Structural Evolution from Metal–Organic Frameworkto Hybrids of Nitrogen-Doped Porous Carbon and Carbon Nanotubes forEnhanced Oxygen Reduction Activity.

A series of hybrids of nitrogen-dopedgraphitic porous carbon andcarbon nanotubes (NGPC/NCNTs) are readily prepared in a stepwise mannerby using a typical metal–organic framework (MOF-5) and ureaas the carbon and nitrogen precursors, and nickel as the graphitizationcatalyst, respectively. These NGPC/NCNTs hybrids have demonstratedprominent catalytic activities toward oxygen reduction reaction (ORR)in alkaline medium. Compared to the benchmark Pt/C catalyst, the optimizedNGPC/NCNT-900 (annealed at 900 °C) exhibits superior catalyticactivity, durability and methanol tolerance, which makes it one ofthe best ORR electrocatalysts derived from MOFs. The promising propertiesin NGPC/NCNT-900 are mainly attributed to synergistic contributionsof its unique hybrid structure, rich nitrogen doping, high graphiticdegree, and large surface area. This attractive route for the preparationof NGPC/NCNTs holds promise for general use of a great number of availableand yet rapidly growing MOFs in constructing high-performance carbon-basedORR electrocatalysts. [ABSTRACT FROM AUTHOR]