Controlling Nanoparticle Interconnectivity in Thin-Film Platinum Catalyst Layers

Abstract

The optimization of conventional hydrogen fuel cell catalyst layers suffers from a poor understanding of their composite nanostructure during both initial preparation and its evolution during use. We demonstrate how highly active, ultralow loading platinum (Pt) catalyst layers can be fabricated in a single, solution-processable step using electroless deposition. Growing Pt nanoparticles directly in the surface of a polyelectrolyte Nafion membrane yields a mechanically robust film with tunable optical reflectance and electronic conductivity. Small changes in the polymer hydration and Pt film thickness critically modulate nanoparticle interconnectivity near the percolation threshold. Conductive atomic force microscopy (AFM) and electron microscopy reveal how the film’s dynamic nanoscale morphology allows control over bulk electrochemical and optical properties. Well-defined composition and structure make these layers an experimentally accessible model system for studying thin-film electrocatalyst architectures.

Libra: An open-Source “methodology discovery” library for quantum and classical dynamics simulations

“…I emphasize that the latter view is only a specific case of a more general group of methods that entangle trajectories. [149][150][151][152][153] Thus, the "ensemble" class is devised as a platform for further development and study of the entangled trajectories methods.…”

Nonadiabatic semiclassical dynamics in the mixed quantum-classical initial value representation

“…6,7 Over the past two decades, several methods for the simulation of nonadiabatic processes have been developed including exact quantum time-propagation, [8][9][10] the symmetrical quasi-classical windowing method, 11 mixed quantum-classical Liouville methods, [12][13][14] and surface hopping. [15][16][17][18][19][20][21][22] In addition, approximate path-integral based methods such as ring polymer molecular dynamics [23][24][25][26][27] and centroid molecular dynamics 28 have also been extended to nonadiabatic systems.…”

“…(14) would also result in a symplectic transformation, but the flow map defined in Eq. (14) requires fewer mathematical operations.…”

Geometry of quantum evolution in a nonequilibrium environment

“…The environment with nonstationary statistics has been taken into extensive consideration, corresponding physically to impulsively environmental excited phonons out of thermal equilibrium states initially. It has drawn much attention in the study of dynamical decoherence, geometric phases and quantum speed limits of open quantum systems in nonequilibrium environments and quantum measurements detected by a voltage-biased quantum point contact (QPC) or a single-electron transistor [61][62][63][64][65][66][67][68][69][70]. Given that a quantum system may interact with a composite or structured environment, where the coupling between the sub-environments plays an essential role in the dynamical evolution of the quantum system, not only the system dynamics but the statistical properties of the environment display the non-Markovian feature, namely, the memory effect of the environmental noise [71][72][73].…”