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Polyaniline (PANi) decorated Mn3O4-coated graphene oxide (GO) nanocomposite was fabricated via a low-temperature chemical process. The nanocomposite was demonstrated as a high-performing electrode material for supercapacitor application. The polyaniline with metal oxide composite was synthesized in two different ways: (i) with stirring and (ii) without stirring. Both gave different morphologies as nanospheres and 1D nanostructures. This 1D nanostructure with Mn3O4 deposited on the surface of graphene oxide formed the nanocomposite was characterized for SEM, TEM, XRD, Raman spectroscopy, FT-IR, and UV-Vis. Finally, we studied electrochemistry for charge storage using ternary material Mn3O4-GO-PANi (1:0.5) synthesized without stirring as a best performing supercapacitor electrode. 1D nanostructures have received great interest for supercapacitor applications in enhancing the mobility of the electrolyte ions between the electrodes to electrolyte interface. The ternary hybrid material Mn3O4-GO-PANi without stirring (1:0.5) showed the specific capacitance value of 829 F/g at current density 0.3 A/g. Specific capacitance showed 94% over 1800 cycles.

We present here the synthesis of three different types of Cu2FeSnS4 (CFTS) nanoparticles with the help of solvothermal route. Different chain length of ethylene glycol (EG) (PEG-200, PEG-400 and PEG-600) were used as solvent in hydrothermal process which resulted in stannite phase CFTS nanoparticles which was confirmed by XRD analysis and other characterizations including Raman, SEM, TEM and XPS. Photoresponse of these as-prepared CFTS nanoparticles were studied and among them PEG-400 sample exhibited higher photoresponse and further electrochemical studies such as, cyclic voltammetry (CV), galvanostatic charge/discharge (GCD) and electrochemical impedance spectroscopy (EIS) were done. The as-prepared CFTS nanoparticles not only exhibit a significant enhancement in the electrochemical activity but also in the photo-enhanced specific capacitance under light irradiation. The CFTS nanoparticles were sulfurized at 500 °C to study the effect of sulfurization on photoresponse and photo-supercapacitive behaviour. Moreover, the sample synthesized with PEG-400 demonstrates an outstanding photoresponse among the three samples. The sulfurized CFTS exhibited less specific capacitance compared to the as-prepared sample probably due to the formation of some secondary phases. This study opens up for the direct utilization of this light harvesting CFTS nanoparticles for solar cell and exhibited high photon induced specific capacitance for supercapacitor application.

Glycine-assisted polyaniline-NiCo2O4 composite porous powder was synthesized by a simple chemical method. The FT-IR and UV-visible spectroscopy analysis confirmed the presence of the corresponding functional groups. Scanning electron microscopy revealed the porous morphology of NiCo2O4 and a brush-like morphology of PANi-NiCo2O4 composite which helps in enhancing the electrochemical performance of the composite. The X-ray diffraction pattern indicates the spinel crystal phase of NiCo2O4 in the synthesized sample. Cyclic voltammetry and impedance analysis were done to understand the electrochemical performance of the material. The specific capacitance calculated by galvanostatic charge-discharge method was found to be 687.5 F/g for PANi-NiCo2O4, whereas for NiCo2O4 and pure PANi, it was 458.5 F/g and 373.75 F/g respectively. Cyclic stability analysis showed 88% retention of specific capacitance over 1000 cycles for the as-synthesized PANi-NiCo2O4 sample.

Vanadium oxides (V3O7) have been used as electrode materials for supercapacitor applications because of its multiple oxidation states. V3O7 nanoparticles were coated on reduced graphene oxide (rGO) from a peroxovanadate-rGO composite by thermal microexplosive decomposition method. These V3O7 decorated rGO were made composite with the flexible multi redox conducting polymer (Polyaniline). The performance of the composite materials as electrode for supercapacitors was analyzed in a 3-electrode cell, obtaining a specific capacitance of about 579 F g−1 at 0.2 A g−1 specific current. Cycling stability is one of the main barriers noticed in V3O7, which limits the practical performance of supercapacitors. This is overcome by modifying V3O7 with rGO and polyaniline composites which produces good electrical contact resulting in higher capacitances and enhanced cycling stability when compared to pristine V3O7. A superior electrochemical performance and ultra-long cyclic stability of 94% over 2500 cycles was obtained through these developed electrodes.

A polyaniline (PANi)-carbon quantum dots (CQDs) nanocomposite material with CQDs made from a PEG (polyethylene glycol and NaOH) source was synthesized. This unique synthesis technique was developed to overcome the setbacks of the PEG method by using UG (urea and glycine). PANi was synthesized by chemical oxidation in the presence of CQDs, which were prepared according to the two above-mentioned methods. The sample was further characterized by morphological, optical, and electrochemical experiments. FE-SEM showed ridge-like morphology and UV-Vis studies revealed the presence of PANi and CQDs. HRTEM images gave details on the uniformly distributed polyaniline, which showed lengthy rod-like rough surfaces with interconnected tiny CQDs. The electrochemical results from CV and GCD studies indicated an enhancement of the specific capacitance for sample PCQ-2 (CQDs synthesized via the UG method as a source) compared to only PANi and PCQ-1 (CQDs prepared by the PEG method). The cyclic stability established was 84.5% retention from initial capacitance values over 3000 cycles. A two-electrode prototype device was also developed with the PCQ-2 sample and it achieved a reasonable capacitance of 161.3 mF/cm2 and demonstrated good retention stability over 5000 cycles. These results may be due to a variety of factors related to compositing CQDs (with urea and glycine as a source) with PANi.

A water-soluble and biocompatible polymer, i.e. biotinylated poly(vinyl alcohol)-grafted graphene oxide (GO), was used as a nanocarrier for targeted delivery of anticancer drug camptothecin (CPT). The extent of CPT release in the presence of glutathione (GSH) from GO–biotinPVA–CPT was monitored by the increase in the fluorescence intensity, at λmax = 450 nm. The cell-specific (HeLa) antiproliferative activity of GO–biotinPVA–CPT makes it suitable to be used for targeted delivery of chemotherapeutics to cancerous cells.

Herein, we have developed a simple and facile technique at 210 °C to obtain nano-structured organic compounds, instead of making carbon dots at a relatively higher temperature. Taking the advantage of stable dispersion of organic nanostructures in an aqueous medium, composite of polyaniline has been developed and subsequently utilized as an active electrode material for supercapacitor application. This composite material confirms noteworthy enhancement in specific capacitance (779 F/g) and also divulges the attractive capacitance retention using three-electrode systems. The suitability of the materials for the solid-state device was tested with a prototype two-electrode device. The symmetric device exhibits 130 F/g gravimetric capacitance and 650 mF/cm2 areal capacitance. The improved performance in the specific capacitance is observed due to the generation of more active charge storage sites in the interfacial interaction of organic nanostructures and polyaniline in the composite. The cyclic stability of the symmetric device reveals excellent retention of 96% in specific capacitance over 5000 cycles.

Polyaniline-based nanocomposites containing carbon nanotubes (CNT), reduced graphene oxide (rGO) and mixture of CNTs and rGO were synthesized. UV-visible spectroscopy and FT-IR spectroscopy confirmed the presence of polyaniline (PANi) and carbon nanomaterials. Scanning electron microscopy revealed that the neat PANi had a granular morphology, which can lead to increased electrical resistance to high interfacial resistance between domains of PANi. Cyclic voltammetry of PANi, PANi/CNT, PANi/rGO and PANi/CNT/rGO showed that in general, specific capacitance reduces with increasing scan rate within the range (10–100 mV s−1). Also the specific capacitance values at any given scan rate within the above range, for PANi, PANi/CNT, PANi/rGO and PANi/CNT/rGO were found to be in increasing order. The specific capacitance of the PANi/CNT/rGO nanocomposite as measured by galvanostatic charge-discharge measurements, was found to be 312.5 F g−1. The introduction of the carbon nanomaterials (CNTs, rGO) in PANi in general leads to improved specific capacitance, while the addition of CNTs and rGO together leads to synergistic improvement in the specific capacitance, owing to a combination of factors.