Ru-Fe alloy mediated α-Fe2O3 particles on mesoporous carbon nanofibers as electrode materials with superior capacitive performance

Abstract

We herein first report Ru-Fe alloy mediated α-Fe2O3 particles on mesoporous carbon nanofibers (RuFe@Fe2O3/mCNF) as electrode materials. Such ternary composites are facilely fabricated by skillful construction of Ru, Fe-containing zinc-trimesic acid metal organic framework fibers before one-step pyrolysis. The resulting RuFe@Fe2O3 particles (20-33 nm) are evenly dispersed and firmly embedded into mesoporous carbon nanofibers formed simultaneously. In-depth characterization reveals that the RuFe@Fe2O3 particles are mainly Ru(+3) substituted α-Fe2O3, present on the periphery of Ru-Fe alloys. Particle size, as well as composite porosity and conductivity are readily tailored by controlling the feed ratio of RuCl3 to FeCl3. The elaborately fabricated RuFe@Fe2O3/mCNF-25% (25 at% Ru in total metals) delivers a large specific capacitance of 285 F g-1 at the scan rate of 1 mV s-1 and a high energy density up to 47.6 W h kg-1 at the current density of 0.25 A g-1. It also shows good rate capability and outstanding cycling stability up to 5000 times (only 4.7% loss). Such a electrode has great potential for practical applications in electrochemical capacitors.