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Accueil > Productions scientifiques > Séminaires à PHENIX > 2021 > Séminaire de Stephan Steinmann (Laboratoire de Chimie, ENS de Lyon) - 08/01/2021 à 11h

Séminaire de Stephan Steinmann (Laboratoire de Chimie, ENS de Lyon) - 08/01/2021 à 11h

par Pierre Illien - 4 janvier

Séminaire de Stephan Steinmann (Laboratoire de Chimie, ENS de Lyon)

Molecular Mechanics for Metal-Water Interactions : Force Field Development and Solvation Free Energies

le vendredi 8 janvier 2021 à 11h (en visio-conférence)

Résumé

Electrocatalysis is at the heart of energy conversion devices such as fuel cells and solar cells or electrolyzers powered by "excess" electricity. These applications have in common that they take place a highly complex interface between the (metal) electrode and a solution that contains a high-dielectric solvent with a high concentration of ions. Furthermore, the surface charge is tuned in order to impose the electrochemical potential. When modelling such systems from first principles in periodic systems, a neutralizing counter charge needs to be introduced, which physically represents the electrical double layer. An attractive solution is the Poisson-Boltzmann (PB) equation, which reduces the environment (solvent and electrolyte) to an easily computable mean-field which can be included in the DFT computations and thus be used for practical applications [1,2]. Nevertheless, the underlying continuum solvation model has major shortcomings, as chemical interaction between the solvent and the surface is not well reproduced. This can, however, be improved upon by moving to a molecular description of the solvent. Due to the high computational cost and slow diffusion at the solid/liquid interface, these atomistic simulations need to be carried out at the molecular mechanics level of theory. However, an accurate force field is a prerequisite for such investigations. Here, I will describe our recent efforts to reach a realistic description of the water-noble metal surface interaction via a classical force field [3,4] and the limitations of such an approach in the absence of many-body (polarization and charge-transfer) interactions [5,6]. Finally, the solvation energies obtained with our water/Pt(111) force field for benzene and phenol adsorption are compared to experimental estimates, showing a semi-quantitative agreement [7].

Figure 1. Left : Snapshot of a 1 ns molecular dynamics simulation of the Pt(111)/H2O interface performed with GAL17 [3]. Middle : Average contributions of frozen, polarization, and charge-transfer to the total interaction energy between water structures (oligomer or adlayers) and metal surfaces. The error bar gives the standard deviation among all the 28 considered systems. Red dots give the specific values for the Hup layers and horizontal dashes, those for the √(39) layers [6]. Right : Adsorption energy of phenol at the Pt(111) interface in the gas-phase, implicit solvent (PCM) and molecular mechanics (SolvHybrid) solvent as a function of the coverage [7].

References

[1] Steinmann and Sautet J. Phys. Chem. C 2016, 120, 5619.

[2] Abidi, Bonduelle-Skrzypczak and Steinmann ACS Appl. Mater. Interfaces, 2020, 12, 31401.

[3] Steinmann, Ferreira de Morais, Goetz, Fleurat-Lessard, Iannuzzi, Sautet and Michel J Chem Theory Comput. 2018, 14, 3238.

[4] Clabaut, Fleurat-Lessard, Michel and Steinmann J. Chem.Theory Comput. 2019, 16, 4565.

[5] Staub, Iannuzzi, Khaliullin and Steinmann J. Chem.Theory Comput. 2019, 15, 265.

[6] Clabaut, Staub, Galiana, Antionetti and Steinmann J. Chem. Phys. 2020, 153, 054703.

[7] Clabaut, Schweitzer, Goetz, Michel and Steinmann J. Chem.Theory Comput. 2020, 16, 6539.