Ultrafast, groove-confined synthesis of ultrafine Pt nanocubes for efficient electrocatalytic ammonia oxidation

Ultrafine Pt nanocrystals with defined crystal structures are desirable for use as a catalyst of various electrochemical reactions; however, their preparation remains challenging, especially for fine control over the crystal size and dominant facet. Here, we report a fast heating and cooling (FHC) method to produce ultrafine (∼2.0 nm) {100} facets-dominant Pt nanocubes (Pt NCs) loaded on single-walled carbon nanotubes (SWCNTs). Experimental and computational investigations demonstrate that the grooves of SWCNT bundles act as a template that guides the growth of Pt NCs along the tube axis direction, while a small amount of oxygen facilitates the {100} facet formation and FHC stabilizes the size and shape of NCs. The resulting monodispersed Pt NCs confined on SWCNT networks exhibited high mass activity, low onset potential, high current density, and exceptional durability in ammonia oxidation reaction. This work offers a novel approach to synthesizing ultrafine Pt nanocrystals with excellent electrocatalysis performance.