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Chen G, Xie Y, Tang Y, Wang T, Wang Z, Yang C. Unraveling the Role of Metal Vacancy Sites and Doped Nitrogen in Enhancing Pseudocapacitance Performance of Defective MXene. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20:e2307408. [PMID: 37940624 DOI: 10.1002/smll.202307408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 10/20/2023] [Indexed: 11/10/2023]
Abstract
Nitrogen-doped titanium carbides (MXene) films exhibit extraordinary volumetric capacitance when high-concentration sulfuric acid electrolyte is utilized owing to the enhancement of pseudocapacitance. However, the energy storage mechanism of nitrogen-doped MXene is unclear due to the complex electrode structure and electrolyte ions' behavior. Here, based on pristine MXene (Ti3C2O2), three different MXene structures are constructed by introducing metal vacancy sites and doped nitrogen atoms, namely, defective MXene (Ti2.9C2O2), nitrogen-doped MXene (Ti3C2O1.9N0.1), and nitrogen-doped MXene with metal vacancy sites (Ti2.9C2O1.9N0.1). Then, the density functional theory (DFT)-based calculations coupled with the effective screening medium reference interaction site method (ESM-RISM) are applied to reveal the electrochemical behavior at the electrode/electrolyte interfacial area. Through analyzing the electronic structure, electrical double-layer capacitance (EDLC), and equilibrium potential of the pseudocapacitance reaction, the specific effect of structural changes on their performance can be clarified: metal vacancy sites can reduce the potential difference of gap layer (Outer Helmholtz plane) at charged state and increase the electronic capacity of Ti, which can be used to explain the high pseudocapacitance, low charge transfer resistance and high-rate capacity properties of nitrogen-doped MXene observed in experiments.
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Affiliation(s)
- Guanglei Chen
- School of Chemistry and Chemical Engineering, Northwestern Polytechnical University, No. 1 Dongxiang Road, Chang'an, Xi'an, Shaanxi, 710129, P. R. China
| | - Yangyang Xie
- School of Chemistry and Chemical Engineering, Northwestern Polytechnical University, No. 1 Dongxiang Road, Chang'an, Xi'an, Shaanxi, 710129, P. R. China
- Innovation Center NPU Chongqing, Northwestern Polytechnical University, Chongqing, 400000, P. R. China
| | - Yi Tang
- College of Materials Science and Engineering, Xi'an University of Science and Technology, Xi'an, Shaanxi, 710054, P. R. China
| | - Tianshuai Wang
- School of Chemistry and Chemical Engineering, Northwestern Polytechnical University, No. 1 Dongxiang Road, Chang'an, Xi'an, Shaanxi, 710129, P. R. China
| | - Zhenyu Wang
- State Key Laboratory of Electrical Insulation and Power Equipment, Center of Nanomaterials for Renewable Energy, School of Electrical Engineering, Xi'an Jiaotong University, Xi'an, 710049, P. R. China
| | - Chenhui Yang
- School of Chemistry and Chemical Engineering, Northwestern Polytechnical University, No. 1 Dongxiang Road, Chang'an, Xi'an, Shaanxi, 710129, P. R. China
- Innovation Center NPU Chongqing, Northwestern Polytechnical University, Chongqing, 400000, P. R. China
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2
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Bruch N, Binninger T, Huang J, Eikerling M. Incorporating Electrolyte Correlation Effects into Variational Models of Electrochemical Interfaces. J Phys Chem Lett 2024; 15:2015-2022. [PMID: 38349906 PMCID: PMC10895655 DOI: 10.1021/acs.jpclett.3c03295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Revised: 01/24/2024] [Accepted: 01/26/2024] [Indexed: 02/15/2024]
Abstract
We propose a way for obtaining a classical free energy density functional for electrolytes based on a first-principle many-body partition function. Via a one-loop expansion, we include coulombic correlations beyond the conventional mean-field approximation. To examine electrochemical interfaces, we integrate the electrolyte free energy functional into a hybrid quantum-classical model. This scheme self-consistently couples electronic, ionic, and solvent degrees of freedom and incorporates electrolyte correlation effects. The derived free energy functional causes a correlation-induced enhancement in interfacial counterion density and leads to an overall increase in capacitance. This effect is partially compensated by a reduction of the dielectric permittivity of interfacial water. At larger surface charge densities, ion crowding at the interface stifles these correlation effects. While scientifically intriguing already at planar interfaces, we anticipate these correlation effects to play an essential role for electrolytes in nanoconfinement.
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Affiliation(s)
- Nils Bruch
- Theory
and Computation of Energy Materials (IEK-13), Institute of Energy
and Climate Research, Forschungszentrum
Jülich GmbH, 52425, Jülich, Germany
- Chair
of Theory and Computation of Energy Materials, Faculty of Georesources
and Materials Engineering, RWTH Aachen University, 52062, Aachen Germany
| | - Tobias Binninger
- Theory
and Computation of Energy Materials (IEK-13), Institute of Energy
and Climate Research, Forschungszentrum
Jülich GmbH, 52425, Jülich, Germany
| | - Jun Huang
- Theory
and Computation of Energy Materials (IEK-13), Institute of Energy
and Climate Research, Forschungszentrum
Jülich GmbH, 52425, Jülich, Germany
- Chair
of Theory and Computation of Energy Materials, Faculty of Georesources
and Materials Engineering, RWTH Aachen University, 52062, Aachen Germany
| | - Michael Eikerling
- Theory
and Computation of Energy Materials (IEK-13), Institute of Energy
and Climate Research, Forschungszentrum
Jülich GmbH, 52425, Jülich, Germany
- Chair
of Theory and Computation of Energy Materials, Faculty of Georesources
and Materials Engineering, RWTH Aachen University, 52062, Aachen Germany
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3
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Imamura K, Yokogawa D, Sato H. Recent developments and applications of reference interaction site model self-consistent field with constrained spatial electron density (RISM-SCF-cSED): A hybrid model of quantum chemistry and integral equation theory of molecular liquids. J Chem Phys 2024; 160:050901. [PMID: 38341702 DOI: 10.1063/5.0190116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Accepted: 01/04/2024] [Indexed: 02/13/2024] Open
Abstract
The significance of solvent effects in electronic structure calculations has long been noted, and various methods have been developed to consider this effect. The reference interaction site model self-consistent field with constrained spatial electron density (RISM-SCF-cSED) is a hybrid model that combines the integral equation theory of molecular liquids with quantum chemistry. This method can consider the statistically convergent solvent distribution at a significantly lower cost than molecular dynamics simulations. Because the RISM theory explicitly considers the solvent structure, it performs well for systems where hydrogen bonds are formed between the solute and solvent molecules, which is a challenge for continuum solvent models. Taking advantage of being founded on the variational principle, theoretical developments have been made in calculating various properties and incorporating electron correlation effects. In this review, we organize the theoretical aspects of RISM-SCF-cSED and its distinctions from other hybrid methods involving integral equation theories. Furthermore, we carefully present its progress in terms of theoretical developments and recent applications.
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Affiliation(s)
- Kosuke Imamura
- Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
| | - Daisuke Yokogawa
- Graduate School of Arts and Science, The University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8902, Japan
| | - Hirofumi Sato
- Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
- Fukui Institute for Fundamental Chemistry, Kyoto University, Kyoto 606-8103, Japan
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4
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Huang J. Density-Potential Functional Theory of Electrochemical Double Layers: Calibration on the Ag(111)-KPF 6 System and Parametric Analysis. J Chem Theory Comput 2023; 19:1003-1013. [PMID: 36651849 PMCID: PMC9933430 DOI: 10.1021/acs.jctc.2c00799] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The density-potential functional theory (DPFT) of electrochemical double layer (EDL) is upgraded by adopting (generalized) gradient approximations for kinetic, exchange, and correlation functionals of metal electrons. A new numerical scheme that is more stable and converges faster is proposed to solve the DPFT model. The DPFT model is calibrated with existing differential double-layer capacitance (Cdl) data of the EDL at Ag(111)-KPF6 aqueous interface at five concentrations at room temperature. Metal electronic effects are essential to explain why the two peaks of the camel-shaped Cdl curves are almost symmetric in spite of the size difference of the hydrated cations and anions. A systematic parametric analysis is then conducted in terms of key EDL properties, including the potential of zero charge and the differential capacitance. The parametric analysis, on the one hand, elucidates how quantum mechanical behaviors of metal electrons as well as interactions between metal electrons and the electrolyte solution impact the EDL properties and, on the other hand, identifies key parameters of the DPFT model, which should be calibrated using first-principles calculations and/or advanced experiments in the future.
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5
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Xi C, Zheng F, Gao G, Song Z, Zhang B, Dong C, Du XW, Wang LW. Ion Solvation Free Energy Calculation Based on Ab Initio Molecular Dynamics Using a Hybrid Solvent Model. J Chem Theory Comput 2022; 18:6878-6891. [PMID: 36253911 DOI: 10.1021/acs.jctc.1c01298] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Free energy calculation of small molecules or ion species in aqueous solvent is one of the most important problems in electrochemistry study. Although there are many previous approaches to calculate such free energies, they are based on ab initio methods and suffer from various limitations and approximations. In the current work, we developed a hybrid approach based on ab initio molecular dynamics (AIMD) simulations to calculate the ion solvation energy. In this approach, a small water cluster surrounding the central ion is used, and implicit solvent model is applied outside the water cluster. A dynamic potential well is used during AIMD to keep the water cluster together. Quasi-harmonic approximation is used to calculate the entropy contribution, while the total energy average is used to calculate the enthalpy term. The obtained solvation voltages of the bulk metal agree with experiments within 0.3 eV, and the simulation results for the solvation energies of gaseous ions are close to the experimental observations. Besides the free energies, radial pair distribution functions and coordination numbers of hydrated cations are also obtained. The remaining challenges of this method are also discussed.
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Affiliation(s)
- Cong Xi
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California94720, United States.,Institute of New Energy Materials, School of Materials Science and Engineering, Tianjin University, Tianjin30072, People's Republic of China
| | - Fan Zheng
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California94720, United States
| | - Guoping Gao
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California94720, United States
| | - Zhigang Song
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California94720, United States
| | - Buyu Zhang
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California94720, United States
| | - Cunku Dong
- Institute of New Energy Materials, School of Materials Science and Engineering, Tianjin University, Tianjin30072, People's Republic of China
| | - Xi-Wen Du
- Institute of New Energy Materials, School of Materials Science and Engineering, Tianjin University, Tianjin30072, People's Republic of China
| | - Lin-Wang Wang
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California94720, United States
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Huang J, Zhang Y. Essays on Conceptual Electrochemistry: I. Bridging Open-Circuit Voltage of Electrochemical Cells and Charge Distribution at Electrode–Electrolyte Interfaces. Front Chem 2022; 10:938064. [PMID: 35958239 PMCID: PMC9358007 DOI: 10.3389/fchem.2022.938064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 06/21/2022] [Indexed: 11/13/2022] Open
Abstract
We ponder over how an electrochemical cell conforms itself to the open-circuit voltage (OCV) given by the Nernst equation, where properties of the electrodes play no role. We first show, via a pedagogical derivation of the Nernst equation, how electrode properties are canceled and then take a closer look into the electrode–electrolyte interface at one electrode by linking charge and potential distributions. We obtain an equilibrium Poisson–Nernst equation that shows how the charge distribution across an electrode–electrolyte interface can be dictated by the chemical potentials of redox species. Taking a H2/O2 fuel cell as an example, we demystify the formal analysis by showing how the two electrodes delicately regulate their “electron tails” to abide by the Nernst equation. In this example, we run into a seemingly counterintuitive phenomenon that two electrodes made of the same transition metal display two distinct potentials of zero charge. This example indicates that the double layer at transition metals with chemisorption can display distinct behaviors compared to ideally polarizable double layers at sp metals.
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Abstract
Hydrogen fuel cell technology is an essential component of a green economy. However, it is limited in practicality and affordability by the oxygen reduction reaction (ORR). Nanoscale silver particles have been proposed as a cost-effective solution to this problem. However, previous computational studies focused on clean and flat surfaces. High-index surfaces can be used to model active steps presented in nanoparticles. Here, we used the stable stepped Ag(322) surface as a model to understand the ORR performance of steps on Ag nanoparticles. Our density functional theory (DFT) results demonstrate a small dissociation energy barrier for O2 molecules on the Ag(322) surface, which can be ascribed to the existence of low-coordination number surface atoms. Consequently, the adsorption of OOH* led to the associative pathway becoming ineffective. Alternatively, the unusual dissociative mechanism is energetically favored on Ag(322) for ORR. Our findings reveal the importance of the coordination numbers of active sites for catalytic performance, which can further guide electrocatalysts’ design.
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Santos E, Schmickler W. Introduction to the special issue: the physics of electrocatalysis. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:290401. [PMID: 35587250 DOI: 10.1088/1361-648x/ac6e1c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Accepted: 05/04/2022] [Indexed: 06/15/2023]
Affiliation(s)
- Elizabeth Santos
- Institute of Theoretical Chemistry, Ulm University, D-89069 Ulm, Germany
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Hagopian A, Doublet ML, Filhol JS, Binninger T. Advancement of the Homogeneous Background Method for the Computational Simulation of Electrochemical Interfaces. J Chem Theory Comput 2022; 18:1883-1893. [PMID: 35170945 DOI: 10.1021/acs.jctc.1c01237] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Computational studies of electrochemical interfaces based on density-functional theory (DFT) play an increasingly important role in the present research on electrochemical processes for energy conversion and storage. The homogeneous background method (HBM) offers a straightforward approach to charge the electrochemical system within DFT simulations, but it typically requires the specification of the active fraction of excess electrons based on a certain choice of the electrode-electrolyte boundary location, which can be difficult in the presence of electrode-surface adsorbates or explicit solvent molecules. In this work, we present a methodological advancement of the HBM, both facilitating and extending its applicability. The advanced version requires neither energy corrections nor the specification of the active fraction of excess electrons, providing a versatile and readily available method for the simulation of charged interfaces when adsorbates or explicit solvent molecules are present. Our computational DFT results for Pt(111), Au(111), and Li(100) metal electrodes in high-dielectric-constant solvents demonstrate an excellent agreement in the interfacial charging characteristics obtained from simulations with the advanced HBM in comparison with the (linearized) Poisson-Boltzmann model (PBM).
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Affiliation(s)
- Arthur Hagopian
- ICGM, Univ Montpellier, CNRS, ENSCM, 34293 Montpellier, France.,Réseau sur le Stockage Electrochimique de l'Energie (RS2E), FR CNRS 3459, Hub de l'Energie, 80039 Amiens, France
| | - Marie-Liesse Doublet
- ICGM, Univ Montpellier, CNRS, ENSCM, 34293 Montpellier, France.,Réseau sur le Stockage Electrochimique de l'Energie (RS2E), FR CNRS 3459, Hub de l'Energie, 80039 Amiens, France
| | - Jean-Sébastien Filhol
- ICGM, Univ Montpellier, CNRS, ENSCM, 34293 Montpellier, France.,Réseau sur le Stockage Electrochimique de l'Energie (RS2E), FR CNRS 3459, Hub de l'Energie, 80039 Amiens, France
| | - Tobias Binninger
- ICGM, Univ Montpellier, CNRS, ENSCM, 34293 Montpellier, France.,Réseau sur le Stockage Electrochimique de l'Energie (RS2E), FR CNRS 3459, Hub de l'Energie, 80039 Amiens, France
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Kovalenko A, Neburchilov V. Response to Comment on "Density Functional Theory and 3D-RISM-KH molecular theory of solvation studies of CO 2 reduction on Cu-, Cu 2O-, Fe-, and F e3O 4-based nanocatalysts". J Mol Model 2022; 28:33. [PMID: 35018503 DOI: 10.1007/s00894-021-05021-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 12/27/2021] [Indexed: 11/27/2022]
Abstract
In response to the Comment on "Density Functional Theory and 3D-RISM-KH molecular theory of solvation studies of CO2 reduction on Cu-, Cu2O-, Fe-, and Fe3O4-based nanocatalysts" (Gusarov J Mol Model 27:344-344, 1), the behavior of a CO* molecule on a Cu21 nanocatalyst slab without a solution considered in the Comment is considerably different from our case of this system in 1.0 Mol KH2PO4 ambient aqueous solution. Moreover, our calculations for CO* on Cu21 without a solution that we presented in our article are similar to those shown in the Comment. The Comment and its conclusions are controversial and should be treated with much caution.
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Affiliation(s)
- Andriy Kovalenko
- Nanotechnology Research Centre, National Research Council Canada, 11421 Saskatchewan Drive, Edmonton, Alberta, T6G 2M9, Canada.
- Department of Biological Sciences, University of Alberta, CW 405, Biological Sciences Bldg., Edmonton, Alberta, T6G 2E9, Canada.
| | - Vladimir Neburchilov
- Energy, Mining & Environment, Institute for Fuel Cell Innovation, National Research Council Canada, Ottawa, Canada
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The Structure of the Electric Double Layer of the Protic Ionic Liquid [Dema][TfO] Analyzed by Atomic Force Spectroscopy. Int J Mol Sci 2021; 22:ijms222312653. [PMID: 34884462 PMCID: PMC8658030 DOI: 10.3390/ijms222312653] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 11/17/2021] [Accepted: 11/18/2021] [Indexed: 12/05/2022] Open
Abstract
Protic ionic liquids are promising electrolytes for fuel cell applications. They would allow for an increase in operation temperatures to more than 100 °C, facilitating water and heat management and, thus, increasing overall efficiency. As ionic liquids consist of bulky charged molecules, the structure of the electric double layer significantly differs from that of aqueous electrolytes. In order to elucidate the nanoscale structure of the electrolyte–electrode interface, we employ atomic force spectroscopy, in conjunction with theoretical modeling using molecular dynamics. Investigations of the low-acidic protic ionic liquid diethylmethylammonium triflate, in contact with a platinum (100) single crystal, reveal a layered structure consisting of alternating anion and cation layers at the interface, as already described for aprotic ionic liquids. The structured double layer depends on the applied electrode potential and extends several nanometers into the liquid, whereby the stiffness decreases with increasing distance from the interface. The presence of water distorts the layering, which, in turn, significantly changes the system’s electrochemical performance. Our results indicate that for low-acidic ionic liquids, a careful adjustment of the water content is needed in order to enhance the proton transport to and from the catalytic electrode.
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Comment on "Density functional theory and 3D-RISM-KH molecular theory of solvation studies of CO 2 reduction on Cu-, Cu 2O-, Fe-, and Fe 3O 4-based nanocatalysts". J Mol Model 2021; 27:344. [PMID: 34741216 DOI: 10.1007/s00894-021-04974-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Accepted: 11/02/2021] [Indexed: 10/19/2022]
Abstract
Recently, A. Kovalenko et al. reported the computational study of molecular structure and energetics of CO2 + H2 reduction reaction on Cu-, Cu2O-, Fe-, and Fe3O4-based nanocatalysts in the J. Mol. Model., 26, 267 (2020). The authors claim that they developed and tested the multiscale modeling description of this process by combining the periodical boundary condition density functional theory (PBC DFT) and molecular theory of solvation. However, due to inappropriate selection of intermediate strictures, in particular, the unfavorite structure of CO* adsorbed on Cu-, Cu2O-, Fe-, and Fe3O4-nanoparticles, and some inconsistency in preparation of initial structures by DFT approach, there are serious concerns about the correctness and quality of the presented results. In addition, by this comment, I would like to help other researchers working on the development of new catalysts for electrochemical reduction of CO2 to avoid further misunderstandings following this study.
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