Co@Pt Core@Shell nanoparticles encapsulated in porous carbon derived from zeolitic imidazolate framework 67 for oxygen electroreduction in alkaline media

Abstract

Abstract Nanocomposites based on Co@Pt core@shell nanoparticles encapsulated in nitrogen-doped porous carbons were prepared as a new type of high-performance electrocatalysts for oxygen reduction reaction (ORR). Controlled pyrolysis of zeolitic imidazolate framework 67 (ZIF-67) led to the formation of Co nanoparticles encapsulated in nitrogen-doped porous carbon (Co-NC), which underwent galvanic replacement reactions with K2PtCl4 forming Co@Pt core@shell nanoparticles. The surface microstructure and composition of the resulting Co@Pt-NC nanocomposite were examined by electron microscopic as well as X-ray photoelectron spectroscopic (XPS) measurements. With the Co@Pt particles encapsulated in nitrogen-doped porous carbon, the hybrids exhibited a high specific surface area and abundant catalytically active sites for ORR. Electrochemically, the specific activity and mass activity of the Co@Pt-NC composite at +0.85 V (0.145 mA cm−2 and 71.9 A g−1) were superior to those of commercial Pt/C (0.123 mA cm−2 and 38.4 A g−1). Furthermore, the Co@Pt-NC composite also exhibited remarkably higher durability and more robust tolerance against methanol crossover than commercial Pt/C.