Design and study on graphene and MWCNT modified perovskite based heterostructured nanocomposites for hybrid supercapacitor

Abstract

Nanocomposite based Supercapacitors gained greater interest, because of its significant development of capacitance both through pseudocapacitance and electrical double layer capacitor (EDLC). In real time applications, the electrical double layer capacitance for a normal material yields a capacitance value of 10-40 mF/cm2 , whereas the supercapacitor can produce 10-100 times higher than this value. The standard Ruthenium oxide is commercially used as a supercapacitor. It was also reported that the better performance was achieved using perovskite structure of Ruthenium oxide like SrRuO3. Among the perovskite ferroelectric materials, bismuth ferrite (BiFeO3) stands as a least band gap material and it is also multiferroic. BiFeO3 is magnetic semiconductor which possesses a low surface area in the order of 8.3 m2g -1 in nano regime and 1.2 m2g -1 in bulk form. It also possess high recombination rate of exciton pairs and this is more favourable for the electron transport ability. The specific capacitance value of polycrystalline BiFeO3 films was reported as 81 F/g at a scan rate of 20 mV/s. It has been proved earlier that the formation of nano architecture of TiO2 on BiFeO3 found to have enhanced the specific capacitance value for about 440 F/g, as nanostructured BiFeO3 provided larger surface area for the fast charge transfer. Attempt of loading carbon nanotube with BiFeO3 had also enhanced the surface area of the resultant nanocomposites. Similarly, Tungsten oxide (WO3) is also a semiconducting material with N- type conduction. It exhibits pseudocapacitance due to its reversible valence states between W6+ and W5+. The primary advantage of WO3 is its higher intrinsic density (gt7gcm-3) and termed as alternative electrode material. Apart from carbonaceous materials and metal oxides, chalogenides compounds like Molybdenum disulfide (MoS2) is a also a unique material iv owing to its Graphene like interlayer covalent bonds separated by the weak van der Waals forces. This property has been rightly utilized for the creation