Stability of Sub—2 nm Pt Nanoparticles on Different Support Surfaces

Abstract

Electrochemical stability of Pt nanoparticles in acidic environments is a pressing issue in the field of catalysis. Pt nanoparticles immobilized on a support tend to undergo the phenomena of dissolution and coarsening leading to loss in effective surface area which undermines the long-term applicability of these supported nanoparticles. Sub-2 nm Pt nanoparticles with controllable size distribution and surface number densities were deposited using tilted target sputtering (TTS). Electron beam-induced coarsening and potentiodynamic cycling in acidic solutions was utilized to study the size-dependent and support-dependent stability of these Pt nanoparticles. Direct evidence of a correlation between Pt nanoparticle coarsening on supporting surfaces and their different surface energies was observed under prolonged E-beam exposure through HRTEM imaging. Utilizing potentiodynamic cycling, it was also observed that crystalline particles above a mean size of 1.5 nm diameter show exceptional stability regardless of supporting surface, meanwhile, sub-nm Pt nanoparticles on few layer graphene (FLG) support show better stability properties compared to those deposited on fluorine-doped tin oxide (FTO) support.