Pt Nanoparticles Supported on N-Doped Porous Carbon Derived from Metal–Organic Frameworks for Oxygen Reduction

Abstract

Metal–organic framework (MOF)-derived materials have attracted increasing attention in the field of energy storage and conversion. Calcining MOFs to carbonized structures is a common route to obtain MOF-derived materials. However, the existing calcination conditions often cause the structural collapse and the specific surface area to be significantly reduced. In this work, we use argon–hydrogen mixed gas for calcination of MOFs to obtain a N-doped porous carbon material with excellent properties. Its BET specific surface area and pore volume up to 2476 m2 g–1 and 1.325 cm3 g–1, respectively, which are higher than those of the precursor ZIF-8 (1960 m2 g–1 and 0.687 cm3 g–1), perfectly inherited the rhombic dodecahedron morphology of the precursor. Hydrogen reduces the zinc in ZIF-8 at high temperature to evaporate, which avoids the carbothermal reduction reaction between the zinc component and the carbon framework of MOFs, protecting the framework of MOFs and leaving a lot of micropores, so that after the carbonization of MOFs it still has extremely high specific surface area and pore volume, even surpassing the MOFs precursors. We loaded Pt nanoparticles on the prepared porous carbon to catalyze the oxygen reduction reaction and showed an excellent half-wave potential of 0.883 V, which is 10 mV higher than that of the commercial Pt/C (Pt 20 wt %), while the Pt loading is only 8.66 wt %. The stability is also much better than Pt/C.