Chemical Kinetics of Metal Single Atom and Nanocluster Formation on Surfaces: An Example of Pt on Hexagonal Boron Nitride

The production of atomically dispersed metal catalystsremainsa significant challenge in the field of heterogeneous catalysis dueto coexistence with continuously packed sites such as nanoclustersand nanoparticles. This work presents a comprehensive guidance onhow to increase the degree of atomization through a selection of appropriateexperimental conditions and supports. It is based on a rigorous macro-kinetictheory that captures relevant competing processes of nucleation andformation of single atoms stabilized by point defects. The effectsof metal-support interactions and deposition parameters onthe resulting single atom to nanocluster ratio as well as the roleof metal centers formed on point defects in the kinetics of nucleationhave been established, thus paving the way to guided synthesis ofsingle atom catalysts. The predictions are supported by experimentalresults on sputter deposition of Pt on exfoliated hexagonal boronnitride, as imaged by aberration-corrected scanning transmission electronmicroscopy.