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Manipulation of materials at nanoscale provides many new and enhanced properties to be utilized for multifaceted applications, which was not possible before. In this study, we fabricated Bi2WO6/rGO composites using hydrothermal method. The obtained composites were then examined using different analytical techniques such as XRD, SEM, TEM, FTIR, XPS, BET, and AFM. Their catalytic properties were assayed by carrying out the degradation of organic dye Rhodamine B (RhB) and employed as a hole transport layer (HTL) in the perovskite solar cells. The fabricated nanocomposites were able to degrade 98% of dye solution within 4 h. The improved photocatalysis is attributed to a large surface area ~86.06 m2/g with pore size 7.812 nm and enhanced separation of electron-hole pair charges due to rGO sheets. The open-circuit voltage was increased up to 0.94 V when composite materials were used as HTL. The power conversion efficiency (PCE) of the device was enhanced to 11% because of the improvement in the interface quality between HTL and the perovskite layer. It is conceived that the fabricated nanomaterial may show excellent potential in smart solar cell applications.

Tungstate nanorods (WO3 -NRs) were synthesized by a facile hydrothermal method using sodium tungstate as a precursor while sodium sulfate and hydrochloric acid were used as stabilizing agents. Scanning electron microscopy (SEM) images showed outstanding growth of WO3-NRs with uniform surface morphology. The X-ray diffraction (XRD) analysis confirmed the purity and crystalline nature of the synthesized material. The material was further characterized by different tools such as TEM, EDX, FTIR, XPS, BET, and Raman spectroscopy. For the electrochemical response of WO3-NRs, cyclic voltammetry measurements were performed for the detection of vitamin C (ascorbic acid). The designed sensor shows a limit of detection of 0.56 µM and higher selectivity in the presence of its structural and functional analogs such as uric acid and lauric acid. Improved sensing properties of WO3-NRs are attributed to the synergistic effects involving the quantum effect, high surface area, fast electron transfer, and highly ordered 1-D nanostructure. Among them, the highly arranged 1-D growth of WO3 nanorods has a greater impact on the efficiency of the biosensor. These results provide a new insight for the synthesis of 1-D nanostructures of transition metal oxides for contributions in sensor devices, solar cells, and capacitor applications.

Nano-food packaging, the emergence of latest technology based on nanomaterials, created enormous trust to the synthesis of novel packaging incorporated by zinc oxide nanoparticles (ZnO-NPs) in polylactic acid (PLA) polymer. The morphology and structure of biogenically fabricated ZnO-NPs by aloe barbadensis leaves extract were analyzed by X-ray diffraction, scanning electron microscopy and Fourier transforms infrared spectroscopy. The fabricated ZnO-NPs were hexagonal in shape and 36.5 nm in size. The zinc oxide nanoparticles at concentration of 0.4% (w/w) and 4% (w/w) are incorporated in polylactic acid (PLA) by solution casting method. Loading of zinc oxide nanoparticle in PLA improved stability, film thickness and elongation. The Vitis vinifera fruit packed in the biofilm was observed for appearance, taste and freshness during ambient storage. ZnO-NPs/PLA packed fruit samples retained their original taste and freshness for 15 days in comparison with the reference samples packed in ZnO-NPs/ PLA (4%) at 400C. The biofilm did not affect the fruit Vitis vinifera quality attributes. The decay content, color change, browning index, gases and metal accumulation observations for Vitis vinifera fruit packed in ZnO-NPs/ PLA (4%) exhibited marvellous results. There were no significant differences between the materials tested (p > 0.05). Intercalation of ZnO-NPs was involved in the form of fillers in PLA by solvent casting method for shelf life augmentation of the selected delicate fruit, Vitis vinifera.

The exploration of electrode functional materials for supercapacitors may bring a revolution to energy storage devices to boost the portable industry. Herein, lanthanum sulfide nanorods and reduced graphene oxide (rGO)–templated lanthanum sulfide nanorods have been synthesized using the hydrothermal process. Structural, morphological, and compositional analyses were conducted using X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The specific surface area has been measured using the Brunauer–Emmett–Teller technique. Individual lanthanum sulfide and rGO-templated lanthanum sulfide showed the morphology of nanorods. Cyclic voltammetry tests predicted the pseudocapacitive nature of the lanthanum sulfides for supercapacitor applications. The rGO effectively improved the electrochemical characteristics of the lanthanum sulfide, which might be due to the facilitation of charge carriers through nanorods, as the rGO-templated lanthanum sulfide nanorod showed a specific capacitance of 75.17 F/g at a scan rate of 30 mV/s evidenced by cyclic voltammetry (CV) curves. The rGO significantly increased the discharge time from 60 to 188 s, specific capacitance from 20.32 to 34.12 F/g, and energy density from 572 to 1185 mW/kg compared to individual lanthanum sulfide nanorods as seen by the galvanostatic charge/discharge profile. The rGO-templated lanthanum sulfide nanorods showed a power density of 255.20 W/kg at a high current density of 0.2 A/g and a specific capacitance retention up to 91.60% for 2000 cycles at scan rate of 20 mV/s. Symmetric cell exhibited the specific capacitance of 94.45 F/g, energy density of 6.43 Wh/kg at the current density of 0.05 A/g, and power density of 351.25 W/kg at the current density of 0.2 A/g. The test results indicate that the use of rGO is effective in improving the electrochemical characteristics of lanthanum sulfide nanorods for supercapacitor applications.

Unconventional and alternative resources are proved incredibly useful for flexible and bendable energy storage devices to meet the demand of modern disposable and bendable technology. Nickle hydroxide [Ni(OH)2] based composites are considered as high-performance electrodes for supercapacitor and batteries applications due to high specific capacitance at higher scan rates. This study presents the fabrication Ni(OH)2 and incorporation of lignocelluloses(LC) fibers as binders to address the inherent rigid structure. Furthermore, electrically conductive properties are address by synthesis of composites with Polypyrrole and Polyaninline. X-Ray diffraction (XRD) results confirm the successful formation of nickel hydroxide whereas scanning microscopy results (SEM) reveal the nanoparticle morphology. Incorporation of LC fibers within Ni(OH)2 particles presented as compact and flexible composite paper electrodes which can be cut with help of scissor in any shape for bulk use. Fourier Transform Infrared (FTIR) confirmed the composite formation and cyclic voltammetry (CV) measurements were performed for all the fabricated samples to observe the electrochemical kinetics by which the best specific capacitance is shown by Ni(OH)2/PPy/LC i.e. 630 Fg−1. These fabricated composites can be used further as flexible electrodes in energy storage applications because of enhanced electrochemical properties. Presented flexible Ni(OH)2 based paper sheets will be highly feasible for modern bendable and disposable energy storage devices due to light-weight and environmentally safe characteristics.

Metal oxide based electrodes are attractive for energy storage applications with limited characteristics of flexibility due to inherent rigid structure. However, incorporation of flexible insulating matrix within metal oxide composites result in poor electrically conductive and energy storage characteristics. This study presents the fabrication of flexible MnO2 based composite electrodes prepared by incorporation of lignocelluloses (LC) fibers, directly collected from a self-growing plant, Monochoria Vaginalis. Furthermore electrodeposition of silver (Ag) nanoparticles was performed on LC/MnO2 in potentiostatic mode to address the electrically conductive characteristics. Morphology, structural, conductive and energy storage properties of fabricated electrodes are analyzed by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), impedance analyzer and potentiostat, respectively. SEM images clearly indicate the deposition of Ag nanoparticles on MnO2 nanorods embedded in LC fibers whereas FTIR results confirm the bonding of the functional groups. Cyclic voltammetry measurements showed efficient kinetics of LC/MnO2 after electrodeposition of Ag nanoparticles. The effects on electrical properties associated with blending MnO2 nanorods in lignocelluloses fibers and Ag deposition on MnO2 in LC/MnO2 are explored in wide frequency range between 10 Hz and 5 MHz. However, deposition of Ag nanoparticles on MnO2 nanorods surfaces acts as a conductive path and reduces the associated resistance. Incorporated flexibility in rigid structure of MnO2 and further improvements in conductive and energy storage characteristics will open the possibilities to be used as electrode in modern bendable energy storage devices.

Graphene oxide based electrode materials show remarkable electrochemical properties due to the improved specific surface area and electrical conductivity for supercapacitor applications. Hydrothermally synthesized graphene oxide based aluminum sulfide nanowalls on nickel foam (NF) have revealed excellent pseudocapacitive behavior with the specific capacitance 2362.15 F g-1 at 2 mVs-1 as observed through cyclic voltammetry. The galvanostatic charge-discharge measurements confirmed a specific capacitance 2373.51 F g-1 at 3 mAcm−2. Hexagonal phase of the graphene oxide (GO) based Al2S3 nanowalls also showed good discharge time of 820 s and energy density 118.68 WhKg−1 at 3 mAcm−2. Moreover, the fabricated electrode material exhibited good power density 2663.58 W kg-1 at 20 mAcm−2. The impedance results also confirmed the pseudocapacitive characteristics and revealed weak contact and Warburg resistances for the electrode material in half cell. Hence, GO based Al2S3 nanowalls performed as a prominent electrode material for asymmetric supercapacitors. Additionally, electrode material also exhibited excellent symmetric behavior, which again suggested a good electrode structure for supercapacitor applications.

Development of cost efficient, flexible and light weight paper electrodes for high-tech applications is high in demand in era of modern disposable technology. In this study α-MnO2 nanorods were fabricated through hydrothermal method by varying growth time and further combined with lignocelluloses fibers extracted from self growing plant, Monochoria Vaginalis. Crystal structure, morphology and thermal properties of MnO2 nanorods were characterized by X. Ray Diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM) and Thermogravimetric Analysis (TGA), respectively. FESEM image analysis revealed the highest aspect ratio of 48.016 for 4 h treated MnO2 sample and high purity level was confirmed by XRD. MnO2 sample with high aspect ratio, relatively pure and larger yield was selected for incorporation of lignocelluloses fibers to fabricate flexible, light-weight and environmentally safe LC/MnO2 composite paper sheet. Furthermore, LC/MnO2 composite sheet was employed as working electrode in 2 M sodium sulfate electrolyte for cyclic voltammetry measurements. Presented LC/MnO2 composite sheet revealed specific capacitances 117, 59, 39, 25 and 23 F/g at scan rates of 5, 10, 20, 50 and 100 mV/s, respectively. Incorporation of LC fibers within MnO2 nanorods as binders will open the possibilities to fabricate the flexible paper electrode for application in supercapacitors and batteries due to facile synthesis, light-weight and environmentally friendly aspects.

Owing to large specific surface area and high electrical conductivity, nanostructured electrodes exhibit improved electrochemical activity for supercapacitor applications. In the present study, structure and morphology of hydrothermally synthesized strontium sulfide and graphene oxide based Strontium sulfide nanorods have been investigated by using XRD and SEM, respectively. Introduction of graphene oxide thin film improves specific surface area and result in the excellent electrical conductivity of Strontium sulfide nanorods. Due to this, graphene oxide based strontium sulfide nanorods illustrate excellent specific capacitance and energy density of 1831.14 F g−1 and 91.56 WhKg−1, respectively, at the current density of 3 mAcm−2, as measured by employing three electrode galvanostatic charge discharge system. Moreover, electrode of graphene oxide based strontium sulfide nanorods also shows good electrochemical performance, according to the measurements by symmetric two electrode system. Energy and power density is measured as 10.55 WhKg−1 and 294.35 W kg−1, respectively. The excellent electrochemical performance of graphene oxide based strontium sulfide nanorods reveals its significance as nanostructured materials for supercapacitor applications.

ZnO based nanostructure composites are attractive for high-tech applications of energy conversion and energy storage due to wide range in operating potential window. This study presents about fabrication of ZnO/MnO2 and ZnO/TiO2 composites via hydrothermal method in two consecutive steps. Furthermore lignocelluloses fiber directly collected form self-growing plant Monochoria Vagina, were incorporated in fabricated ZnO/MnO2 and ZnO/TiO2 composites for development of flexible and bulk paper composite electrode. The structural and morphological analysis were carried out using X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), respectively. XRD analysis confirm the crystalline structures for ZnO/MnO2 and ZnO/TiO2 samples with crystallite size ∼62 nm and ∼63 nm, respectively. SEM images shows the sheet-like and nanorods morphology for ZnO and MnO2 nanostructures, respectively. Fourier Transform Infrared (FTIR) Spectroscopy absorbance spectrum reveal the composite formation of ZnO/MnO2/LC and ZnO/TiO2/LC as bulk paper electrodes whereas cyclic Voltammetry measurement showed the capacitive behavior of composite paper electrodes for the suitable applications in supercapacitors and batteries.

Tremendous efforts have been devoted for designing the excellent electrochemical electrode structures, exhibiting good electrochemical characteristics for supercapacitor applications. Herein, nickel sulfide nanoplates on graphene oxide thin film (GO NSNPs) were fabricated on nickel foam using hydrothermal method. The structural, morphological, electrical and electrochemical study was carried out using the X-ray diffractometer, scanning electron microscope, four probe electrical set up and electrochemical work station. GO NSNPs showed oxidation and reduction peaks in cyclic voltammetry curves and recommended the pseudocapacitive nature. The specific capacitance and specific energy was found as 1745.50 Fg−1 and 87.30 WhKg−1 at 5 mAcm−2, respectively, through galvanostatic charge and discharge profile using three electrodes system. While, the measured specific energy from two electrodes symmetric measurements was 15.72 WhKg−1 at 1 mAcm−2. Hence, GO NSNPs electrodes were suggested as suitable for high performance asymmetric and symmetric supercapacitor applications.

The working electrode is considered a major component of the dye-sensitized solar cell (DSSC) to influence the efficiency and morphology attributes in different high-tech applications. This study presents the fabrication of flexible composite sheets of titanium dioxide (TiO2) by incorporation of natural lignocelluloses fibers extracted from the self-growing plant, Typha Angustifolia to address the inherent rigid structure and superior absorption properties of the working electrode. Furthermore, fabricated TiO2 based composites were characterized by scanning electron microscope (SEM), Fourier transforms infrared (FTIR), ultraviolet-visible (UV–vis) spectroscopy and employed as a working electrode for DSSC after deposition on fluorine doped tin oxide (FTO) glass substrate. SEM morphology reveals that LC fibers acted as a thread to bind the TiO2 nanoparticles and also with better voids for adsorption of electrolyte whereas FTIR spectroscopy confirms the successful formation of the paper composite. J-V measurements reveal the high efficiency of 2.95% for TiO2/LC flexible and environmentally safe composite which can be feasible for modern bendable DSSC.

Nanostructured metal oxides have opened innovative and exciting opportunities for exploring intracellular biosensing applications. Metal-oxides-based nanostructures such as zinc oxide/copper oxide (ZnO/CuO) is relatively a biosafe, biocompatible, and large surface area nanostructures with polar surface that can be used for biomedical applications. Metal oxide nanostructures have been widely explored to develop biosensors with high sensitivity, fast response time, and sufficient stability for the determination of intracellular metal ions and glucose by electrochemical methods. In this chapter, we report on a functionalized ZnO-nanostructure-based selective electrochemical sensor for intracellular metal ions and glucose. To apply the biosensor concept to intracellular and less invasive measurements based on nanostructured metal oxides, hexagonal ZnO nanorods were grown on the tip of a silver-covered borosilicate glass capillary (0.7 µm diameter) and coated with the membrane/enzyme. The membrane/enzyme-coated ZnO nanorods exhibited a metal ions/glucose-dependent electrochemical potential difference versus an Ag/AgCl reference microelectrode. The potential difference was linear over a wide concentration range of interest. The effect of the hormone insulin and extracellular injected metal ions, which increased the concentration of intracellular glucose/metal ions, was also demonstrated. These results demonstrate the capability to perform biologically relevant measurements of metal ions/glucose within living cells. The ZnO nanorod metal ions/glucose electrode thus holds promise for minimally invasive dynamic analyses of single cells. The measured metal ions/glucose concentration in human adipocytes or frog oocytes using ZnO nanorod sensor was consistent with values reported in the literature. This microelectrode device represents a simple but powerful technique to measure intracellular metal ions/glucose concentration which is of particular importance with regard to investigations into bone destruction/diabetes and its consequences.

In era of modern disposable and bendable energy storage technology, flexible and environmentally safe electrodes are extremely feasible. This study elaborates the synthesis of highly flexible and stretchable polymer gel membrane by covalently cross linking of chitosan (CS) and poly vinyl alcohol (PVA) immobilized MnO2 for efficient, light-weight and cost-effective energy storage technologies. Fourier transform infrared spectroscopy (FTIR) revealed the existence of CS/PVA as well as MnO2 in original form without any chemical change. 3-dimensional morphology including porosity of the presented fabricated membranes are examined by scanning electron microscopy (SEM). Presented CS/PVA based MnO2 membranes were bendable and can be cut in any shape by the simple usage of scissor to employ by means of working electrode. Furthermore, electrochemical behaviour was tested by cyclic voltammetry (CV) and Galvanostatic charge/discharge (GCD) measurements in neutral/acidic electrolytes. CS/PVA based MnO2 membranes showed excellent capacitive behaviour with specific capacitance of ~140 F g−1. GCD measurements also verified efficient kinetics of charging/discharging at low and high current rates as curves were symmetric. Presented flexible and electroactive CS/PVA based MnO2 membranes will be highly suitable candidates for bendable electrode material in modern high-tech flexible energy storage devices.

The energy-filtered transmission electron microscopy (EFTEM) technique has been used to study ion-exchange processes in conductive polymer composite nanofibers. The elemental distributions of carbon, nitrogen, oxygen, chlorine, boron, phosphorus, molybdenum, and sulfur within polypyrrole-cellulose nanofibers, used as potential controlled electrochemical solid phase extraction media, have been studied by EFTEM. The distribution of ions within the polypyrrole-cellulose nanofibers and the penetration depth of ions into the material as a function of the size and charge of the latter were investigated. Further, the spatial distribution of single stranded DNA hexamers inside polypyrrole-cellulose nanofibers was mapped subsequent to the electrochemically controlled extraction of DNA from a borate buffer solution. The results show that the EFTEM mapping technique provides unpreceded possibilities for studies of the distribution of ions inside conductive polymer composites.

It is demonstrated that it is possible to coat the individual fibers of wood-based nanocellulose with polypyrrole using in situ chemical polymerization to obtain an electrically conducting continuous high-surface-area composite. The experimental results indicate that the high surface area of the water dispersed material, to a large extent, is maintained upon normal drying without the use of any solvent exchange. Thus, the employed chemical polymerization of polypyrrole on the microfibrillated cellulose (MFC) nanofibers in the hydrogel gives rise to a composite, the structure of which-unlike that of uncoated MFC paper-does not collapse upon drying. The dry composite has a surface area of approximately 90 m(2)/g and a conductivity of approximately 1.5 S/cm, is electrochemically active, and exhibits an ion-exchange capacity for chloride ions of 289 C/g corresponding to a specific capacity of 80 mAh/g. The straightforwardness of the fabrication of the present nanocellulose composites should significantly facilitate industrial manufacturing of highly porous, electroactive conductive paper materials for applications including ion-exchange and paper-based energy storage devices.

Highly porous polypyrrole (PPy)-nanocellulose paper sheets have been evaluated as inexpensive and disposable electrochemically controlled three-dimensional solid phase extraction materials. The composites, which had a total anion exchange capacity of about 1.1 mol kg(-1), were used for extraction and subsequent release of negatively charged fluorophore tagged DNA oligomers via galvanostatic oxidation and reduction of a 30-50 nm conformal PPy layer on the cellulose substrate. The ion exchange capacity, which was, at least, two orders of magnitude higher than those previously reached in electrochemically controlled extraction, originated from the high surface area (i.e. 80 m(2) g(-1)) of the porous composites and the thin PPy layer which ensured excellent access to the ion exchange material. This enabled the extractions to be carried out faster and with better control of the PPy charge than with previously employed approaches. Experiments in equimolar mixtures of (dT)(6), (dT)(20), and (dT)(40) DNA oligomers showed that all oligomers could be extracted, and that the smallest oligomer was preferentially released with an efficiency of up to 40% during the reduction of the PPy layer. These results indicate that the present material is very promising for the development of inexpensive and efficient electrochemically controlled ion-exchange membranes for batch-wise extraction of biomolecules.