Confined Flash Pt₁/WC inside Carbon Nanotubes for Efficient and Durable Electrocatalysis

Exploiting cost-effective hydrogen evolution reaction (HER) catalysts is crucial for sustainable hydrogen production. However, currently reported nanocatalysts usually cannot simultaneously sustain high catalytic activity and long-term durability. Here, we report the efficient synthesis and activity tailoring of a chainmail catalyst, isolated platinum atom anchored tungsten carbide nanocrystals encapsulated inside carbon nanotubes (Pt₁/WC@CNTs), by confined flash Joule heating technique. The instantaneous carbothermal reduction reaction enables the millisecond formation of Pt₁/WC nanostructures from CNT-encapsulated polyoxometalates, where nanotubes serve as both heating conductors and robust chainmails. The Pt₁/WC@CNTs exhibit prominent catalytic performance toward acid HER with a low overpotential of 45.2 mV at 10 mA cm^-2 and long-term durability over 500 h of continuous running. Mechanism studies reveal the strong metal-support interaction on Pt₁/WC optimizes the charge redistribution at the Pt₁-W₂C interface and the hydrogen adsorption/desorption behavior. This study offers a potential avenue for ultrafast and activity-controllable synthesis of highly stable single-atom catalysts.