Morphological tuning of CuO nanostructures by simple preparative parameters in SILAR method and their consequent effect on supercapacitors

Morphology-controlled synthesis of nanomaterials by tuning simple preparative parameters is an impressive path to develop diverse nanostructured materials. Here, we are exploring a successful example of fabrication of hierarchical CuO nanostructures (nanoflakes, nanopetals and diffused nanorods) by simply controlling temperature of reaction bath (3rd beaker) in SILAR method. These CuO nanostructures are further successfully employed as electrode material in supercapacitors. The correlation between electrochemical supercapacitive properties and nanostructures of CuO is investigated in detail. It is revealed that, the supercapacitive properties strongly depend on CuO nanostructures. The specific capacitance values for nanoflakes, nanopetals and diffused nanorods of CuO are found to be 664 F/g, 790 F/g and 695 F/g, respectively at 5 mV/s scan rate. Ragone plot ascertains that CuO nanostructures obtained by SILAR method are potential candidates for high power and high energy density supercapacitors. In addition, EIS analyses show lower ESR values and excellent frequency response for CuO nanostructures.One of the authors (SKS) is grateful to the University Grants Commission (UGC), New Delhi for financial support through the scheme UGC-BSR. The authors are thankful to the DST (DST-FIST, DST-PURSE) India for providing instrumental facilities at Department of Physics, Shivaji University, and Kolhapur. One of the authors (VJF) is grateful to the University Grants Commission (UGC), New Delhi for financial support through the scheme no. MRP. MAJOR-PHYS-2013-35168. Analysis of CuO samples was supported by Dongguk University, Seoul, Korea Research Fund 2014–2015.Peer Reviewe

Influence of Mn incorporation on the supercapacitive properties of hybrid CuO/Cu(OH)2 electrodes

Here, we are presenting the effect of Mn doping on the supercapacitive properties of CuO/Cu(OH)2 hybrid electrodes. Briefly, Mn doped CuO/Cu(OH)2 (Mn:CuO/Cu(OH)2) thin films have been synthesized by a successive ionic layer adsorption and reaction (SILAR) method which are further characterized by different physiochemical techniques. Our results revealed the formation of hybrid CuO/Cu(OH)2 thin films with significant morphological deviation through Mn doping. Moreover, considerable positive effect of Mn doping on the electrochemical properties of hybrid CuO/Cu(OH)2 electrodes have been witnessed. Later, the results suggest that at 3% Mn doping in CuO/Cu(OH)2 electrodes with nanoflower-like nanostructures exhibits the highest specific capacitance. The maximum specific capacitance achieved for a 3% Mn:CuO/Cu(OH)2 hybrid electrode is 600 F g-1 at 5 mV s-1 in 1 M Na2SO4 electrolyte. Additionally, a Ragone plot confirms the potential of the Mn:CuO/Cu(OH)2 hybrid electrode for electrical energy storage applications.One of the authors SKS wishes to acknowledge the UGC-SAP DSA-I, New Delhi INDIA for financial support through UGC-BSR scheme.Peer Reviewe

Impact of annealing temperature on the morphological, optical and photoelectrochemical properties of cauliflower‐like cdse0.6te0.4 photoelectrodes; enhanced solar cell performance

We are reporting on the impact of air annealing temperatures on the physicochemical properties of electrochemically synthesized cadmium selenium telluride (CdSe0.6Te0.4) samples for their application in a photoelectrochemical (PEC) solar cell. The CdSe0.6Te0.4 samples were charac-terized with several sophisticated techniques to understand their characteristic properties. The XRD results presented the pure phase formation of the ternary CdSe0.6Te0.4 nanocompound with a hexagonal crystal structure, indicating that the annealing temperature influences the XRD peak intensity. The XPS study confirmed the existence of Cd, Se, and Te elements, indicating the formation of ternary CdSe0.6Te0.4 compounds. The FE‐SEM results showed that the morphological engineering of the CdSe0.6Te0.4 samples can be achieved simply by changing the annealing temperatures from 300 to 400 °C with intervals of 50 °C. The efficiencies (ƞ) of the CdSe0.6Te0.4 photoelectrodes were found to be 2.0% for the non‐annealed and 3.1, 3.6, and 2.5% for the annealed at 300, 350, and 400 °C, respectively. Most interestingly, the PEC cell analysis indicated that the annealing temperatures played an important role in boosting the performance of the photoelectrochemical properties of the solar cells.</p

Electrochemical synthesis: Monoclinic Cu2Se nano-dendrites with high performance for supercapacitors

et al.Morphology is a key factor in designing novel nanomaterials with controlled functional properties for the electrochemical application. Herein, we demonstrate the supercapacitor applications of the copper selenide (CuSe) electrodes with different morphologies prepared by electrodeposition at -0.65, -0.75, and -0.85 V/SCE deposition potentials. The well-defined morphologies of the CuSe nanostructures have been useful to develop potential applications in the supercapacitor devices. The nanodendrite-like morphology obtained at the deposition potential -0.75 V/SCE showed maximum specific capacitance (688 F/g at 5 mV/s) as compared to the other morphologies.Analysis of CdSe0.6Te0.4 samples was supported by Dongguk University, Seoul, Korea Research Fund 2016–2018.Peer Reviewe

Enhanced photoelectrochemical properties of nanoflower-like hexagonal CdSe0.6Te0.4: Effect of electron beam irradiation

Present investigation deals with the effect of electron beam irradiation on the photoelectrochemical properties of cadmium selenium telluride (CdSeTe) thin films. Initially, CdSeTe thin films were electrodeposited on fluorine doped tin oxide (FTO) coated glass and stainless steel substrates. Later, these CdSeTe thin films were irradiated with high energy electron beam (10 MeV) of different doses from 10 to 30 kilograys (kGy). The effect of electron beam irradiation on different physico-chemical properties of CdSeTe thin films such as morphological, structural, optical and photoelectrochemical has been investigated. It is observed that, the electron beam irradiation treatment considerably affects the properties of CdSeTe thin films. The surface morphology of CdSeTe thin films was changed from cauliflowers to nanoflowers, nanoroses and interconnected nanoflakes with doses of electron beams. Furthermore, the effect of electron beam irradiation on photoelectrochemical properties of CdSeTe films was investigated. It is interesting to note that, the photoelectrochemical (PEC) properties of CdSeTe thin films are extensively affected by electron beam irradiation. The photoconversion efficiency values of CdSeTe films for different doses of electron beam are found to be 0.9%, 1.1%, 2.0% and 1.5%, respectively.Analysis of CdSe0.6Te0.4 samples was supported by Dongguk University, Seoul, Korea Research Fund 2016–2018. One of the authors (VJF) is grateful to the University Grants Commission (UGC), New Delhi for financial support through the scheme no. MRP. MAJOR-PHYS-2013-35168.Peer Reviewe

Thiolation of Chitosan Loaded over Super-Magnetic Halloysite Nanotubes for Enhanced Laccase Immobilization

This study focuses on the development of a nanosupport based on halloysite nanotubes (HNTs), Fe3O4 nanoparticles (NPs), and thiolated chitosan (CTs) for laccase immobilization. First, HNTs were modified with Fe3O4 NPs (HNTs-Fe3O4) by the coprecipitation method. Then, the HNTs-Fe3O4 surface was tuned with the CTs (HNTs-Fe3O4-CTs) by a simple refluxing method. Finally, the HNTs- Fe3O4-CTs surface was thiolated (-SH) (denoted as; HNTs- Fe3O4-CTs-SH) by using the reactive NHS-ester reaction. The thiol-modified HNTs (HNTs- Fe3O4-CTs-SH) were characterized by FE-SEM, HR-TEM, XPS, XRD, FT-IR, and VSM analyses. The HNTs-Fe3O4-CTs-SH was applied for the laccase immobilization. It gave excellent immobilization of laccase with 100% activity recovery and 144 mg/g laccase loading capacity. The immobilized laccase on HNTs-Fe3O4-CTs-SH (HNTs-Fe3O4-CTs-S-S-Laccase) exhibited enhanced biocatalytic performance with improved thermal, storage, and pH stabilities. HNTs-Fe3O4-CTs-S-S-Laccase gave outstanding repeated cycle capability, at the end of the 15th cycle, it kept 61% of the laccase activity. Furthermore, HNTs-Fe3O4-CTs-S-S-Laccase was applied for redox-mediated removal of textile dye DR80 and pharmaceutical compound ampicillin. The obtained result marked the potential of the HNTs-Fe3O4-CTs-S-S-Laccase for the removal of hazardous pollutants. This nanosupport is based on clay mineral HNTs, made from low-cost biopolymer CTs, super-magnetic in nature, and can be applied in laccase-based decontamination of environmental pollutants. This study also gave excellent material HNTs-Fe3O4-CTs-SH for other enzyme immobilization processes

α-Cellulose Fibers of Paper-Waste Origin Surface-Modified with Fe3O4 and Thiolated-Chitosan for Efficacious Immobilization of Laccase

The utilization of waste-paper-biomass for extraction of important α-cellulose biopolymer, and modification of extracted α-cellulose for application in enzyme immobilization can be extremely vital for green circular bio-economy. Thus, in this study, α-cellulose fibers were super-magnetized (Fe3O4), grafted with chitosan (CTNs), and thiol (-SH) modified for laccase immobilization. The developed material was characterized by high-resolution transmission electron microscopy (HR-TEM), HR-TEM energy dispersive X-ray spectroscopy (HR-TEM-EDS), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FT-IR) analyses. Laccase immobilized on α-Cellulose-Fe3O4-CTNs (α-Cellulose-Fe3O4-CTNs-Laccase) gave significant activity recovery (99.16%) and laccase loading potential (169.36 mg/g). The α-Cellulose-Fe3O4-CTNs-Laccase displayed excellent stabilities for temperature, pH, and storage time. The α-Cellulose-Fe3O4-CTNs-Laccase applied in repeated cycles shown remarkable consistency of activity retention for 10 cycles. After the 10th cycle, α-Cellulose-Fe3O4-CTNs possessed 80.65% relative activity. Furthermore, α-Cellulose-Fe3O4-CTNs-Laccase shown excellent degradation of pharmaceutical contaminant sulfamethoxazole (SMX). The SMX degradation by α-Cellulose-Fe3O4-CTNs-Laccase was found optimum at incubation time (20 h), pH (3), temperatures (30 °C), and shaking conditions (200 rpm). Finally, α-Cellulose-Fe3O4-CTNs-Laccase gave repeated degradation of SMX. Thus, this study presents a novel, waste-derived, highly capable, and super-magnetic nanocomposite for enzyme immobilization applications

Recent Advances in the Development of Laccase-Based Biosensors via Nano-Immobilization Techniques

Monitoring phenolic compounds is critical in the environmental, food, and medical sectors. Among many recent advanced detection platforms, laccase-based biosensing platforms gave very rapid, effective, online, and in situ sensing of phenolic compounds. In laccase-based biosensors, laccase immobilization techniques have a vital role. However, a detailing of the advancements in laccase immobilization techniques employed in laccase-based biosensors is lacking in the literature. Thus, in this review, we assessed how the nano-immobilization techniques shaped the laccase biosensing platforms. We discussed novel developments in laccase immobilization techniques such as entrapment, adsorption, cross-linking, and covalent over new nanocomposites in laccase biosensors. We made a comprehensive assessment based on the current literature for future perspectives of nano-immobilized laccase biosensors. We found the important key areas toward which future laccase biosensor research seems to be heading. These include 1. A focus on the development of multi-layer laccase over electrode surface, 2. The need to utilize more covalent immobilization routes, as they change the laccase specificity toward phenolic compounds, 3. The advancement in polymeric matrices with electroconductive properties, and 4. novel entrapment techniques like biomineralization using laccase molecules. Thus, in this review, we provided a detailed account of immobilization in laccase biosensors and their feasibility in the future for the development of highly specific laccase biosensors in industrial, medicinal, food, and environmental applications

Utilization of Noxious Weed Water Hyacinth Biomass as a Potential Feedstock for Biopolymers Production: A Novel Approach

This study aims to utilize a noxious weed water hyacinth biomass (WH) for polyhydroxybutyrate (PHB) production. Alkaline and peracetic acid pretreatment was employed for the hydrolysis of WH and consequently enzymatic saccharification to produce fermentable sugars for PHB production. The pretreatment competence was determined using various operational parameters. By applying ambient conditions, alkaline pretreatment gave higher lignin removal of 65.0%, with 80.8% hydrolysis yield, and on enzyme hydrolysis (40 FPU/g of dry WH), produced total reducing sugar of about 523 mg/g of WH. The resulted WH enzymatic hydolysates were evaluated for the production of PHB by Ralstonia eutropha (ATCC 17699). The WH hydrolysates cultivation was compared to synthetic hydrolysates that contain a similar carbon composition in terms of bacterial growth and PHB synthesis. The effects of various supplements to enhance PHB production were estimated. Supplementation of corn steep liquor (CSL) as a cheap nitrogen source with WH hydrolysates favored a higher amount of PHB synthesis (73%), PHB titer of 7.30 g/L and PHB yield of 0.429 g/g of reducing sugar. Finally, using standard analytical tools, the physical and thermal characteristics of the extracted PHB were evaluated. The findings revealed WH was a promising and technically feasible option for transforming biomass into sustainable biopolymer conversion on a large scale

Green-Synthesis of Anisotropic Peptone-Silver Nanoparticles and Its Potential Application as Anti-Bacterial Agent

This study demonstrates a green-route-based synthesis of high-concentration suspensions of anisotropic silver nanoparticles (AgNPs) by peptone (Pep), a soluble protein hydrolysate and an abundantly used nutrient source in microbial-media. The transformation of Ag ions from solution into a high-concentration suspension of anisotropic Pep-AgNPs, at an extremely low concentration of peptone (0.02%), indicates that the present green-route synthesis method follows &#8220;low volume high concentration nano-synthesis&#8222;, and, hence, enhances the economic significance of the process. Process optimization with different concentrations of AgNPs (1&#8315;5 mM), NaOH solution (5&#8315;40 mM), and peptone (0.004%&#8315;0.12%) gave the optimized Pep-AgNPs synthesis at 3 mM of AgNO3, 20 mM of NaOH, and 0.02% of the peptone concentrations. The green-route synthesized Pep-AgNPs were structurally characterized by the TEM, XPS, FT-IR, and XRD analyses. The Pep-AgNPs against the clinically relevant bacteria Escherichia coli and Staphylococcus aureus gave significant anti-bacterial properties, with a MIC (minimum inhibitory concentration) of 100 ppm. The colony counting and morphological observation of the bacterial cell under SEM corroborated an anti-bacterial potential of the Pep-AgNPs. Therefore, Pep-AgNPs are green-route synthesized, anisotropic, and have a significant anti-bacterial potential that can be used in many relevant applications