Top-down fabrication of active interface between TiO2 and Pt nanoclusters. Part 1: Redispersion process and mechanism

Supported metal nanoclusters (NCs) are regarded as the next generation of catalyst that bridge the nanocatalyst and single-atom catalyst. However, feasible fabrication of thermally stable NCs has remained a daunting challenge. In this paper, the first part of an extended work, we report a simple route to fabricate Pt NCs in size of around 1 nm through redispersion of Pt nanoparticles (NPs) or commercial PtO2 by a calcination treatment. Combining control experiments and detailed DFT simulation, the whole redispersion process was described and evidenced to proceed via a gas-phase trapping way: Under promotion of oxygen atmosphere and high temperature, volatile oxidized Pt monomers were firstly generated and then trapped by surface defects, forming special sites that preferentially induce the growth of clusters on them. The growing clusters have both size- and temperature-dependent stability, resulting a most stable size distribution of around 1 nm when fabricated at 550 °C. This work provides a feasible top-down strategy to fabricate highly dispersed metal clusters.