Sub-5 nm palladium nanoparticles in situ embedded in N-doped carbon nanoframes: facile synthesis, excellent sinter resistance and electrocatalytic properties

Carbon-supported palladium (Pd/C) is well known for its excellent electrocatalytic performance in fuel cells. However, effective synthesis of small Pd nanoparticles uniformly distributed on carbon supports with high sinter resistance remains a considerable challenge. Here, we report an efficient 1-naphthylamine (C10H7-NH2)-driven pyrolysis strategy for the facile preparation of N-doped carbon nanoframes with 4.6 nm Pd nanoparticles uniformly embedded in their surface (Pd@N-C NFs). The synthetic strategy greatly depends on the formation of a planar Pd-II-(C10H7-NH2) coordination complex, which provides a confined environment for the growth of sub-5 nm Pd nanoparticles and prevents the aggregation of the particles at elevated temperatures. Compared with traditional Pd/C, Pd@N-C NFs exhibit good sinter resistance when subjected to heat treatment at different elevated temperatures. Benefiting from the unique composition/structure-dependent properties, the newly developed Pd@N-C NFs present good excellent activity and stability for the formic acid oxidation and oxygen reduction reaction. We believe that this strategy can be extended as a general method for fabricating other metal-embedded carbon materials.