Structural Evolution from Metal-Organic Framework to Hybrids of Nitrogen-Doped Porous Carbon and Carbon Nanotubes for Enhanced Oxygen Reduction Activity

A series of hybrids of nitrogen-doped graphitic porous carbon and carbon nanotubes (NGPC/NCNTs) are readily prepared in a stepwise manner by using a typical metal-organic framework (MOF-5) and urea as the carbon and nitrogen precursors, and nickel as the graphitization catalyst, respectively. These NGPC/NCNTs hybrids have demonstrated prominent catalytic activities toward oxygen reduction reaction (ORR) in alkaline medium. Compared to the benchmark Pt/C catalyst, the optimized NGPC/NCNT-900 (annealed at 900 degrees C) exhibits superior catalytic activity, durability and methanol tolerance, which makes it one of the best ORR electrocatalysts derived from MOFs. The promising properties in NGPC/NCNT-900 are mainly attributed to synergistic contributions of its unique hybrid structure, rich nitrogen doping, high graphitic degree, and large surface area. This attractive route for the preparation of NGPC/NCNTs holds promise for general use of a great number of available and yet rapidly growing MOFs in constructing high-performance carbon-based ORE. electrocatalysts.