Hierarchically porous Co3O4/C nanowire arrays derived from a metal–organic framework for high performance supercapacitors and the oxygen evolution reaction. Issue 42 (7th October 2016) - Zhang, Chao
Abstract : Porous Co3 O4 /C nanocomposites derived from a Co-MOF exhibit an excellent electrochemical performance for high performance supercapacitors and the oxygen evolution reaction. Abstract : Transition metal oxides with hierarchically porous structures supported by conductive substrates have been considered as promising electrodes for electrochemical energy storage and catalysis. Herein we configure porous Co3 O4 /C nanowire arrays (NAs) by thermally annealing a Co-based metal–organic framework (Co-MOF) in Ar and air, respectively. The hybrid Co3 O4 /C NAs demonstrate a high specific capacitance of 1.32 F cm −2 at a current density of 1 mA cm −2, which is much superior to that of bare Co3 O4 NAs. A highly stable symmetric supercapacitor based on Co3 O4 /C exhibits an excellent durability with only 21.7% capacitance decay after 5000 cycles. Besides electrochemical energy storage, the Co3 O4 /C hybrids demonstrate an outstanding electrochemical catalysis ability for the oxygen evolution reaction, identified by the high current density of 30 mA cm −2 at low overpotential ( η 30 = 318 mV) and a small Tafel slope (81 mV dec −1 ). The electrical conductivity of the interconnected C infrastructures and ion diffusion within the hierarchical pores are intrinsic causes to promote the pseudo-capacitive performance and enhance catalytic activity. The synthesis strategy reported here opens an avenue to design high performance electrodes for energy storage and electrochemical catalysis.