Electrochemical behaviors of iron-based layered double hydroxide thin-films

The ordered ultrathin films based on the fabrication of Mg/Fe-LDHs ([Mg₆Fe₂(OH)₁₆CO₃·(H₂O)_4.5]_0.375) nanosheets and hexacyanoferrate(III) anions via the self-assembly procedure were prepared. The electrodes modified by the films demonstrated a couple of well-defined reversible redox peaks attributed to [Fe(CN)₆]^3?/4? and Fe^2+/3+ couples. The effects of cycle number, scan rate and Mg/Fe molar ratio on the CV performance of the thin-film electrodes were observed in K₃[Fe(CN)₆] electrolyte. The [Fe(CN)₆]^3? pillared Mg/Fe-LDHs with Mg/Fe molar ratio of 3 (LDH-(CN)-3) demonstrated an excellent electrochemical behavior with a potential window between ??0.2 and 1.0 V, high specific capacitance and sensitivity, indicating that the high crystallinity, large specific surface area and plentiful [Fe(CN)₆]^3? anions in interlayer spaces were necessary. Especially, the interlayer [Fe(CN)₆]^3? anions significantly affected the electrochemical behavior of the electrode, where the electrode reaction was controlled by the diffusion of [Fe(CN)₆]^3?/4? and Fe^2+/3+ couples. Under current density of 2.5 A g^?1, the optimized LDH-(CN)-3 electrode exhibited high specific capacitance of 250.81 F g^?1 with good cycling stability. This facile synthesis strategy and the good electrochemical properties indicated that the LDH-(CN)-3 was a potential economical alternative material for supercapacitor application.