Seminar on Wed.

[Cond.Matt. & Stat.Mech.Section]

CONDENSED MATTER AND  STATISTICAL PHYSICS   SEMINAR
 

 
Wednesday, 15 Apri l-    4:00 p.m.

 

Luigi Stasi Seminar Room -   ICTP Leonardo Building   (first floor)

 

Stefano FABRIS    (CNR-IOM DEMOCRITOS & SISSA)

 

"Combining electronic-structure and enhanced-sampling molecular dynamics methods to   model fuel-cell electrodes in working conditions"

 
Abstract

Platinum-group metals supported and dispersed on highly reducible oxides are common active catalysts for the industrial synthesis of chemical products and for renewable-energy applications such as fuel cells or artificial photosynthesis. Due to the high price of Pt, the sustainable development of these technologies requires new materials that reduces the content of precious metal without affecting the device efficiency.

I will discuss the challenges opened by these systems to electronic-structure modelling and will present a case study in the context of fuel-cell electrodes. Ab-initio materials modelling is used to provide key insight into the properties of a novel class of non-conventional catalysts with ultra-low metal loading.

We combine DFT simulations with ab-initio molecular dynamics, atomistic thermodynamics, metadynamics, and umbrella sampling methods to reveal the new surface chemistry opened by these systems. The calculations are used to characterise the structure and the reactivity of the electrode active sites in a wide range of compositions and environments, ranging from model surfaces at T=0K in vacuum conditions to realistic wet electrodes at finite temperatures, i.e. chemical reactions at complex solid-liquid interfaces comprising nano-structured surfaces in contact with a solution.

The calculated results allow for rationalising the available experimental data and identify correlations among the reaction mechanisms, thermodynamic efficiency, and local structure of the active sites, thus shedding light on the origins of the amplified reactivity and stability of these novel electrodes.