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Design of nanostructured surface architecture is currently playing a vital role to enhance the energy storage capability of electrode materials and opening up a new era for future technologies through electrochemical supercapacitors. Present effort portrays the growth of nanostructured bismuth vanadate (BiVO4) as an active electrode for supercapacitor application by using ease and industry scalable successive ionic layer adsorption and reaction (SILAR) method. Structural analysis reveals the development of orthorhombic structured BiVO4 with spongy nano-pebbles like surface architecture. Synthesized BiVO4 electrode yields remarkable capacitance of 707 F/g @3 mV/s scan rate. Faradaic and capacitive type contributions have been evaluated for in-depth understanding along with the estimation of electrochemical active surface area. Electrochemical impedance spectroscopy (EIS) analysis of BiVO4 electrode exhibits 5.723 and 0.89 Ω cm2 values of series and charge transfer resistances, respectively. Interestingly, BiVO4 electrode delivers outstanding capacitive retention of 102% even at 3500 cycles, indicating its potential candidature for the advancement in high capability supercapacitors with excellent stability for the future technologies.

We report the synthesis of two-dimensional porous ZnO nanosheets, CuSCN nanocoins, and ZnO/CuSCN nano-heterostructure thin films grown on fluorine-doped tin oxide substrates via two simple and low-cost solution chemical routes, i.e., chemical bath deposition and successive ionic layer adsorption and reaction methods. Detail characterizations regarding the structural, optoelectronic, and morphological properties have been carried out, which reveal high-quality and crystalline synthesized materials. Field emission (FE) investigations performed at room temperature with a base pressure of 1 × 10–8 mbar demonstrate superior FE performance of the ZnO/CuSCN nano-heterostructure compared to the isolated porous ZnO nanosheets and CuSCN nanocoins. For instance, the turn-on field required to draw a current density of 10 μA/cm2 is found to be 2.2, 1.1, and 0.7 V/μm for the ZnO, CuSCN, and ZnO/CuSCN nano-heterostructure, respectively. The observed significant improvement in the FE characteristics (ultralow turn-on field of 0.7 V/μm for an emission current density of 10 μA/cm2 and the achieved high current density of 2.2 mA/cm2 at a relatively low applied electric field of 1.8 V/μm) for the ZnO/CuSCN nano-heterostructure is superior to the isolated porous ZnO nanosheets, CuSCN nanocoins, and other reported semiconducting nano-heterostructures. Complementary first-principles density functional theory calculations predict a lower work function for the ZnO/CuSCN nano-heterostructure (4.58 eV), compared to the isolated ZnO (5.24 eV) and CuSCN (4.91 eV), validating the superior FE characteristics of the ZnO/CuSCN nano-heterostructure. The ZnO/CuSCN nanocomposite could provide a promising class of FE cathodes, flat panel displays, microwave tubes, and electron sources.

Enhancing energy storing capability with the aid of unique nanostructured morphologies is beneficial for the development of high performance supercapacitors. Developing earth abundant and low-cost transition metal selenides (TMSs) with enhanced charge transfer capabilities and good stability is still a challenge. Herein, state of the art for iron selenide with a nanoflake surface architecture, synthesized with the aid of a simple, industry-scalable and ionic layer controlled chemical approach, namely the successive ionic layer adsorption and reaction (SILAR) method, is presented. The iron selenide electrode yields a capacitance of 671.7 F g−1 at 2 mV s−1 scan rate and 434.6 F g−1 at 2 mA cm−2 current density through cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD) studies, respectively, with 91.9% cyclic retention at 4000 cycles. The developed bendable solid-state supercapacitor reveals a remarkable power density of 5.1 kW kg−1 with outstanding deformation tolerance, including its use in a practical demo to run a small fan, demonstrating its capability for advanced energy storage applications. A complementary first-principles density functional theory (DFT) approach is used in combination with the experimental supercapacitive performance to achieve an understanding of the electronic structure.

Cadmium sulphide and titanium dioxide-based junctionless transistor (JLT) has been demonstrated by using simple and low-cost chemical bath deposition method. The morphological and structural study has been performed to speculate the crystallinity and the topography of individual layers of the proposed device. The optimised sputtering conditions lead to the formation of source and drain electrical contacts of the device. The fabricated device successfully functionalised as a p-channel JLT. At the source-to-drain voltage of −50 V, the ON-state drive current and OFF-state leakage current of the fabricated JLT are found to be −6 µA and 1.3 nA, respectively.

Thin film consisting of hierarchical cadmium oxide nanonecklaces has been synthesized through room temperature chemically deposited cadmium hydroxide nanowires as template followed by air annealing. Formation of thin film has been confirmed with aid of structural, surface morphological, valence state and optical, studies performed by X-ray diffraction, Raman analysis, scanning electron microscopy, X-ray photoelectron spectroscopy, and UV–visible spectroscopy. Air annealing at 330 °C has enhanced the photo electrochemical power conversion efficiency of the CdO as photoanode to 0.21% configured through platinum as counter electrode and polyiodide as a liquid electrolyte. Complete device performance have been correlated through rate of recombination, and electron life time. The schematic energy band alignment also has been comprehended herein.

An investigation of field emission on solution processed MWCNTs, MoS2 and MoS2 anchored MWCNTs thin films on low cost stainless steel substrates have been performed. Decorative morphology of MoS2 nanoflakes over MWCNTs interconnected high surface area nanonetwork supports the active path for the application of field emission. Drastic diminishing in turn-on field value has been obtained for MWCNTs/MoS2 nanocomposite compared to bare MWCNTs and MoS2. Hence, present investigation opens path for the development of low-temperature solution processed MWCNTs/MoS2 thin film in the field of nanoelectronics and the used process can be integrated for large scale.

A complete solid state device with FTO/PANI/PTh/ZnO/Al assembly prepared by absolute wet chemical methods including chemical bath deposition (CBD), successive ionic layer adsorption and reaction (SILAR) and spin coating has been studied to investigate the effect of thickness of active PANI layer on device performance. Structural, morphological and chemical bond features have been investigated by using X-ray diffraction, Field Emission Scanning Electron Microscopy and Fourier Transform Infrared spectroscopy of the layers and are discussed herein. Effect of PANI thickness on current-voltage characteristic has been studied under dark and illumination (100 mW/cm2, AM 1.5G, 1 Sun) condition to know the solar cell performance.

Present work portrays the surface morphology dependent electrochemical behaviors tuned by annealing the chemical bath deposited (CBD) cerium oxide electrodes. The altered nanostructure properties are well-supported by in-depth structural and morphological analysis. Cerium oxide electrode annealed at 200 °C exhibits good surface properties enabling maximum electro-active porous cavities to penetrate electrolyte ions towards enhanced electron transfer. Consequently, the electrode exhibits maximum specific capacitance of 750 F/g with remarkably stable charge-discharge cycles. Fabricated symmetric solid-state supercapacitor device impressively expands potential window to 1.2 V with the aid of PVA-LiClO4 gel electrolyte with a peak specific capacitance of 321.3 F/g with top-up of 61.4 Wh/kg specific energy. The series combination of two devices confirms the strong energy storage ability by glowing ‘VNIT’ acronym designed through 21 red LEDs from the practical point of view.

The fiber wrapped tuberose structured Fe:Sr(OH)2 have been successfully deposited by using a simple and low cost chemical approach of successive ion layer adsorption and reaction (SILAR) method as binder-free electrodes for supercapacitors. The structural properties have been obtained by the XRD patterns, while FTIR shows the chemical bond analysis. The FE-SEM micrographs show fiber wrapped tuberose structured morphology and the Fe doping into Sr(OH)2 is confirmed by EDX. The deposited films show the battery type electrode behaviour in 1 M Na2SO4 aqueous solution. As an active electrode material, the specific capacity of 871 C g−1 (specific capacitance of 792 F g−1) at 1.2 mA cm−2 with cycle retention of ∼79% at 5 mA cm−2 has been obtained for 0.5 at.% Fe:Sr(OH)2. The electrochemical properties of the synthesised electrode reveal that it has the great potential for next-generation energy storage applications.

Portable and furnished electronics appliances demand power efficient energy storage devices where electrochemical supercapacitors gain much more attention. In this concern, a simple, low-cost and industry scalable successive ionic layer adsorption and reaction (SILAR) approach has been adopted to deposit nanostructured VS2 onto flexible and light-weight stainless steel (SS) substrate towards supercapacitor application. The nanocrystalline nature with hexagonal crystal structure has been confirmed for VS2 through structural analysis. The VS2 electrode exhibits a maximum specific capacitance of 349 F g−1 with a super stable behavior in three-electrode liquid-state configuration. Fabricated flexible symmetric solid-state supercapacitor (FSSC) device using gel electrolyte yields specific power of 1.5 kW kg−1 (specific energy of 25.9 Wh kg−1) with a widen voltage window of 1.6 V. A red LED has been glown for 30 s using the system consisted of two devices in series combination. Furthermore, the system glows a combination of 21 red LEDs network with acronym ‘VNIT’, demonstrating commercial exposure. The attribution of device demonstration even under mechanical stress holds great promise towards advanced flexible electronics application.

Through simple chemical route, nanoheterojunction has been developed between CdS-nanowires (NWs) as core with PbS nanoparticles as a shell for photoelectrochemical solar cell application. The use of simple, cost effective and industry scalable chemical bath deposition (CBD) and successive ionic layer adsorption and reaction (SILAR) approaches for the deposition of CdS NWs and PbS nanoparticles, respectively has the added advantage. Well-tuned nano particle size of PbS through number of SILAR cycles over wide band gap CdS resulted into optical red shift which maximize the absorption region of solar spectrum responsible for yielding enhancement in light conversion efficiency than bare CdS. Device configured solar cell yields 15 fold enhancement in the power conversion efficiency in liquid configuration due to the well aligned nanoheterojunction between CdS and PbS analysed through photoelectron X-ray spectroscopy. This enhancement in efficiency has been correlated through flat band potential, electron life time, rate of recombination and external quantum efficiency.

Rectangular shaped α-Ce2S3 microrods have been grown with the aid of a facile, efficient, low cost and low temperature chemical bath deposition (CBD) approach in thin film form. Characterizations of α-Ce2S3 have been performed through structural, morphological and surface wettability studies. Intermixed rectangular microrods with lower contact angle provide a reduction in intrinsic resistance and effective ion diffusion path during electrochemical activities ensuring maximum utilization of the active electrode species. This leads to achieve a remarkable specific capacitance of 726 F/g at 2 mV/s scan rate with the excellent electrochemical stability of 93% at 2000 CV cycles. Efficient electrochemical findings exhibit excellent scope of α-Ce2S3 towards next-generation energy storage devices.

Next-generation portable flexible electronic appliances require liquid-free energy storage supercapacitor devices to eliminate leakage and to support mechanical bending that is compatible with roll-to-roll technologies. Hence, a state-of-the-art process is presented to design a solid-state, wide-potential and flexible supercapacitor through the use of nano-pebbles of cerium selenide via a simple successive ionic layer adsorption and reaction (SILAR) method that could allow an industry scalable route. We strongly believe that this is the first approach amongst physical and chemical routes not only for synthesizing cerium selenide in thin-film form but also using it for device-grade supercapacitor applications. The designed solid-state symmetric supercapacitor assembled from cerium selenide electrodes sandwiched by PVA–LiClO4 gel electrolyte attains a wide potential window of 1.8 V with capacitance of 48.8 F g−1 at 2 mV s−1 and reveals excellent power density of 4.89 kW kg−1 at an energy density of 11.63 W h kg−1. The formed device is capable of 87% capacitive retention even at a mechanical bending angle of 175°. Lighting up a strip of 21 parallel connected red LEDs clearly demonstrates the practical use of the designed symmetric solid-state supercapacitor, aiming towards the commercialization of the product in the future. The authors gratefully acknowledge DST/TMD/MES/2k16/09 project, Government of India.

Design and development of cadmium sulphide core with silver sulphide shell assembly in nanowire (NWs) surface architecture has been explored through room temperature, simple chemical route towards photoelectrochemical solar cell application. Incorporation of low band gap Ag2S nanoparticles over the outer surface of the chemical bath deposited CdS NWs has been achieved by simple cation exchange route based on negative free energy of formation. Shell optimization has been performed by investigating structure, surface morphologies and optical analyses and correlated with the photovoltaic parameters. Interestingly, core-shell CdS NWs/ Ag2S exhibits 1.5 better performance in terms of linear voltammetry, photocurrent transient response and the photo stability than bare CdS. Furthermore, three-fold enhancement in photoelectrochemical conversion efficiency have been observed for optimized FTO/ CdS NWs/Ag2S compared to bare FTO/CdS NWs due to the augmented light harvesting and condensed charge recombination. External quantum efficiency exhibits 24% for the optimized CdS NWs/ Ag2S core shell structure. Mott-Schottky and electrochemical impedance spectroscopy measurements have been used for better understanding the impact of gradual growth of Ag2S over CdS NWs which directly influences the overall photocurrent density of the devices.

Present innovation emphasizes the design and development of hybrid nanoarchitecture by using simple two-step chemical routes, namely, “dip and dry”, for multiwalled carbon nanotubes (MWCNTs) follow...

Supercapacitors as one of the most important energy storage devices have been receiving worldwide attention due to their high capacitance, power density, long cycle life, and rapid charge/discharge rates as compared to conventional electrolytic capacitors and rechargeable batteries. A nanocomposite has been prepared using mercury sulfide (HgS) and multiwalled carbon nanotubes (MWCNTs) via novel, simple, and low-cost ‘dip and dry’ process followed by successive ionic layer adsorption and reaction (SILAR) method. The association of HgS nanoparticles with high surface area reinforced MWCNTs nanonetwork boosts the electrochemical supercapacitive performance of nanocomposite compared to bare HgS and MWCNTs. This nanocomposite yields excellent specific capacitance of 946.43 F/g at scan rate of 2 mV/s and an outstanding rate capability of 93% retention over 4000 cycles with decent charge–discharge cycles. Moreover, the electrode exhibits maximum specific energy and power densities of 42.97 Wh/kg and 1.60 kW/kg, respectively. The promising capabilities of formed nanocomposite can explore the opportunities as alternative electrode material for energy storage applications.

Recently, thin-film supercapacitors have received much interest because they can achieve both high energy densities and high power densities, which make them suitable for practical applications. Here, thin films consisting of zinc ferrite (ZnFe2O4) anchored on multiwalled carbon nanotubes (CNT) were prepared through a simple and inexpensive successive ionic layer adsorption and reaction (SILAR) method. This method has the advantage of direct electrode formation without the use of any binder. The synergy of the composite electrode (ZnFe2O4-CNT) yields a high specific capacity of 217 mAhg(-1) at 5 mVs(-1), which is realized by contributions from the inner and outer active surfaces of the hybrid ZnFe2O4-CNT electrode. Furthermore, a solid-state symmetric device exhibits a highest specific energy of 12.80 Whkg(-1) and a specific power of 377.86 Wkg(-1), which clearly demonstrates that our hybrid ZnFe2O4-CNT electrode is promising and innovative for energy-storage applications.

Transition metal chalcogenides (TMCs) embedded with a carbon network are gaining much attention because of their high power capability, which can be easily integrated to portable electronic devices. Facile chemical route has been explored to synthesize hexagonal structured VS2 nanoparticles onto multiwalled carbon nanotubes (MWCNTs) matrix. Such surface-modified VS2/MWCNTs electrode has boosted the electrochemical performance to reach high capacitance to 830 F/g and excellent stability to 95.9% over 10 000 cycles. Designed flexible solid-state symmetric supercapacitor device (FSSD) with a wide voltage window of 1.6 V exhibited maximum gain in specific capacitance value of 182 F/g at scan rate of 2 mV/s along with specific energy of 42 Wh/kg and a superb stability of 93.2% over 5000 cycles. As a practical approach, FSSD has lightened up “VNIT” panel consisting of 21 red LEDs.

Efforts have been put forth to grow HgS with cauliflower like surface architecture through simple and low-cost successive ionic layer adsorption and reaction (SILAR) method at room temperature for supercapacitive electrode application. Such a unique morphology facilitates the electrolyte ions to penetrate during electrochemical activities. Maximum specific capacitance of 446 F/g was obtained from cyclic voltammetry measurement at 2 mV/s scan rate in 1 M KCl electrolyte. After initial drop of capacitance up to 500 cycles, reduction was relatively slow up to 2000 cycles during stability analysis. Most importantly, the revealed specific energy of 15.45 Wh/kg of electrode has promised as decent electrode in energy storage field for future scope.

Silver (Ag) nanoparticles were synthesized through an electroless deposition providing high surface coverage of porous material. The structural and morphological characteristics were investigated along with electrochemical studies to evaluate the charge storage performance. The nanoparticle morphology provides more active sites and diffusion paths for the electrolyte ions resulting in maximum utilization of active electrode material. Ag nanoparticles based electrode not only exhibited a maximum specific capacitance of 452 F/g (at scan rate of 2 mV/s) and specific energy of 27.8 Wh/kg, but also achieved a tremendous gain over cyclic stability by retrieving 63% capacitance after 10,000 cycles. Such attractive electrochemical behavior of the formed electrode is suitable for the manufacturing of the good quality supercapacitors by utilizing a roll-to-roll industrial production technology.

The first report, on tuberose surface morphology of strontium hydroxide (Sr(OH) 2 ) has been achieved on stainless-steel (SS) substrate in the form of thin film by easy, economical efficient and less time consuming successive ionic layer adsorption and reaction (SILAR) technique at room temperature. X-ray diffraction analysis reveals polycrystalline nature of film with orthorhombic crystal structure. Fourier Transmission Infrared Spectroscopy (FTIR), Energy-dispersive X-ray spectroscopy (EDS) and Raman analyses reveal the composition and phase purity of the active material. The morphology of the prepared sample was characterized by Field Emission Scanning Electron Microscopy (FE-SEM), Higher Resolution Transmission Emission Microscopy (HR-TEM) which confirms the tuberose morphology of the Sr(OH) 2 thin film. Furthermore, tuberose surface architecture has been successfully utilized as supercapacitive electrode with high specific capacity of 413C g −1 in 1 M NaOH aqueous electrolyte at 2 Ag −1 current density. Also, the electrode has emerged with 45.95 Whkg −1 of energy density and 2.6 kWkg −1 as power density at 2 Ag −1 current density.

Phosphate based materials are emerging as advanced class of potential electrode materials for energy storage systems owing to their unprecedented redox activity, and high electrical conductivity. Fascinated by these exceptional physico-chemical properties of metal phosphates (MPhs), present work exclusively stands out as a first report on simple and industry scalable, successive ionic layer adsorption and reaction (SILAR) route to construct a binder-free electrode of ultrathin Cu2P2O7 nanoflakes with honeycomb analogues surface architecture directly grown on flexible stainless steel (SS) substrate. Unique nano-architecture with refined porosity furnishes a high specific surface area of 86.12 m2 g−1 and promotes effortless propagation of electrolyte ions, endowing enhanced extrinsic pseudocapacitive nature with excellent specific capacitance (332.9 F g−1, 399.6 mF cm−2, 268.9 F cm−3 at 10 A g−1). In addition, the contribution of surface-controlled and diffusion-limited processes to the total charge storage capacity of an electrode has been well distinguished. More importantly, the first-ever designed Cu2P2O7 based symmetric all-solid-state supercapacitor yields competent energy density of 11.54 Wh kg−1, commendable specific power of 7.06 kW kg−1, and noteworthy retention of 85% even at 4500 charge–discharge cycles. Furthermore, supremely flexible developed device lightens up an array of 21 red light emitting diodes (LEDs) depicting its glorious commercial feasibility towards next generation portable energy storage technologies.

We designed and synthesized two diketopyrrolopyrrole (DPP) derivatives (DPP1 and DPP2) which are substituted with phenyl and thiophene moieties in between DPP core and merocyanine dyes, respectively. The introduction of thiophene ring subunit at core position endows DPP2 significantly alters the photophysical, electrochemical and aggregation induces enhanced emissive (AIEE) properties compared to those of DPP1. As a practical point of view, we successfully employed DPP1 and DPP2 as sensitizer on CdS nanowires for fabrication of dye sensitized solar cell (DSSCs). The DSSC based on DPP2 (0.268%) dye yielded higher power conversion efficiency (PCE) as compared to DPP1 (0.195%) under standard illumination of Sunlight (AM 1.5 G, 100 mW/cm2). The basis for this different behaviour has been discussed.

Ultrathin nanoflakes surface architecture of MoS2 thin film has been successfully decorated by simple and inexpensive chemical bath deposition onto dip and dry coated multiwalled carbon nanotubes (MWCNTs) to compare electrochemical performance with respect to individual MWCNTs and MoS2 thin films on flexible stainless steel (SS) substrates. Two dimensional thin films of MWCNTs, MoS2 and MoS2/MWCNTs (MCT) have been characterized through X‐ray diffraction, X‐ray photospectroscopy, Raman spectroscopy and scanning/transmission electron microscopes. The unique nanostructured morphology of well anchored nanoflakes over MWCNTs enhances the value of specific capacitance and improves the cycle stability compare to bare MoS2. Strikingly, all‐solid‐state (ASS) symmetric SS/MCT//MCT/SS supercapacitor device has been constructed using flexible stainless steel substrate with the aid of PVA‐LiClO4 gel electrolyte and results are discussed herein.

Heterojunction between bi-layer structured nanocrystalline films has been developed towards the liquefied petroleum gas (LPG) sensor at room temperature (27 °C) without post annealing treatment. These films consists of n-type Bi 2 S 3 layer on fluorine doped tin oxide (FTO) coated glass substrate followed by deposition of p-type PbS layer to form heterojunction. However, simple and versatile successive ionic layer adsorption and reaction (SILAR) technique have been employed at room temperature (27 °C) to deposit the films. This technique involves ions as basic building blocks instead of atoms and hence growth rate can be controlled at ionic level. The completion of device was made by use of ohmic contacts using small drop of silver paste over p -PbS layer as a front contact and FTO coated glass substrate as a back contact. The device was kept overnight in order to dry the paste to ensure good contact. The formed heterojunction is porous with high surface area which enables enough space to adsorb and de-adsorb gas molecules easily and shows the gas response of 71% under the exposure of 1000 ppm concentration of LPG with 170 s and 300 s response and recovery time, respectively along with long term stability.

Low-cost, easily synthesized, and high energy/power density embedded stable supercapacitive electrodes are the demands for today’s renewable and green energy dependent generation. In search of that, Bi2S3:PbS solid solution in thin film form has been synthesized by modest successive ionic layer adsorption and reaction (SILAR) method and characterized by XRD, FESEM, and HRTEM. Formation of solid solution in the form of nanoparticles gilded thin film exposes sufficient electroactive cavities for electroactive ions to incorporate. The composite exhibited excellent specific capacitance of 402.4 F/g at current density of 1 mA/cm2 with modest charge-discharge cycles. In terms of energy storage, it exhibited maximum specific power of 20.1 Wh/kg with accepting specific power of 1.2 kW/kg. The combination of two nanoparticles in nanocomposites thin film supplies new tactic for energy storage applications.

Demonstration of the two step synthesis of MoSe2/MWCNTs (MSMC) hybrid thin films has been performed by simple and cost effective ‘dip and dry’ followed by chemical bath deposition (CBD) method. The uniform and porous nanonetwork of MWCNTs facilitates high surface area to anchor cryptomelane MoSe2. Due to the synergic effect and interfacial conjugation between MoSe2 and MWCNTs, the MSMC hybrid electrode and all-solid-state symmetric MSMC//MSMC device reveals excellent high potential electrochemical performance. The remarkable specific capacitance, energy density, power density and excellent cycle durability of all-solid-state symmetric MSMC supercapacitor device imply its potential applicability in the developing supercapacitors for hands-on applications.

Due to highly conducting and extraordinary stable nature, carbon based materials expand the arms of energy storage devices in terms of supercapacitor. Hence, emphasis has been made to use flexible and free-standing multi-walled carbon nanotubes (MWCNTs) bucky paper synthesized by chemical vapor deposition for electrochemical supercapacitive electrode. The high specific capacitance of 270 F/g (2 mV/s) with superb stable behavior (88% at 10000 cycles) of bucky paper has promised as decent electrode in energy storage application. Aqueous symmetric supercapacitor (ASSC) device developed through bucky paper exhibits voltage frame of 1.6 V yielding specific capacitance of 91 F/g along with specific energy of 32 Wh/kg at a current density of 1 mA/cm2 with trustworthy stability of 107% at 6000 cycles. The hands-on practicability to light up a red LED offers its promising approach in energy storage domain.

Simple chemical route has been employed to grow interconnected nanobeads of CdO having necklace like structure through air annealing of cadmium hydroxide nanowires. This nanobeads of n-CdO with high surface area has been decorated with p-PbS nanoparticles resulting in the formation of nano-heterojunction which has been utilized effectively as room temperature liquefied petroleum gas (LPG) sensor. The room temperature gas response towards C2H5OH, Cl2, NH3, CO2 and LPG was investigated, among which LPG exhibits significant response. The maximum gas response of 51.10% is achieved with 94.54% stability upon exposure of 1176 ppm concentration of LPG at room temperature (27 °C). The resulting parameters like gas response, response and recovery time along with stability studies has been studied and results are discussed herein.

Nested CdS@HgS core–shell heterostructure nanowires with large surface area has been grown on stainless steel current collector via a simple and versatile chemical route at room temperature (300 K) without any surfactant or binder. Mercury sulfide shell has been derived through ion-exchange method from cadmium sulfide core nanowires. Cadmium sulfide nanowire, mercury sulfide nanowire and CdS@HgS core–shell heterostructure nanowire have been obtained through controlled conversion process which were successfully employed as supercapacitive electrodes. CdS@HgS core–shell heterostructure nanowire exhibited a significant supercapacitance of 224.97 F/g at a scan rate of 5 mV/s in 1.5 M Na2SO3 electrolyte along with capacitance retention of 87% over 1250 cycles in comparison to individual CdS and HgS nanowires.

An interconnected needle-like structure of Bi2O3 has been directly grown on stainless steel (SS) substrate by binder-free successive ionic layer adsorption and reaction (SILAR) method. The structural study confirms the formation of cubic δ-Bi2O3 phase. The coverage of interconnected needle-like network structure has been seen from surface morphological study. The electrochemical performance of Bi2O3 has been tested as an electrode material through cyclic voltammetry, charge–discharge, and electrochemical impedance spectroscopy techniques in aqueous electrolyte. The electrochemical tests manifest the pseudocapacitive behavior of Bi2O3 thin-film electrode with a specific capacitance of 329.6 F g−1 at 5 mV s−1 scan rate. In addition, the Bi2O3 electrode exhibits long-term cycling performance with 72% capacitance retention after 3000 cycles.

Bi 2 S 3 thin film electrode has been synthesized by simple and low cost successive ionic layer adsorption and reaction (SILAR) method on stainless steel (SS) substrate at room temperature. The formation of interconnected nanoparticles with nanoporous surface morphology has been achieved and which is favourable to the supercapacitor applications. Electrochemical supercapacitive performance of Bi 2 S 3 thin film electrode has been performed through cyclic voltammetry, charge-discharge and stability studies in aqueous Na 2 SO 4 electrolyte. The Bi 2 S 3 thin film electrode exhibits the specific capacitance of 289 Fg −1 at 5 mVs −1 scan rate in 1 M Na 2 SO 4 electrolyte.

To address the problem of operational stability in conventional design of Organic Solar Cells (OSC), inverted solar cell structures are being investigated extensively. Inverted solar cell structures with ZnO nano-rods array (NRA) as interfacial layer is attracting much attention due to beneficial role played by ZnO NRAs. It not only addresses the limitation on charge extraction due to limited charge mobility but also simultaneously it can provide high-mobility routes to the charge carriers to reach to the cathode electrode also. In this paper we report synthesis of inverted OSC with active layer infiltrated in the ZnO nanorods array using Ultrasonic Spray method and confirmed total infiltration. Performance enhancement has been observed by addition of a thin PCBM layer between the electron transport layer and the active layer. The improvement has been attributed to the improved charge collection efficiency due to presence of PCBM layer.

One-step, simple and inexpensive successive ionic layer adsorption and reaction (SILAR) method has been used to synthesize porous network of zinc cobaltite (ZnCo 2 O 4 ) in 2D form on stainless steel (SS) substrate. Porous structure of ZnCo 2 O 4 electrode enables electrochemical specific capacitance of 675 Fg −1 at 5 mV s −1 sweep rate with high rate capability and cycling performance of 69% over 2000 cycles. Furthermore, fabricated ZnCo 2 O 4 solid-state supercapacitor cell in symmetric mode using PVA-KOH gel electrolyte exhibited a specific capacitance of 69.65 Fg −1 with specific energy of 9.67 Wh kg −1 and specific power of 1.45 kW kg −1 at a current density of 1.07 Ag −1 . The results clearly demonstrate the facile method for the synthesis of porous network of ZnCo 2 O 4 and make them promising electrode material for energy storage application.

A high specific energy and specific power can be attained for the supercapacitor devices with the aid of optimum potential. The use of a flexible approach employing a solid-state device structure is always beneficial for advanced technological applications. Hence, effort has been made towards the fabrication of a complete solid-state symmetric and flexible supercapacitor device based on environmentally friendly and abundant iron sulfide as an electrode material, which has been obtained using a successive ionic layer adsorption and reaction method operated at room temperature (27 °C). An operating voltage of 2 V was achieved for the flexible device with a bending stability of 100% over a bending angle of 175° along with the LED glow working model. These outcomes can give new vision towards the construction of solid-state and flexible devices using a simple and low-cost method with potential ability towards roll-to-roll technology for commercialization.

Simple, cost-effective, and room-temperature electroless reduction process has been advanced to anchor silver nanoparticles over multi-walled carbon nanotubes (MWCNTs). The impact of conductive MWCNT/Ag films with respect to structural, morphological, and electrochemical assets has been investigated. The highly stable and large surface area-aligned MWCNTs combined with conductive silver nanoparticles boost the electrochemical performance of the composite electrode. Remarkable specific capacitance of 757 F g−1 along with a significant cyclic stability of 83% over 3000 cycles has been achieved due to the strong synergistic effect between MWCNTs and silver nanoparticles. Moreover, the electrode exhibits a maximum specific energy and power of 60.7 W h kg−1 and 3.3 kW kg−1, respectively. This superior finding obviously offers future pathways for development in the energy storage field.

Surface coating of CdS nanoparticles over the ZnO nanorods have been performed by using simple successive ionic layer adsorption and reaction at room temperature. Initially, the seed/compact ZnO layer have been deposited via SILAR (successive ionic layer adsorption and reaction) on to fluorine doped tin oxide coated glass (FTO) substrate followed by synthesis of ZnO nanorods by chemical bath deposition method. The synthesized nano heterostructure was characterized by X-ray diffraction (XRD), UV–Vis spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), field emission-scanning electron microscopy (FE-SEM), energy dispersive X-ray analysis (EDX) and high resolution-transmission electron microscopy (HR-TEM) techniques. The photovoltaic performance of the cell was recorded with a conversion efficiency of 0.123% under 100 mW/cm 2 simulated sunlight at AM 1.5G conditions.

As a first report, use of room temperature non-aqueous chemical bath deposited Sb2S3 thin film as active material for supercapacitor application; opens new era in energy storage field. Obtained films were characterized by using structural, surface morphological and compositional analysis. The electrochemical performance has been evaluated by using cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance techniques. The maximum specific capacitance of 248 F/g at 0.5 A/g has been achieved within 0.2 to −0.5 V potential windows in 1M Na2SO4 electrolyte. In addition, the Ragone plot confirms the better specific power and specific energy for Sb2S3 electrode.

Present investigation focused on the fundamental understanding regarding the tailoring of photovoltaic (PV) device efficiency of 3D-CdS nanonetwork through annealing with the aid of electrochemical studies. The synthesis of CdS nanowires (NWs) have been performed using Cd(OH)2 NWs as intermediate sacrificial templates based on negative free energy of formation. The changes in structure, morphology and optical properties of CdS by annealing have been studied. The enhancement in crystallite size by annealing was correlated to the negative shift of the conduction band position, charge transport and electron life time towards PV performance. These have been performed by studying lattice parameters which in turn correlated to the capacitance, external quantum efficiency and impedance analysis through light-induced electrochemical studies.

Proper selection of electrode material with sensible scheme is definitely significant to dodge commercial obstacles of supercapacitors. This challenge has been addressed by engineering prototype symmetric supercapacitor (SSC) device fabricated with enhanced supercapacitive vanadium (V) oxide integrated multi-walled carbon nanotubes (MWCNTs) composite as electrode material with Li-ion associating LiClO4 electrolyte. The V2O5/MWCNTs composite with nanoscale architecture has been synthesized with inexpensive and simple chemical bath deposition (CBD) method. The cyclic voltammetry of SSC device has exhibited the involvement of electrochemically active reversible redox process in the composite. The specific capacitance of 569.7 F/g at scan rate of 2 mV/s including excellent electrochemical stability of 89.2% at 4000 CV cycles have been achieved with operating potential window of 2 V. Furthermore, the device exhibits excellent energy density of 62 Wh/kg and exceptional power density of 11.5 kW/kg. The low resistive factors have driven the device towards the potential application as glowing of red LED for 10 s. Keywords: Nanocomposite, Energy storage, Symmetric supercapacitor, Wide voltage window

Prototype solid-state symmetric supercapacitor (SSS) device has been designed by using two MWCNT/Fe2O3 electrodes assembled through polyvinyl alcohol-lithium chloride gel electrolyte as mediator onto flexible stainless steel substrate. Through electrochemical investigation as-fabricated device demonstrated 70.16 F g−1 of specific capacitance with remarkable 9.74 W h kg−1 specific energy and 487 W kg−1 specific power at current density of 0.57 A g−1. Assembled device delivers an outstanding volumetric energy of 24.36 mW h cm−3 compensating volumetric power of 1218 mW cm−3 at a current density of 1.42 mA cm−3. The cycle repeatability test of MWCNTs/Fe2O3 SSS device exhibited capacitance retention of 75% for 1500 cycles.

The ordered arrays of nanostructure with vertically aligned tube like structure hold great promise as an electrode material for high-performance energy storage devices. Such binder-free structure of Titanium dioxide (TiO 2 ) has been synthesized by anodization of titanium (Ti) foil. The use of TiO 2 nanotube as an electrode material attain a specific capacitance of 207 F g − 1 at 5 mV s − 1 scan rate in 1 M potassium hydroxide (KOH) electrolyte. Extra ordinary cycling performance with 103% capacitance retention of their initial capacitance for 1500 cycles has been achieved, suggests its promising candidate as highly stable electrode material for supercapacitor application.

Simple and cost effective ‘dip and dry’ approach has been demonstrated for the coating of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) onto multiwalled carbon nanotubes (MWNCTs) thin film, films are characterized by different techniques such as X-ray diffraction, Fourier transform infrared spectroscopy and scanning and transmission electron microscopy techniques where uniform coating of amorphous PEDOT:PSS on MWCNTs has been confirmed. The electrochemical performance of the PEDOT:PSS/MWCNTs electrode has been evaluated by using cyclic voltammetry and galvanostatic charge-discharge techniques. The specific capacitance of 235 Fg− 1 at 5 mVs− 1 has been achieved within 0 to 0.9 V potential range in 1 M aqueous H2SO4 electrolyte. Furthermore, electrochemical impedance spectroscopy (EIS) analysis showed the lower equivalent series resistance and excellent frequency response of PEDOT:PSS/MWCNTs electrode material.

Cadmium sulfide (CdS) thin film consisting of nanowires over a flat CdS thin film were synthesized by depositing cadmium hydroxide [Cd(OH)2] nanowires (NW) bundles, followed by conversion to sulfide phase by using ion exchange route at room temperature (300 K) based on negative free energy of formation. The influence of post annealing treatment on as-deposited CdS NW films has been studied in the temperature range 423–523 K through the observation of nanowires alignments. The annealing effect on the intrinsic properties have been studied in relation with the crystallites sizes, micro strain, dislocation density and optical band gap of the deposited films. Furthermore, the behavior of inter- and intramolecular hydroxide ion (OH−) has been investigated from FTIR analysis. Additionally, the effects of post annealing on photovoltaic device performance has been scrutinized and the obtained results were correlated with structural and optical properties.

ZnFe 2 O 4 thin film has been synthesized by a simple and low cost successive ionic layer adsorption and reaction (SILAR) method without the use of surfactant or template. The nanoplate composed of nanoparticles with porous surface morphology has been revealed which is beneficial towards supercapacitor application. Formed ZnFe 2 O 4 thin film has been tested as an electrode material for supercapacitor through electrochemical analysis. First attempt for SILAR synthesized ZnFe 2 O 4 thin film exhibited a specific capacitance of 471 Fg −1 at a scan rate of 5 mVs −1 in 1 M NaOH aqueous solution. Further, ZnFe 2 O 4 solid-state symmetric (SSS) supercapacitor device demonstrated voltage window of 1.0 V with specific capacitance of 32 Fg −1 , energy density of 4.47 Whkg −1 and power density of 277 Wkg −1 at 1 Ag −1 current density. Such high performance capacitive behavior indicates ZnFe 2 O 4 thin film is promising and low cost electrode material towards energy storage devices for various portable electronic systems.

The state of art is shown to develop attractive, low cost, colorful, and device grade dye sensitized solar cells using chemically synthesized ZnO. Metal free organic dyes showing unlike absorption coverage in the visible part of solar spectrum has been used to produce colorful solar cells. By mimicking the basic idea of blending two individual colors of the dyes namely, Coumarin 343 (yellow) and Eosin-Y (red) to get orange color which has been utilized toward advanced colorful approach in order to boost the device performance. Correlation is made between the optical absorption spectra of individual and blended dyes with incident photon to current conversion efficiency (IPCE). The solar cell performance under illumination (100 mW/cm, AM 1.5G) of individual and blended dyes on ZnO films have been investigated. The obtained efficiency ranges from 0.02 to 1.98% for individual dyes whereas the efficiency boosts up to 2.45% has been observed for blended dye., PKB is thankful to DST-SERB in support of financial assistance through the Fast Track Young Scientist Project (SR/FTP/PS-063/2012, dated 06/11/2013). BRS is thankful to DST Project (SR/S2/CMP-0026/2010 and SB/S2/CMP-32/2013) And Director, VNIT for financial support under ULR grant.

A low turn-on field of 2.4 V μm−1 is observed for the emission current density of 10 μA cm−2 from aligned copper thiocyanate (CuSCN) nanosheets. The observed low turn-on field is found to be superior to that of inorganic semiconducting and carbon based nanomaterials reported in the literature. The field emission current stability for the preset value of 1 μA over the period of 3 h is found to be better. Aligned CuSCN nanosheets were grown on fluorine doped tin oxide (FTO) coated glass substrates by a simple, low cost Successive Ion Layer Adsorption and Reaction (SILAR) technique at room temperature. Detail characterization of aligned CuSCN nanosheets has been carried out using Field Emission Scanning Electron Microscopy (FESEM), X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM). To the best of our knowledge this is the first report on the field emission studies of aligned CuSCN nanosheets. The simple and inexpensive synthesis route coupled with superior field emission make the present emitter suitable for micro/nano electronic devices.

The synthesis of two D–D–A type novel small molecules bearing N,N-dimethyl/ethyl aniline as a donor and a methine unit connected with cyano and carboxyl groups as an acceptor linked with conjugated π-linkers has been performed. The obtained compounds were characterized by using FT-IR, 1H-NMR, 13C-NMR, LC-HR-MS, TGA, FE-SEM and UV-Vis spectroscopic techniques. These designed small organic molecules have been utilized for the fabrication of novel organic solar cells on high surface area titanium dioxide films consisting of interconnected nanoparticles with the device configuration FTO/TiO2/organic compound/electrolyte/platinum. The effect of cholic acid and dodecylamine as co-adsorbents with an organic compound has been studied towards the device performances and the results are incorporated herein.

We design and establish an environmentally benign synthesis of new D–π–A dyes containing imidazole derivatives structured to triphenylamine (TPA) as a donor and cyano acrylic groups acting as acceptors without using any toxic catalysts. These newly synthesized imidazole derivatives are anchored on TiO2, towards a cost effective dye sensitized organic solar cell, and achieve 0.22% solar-light to electricity conversion efficiency under standard AM 1.5G irradiation (100 mW cm−2). The most widely significant findings of this study are high thermal stability, smooth surface, strong intramolecular interaction between dyes and TiO2 which improve the performance of the dye sensitized solar cell. The metal ion sensing properties of both the dyes were investigated optically using UV-Vis absorption spectroscopy. The results exhibited high selectivity and sensitivity towards toxic Hg(II) ions compared to other tested metal ions. The binding constants (Ka) of receptors 1 and 2 are 2.53 × 105 M−1 and 0.99 × 105 M−1, respectively, which are reported with the help of Benesi–Hildebrand method.