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@article{Zhu:2024:10.1021/acs.jpcc.4c04412,
author = {Zhu, Z and Ewen, JP and Kritikos, EM and Giusti, A and Dini, D},
doi = {10.1021/acs.jpcc.4c04412},
journal = {The Journal of Physical Chemistry C: Energy Conversion and Storage, Optical and Electronic Devices, Interfaces, Nanomaterials, and Hard Matter},
title = {Effect of electric fields on the decomposition of phosphate esters},
url = {http://dx.doi.org/10.1021/acs.jpcc.4c04412},
year = {2024}
}
TY - JOUR
AB - Phosphate esters decompose on metal surfaces and form protective polyphosphate films. For many applications, such as in lubricants for electric vehicles and wind turbines, an understanding of the effect of electric fields on molecular decomposition is urgently required. Experimental investigations have yielded contradictory results, with some suggesting that electric fields improve tribological performance, while others have reported the opposite effect. Here, we use nonequilibrium molecular dynamics (NEMD) simulations to study the decomposition of tri-n-butyl phosphate (TNBP) molecules nanoconfined between ferrous surfaces (iron and iron oxide) under electrostatic fields. The reactive force field (ReaxFF) method is used to model the effects of chemical bonding and molecular dissociation. We show that the charge transfer with the polarization current equalization (QTPIE) method gives more realistic behavior compared to the standard charge equilibration (QEq) method under applied electrostatic fields. The rate of TNBP decomposition via carbon–oxygen bond dissociation is faster in the nanoconfined systems than that in the bulk due to the catalytic action of the surfaces. In all cases, the application of an electric field accelerates TNBP decomposition. When electric fields are applied to the confined systems, the phosphate anions are pulled toward the surface with high electric potential, while the alkyl cations are pulled to the surface with lower potential, leading to asymmetric film growth. Analysis of the temperature- and electric field strength-dependent dissociation rate constants using the Arrhenius equation suggests that, on reactive iron surfaces, the increased reactivity under an applied electric field is driven mostly by an increase in the pre-exponential factor, which is linked to the number of molecule–surface collisions. Conversely, the accelerated decomposition of TNBP on iron oxide surfaces can be attributed to a reduction in the activation
AU - Zhu,Z
AU - Ewen,JP
AU - Kritikos,EM
AU - Giusti,A
AU - Dini,D
DO - 10.1021/acs.jpcc.4c04412
PY - 2024///
SN - 1932-7447
TI - Effect of electric fields on the decomposition of phosphate esters
T2 - The Journal of Physical Chemistry C: Energy Conversion and Storage, Optical and Electronic Devices, Interfaces, Nanomaterials, and Hard Matter
UR - http://dx.doi.org/10.1021/acs.jpcc.4c04412
ER -