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.