A multiscale theoretical methodology for the calculation of electrochemical observables from ab initio data: Application to the oxygen reduction reaction in a Pt(111)-based polymer electrolyte membrane fuel cell

Electrochemical mechanism of ion current rectification of polyelectrolyte gel diodes

“…Our theory may not be effective for the cases in which electrochemical reactions at the electrodes are limited by the transport of reactants (for example, for the cases that counterions are the reactants or products of the electrochemical reactions 10,11,[24][25][26][27] ). Second, polyelectrolyte gels that are used to prepare PGDs are stiff enough; polyelectrolyte gels that do not have enough stiffness may locally collapse to neutralize electric charges on the electrodes 20,21,36 .…”

“…The ionic groups of polyelectrolyte gels are essentially immobile (and thus are treated as uniform fixed charges), and, in contrast, their counterions freely diffuse in the entire volume of the system; our model thus extends the treatments of these ions that have been developed in soft matter physics [17][18][19][20][21][22][23] to electrochemical systems. Analogous models are used to treat electrolyzers [13][14][15]24,25 and fuel cells [26][27][28] that use polymer electrolyte membranes. We treat the cases in which counterions are not the reactants or products of electrochemical reactions.…”

“…In practice, exchange current densities J 0 may be sensitive to the electrostatics and chemistry of polyelectrolyte gels and the metals that are used for electrodes [24][25][26][27] . Because water molecules in the solvent of polyelectrolyte gels are relatively abundant, compared with products, we neglect backward reactions that produce water molecules; equations (7) and (8) are only effective for DV40 and DVo0, respectively.…”

Oxygen reduction on a Pt(111) catalyst in HT-PEM fuel cells by density functional theory

“…34,35 Then, the Pt(111) surface was cut from the optimized Pt primitive cell. 41 To develop a super cell as a geometric model system, four layers of Pt atoms were placed in this system; the lowest two layers were restrained on the bottom of this system, and a vacuum thickness of 2.0 nm was set up above the Pt atoms (Fig. 2).…”

“…40 In addition, a multi-scale theoretical methodology has been used to simulate the oxygen reduction reaction on Pt(111). 41 In this study, a molecular dynamics model based on the density functional theory and coupling the system energy, the exchange-correlation energy functional, the charge density distribution function, and the simplified Kohn-Sham equation is established to simulate the oxygen reduction reaction on a Pt(111) surface. A super-cell system was developed by using Materials Studio software, and then the structure of this system was optimized by relaxation.…”