Nonequilibrium pulsed heating freezes sintering of supported metal nanocatalysts

Supported metal nanoparticles always experience thermal-induced sintering that severely depresses their catalytic performance and durability. Recently, ultrafast heating technology has been widely adopted in synthesizing diverse metal nanoparticles or even single atoms on supporting materials, offering enhanced anti-sintering capabilities compared to conventional heating protocols. However, the mechanisms and kinetics underlying this anti-sintering behavior during ultrafast heating processes remain poorly understood. Here, using in situ scanning transmission electron microscopy and theoretical analysis, we microscopically reveal a metastable state for supported metal nanoparticles induced by ultrafast heating pulses, which significantly mitigates the thermal-induced sintering while effectively improves the crystallization degree of metal nanoparticles together with the metal/support interfaces. Our results show that Pt nanoparticles supported on graphene flakes are thermodynamically unstable yet kinetically stable across the ultrafast heating pulses; as a consequence, the Pt/graphene interface is gradually optimized in a lattice scale, leading to remarkable sintering resistance for Pt nanoparticles. These atomic-scale insights provide thorough fundamental understandings for ultrafast heating in stabilizing metal nanoparticles and may further guide the high-throughput production of robust supported metal nanocatalysts.