Size-Controlled Intermetallic PtZn Nanoparticles on N-Doped Carbon Support for Enhanced Electrocatalytic Oxygen Reduction

Recently, Pt-based intermetallic nanoparticles (iNPs) have been intensely studied to improve the electrocatalytic activity/stability and Pt atomic utilization, but how to control the size of Pt-based iNPs is still a great challenge to date. Here, uniform PtZn intermetallic nanoparticles with a well-defined size supported on a conductive N-doped carbon (NC) were facilely synthesized by direct pyrolysis of sandwich-like zeolithic imidazolate framework (ZIF)-8@GO composites modified with tetra(4-carboxyphenyl)porphine (TCPP) anchored Pt sites. Innovatively, TCPP was used as a bifunctional coordination agent to coordinate with both Pt ions and ZIF-8. The size of intermetallic PtZn nanoparticles could be well controlled from ca. 2 to 5 and 7 nm by increasing calcination temperature. Compared to the benchmark Pt/C (E-1/2 of 0.875 V), the 5 nm PtZn/NC composites (E-1/2 of 0.911 V) exhibited a significantly improved electrocatalytic performance for oxygen reduction reaction. The size uniformity control strategy presented in this work opens up a new way to boost the activity and stability of Pt-based catalysts in fuel cells.