2D MXenes are an emerging class of metal carbides/nitrides. These materials are promising supports for metal nanoparticle catalysts because of their compositional tuneability. Electronic interactions between metal nanoparticles and MXene supports can be tuned by changing the surface terminating atoms (p-block elements like O*, OH*, F*, C*, N*, NH*) through post-synthesis treatments. Probe reactions like CO2 hydrogenation have shown how altering the surface termination of MXenes influences the rates and selectivity of supported metal nanoparticles. It is equally important however, to determine the stability and morphology of metal nanoparticles on MXene supports. Such studies will bridge the materials gap between computational models and catalyst morphologies in operando. Herein, we present a first principles framework that predicts the adhesion energies of epitaxial metal films (strain within +/- 5%) on MXenes. Our approach is valid across late transition metal films having arbitrary thickness and supported on MXenes terminated by different p-block elements. MXenes terminated by more than one element (e.g. C* and F*) are also considered. This framework uses a feature set composed of properties reflecting charge transfer at the metal-support interface. These features include: strain, electronegativity of surface terminations, work function of MXenes, d-band centre of the metal atoms, and interaction energies between surface terminations and metal atoms. All inputs are either extracted from databases or predicted using separate machine learning models, thus yielding on-the-fly predictions for new materials. This framework predicts adhesion energies with errors of 0.03 eV/Å2. Model-predicted adhesion energies are then used to estimate adsorption energies of metal adatoms on supports, through linear correlations. Taken together, adhesion energies and adsorption energies of adatoms, serve as descriptors to identify sintering resistant metal/MXene combinations. The estimated adhesion energies are combined with surface energies extracted from databases, to yield on-the-fly Winterbottom constructions. These Winterbottom constructions represent equilibrium morphologies of supported metal nanoparticles under reaction conditions. Our analysis reveals that tuning surface terminations of MXene supports can optimize both resistance to sintering and the density of interfacial active sites, thus yielding supported metal catalysts having high stability and reactivity.

On the stability and morphology of metal nanoparticles supported on two-dimensional MXenes: Insights from first principles

Where thousands of chemistry professionals meet to share ideas and advance scientific and technical knowledge. Spring 2023 abstracts, posters, and presentations will launch at the end of March.

ACS Spring 2023

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.