Design of Metal Free Fluorescent Pyridine Dyes Anchored on Cadmium Sulfide Nanowires: Optical, Electrochemical and Photovoltaic Applications.

Through a facile two-step synthetic procedure, three metal-free organic dyes having D-π-A kind of structure, belonging to chalcone family have been designed, produced and anchored on one dimensional cadmium sulfide nanowires (1D CdS NWs) to serve as a light energy harvester through dye-sensitized solar cells (DSSC) assembly. In order to anchor dye on CdS NWs nano-network, solution chemistry has been used in an easy and effective manner. The sensitizing capability of synthesized materials has been evaluated using optical and electrochemical studies, density functional theory (DFT) simulations, and photovoltaic performances. In line with a detailed analysis of fabricated Dye sensitized solar cells containing T4PC a photovoltaic efficiency yields 4.35 times (0.487%) more than that of bare CdS NWs (0.112%), while the other devices having T3PC and T2PC have shown 3.0 (0.338%) and 2.40 (0.273%) times greater photovoltaic efficiencies, respectively under standard light illumination. The obtained results offer solid evidence in favour of boosting external quantum efficiency (EQE) and reflect good agreement with the optical studies.

Green biochemistry approach for synthesis of silver and gold nanoparticles using Ficus racemosa latex and their pH-dependent binding study with different amino acids using UV/Vis absorption spectroscopy.

Simple and eco-friendly biosynthesis approach was developed to synthesize silver nanoparticles (SNPs) and gold nanoparticles (GNPs) using Ficus racemosa latex as reducing agent. The presence of sunlight is utilized with latex and achieved the nanoparticles whose average size was in the range of 50-120 nm for SNPs and 20-50 nm for GNPs. The synthesized nanoparticles were characterized by UV/Visible absorption spectroscopy, X-ray diffraction, and field emission-scanning electron microscopy techniques toget understand the obtained nanoparticles. The pH-dependent binding studies of SNPs and GNPs with four amino acids, namely L-lysine, L-arginine, L-glutamine and glycin have been reported.

"Unveiling marigold assembled micro flowers of tungsten oxide towards solid-state flexible pouch and coin cell supercapacitors".

Marigold analogues micro flowers of tungsten oxide (WO3) have been grown in thin film form through simple and cost-effective solution chemistry approach on stainless steel substrate. Aqueous precursor involving WO4-2 ions agglomerated as self-sacrificing template growing initially into the nano-petal, followed by self-assembly; leading to marigold analogues micro flower surface architecture. This enthralling morphology motivated us not only to fabricate supercapacitive electrode but also to design complete solid-state supercapacitor devices in dual configurations: flexible pouch cell and coin cell. Interestingly, both devices even in symmetric configuration yields remarkable potential window of 1.82 V when sandwiched by gel inclusive of Li+ ions dispersed in non-conducting polyvinyl alcohol matrix. Solid-state flexible pouch cell and coin cell delivered specific capacitances of 103.98 ± 3.59 and 30.09 ± 1.03 F/g respectively at a scan rate of 5 mV/s. Assembled electrode, coin-cell and flexible pouch-cells have been well assessed in-depth through specific capacitances using cyclic voltammetry and galvanostatic charge discharge, diffusive and capacitive contributions, mechanical bending tests, electrochemical active surface area, and electrochemical impedance analysis. Practical applicability has been demonstrated for designed flexible pouch cell to run small fan and light emitting diode panel whereas coin cell to run light emitting diode panel.

An overview of green synthesized silver nanoparticles towards bioactive antibacterial, antimicrobial and antifungal applications.

Present review emphatically introduces the synthesis, biocompatibility, and applications of silver nanoparticles (AgNPs), including their antibacterial, antimicrobial, and antifungal properties. A comprehensive discussion of various synthesis methods for AgNPs, with a particular focus on green chemistry mediated by plant extracts has been made. Recent research has revealed that the optical properties of AgNPs, including surface plasmon resonance (SPR), depend on the particle size, as well as the synthesis methods, preparation synthesis parameters, and used reducing agents. The significant emphasis on the use of synthesized AgNPs as antibacterial, antimicrobial, and antifungal agents in various applications has been reviewed. Furthermore, the application areas have been thoroughly examined, providing a detailed discussion of the underlying mechanisms, which aids in determining the optimal control parameters during the synthesis process of AgNPs. Furthermore, the challenges encountered while utilizing AgNPs and the corresponding advancements to overcome them have also been addressed. This review not only summarizes the achievements and current status of plant-mediated green synthesis of AgNPs but also explores the future prospects of these materials and technology in diverse areas, including bioactive applications.

La-Fe-O Perovskite Based Gas Sensors: Recent Advances and Future Challenges.

Interest in the importance of gas sensing devices has increased significantly due to their critical function in monitoring the environment and controlling pollution, resulting in an increased market demand. The present review explores perovskite La-Fe-O based gas sensors with a special focus on LaFeO3 and evaluates their sensitivity to a diverse range of practical target gases that need to be monitored. An analysis has been conducted to assess different routes not only of synthesizing LaFeO3 material but also of characterization with the targeted use for their gas sensing abilities. Additionally, a comprehensive analysis has been performed to explore the effect of introducing other elements through doping. In view of the LaFeO3 sensing performance, more common gases like acetone, ethanol, methanol, formaldehyde, NO x , and CO2 have been targeted. In addition, a discussion on uncommon gases such as CO, SO2, TEA, C2H5, C6H6, and others is also made to give a complete picture of LaFeO3-based gas sensors. The summary and conclusion section of the study addresses the primary obstacles in the synthesis process, the variables that restrict the sensing capabilities of LaFeO3, and its commercial fulfillment.

Exploring Vacuum-Assisted Thin Films toward Supercapacitor Applications: Present Status and Future Prospects.

Demand for high-performance energy storage devices is growing tremendously. Supercapacitors possess an excellent candidature to fulfill the energy storage requisites such as high energy density when compared to conventional capacitors, high power density, and cycling stability as compared to batteries, though not only for large-scale devices for higher energy/power density applications but also for macro- to microdevices for miniaturized electrical components. With the aid of various routes, many materials have been explored with well-tuned properties with controlled surface architecture through various preparative parameters to find those best suited for supercapacitive electrodes. Growth of a thin film can be accomplished through chemical or physical (vacuum-assisted) routes. Vacuum-assisted (physical) growth yields high purity, precise dimensions with a line-of-sight deposition, along with high adhesion between the film and the substrates, and hence, these techniques are necessary to manufacture many macro- to microscale supercapacitor devices. Still, much effort has not been put forth to explore vacuum-assisted techniques to fabricate supercapacitive electrodes and energy storage applications. The present review explores the first comprehensive report on the growth of widespread materials through vacuum-assisted physical deposition techniques inclusive of thermal evaporation, e-beam evaporation, sputtering, and laser beam ablation toward supercapacitive energy storage applications on one platform. The theoretical background of nucleation and growth through physical deposition, optimization of process parameters, and characterization to supercapacitor applications from macro- to microscale devices has been well explored to a provide critical analysis with literature-reviewed materials. The review ends with future challenges to bring out upcoming prospects to further enhance supercapacitive performance, as much work and materials need to be explored through these routes.

Lamellar structured Ni3P2O8: first-ever use to design 1.8 V operated flexible all-solid-state symmetric supercapacitor.

Increasing demand for microelectronic devices necessitates the development of highly flexible energy storage technologies with a wide operating voltage. Thus, flexible electrodes and their devices with the requisite mechanical and electrochemical characteristics have prime importance. In this regard, the present article demonstrates the feasibility of designing a flexible all-solid-state supercapacitor using a chemically grown Ni3P2O8 lamellar microstructured electrode embedded with carboxy methyl cellulose-Na2SO4 (CMC-Na2SO4) gel electrolyte. The formed symmetric device impressively exhibited a maximum working voltage window of 1.8 V with a high specific energy of 44.7 W h kg-1 and specific power of 3.3 kW kg-1 along with prolonged cycle life. Also, the device's high deformation tolerance (95%) when bent at 170° with a flashing light-emitting diode (LED) working demonstration showcases its viability for advanced flexible energy storage applications.

The electrochemical kinetics of cerium selenide nano-pebbles: the design of a device-grade symmetric configured wide-potential flexible solid-state supercapacitor.

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.

Core-shell cadmium sulphide @ silver sulphide nanowires surface architecture: Design towards photoelectrochemical solar cells.

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.

ZnO/CuSCN Nano-Heterostructure as a Highly Efficient Field Emitter: a Combined Experimental and Theoretical Investigation.

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.

Novel chemical route for CeO2/MWCNTs composite towards highly bendable solid-state supercapacitor device.

Electrode materials having high capacitance with outstanding stability are the critical issues for the development of flexible supercapacitors (SCs), which have recently received increasing attention. To meet these demands, coating of CeO2 nanoparticles have been performed onto MWCNTs by using facile chemical bath deposition (CBD) method. The formed CeO2/MWCNTs nanocomposite exhibits excellent electrochemical specific capacitance of 1215.7 F/g with 92.3% remarkable cyclic stability at 10000 cycles. Light-weight flexible symmetric solid-state supercapacitor (FSSC) device have been engineered by sandwiching PVA-LiClO4 gel between two CeO2/MWCNTs electrodes which exhibit an excellent supercapacitive performance owing to the integration of pseudocapacitive CeO2 nanoparticles onto electrochemical double layer capacitance (EDLC) behaved MWCNTs complex web-like structure. Remarkable specific capacitance of 486.5 F/g with much higher energy density of 85.7 Wh/kg shows the inherent potential of the fabricated device. Moreover, the low internal resistance adds exceptional stability along with unperturbed behavior even under high mechanical stress which can explore its applicability towards high-performance flexible supercapacitor for advanced portable electronic devices.

First report on solution processed α-Ce2S3 rectangular microrods: An efficient energy storage supercapacitive electrode.

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.

Facile chemical route for multiwalled carbon nanotube/mercury sulfide nanocomposite: High performance supercapacitive electrode.

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.

SILAR controlled CdSe nanoparticles sensitized ZnO nanorods photoanode for solar cell application: Electrolyte effect.

Controlled growth of different sizes of cadmium selenide (CdSe) nanoparticles over well aligned ZnO nanorods have been performed using successive ionic layer adsorption and reaction (SILAR) technique at room temperature (27 °C) in order to form nano heterostructure solar cells. Deposition of compact layer of zinc oxide (ZnO) by SILAR technique on fluorine doped tin oxide (FTO) coated glass substrate followed by growth of vertically aligned ZnO nanorods array using chemical bath deposition (CBD) at low temperature (<100 °C). Different characterization techniques viz. X-ray diffractometer, UV-Vis spectrophotometer, field emission scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy have been used to know the structural, optical, morphological and compositional properties of synthesized nano heterostructure. The photovoltaic performance of the cells with variation in SILAR cycles for CdSe and with use of different electrolytes have been recorded as J-V characteristics and the maximum conversion efficiency of 0.63% have been attained with ferro/ferri cyanide electrolyte for 12 cycles CdSe coating over 1-D ZnO nanorods.

Porous zinc cobaltite (ZnCo2O4) film by successive ionic layer adsorption and reaction towards solid-state symmetric supercapacitive device.

One-step, simple and inexpensive successive ionic layer adsorption and reaction (SILAR) method has been used to synthesize porous network of zinc cobaltite (ZnCo2O4) in 2D form on stainless steel (SS) substrate. Porous structure of ZnCo2O4 electrode enables electrochemical specific capacitance of 675Fg-1 at 5mVs-1 sweep rate with high rate capability and cycling performance of 69% over 2000 cycles. Furthermore, fabricated ZnCo2O4 solid-state supercapacitor cell in symmetric mode using PVA-KOH gel electrolyte exhibited a specific capacitance of 69.65Fg-1 with specific energy of 9.67Whkg-1 and specific power of 1.45kWkg-1 at a current density of 1.07Ag-1. The results clearly demonstrate the facile method for the synthesis of porous network of ZnCo2O4 and make them promising electrode material for energy storage application.

Chemically deposited Bi2S3:PbS solid solution thin film as supercapacitive electrode.

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 402.4F/g at current density of 1mA/cm2 with modest charge-discharge cycles. In terms of energy storage, it exhibited maximum specific power of 20.1Wh/kg with accepting specific power of 1.2kW/kg. The combination of two nanoparticles in nanocomposites thin film supplies new tactic for energy storage applications.

Hexagonal VS2 Anchored MWCNTs: First Approach to Design Flexible Solid-State Symmetric Supercapacitor Device.

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.

V2O5 encapsulated MWCNTs in 2D surface architecture: Complete solid-state bendable highly stabilized energy efficient supercapacitor device.

A simple and scalable approach has been reported for V2O5 encapsulation over interconnected multi-walled carbon nanotubes (MWCNTs) network using chemical bath deposition method. Chemically synthesized V2O5/MWCNTs electrode exhibited excellent charge-discharge capability with extraordinary cycling retention of 93% over 4000 cycles in liquid-electrolyte. Electrochemical investigations have been performed to evaluate the origin of capacitive behavior from dual contribution of surface-controlled and diffusion-controlled charge components. Furthermore, a complete flexible solid-state, flexible symmetric supercapacitor (FSS-SSC) device was assembled with V2O5/MWCNTs electrodes which yield remarkable values of specific power and energy densities along with enhanced cyclic stability over liquid configuration. As a practical demonstration, the constructed device was used to lit the 'VNIT' acronym assembled using 21 LED's.