Mixed phase FeTe: Fe2TeO5 nanopebbles through solution chemistry: Electrochemical supercapacitor application

Mixed phase of iron telluride based thin films consisting of nanopebbles has been grown successfully over conducting stainless steel (SS) substrate through successive ionic layer adsorption reaction (SILAR) process. Crystal structural and elemental states through XPS revealed clear indication of FeTe: Fe2TeO5 mixed phase growth and well supported through FTIR studies. Agglomeration of embedded quantum dots forming nanopebbles like surface architecture resulting in enhanced hydrophilic nature evident through contact angle and higher surface roughness by atomic force micrographs found beneficial as more electroactive surface area for electrolyte ions to interact. This helped to achieve a significant specific capacitance of 591 F/g (166 mF/cm2) @3 mV/s potential scan rate and, 107 F/g (30 mF/cm2) @0.4 mA/cm2 in NaCl electrolyte. Performed electrochemical impedance spectroscopy (EIS) studies explored clear insight of the solution and charge transfer resistances, and relaxation time constant. Iron telluride based thin film clearly demonstrates very high value of pseudo capacitive contribution than the electric double layer due to the intrinsic pseudocapacitive behavior of mixed phase.