Ultrafast, Controllable Synthesis of Sub-Nano Metallic Clusters through Defect Engineering

Supported metallic nanoclusters (NCs, < 2 nm) are of great interests in various catalytic reactions with enhanced activities and selectivities, yet it is still challenging to efficiently and controllably synthesize ultrasmall NCs with a high-dispersal density. Here we report the in situ synthesis of surfactant-free, ultrasmall, and uniform NCs via a rapid thermal shock on defective substrates. This is achieved by using high-temperature synthesis with extremely fast kinetics while limiting the synthesis time down to milliseconds (e.g., ∼1800 K for 55 ms) to avoid aggregation. Through defect engineering and optimized loading, the particle size can be robustly tuned from >50 nm nanoparticles to