Compositing of MIL-101(Fe) with reduced graphene oxide and polyaniline for capacitive energy storage

Metal−organic frameworks (MOFs) have attracted attention for various applications in electrochemistry due to their high porosity and potential high charge storage abilities. New MIL-101(Fe)-based nanocomposite materials were synthesized with reduced graphene oxide (rGO) and polyaniline (PANI). The prepared composites were characterized by various techniques. The electrochemical properties of the materials were investigated in 1 M Na2SO4 and 2 M KOH as electrolytes. To the best of our knowledge, the capacitive energy storage properties of rGO/MIL-101(Fe)/PANI as a supercapacitor electrode is reported for the first time. Among the prepared compounds, rGO/MIL-101(Fe) in alkaline electrolyte exhibited the highest specific capacitance of 250.63 F/g at 0.5 A/g which has very low charge transfer resistance of 0.141Ω. Compared to rGO/MIL-101(Fe), rGO/MIL-101(Fe)/PANI exhibited higher capacitance in neutral electrolyte, while showed lower capacitance in alkaline electrolyte. The capacitive properties of MIL-101(Fe) based composite electrodes were found to greatly depend on charge transfer processes, obtained by detailed analyses and EIS measurements. •The energy storage properties of MIL-101(Fe) based nanocomposites were investigated for the first time.•The rGO/MIL-101(Fe) exhibited very low charge transfer resistance of 0.141Ω.•The rGO/MIL-101(Fe)/PANI exhibited superior cycle performance without capacity retention after 3000 cycles.•The charge transfer resistance of electrodes designated the capacitive properties of nanocomposites.