In Situ Grown Iron Oxides on Carbon Nanofibers as Freestanding Anodes in Aqueous Supercapacitors

Abstract

Iron oxides are promising materials for application in supercapacitors owing to their high theoretical redox capacitance (2299 F g À1 ). Nevertheless, iron oxide nanostructures experience constant stress during cycling due to repeated expansion and contraction resulting in structural degradation. Such structural instability makes it challenging to develop freestanding and binderfree iron oxide-based electrodes with superior electrochemical performance. In this work, the authors report a facile way to fabricate iron-based carbon nanofibers using a simple and fast technique of electrospinning followed by an in situ electrochemical conversion. The final composite electrode consists of iron oxide embedded in carbon nanofibers which possesses a robust contact and support in addition to freestanding and binder-free nature. The electrodes exhibit a capacitance of 460 F g À1 at a galvanostatic discharge current density of 1 A g À1 and retains $82% of its capacitance after 5000 cycles in a wide negative potential window of 1.3 V. Extensive spectroscopic investigation is conducted to monitor phase transformation of the electrodes during oxidation and reduction to provide a understanding of the redox mechanism during electrochemical cycling.

Layered Vanadium Phosphates as Electrodes for Electrochemical Capacitors Part I: The Case of VOPO4·2H2O

“…Figure 2a shows the three different electrochemical windows of VOPO 4 •2H 2 O at a scan rate of 5 mVs -1 . In alkaline electrolytes, the electrochemical window is 1.0 V and in neutral electrolyte (3M LiNO 3 ) it can be extended up to 1.1 V. These ranges of potential agree with the reports from literature for aqueous electrolytes [4,24,33,34]. It is worthy to highlight the electrochemical response found from 5 up to 100 mVs -1 , that indicates a fast charge-discharge process for VOPO 4 •2H 2 O in these three electrolytes (see Figure SI2).…”

Antibiotic removal by agricultural waste biochars with different forms of iron oxide

“…For IP, deconvolution of O1s spectra produced two peaks located at 530.1 eV and 531.4 eV, corresponding to lattice-O 2À and -OH lat /C-O. 37,38 Aer TC and LEV adsorption, the ratio of -OH lat decreased from 34.38% to 27.52% and 26.62%, respectively. It indicated that the -OH lat was one of the functional groups in the adsorption process.…”

Partially Graphitized Iron-Carbon Hybrid Composite as Electrochemical Supercapacitor Material

“…44 The decrease in specific capacitance is due to the diffusion limitation and underutilization of the active material at higher specific currents. 45 The contribution of Ni foam substrate to the capacitances is found negligible. Importantly, for the application point of view, cyclic stability of an electrode material plays a significant role.…”