Growth of Vertically Aligned Tunable Polyaniline on Graphene/ZrO₂ Nanocomposites for Supercapacitor Energy‐Storage Application

Abstract

1312www.MaterialsViews.com wileyonlinelibrary.com . IntroductionWith the rising progress of global economy and industry, the impending energy crisis has stimulated intense research on the low cost, environmentally friendly, and renewable energy resources. [ 1 ] Therefore, great efforts have been devoted to develop low cost electrode materials with high energy density, high power density, and excellent cycling stability. Supercapacitors, can be considered as the supreme candidate of the nextgeneration energy storage/conversion systems with the unique ability to store energy in a fraction of second and delivering the stored energy rapid enough than any other conventional energy storage devices. It also ensures high power density when coupled with batteries or fuel cells. [1][2][3][4] However, the supercapacitors suffer from low working potential that result in low energy density than conventional batteries. So, it's essential to improve their performances to encounter the higher requirements of future technologies by developing new materials with the interfaces at the nanoscale dimension. Lower specifi c energy of electrochemical double layer capacitors (EDLCs) with respect to the batteries and lower power densities of pseudocapacitors than EDLCs has motivated to develop the better performance characteristics hybrid supercapacitors. These hybrid supercapacitors use both Faradaic and non-Faradaic processes to store charge and thereby have achieved higher energy density and moderated power density accompanied with high cycling stability and thus have restricted the monopolism of pseudocapacitor.Intense research has established that combination of the micro structured carbonaceous materials with electroactive materials into a single system can take the benefi ts of both the double layer capacitance and pseudocapacitance arising from the synergistic interaction of the two. In this sense, graphene is the most interesting carbonaceous material with ultrahigh surface area (2600 m 2 g −1 ), excellent electric conductivity, two-dimensional sp 2 carbon arrangement with one-atom thickness. However, the strong electrostatic interaction amongst the graphene sheets leads to restacking of the sheets resulting in lower specifi c surface area and lower capacitance. [ 5 ] This drawbacks can be overcome by functionalization on the surface or incorporating nanocrystals in form of nanocomposites. The conducting polymers and transition metal oxides are two typical pseudocapacitive materials, which are capable of storing more charges than carbonaceous materials, but are limited by their poor stability and high resistance during cycling. The conducting polymer is frequently used into supercapacitor materials for obtaining the effi cient charge storage and delivery which strongly depends on the orientation of polymer chains into inorganic host. The polymer molecules are directed to grow along the large oriented tunnels of 3D hosts or interlayer space of the 2D hosts where the structurally organized frameworks are provided by the inorganic ...

High performance electrode material prepared through in-situ polymerization of aniline in the presence of zinc acetate and graphene nanoplatelets for supercapacitor application

“…The Cyclic Voltammetry measurements were done in 1 (M) KCl aqueous electrolyte solution at a potential window from À0.4 to +0.8 V and at different scan rates from 10 mV/s to 100 mV/s. The specific capacitances (C sp ) of PZG composite at different scan rates were calculated on the basis of the following equation [27,29]:…”

“…They have observed that specific capacitance value of the composite decreased from %242 F/g to %193 F/g for modification of graphene. Giri et al [29] have developed an electrically conducting (70.8 S cm À1 ) PANI/ graphene/zirconium oxide (ZrO) nanocomposite with high specific capacitance value of %1360 F/g at 1 mV/s.…”

Controlled synthesis of NiCo2O4 nanowires and nanosheets on reduced graphene oxide nanosheets for supercapacitors

“…However, there is limitation to use of pure graphene as electrodes for SCs, because graphene sheets can readily aggregation or restacking, leading to a greatly reduced surface area and diffusion rate [16]. Recently, one effective strategy to overcome the drawback is incorporate nanocrystals of transition metal oxides/ hydroxides in form of nanocomposites [17,18]. To date, reduced graphene oxide (rGO) nanosheets have been coupled with various transition metal oxides such as RuO 2 [8], MnO 2 [19], NiO [20], Co 3 O 4 [21], NiCo 2 O 4 [22], etc., to keep the graphene sheets separated.…”

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“…In addition, the remaining hole in ZrO 2 takes part in the redox reaction to generate OH, which is further used to remove cadmium ions. Owing to the high specific surface area and superior electron mobility of GO, an appropriate integration of GO and ZrO 2 would give rise to a hybrid nanocomposite to achieve high photodegradation activity [22]. In this case, the recombination of photo-generated electrons and holes is suppressed, and their lifetime is prolonged.…”

“…Researchers have also demonstrated that ZrO 2 has a strong affinity to negatively charge moieties [19], which motivated us to use graphene oxide (GO)-ZrO 2 nanocomposite as selective photocatalyst for heavy metals. Moreover, various papers have been published recently on the graphene-ZrO 2 nanocomposites applications, which include the deoxyribonucleic acid sensing detection [20], organophosphorus agents [21], supercapacitor energy-storage application [22], and photocatalytic degradation of antimonite (Sb(III)) and antimonate (Sb(V)) from aqueous solution [23].…”