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A semi-flexible binder-free graphitic carbon nitride (g-C3N4) intercalated polypyrrole (PPy) nanocomposite thin film was prepared via hybrid electrospray technique. A homogeneous thin film was achieved by the controlled spray process. A deposited thin film illustrated the amorphous nature of composite with high surface purity and good chemical composition. The surface analysis confirmed the smoother surface with well-defined distinct phases of g-C3N4 and PPy matrix in the composite thin film. The electrochemical studies exhibited that a maximum areal capacity of the thin film was achieved to be 289.6 mF/cm2 at a current density of 0.4 mA/cm2, which is higher than that of pristine PPy (194.8 mF/cm2). The heterostructure electrode illustrated that the life cycles of 99% could be up to 10,000 cycles with low resistance due to the synergetic effect of g-C3N4 and PPy matrix with strong material adhesion (hybrid spray process) on the surface. A binder-free heterostructure thin film will play a significant role in the energy storage application.

We developed a facile hydrothermal route to synthesize hexagonal shaped CuS/reduced graphene oxide (rGO) composite for high performance supercapacitors. The as-obtained products were characterized by powder X-ray diffraction, Raman spectra, Transmission electron microscope, Energy dispersive spectra, X-ray photoelectron spectra, and Brunauer Emmett Teller (BET) analysis. XRD and TEM results suggest that CuS crystalline with hexagonal shaped particles are uniformly distributed onto the surface of rGO or wrapped in the rGO. The Lattice parameter of bare CuS was found to be a = b = c = 3.631 A and volume = 47.83 A3, further it was decreased to a = b = c = 3.591 A and volume = 46.26 A3 for CuS/rGO composite. The XPS result confirms that presence of C and valance state of Cu2+ in the CuS/rGO composite. The BET analysis confirms that CuS/rGO composite shows high specific area (122 m2g−1) and lower pore size 8–10 nm compared with bare CuS (surface area = 71 m2g−1 and pore size = 12–15 nm). Remarkably, the electrochemical performance of the CuS/rGO composite electrode exhibits a maximum capacity of 1604 Fg−1 at a specific current of 2 Ag−1 and results in good long term cyclic stability 97% capacitance retention after 5000 cycles. Furthermore, the fabricated CuS/rGO//AC based asymmetric supercapacitor showed outstanding cyclability (capacitance retention of 99.5% after 5000 cycles at 2 Ag−1), and high-energy density (21 Wh kg−1 at a power density of 315 W kg−1).

In the present work, a well-defined dumbbell shaped ZnO was synthesized by hydrothermal method and ZnO dumbbell/reduced graphene oxide (ZnO/rGO) nanocomposites were prepared by a simple solution mixing method with the different rGO loading amount. The formation of nanocomposites, crystal structure, shape, size and optical properties of the ZnO/rGO nanocomposites were investigated using various analytical techniques. The photocatalytic degradation efficiency of synthesized materials was evaluated by the degradation of aqueous Methyl Orange (MO) and Methylene Blue (MB) under UV–Visible light irradiation. The results revealed that 3 wt% rGO loaded ZnO dumbbell (ZnO-3% rGO) exhibited the higher photocatalytic degradation efficiency than pure ZnO dumbbell and rGO. The enhancement in the photocatalytic dye degradation efficiency of ZnO-3% rGO is attributed to the efficient dye adsorption nature, a red shift in light absorption and inhibition of photo-excited electron-hole pair recombination rate. The photocatalytic dye degradation efficiency also evaluated for various catalyst dosage, dye concentration and pH of the solution. Moreover, it was demonstrated the stability of catalyst over a repeated cycle of dye treatment.

Carbonate intercalated layered Zn, ZnNi and ZnCu hydroxides were synthesized by a facile hydrothermal method for the visible light driven photocatalytic methylene blue dye degradation. The crystalline phase, surface states, optical and morphological properties were studied by using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (DRS), Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) measurements. The XRD measurement demonstrated that all the synthesized materials were in a regular layered structure. Optical spectra of the samples were revealed that layered ZnNi hydroxide showed the visible light absorption property. The photocatalytic activities of the prepared layered materials examined by the degradation of methyl blue (MB) dye solution under visible light illumination. Among the prepared layered hydroxide, ZnNi hydroxide exhibited the 90% removal rate for MB under visible light illumination. The enhanced photocatalytic activity of ZnNi hydroxide is due to combined visible light absorption nature and hierarchical flower-like structure with a large number of active sites. Moreover, the ZnNi hydroxide has very good recyclability until remain active after the complete fourth degradation cycle.

The optimisation of DC plasma process towards maximising the fabric's hydrophilicity using Design-Expert 7.0.0 software has been reported in this paper. Out of various designs available, the Box-Behnken design was adopted for this purpose. The process parameters considered for optimisation were pressure of the gas (commercial grade air) used to produce plasma, DC current and the time for which the fabric was exposed to the plasma. These were keyed in as the three input parameters and the corresponding measure of hydrophilicity was fed as the response. Analysis of Variance (ANOVA) of the model and an associated discussion on the basis of Langmuir probe analysis, Physical analysis and ATR-FTIR analysis has been reported. The response predicted by the model was in good agreement with that obtained through experiment.

Transition Metal oxide decorated graphene nanosheets have accumulated a lot of consideration due to their potential applications in electrochemical energy storage devices especially in supercapacitors (SCs). Nanostructured mixed multi-metal oxides have been employed as promising electrodes for creating more active site for electron transfer. All-solid-state asymmetric supercapacitors (ASC) have significant theoretical capacitance, good rate capability, and excellent cycling stability suitable for energy storage device fabrication with optimum energy and power density. Here, we demonstrate a Solvothermal route to synthesis ternary α-Fe2O3/MnO2/rGO composites.. The hybrid ternary composites in 3-electrode configuration showed maximum capacitance of 447 F g−1 at optimum current density at1A g−1 and 96 % of capacitance retention after 10,000 GCD cycles at 10 A g−1in an alkaline medium. The fabricated ASC device with ternary composites (positive) and negative electrodes (rGO) separated by PVA/KOH gel-electrolyte separator exhibits maximum cell voltage of 1.4 V with high specific capacitance of 97 F g−1 at 1 A g−1. Additionally, the assembled device delivered a high energy density of 13.2 W h kg−1and a high power density of 6124 W kg−1 with an excellent capacitance retention of 92% and columbic efficiency of 96 % preserved over 5000 cycles at 10 A g−1with good reversibility. Besides, the Solvothermal strategy supports for the fabrication of metal oxide could be applicable for other metal oxide electrode materials preparation.

In the present work, spindle-shaped ZnO and reduced graphene oxide sheets were successfully synthesized by a hydrothermal method and then ZnO/r-GO composite was prepared by a direct solution mixing method. Various characterization results confirmed the interior and surface decoration of spindle-shaped ZnO on the reduced graphene oxide sheets. The phase formation, crystalline structure, morphology, surface states and optical properties were characterized using Powder X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier Transform Infrared Spectroscopy (FTIR) and UV–Vis spectroscopy. The X-ray diffraction analysis showed the formation of the hexagonal wurtzite crystalline structure of ZnO with high crystalline quality. The band gap of the ZnO/r-GO composite was found to be low (3.03eV) compared to the band gap of spindle shaped ZnO (3.13 eV), as calculated from optical studies. The spindle-like morphology of the single crystalline ZnO was clearly shown in the electron microscopic images. The chemical bonding and surface states of the samples were studied using XPS measurement. Moreover, a possible growth mechanism for the ZnO spindle was proposed. The catalytic activity of the as-synthesized samples was evaluated for the photodegradation of methylene blue under visible light irradiation. Among the synthesized samples, the ZnO/r-GO composite showed higher degradation efficiency of 93% and successfully reused for four consecutive run without any activity loss.

The polyindole/Graphitic carbon nitride (PIn/g-C3N4) composites synthesized by the reflux method. The characterization results showed that the composites possess balanced porosity, good charge diffusion, high energy and power densities. PIn/g-C3N4 composite showed the specific capacity (QS) of 440.8 C/g at 6 A/g in 1 mol/L aqueous H2SO4 electrolyte. The asymmetric device of PIn/g-C3N4//rGO showed QS of 73.84 C/g at 3 A/g. PIn/g-C3N4//rGO device offered a moderate cyclic retention of 72% at 18 A/g after 5,000 cycles with an energy density of 23.2 Wh/Kg and power density of 2307 W/Kg at 3 A/g. The results demonstrated that PIn/g-C3N4 composite has a potential application in field of energy storage devices.

In the present work, we have performed Raman spectral analysis, scanning electron microscopic analysis and electrochemical measurements of dynamic shock wave loaded cobalt ferrite nano-particles (CoFe2O4 NPs) for different number of shock pulses as that of 0, 50,100 and 150 such that the respective observations have been investigated and the results are reported. Interestingly, among the four samples, 50 shocks loaded sample has homogenous particle size distribution and a high value of specific capacitance due to the occurrence of the shock wave-induced dynamic re-crystallization. Based on the observed electrochemical properties, shock wave loaded CoFe2O4 NPs are strongly suggested for energy storage applications.

Here in, ZnO sphere/r-GO composites was synthesized by a simple hydrothermal method. The morphological characterizations (FE-SEM and TEM) indicated the ZnO sphere covered by r-GO nanosheets. The formation of the prepared ZnO sphere/r-GO composites was investigated by XRD and FT-IR analytical techniques, respectively. The composite electrode material exhibited high specific capacitance of 293.5 F/g at the current density 1 A g−1 and also outstanding cyclic stability of 96% retained after 10,000 charge discharge (GCD) cycles at of 6 A g−1. The catalytic activity of ZnO sphere and ZnO sphere/r-GO composites shows the degradation percentage if 76.2 and 94.6%, respectively. ZnO sphere/r-GO composite shows around 24% of catalytic enhancement due to the high specific surface area of r-GO, and also the composite shows high reliability and degradation efficiency is still retained at 96.9% upto 5 cycles. The composite material is a potential candidate for high performance energy storage and photocatalytic applications.

In this work, we developed lab waste tissue paper derived activated carbon and bare Mn2P2O7/NF and polypyrrole (PPy) incorporated Mn2P2O7/NF@PPy materials by using hydrothermal and chemical polymerization methods. The phase confirmation, structural morphology, surface area information and chemical compositions of prepared materials were characterized by using XRD, FESEM, BET and XPS analysis. In electrochemical results of activated carbon, Mn2P2O7/NF and Mn2P2O7/NF@PPy electrodes capacitive and diffusive behaviours are discussed in this article. In effect of polypyrrole incorporated Mn2P2O7/NF@PPy electrode exhibits high specific capacitance of 658 Fg−1 at a current density of 1 Ag−1 compared with a bare electrode. The fabricated asymmetric device by using activated carbon as anode and Mn2P2O7/NF@PPy material as cathode material and delivers a high energy density of 27.4 Whkg−1 compared with recent developed activated carbon and polypyrrole based devices.

Identification of electrode materials with excellent specific capacity and energy density are significant factors for the development of high-performance supercapattery device. Transition metal tungstate is an emerging electroactive material for supercapattery due to its excellent electrical conductivity and electrochemical properties. Herein, the mesoporous Ni(1−x)Co(x)WO4 nanomaterials were synthesized by a one-step hydrothermal method as an anode material for supercapattery. The apparent discrepancy in mesoporous structures was incited by varying the stoichiometric ratio of Ni/Co in the Ni(1−x)Co(x)WO4 system which lead to an increase in the electrochemical properties. Among the synthesized electrode materials, Ni0.5Co0.5WO4 electrode material delivers the high specific capacity of 634.55 Cg−1 at 1 Ag−1 with an excellent rate capability of 92% after 10,000 cycles at 10 Ag−1. The solid-state supercapattery constructed with Nio.5Co0.5WO4 and reduced graphene oxide as positive and negative electrodes, respectively. The device exhibits the maximum specific capacity of 134.70 Cg−1 at 0.5 Ag−1 and energy density of 56.12 Wh kg−1 at 500 W kg−1 with long-term cyclic stability (90% capacity retentively after 20,000 cycles). The high performance of this electrode material has been attributed to the synergetic effect between bimetallic (Ni and Co) redox centers, a mesoporous structure that provides a larger redox cites, rich electrical conductivity, shorter diffusion length, and faster electrochemical kinetic rates for electrochemical reactions.

The performances of the supercapacitor mainly rely on the design of electrode materials. The transition metal molybdates have been attracted as electrode material in supercapacitor due to their physicochemical properties. In the present work, a petal-like CoMoO4/r-GO composite was synthesized by a one-step hydrothermal method. The structural, morphological, and electrochemical properties were studied by using different analytical methods. As an electrode material, the CoMoO4/r-GO composite exhibited a high specific capacity of 425Cg-1at current density 1 Ag−1 with an excellent rate capability of 92.2% retained over 10,000 charge–discharge cycles at current density 10 Ag−1. Besides, the constructed asymmetric supercapacitor delivered a high energy density of 63.5 Wh kg−1 at a power density of 500 W kg−1.

Cotton fabric was processed with microwave (Ar) plasma to alter its hydrophilicity. The process parameters namely microwave power, process gas pressure and processing time were optimized using Box-Behnken method available in the Design Expert software. It was observed that certain combinations of process parameters improved existing hydrophilicity while the other combinations decreased it. ATR-FTIR spectral analysis was used to identify the strain induced in inter chain, intra chain, and inter sheet hydrogen bond and glycosidic covalent bond due to plasma treatment. X-ray diffraction (XRD) studies was used to analyze the effect of plasma on unit cell parameters and degree of crystallinity. Fabric surface etching was identified using FESEM analysis. Thus, it can be concluded that the increase/decrease in the hydrophilicity of the plasma treated fabric was due to these structural and physical changes.

The supercapacitors have been widely used in the field of electronics appliances and automobiles, but its utility is limited by low energy density and poor specific capacitance. Energy density and specific capacitance of the supercapacitor is invariably determined by the electrode materials. Herein, a novel 3D flower-like CuO/Co3O4/r-GO heterostructure was synthesized by the hydrothermal method and used as an anode material for high-performance supercapacitors in an alkaline electrolyte solution. The as-prepared 3D flower-like CuO/Co3O4/r-GO heterostructure with high surface area provides vast interfacial contact area between electrode and electrolyte solution which offers a fast surface reaction kinetics and improved conductivity, thereby the remarkable electrochemical performance is achieved. The prepared CuO/Co3O4/r-GO heterostructure material shows an ultra-high specific capacitance of 1458 Fg-1 at a current density of 0.5 Ag-1, exceptional rate capability, and stable long- term cycling performance (97% retention after 10000 successive charge-discharge cycles at 5 Ag-1). In as-assembled asymmetric supercapacitor, CuO/Co3O4/r-GO heterostructure is an anode material and r-GO is a cathode material. The assembled device shows a high specific capacitance of 198 Fg-1 at 2 Ag-1, an ultra-high power density of 10510.30 W kg−1, and a high energy density of 34.20 Wh kg−1. Meanwhile, the ASC device exhibits excellent rate capability (97%) after 10000 successive charge-discharge cycles at 5 Ag-1 in the PVA-KOH gel electrolyte.

In this paper, we report the synthesis of spinel CuCo2S4 nanoparticles (NPs) via a one-step hydrothermal method using two kinds of sulfur precursor's thioacetamide-TAA and thiourea-TU separately. The X-ray powder diffraction (XRD) analysis of both samples revealed a cubic phase of spinel CuCo2S4 crystal structure with Fd3m space group. The spherical (19–20 nm) and hexagonal (17–19 nm) shaped NPs were observed by transmission electron microscope (TEM) images. N2 adsorption-desorption results showed the high surface area of TAA-CuCo2S4 (91.03 m2 g-1) than TU-CuCo2S4 (59.82 m2 g-1). XPS spectra exhibited the coexistence of Cu2+ and Cu3+ valence states of spinel cubic CuCo2S4. Electrochemical measurements showed that the TAA based CuCo2S4/Ni foam electrode has high specific capacity (1885 C g−1/523 mA h g−1 at a current density of 2 A g-1 about 5.4 times higher than thiourea based electrodes), ultrahigh capacity retention of 98% after 6000 GCD cycles at high current density of 10 A g-1 and excellent energy density of 41.89 provided with a power density of 318.31 W kg−1. These results suggest that TAA assisted electrode material is suitable for improving electrochemical performance of supercapacitors.

In this present work, a novel heterostructure rGO - SrSnO3 nanocomposites with different weight percentage of reduced graphene oxide were successfully synthesised by hydrothermal method. The formation of crystalline structure, morphology, elemental composition and optical properties were characterized using Powder X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR), Energy dispersive X-ray analysis (EDX), and UV–vis diffuse reflectance spectroscopy (UV DRS) and photoluminescence (PL) spectroscopy techniques. The photocatalytic activity of pure and composite materials was assessed by degradation of aqueous methylene blue dye under UV light irradiation. The highest degradation efficiency of 97 % was obtained for 10 wt.% rGO - SrSnO3 composite. Enhancement in the photocatalytic activity is mainly due to the suppressed photoexcited charge carrier’s recombination rate. Moreover, the reusable and stability of the photocatalyst demonstrated after four consecutive runs of photocatalytic test.

In this work, djembe like ZnO microstructures was successfully synthesized by surfactant-assisted hydrothermal method and its composite with g-C3N4 was prepared by an ethanolic reflux method for the first time. Moreover, the structural, morphological, electrical, optical properties and its photocatalytic activities were studied. The result revealed that the formation heterojunction between djembe like ZnO and g-C3N4, decreased the optical band gap energy thereby the light absorption was shifted towards visible region. The photocatalytic performance was studied by dye degradation experiment under visible light irradiation. The degradation efficiency of the ZnO/g-C3N4 composite for MB and RhB degradation was found to be ~95% and ~97% respectively, which is higher than that of the same for pure ZnO and g-C3N4. The scavenger studies indicated the active role of hydroxyl radicals in the degradation process. Furthermore, djembe like ZnO/g-C3N4 composite was successfully reused for five cycles of photodegradation without any drastic change in its activity and crystalline properties.