, is conserved between the bulk liquid and the electrode interface. However, the thermodynamic and kinetic details of the process differ between these two environments in a way that depends on ion type. In the case of the classical ion pairs, a higher free-energy barrier to charge separation and a smaller flux over that barrier at the interface result in a rate of dissociation that is 40 times slower relative to the bulk. For water ions, a slightly higher free-energy barrier is offset by a higher flux over the barrier from longer lived hydrogen-bonding patterns at the interface, resulting in a rate of association that is similar both at and away from the interface. We find that these differences in rates and stabilities of charge separation are due to the altered ability of water to solvate and reorganize in the vicinity of the metal interface.chemical kinetics | catalysis | surface science | ion pairing I n aqueous solution, the association or dissociation of oppositely charged ions requires the collective rearrangement of surrounding water molecules (1, 2), which solvate bound ion pairs differently than individual ions (3-6). The solvent fluctuations that enable these collective rearrangements drive the dynamics of ion pairing and unpairing and therefore play a fundamental role in many chemical reactions. Near the surface of an electrode, these collective solvent fluctuations can differ significantly from that of the bulk liquid (7,8), and these differences can affect the rates and mechanisms of aqueous electrochemical reactions. In this work, we use molecular simulation to investigate the microscopic processes of aqueous ion pairing when it takes place near, but not in direct contact with, an extended metallic electrode. We identify the specific effects of the electrode interface by comparing our results to those generated in the environment of the bulk liquid. We find that the presence of an electrode has little effect on the mechanistic details of ionic charge separation, but can significantly influence the thermodynamics and kinetics of the process. We highlight that this influence is different for simple monovalent salts like Na + and I − , whose transport is limited by the mobility of an aqueous solvation shell (9), than it is for water ions, like H3O + and OH − , whose transport is limited by the concerted hopping of protons along hydrogen-bonding chains (10). This fundamental difference is controlled by the microscopic details of electrode-water interactions and thus has implications for...

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Joint density functional theory of the electrode-electrolyte interface: Application to fixed electrode potentials, interfacial capacitances, and potentials of zero charge

Cited by 294 publications

References 47 publications

Ab Initio Electrochemistry: Exploring the Hydrogen Evolution Reaction on Carbon Nanotubes

Ab Initio Electrochemistry: Exploring the Hydrogen Evolution Reaction on Carbon Nanotubes

Cu metal embedded in oxidized matrix catalyst to promote CO ₂ activation and CO dimerization for electrochemical reduction of CO ₂

Microscopic dynamics of charge separation at the aqueous electrochemical interface

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Joint density functional theory of the electrode-electrolyte interface: Application to fixed electrode potentials, interfacial capacitances, and potentials of zero charge

Cited by 294 publications

References 47 publications

Ab Initio Electrochemistry: Exploring the Hydrogen Evolution Reaction on Carbon Nanotubes

Ab Initio Electrochemistry: Exploring the Hydrogen Evolution Reaction on Carbon Nanotubes

Cu metal embedded in oxidized matrix catalyst to promote CO 2 activation and CO dimerization for electrochemical reduction of CO 2

Microscopic dynamics of charge separation at the aqueous electrochemical interface

Contact Info

Product

Resources

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Cu metal embedded in oxidized matrix catalyst to promote CO ₂ activation and CO dimerization for electrochemical reduction of CO ₂