Computing free energy landscapes: Application to Ni-based electrocatalysts with pendant amines for H2 production and oxidation

Research output: Contribution to journalArticle

49 Citations (Scopus)

Abstract

A general strategy is reported for the computational exploration of catalytic pathways of molecular catalysts. Our results are based on a set of linear free energy relationships derived from extensive electronic structure calculations that permit predicting the thermodynamics of intermediates, with accuracy comparable to experimental data. The approach is exemplified with the catalytic oxidation and production of H2 by [Ni(diphosphine) 2]2+ electrocatalysts with pendant amines incorporated in the second coordination sphere of the metal center. The analysis focuses upon prediction of thermodynamic properties including reduction potentials, hydride donor abilities, and pKa values of both the protonated Ni center and the pendant amine. It is shown that all of these chemical properties can be estimated from the knowledge of only the two redox potentials for the Ni(II)/Ni(I) and Ni(I)/Ni(0) couples of the nonprotonated complex, and the pKa of the parent primary aminium ion. These three quantities are easily accessible either experimentally or theoretically. The proposed correlations reveal intimate details about the nature of the catalytic mechanism and its dependence on chemical structure and thermodynamic conditions such as applied external voltage and species concentration. This computational methodology is applied to the exploration of possible catalytic pathways, identifying low and high-energy intermediates and, consequently, possibly avoiding bottlenecks associated with undesirable intermediates in the catalytic reactions. We discuss how to optimize some of the critical reaction steps to favor catalytically more efficient intermediates. The results of this study highlight the substantial interplay between the various parameters characterizing the catalytic activity, and form the basis needed to optimize the performance of this class of catalysts.

Original languageEnglish
Pages (from-to)229-242
Number of pages14
JournalACS Catalysis
Volume4
Issue number1
DOIs
Publication statusPublished - Jan 3 2014

Fingerprint

Electrocatalysts
Free energy
Amines
Thermodynamics
Oxidation
Catalysts
Catalytic oxidation
Hydrides
Chemical properties
Electronic structure
Catalyst activity
Thermodynamic properties
Metals
Ions
Electric potential
Oxidation-Reduction

Keywords

  • catalyst optimization
  • computational chemistry
  • hydrogen oxidation and production
  • molecular electrocatalysis
  • Ni complexes
  • thermodynamics

ASJC Scopus subject areas

  • Catalysis

Cite this

@article{0a885fe31eff4994b858a45a0a881d03,
title = "Computing free energy landscapes: Application to Ni-based electrocatalysts with pendant amines for H2 production and oxidation",
abstract = "A general strategy is reported for the computational exploration of catalytic pathways of molecular catalysts. Our results are based on a set of linear free energy relationships derived from extensive electronic structure calculations that permit predicting the thermodynamics of intermediates, with accuracy comparable to experimental data. The approach is exemplified with the catalytic oxidation and production of H2 by [Ni(diphosphine) 2]2+ electrocatalysts with pendant amines incorporated in the second coordination sphere of the metal center. The analysis focuses upon prediction of thermodynamic properties including reduction potentials, hydride donor abilities, and pKa values of both the protonated Ni center and the pendant amine. It is shown that all of these chemical properties can be estimated from the knowledge of only the two redox potentials for the Ni(II)/Ni(I) and Ni(I)/Ni(0) couples of the nonprotonated complex, and the pKa of the parent primary aminium ion. These three quantities are easily accessible either experimentally or theoretically. The proposed correlations reveal intimate details about the nature of the catalytic mechanism and its dependence on chemical structure and thermodynamic conditions such as applied external voltage and species concentration. This computational methodology is applied to the exploration of possible catalytic pathways, identifying low and high-energy intermediates and, consequently, possibly avoiding bottlenecks associated with undesirable intermediates in the catalytic reactions. We discuss how to optimize some of the critical reaction steps to favor catalytically more efficient intermediates. The results of this study highlight the substantial interplay between the various parameters characterizing the catalytic activity, and form the basis needed to optimize the performance of this class of catalysts.",
keywords = "catalyst optimization, computational chemistry, hydrogen oxidation and production, molecular electrocatalysis, Ni complexes, thermodynamics",
author = "Shentan Chen and Ho, {Ming Hsun} and Bullock, {R Morris} and DuBois, {Daniel L} and Michel Dupuis and Roger Rousseau and Simone Raugei",
year = "2014",
month = "1",
day = "3",
doi = "10.1021/cs401104w",
language = "English",
volume = "4",
pages = "229--242",
journal = "ACS Catalysis",
issn = "2155-5435",
publisher = "American Chemical Society",
number = "1",

}

TY - JOUR

T1 - Computing free energy landscapes

T2 - Application to Ni-based electrocatalysts with pendant amines for H2 production and oxidation

AU - Chen, Shentan

AU - Ho, Ming Hsun

AU - Bullock, R Morris

AU - DuBois, Daniel L

AU - Dupuis, Michel

AU - Rousseau, Roger

AU - Raugei, Simone

PY - 2014/1/3

Y1 - 2014/1/3

N2 - A general strategy is reported for the computational exploration of catalytic pathways of molecular catalysts. Our results are based on a set of linear free energy relationships derived from extensive electronic structure calculations that permit predicting the thermodynamics of intermediates, with accuracy comparable to experimental data. The approach is exemplified with the catalytic oxidation and production of H2 by [Ni(diphosphine) 2]2+ electrocatalysts with pendant amines incorporated in the second coordination sphere of the metal center. The analysis focuses upon prediction of thermodynamic properties including reduction potentials, hydride donor abilities, and pKa values of both the protonated Ni center and the pendant amine. It is shown that all of these chemical properties can be estimated from the knowledge of only the two redox potentials for the Ni(II)/Ni(I) and Ni(I)/Ni(0) couples of the nonprotonated complex, and the pKa of the parent primary aminium ion. These three quantities are easily accessible either experimentally or theoretically. The proposed correlations reveal intimate details about the nature of the catalytic mechanism and its dependence on chemical structure and thermodynamic conditions such as applied external voltage and species concentration. This computational methodology is applied to the exploration of possible catalytic pathways, identifying low and high-energy intermediates and, consequently, possibly avoiding bottlenecks associated with undesirable intermediates in the catalytic reactions. We discuss how to optimize some of the critical reaction steps to favor catalytically more efficient intermediates. The results of this study highlight the substantial interplay between the various parameters characterizing the catalytic activity, and form the basis needed to optimize the performance of this class of catalysts.

AB - A general strategy is reported for the computational exploration of catalytic pathways of molecular catalysts. Our results are based on a set of linear free energy relationships derived from extensive electronic structure calculations that permit predicting the thermodynamics of intermediates, with accuracy comparable to experimental data. The approach is exemplified with the catalytic oxidation and production of H2 by [Ni(diphosphine) 2]2+ electrocatalysts with pendant amines incorporated in the second coordination sphere of the metal center. The analysis focuses upon prediction of thermodynamic properties including reduction potentials, hydride donor abilities, and pKa values of both the protonated Ni center and the pendant amine. It is shown that all of these chemical properties can be estimated from the knowledge of only the two redox potentials for the Ni(II)/Ni(I) and Ni(I)/Ni(0) couples of the nonprotonated complex, and the pKa of the parent primary aminium ion. These three quantities are easily accessible either experimentally or theoretically. The proposed correlations reveal intimate details about the nature of the catalytic mechanism and its dependence on chemical structure and thermodynamic conditions such as applied external voltage and species concentration. This computational methodology is applied to the exploration of possible catalytic pathways, identifying low and high-energy intermediates and, consequently, possibly avoiding bottlenecks associated with undesirable intermediates in the catalytic reactions. We discuss how to optimize some of the critical reaction steps to favor catalytically more efficient intermediates. The results of this study highlight the substantial interplay between the various parameters characterizing the catalytic activity, and form the basis needed to optimize the performance of this class of catalysts.

KW - catalyst optimization

KW - computational chemistry

KW - hydrogen oxidation and production

KW - molecular electrocatalysis

KW - Ni complexes

KW - thermodynamics

UR - http://www.scopus.com/inward/record.url?scp=84891769480&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84891769480&partnerID=8YFLogxK

U2 - 10.1021/cs401104w

DO - 10.1021/cs401104w

M3 - Article

AN - SCOPUS:84891769480

VL - 4

SP - 229

EP - 242

JO - ACS Catalysis

JF - ACS Catalysis

SN - 2155-5435

IS - 1

ER -