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A simple and low-cost and highly calibrated probe sonication method was used to prepare bismuth oxide nanoparticles (Bi2O3 NPs). The formation of a well-crystalline sample at the end of the product has been further calcined at 600°C for 2 hrs. The powder X-ray diffraction (PXRD) patterns of the NPs substantiated the monoclinic structure (space group P21/c), and the average crystallite size was found to be 60 nm, which was also confirmed by transmission electron microscopic (TEM) studies. Scanning electron microscopic (SEM) images depicted highly porous Bi2O3 NPs with little agglomeration. Utilizing diffused reflectance spectra (DRS) data, the energy bandgap ( E g ) value of 3.3 eV was deduced for Bi2O3 NPs, and their semiconductor behavior has been confirmed. Two dyes, methylene blue (MB) and acid green (AG) were utilized for degradation studies using Bi2O3 NPs under UV light irradiation (from 0 to 120 min). The photocatalytic degradation was found to be maximum for MB (93.45%) and AR (97.80%) dyes. Cyclic voltammetric (CV) and sensor studies using the electrochemical impedance spectroscopy (EIS) were performed. The specific capacitance value of 25.5 Fg-1 was deduced from the cyclic voltammograms of the Bi2O3 electrode in 0.1 N HCl with a scan rate of 10 to 50 mV/s. From the obtained EIS data, the Bi2O3 electrode showed pseudocapacitive characteristics. The prepared electrodes also exhibited high sensitivity towards the detection of ascorbic acid and lead. Hence, sonochemically synthesized Bi2O3 NPs are possibly hopeful for excellent photocatalytic and electrochemical sensing of biomolecules.

The conversion of nitrogen to ammonia offers a sustainable and environmentally friendly approach for producing precursors for fertilizers and efficient energy carriers. Owing to the large energy density and significant gravimetric hydrogen content, NH

Research and technology development of lithium ion battery is very important nowadays because of its high energy and power density, low self discharge, no/less memory effect, comparatively high current output. It has been largely used in various fields like hybrid electric vehicles (EV's), portable devices, digital cameras and many more. As per our knowledge this is the first report on the synthesis of KTaO3 and examination of electrochemical performance on lithium ion batteries (LIB). The flower like nanostructured KTaO3 exhibits high interfacial area and less path length for charge transfer, which was the main reason to exhibit good electrochemical properties. The average crystallite size of material was confirmed by XRD analysis and found to be ~26 nm. The high irreversible capacity was recorded at 1307 mAh g−1 with high Columbic efficiency (~99%) at potential window of 0.01–3.00 V. Moreover, reversible first discharge capacity was measured at 432 mAh g−1 at 0.1 C current rates with exemplary cyclic stability. The capacity fade was negligible for consecutive cycles. Even at very high current rate (3C) also it presents good capacity of 74 m Ahg−1 with excellent reversibility. In addition, electrochemical impedance spectra prove the less conductive resistance at higher frequency region. Finally the present work explains the excellent electrochemical performance of nanostructured flower like KTaO3 for Li-ion battery as anode material.

Two-dimensional (2D) conducting metal-organic frameworks (MOFs) is an emerging family of porous materials that have attracted a great attention due to their outstanding inherent properties such as hierarchical porosity, diverse architectures with high surface area and excellent electrical conductivity. These unique features make them ideal candidates for electrochemical energy storage technologies. This review highlights the key innovations on 2D conducting MOFs with emphasis on the design and synthesis strategies, and their potential applications in energy storage systems. Several recent breakthrough examples of 2D conducting MOFs with enhanced electrochemical performances are outlined. The review further extends the discussion on the significance of Nuclear Magnetic Resonance Spectroscopy (NMR) to understand the charge storage kinetics and their impact on structural implications of the materials. The elucidation of structure-property-performance relationship will further guide the development of new architectures of 2D conducting MOFs for the high-performance energy storage devices.

Lightweight computing technologies such as the Internet of Things and flexible wearable systems have penetrated our everyday lives exponentially in recent years. Without a question, the running of such electronic devices is a major energy problem. Generally, these devices need power within the range of microwatts and operate mostly indoors. Thus, it is appropriate to have a self-sustainable power source, such as the photovoltaic (PV) cell, which can harvest indoor light. Among other PV cells, the dye-sensitized solar cell (DSSC) has immense capacity to satisfy the energy demands of most indoor electronics, making it a very attractive power candidates because of its many benefits such as readily available materials, relatively cheap manufacturing methods, roll-to-roll compatibility, easy processing capabilities on flexible substrates and exceptional diffuse/low-light performance. This review discusses the recent developments in DSSC materials for its indoor applications. Ultimately, the perspective on this topic is presented after summing up the current progress of the research. Graphic abstract

3D chitosan scaffolds treated with alkali showed enhanced mechanical properties and stability in aqueous conditions. Chitosan is a preferred polymer for biomedical applications due to its antimicrobial, antioxidant and wound healing properties. Chitosan has been made into films, fibers, micro and nanoparticles and electrospun membranes for tissue engineering, drug delivery and other medical applications. However, materials made from chitosan have poor strength and stability. Compared to other forms, 3D scaffolds are more suitable for tissue engineering and other applications but are relatively easily susceptible to moisture and have poor strength due to their porous structure. Several physical and chemical approaches have been used to increase the strength and stability of chitosan biomaterials. In this study, we demonstrate that a simple treatment with alkali will substantially improve the strength and stability of freeze-dried 3D chitosan scaffolds. Three different concentrations of chitosan were lyophilized and made into scaffolds with varying properties. These scaffolds were alkali treated and tested for their increase in strength, resistance to water and other properties. Up to 50% increase in strength was possible when higher concentrations of chitosan and alkali treatment were used. The scaffolds have good activity against both gram positive and gram negative bacteria with the highest percentage of inhibition being 97%. Scaffolds also showed the ability to generate hydroxyapatite when incubated in phosphate buffered saline (PBS) for 7 days. This study provides a novel approach to obtain 3D chitosan scaffolds with properties suitable for medical, food and other applications.

Metal/metal oxide nanocomposites (NCs) have been attracting significant attention in recent times because of their applications in the fields of energy and environment. In the present work, we investigate the photocatalytic and electrochemical performances of Ni/NiO NCs synthesized by a facile and cost-effective reduction method using lithium salt as the dopant. Lithium influences the size, morphology and structural constitution of the final product. A variation in the lithium percentage was seen to have a direct effect on the Ni content. The structural conformation of the samples has been analyzed by XRD and further confirmed by XPS. A low optical energy bandgap (∼3.7 eV) and a mesoporous structure of the as-prepared samples were seen to play a crucial role in achieving the photocatalytic degradation of the cationic organic dyes concomitant to its electrochemical activity. On illumination with UV light, the Li-doped Ni/NiO NCs demonstrated rapid degradation of crystal violet and methyl violet 2B dyes. The synergism arising due to the substitutional doping of lithium and the presence of metallic nickel leads to efficient photodegradation of the dye pollutants by the catalysts. Further, the Li-doped Ni/NiO NCs displayed a better electrochemical performance than the undoped samples. The NC with 1 wt% Li exhibited the best values of specific capacitance (276.2 F g−1 at 5 A g−1) with an excellent cycling ability (

In the recent times, global interest on plant-based research has increased significantly. Through this article, a simple heat treatment method to synthesize Centella asiatica (CA) powder has been suggested. The synthesized samples have been subjected to various structural and morphological characterizations, in addition to electrochemical studies. Although the medicinal value of Centella asiatica is well known, its use in other applications is hardly explored. Hence, by combining the cyclic nature of CA and the layered structures of carbonaceous materials, composites of Centella asiatica with graphite powder, GO and rGO have been prepared for the first time and their photocatalytic and electrochemical properties have been investigated. In spite of some agglomeration and flake like structures, the nanosize (14 nm) of the prepared CA sample contributes largely to the aforementioned applications. One of the phenomenal aspects of the synthesized sample is that the low energy gap and high conductivity makes it an excellent photocatalytic material which is also evident from its ability to decolorize AO 8 dye under UV light to a great extent. Among the composites of CA-carbonaceous materials prepared, Centella asiatica-rGO exhibited superior electrochemical properties with high capacitance and low charge transfer resistance.

A rapid and facile method for the detection of hydrogen peroxide (H2O2) in chemical reactions has been reported using molybdenum oxide Nanoparticles (MoO3 NPs) synthesized via an eco-friendly and economical solution combustion route using Centella Asiatica leaf powder. The formation of porous agglomerated NPs has been confirmed by subjecting the synthesized material to various analytical and spectroscopic techniques to understand their size, morphology, and nature. In this study, MoO3 NPs-based electrode has been fabricated and its electrochemical sensing capabilities have been investigated. Electrochemical investigation of hydrogen peroxide exhibits an increase in the peak current response at pH 13. The cyclic voltammetry (CV) results indicate an appreciable reversibility of the electrode reaction. The anodic and cathodic peaks show a greater inclination towards the positive and negative sides with a significant development in the reversibility of the oxidation and reduction states. These findings open up new avenues for the exploration of various other metal oxide based NPs as sensors for the detection of chemically toxic substances.

Textiles are known to be the best substrates for growing a variety of microorganisms efficiently at appropriate temperatures and humidity in contact with the human body. Currently, increasing public concern about hygiene has been driving many investigations about antimicrobial surface modification of textiles. The present research reports on the synthesis and characterization of nanosized copper oxide nanoparticles (CuONPs) and their application on cotton fabric to increase the bactericidal and hydrophobic properties. The synthesized materials have been subjected to spectroscopic and microscopic characterizations to help in understanding their structure, morphology, size, and composition. Further, upon dispersion of the nanoparticles onto the fabric, its hydrophobicity and mechanical properties were evaluated using electron microscopy and universal testing machine. Treated cotton fabric exhibits higher tensile strength (32 MPa) than the untreated one (27 MPa), whereas copper nanoparticle-coated cotton fabric shows a fair hydrophobicity. Moreover, CuONPs-treated and untreated cotton fabrics have been analyzed for bactericidal activity against various gram-negative and gram-positive strains. Finally, the CuONPs-coated cotton fabric displays greater antibacterial activity against E. coli and exhibits superior antimicrobial activity even after 30 cycles of washing, indicating that the CuONPs-coated cotton fabric has a higher potential to be employed as a medical textile to avoid cross-infection within a clinical environment.

A green combustion method using Aloe vera latex as a fuel was employed to synthesize nanocrystalline cupric oxide (CuO). The nanocrystalline nature and phase of CuO was confirmed by powder X-ray diffraction. Applying the Kubelka–Monk function to diffuse reflectance spectra showed the band gap of CuO to be 1.632 eV. Paracetamol and d -glucose in 1 M KOH solution were sensed using a carbon paste electrode modified using CuO nanoparticles (NPs). The cyclic voltammetry results suggest that CuO NPs possess superior electrochemical properties due to a lower value of the difference between oxidation and reduction potential (EO-ER). The proton diffusion coefficient for CuO electrode material was1.5047 × 10−5cm2s−1. Electrochemical impedance and Bode studies confirmed that the charge-transfer resistance value of CuO NPs was on the lower side due to the phase angle (55°) being near to ф = ᴨ/2. The electrochemical behavior indicates that CuO is a promising electrode material for sensing molecules such as paracetamol and glucose.

Atmospheric gravity waves over the Polar Regions are found to have myriad effects on the dynamics and chemistry of the middle atmosphere. Data collected from high vertical resolution radiosonde measurements carried out in campaign mode from the Indian research base in Antarctica, Bharati (69.4°S, 76.2°E) during the austral summer seasons of 2014–2015, 2015–2016 and 2016–2017 were used to characterize inertia gravity waves (IGWs). Wavelet analysis technique is employed to identify and isolate individual IGW packets. IGWs in the lower stratosphere region are characterized in terms of their vertical and horizontal wavelengths, intrinsic frequencies, directions of propagation, momentum fluxes, energy densities and ground based phase speeds. The observed gravity waves have short vertical wavelengths (~ 2 km) and low intrinsic frequencies (1f–2f). Zonal and meridional components of momentum fluxes are found to have comparable magnitudes. From the direction of propagation estimates, it is observed that the IGWs have a marginal predisposition towards eastward propagation during austral summers. It is found that the lower stratospheric region over Bharati during summertime is dominated by IGWs from non-orographic sources. Evidences for generation of IGWs from an upper tropospheric jet streak observed over Bharati station are provided. The jet streak is found to be associated with the intrusion of low potential vorticity air from middle latitudes and the accompanied development of an anti-cyclonic circulation. The observations suggest that low potential vorticity intrusion happened as a result of breaking of poleward propagating Rossby wave. Spontaneous adjustment of the unstable jet could be responsible for the IGW generation. The significance of the present results lie in characterizing the summer time IGW over the Bharati station for the first time using wavelet based approach and identifying the possible source mechanism.

The present study confirms the application of phytochemicals of Lemon rind (LR) towards the synthesis of activated carbon using a low temperature carbonization method. The structural, morphological, and electrochemical properties of the prepared carbonized flakes epoxy (CFE) electrode has been analyzed using various characterization techniques. The electrochemical double layer capacitance (EDLC) behavior of the LR-activated carbon has been evaluated. The synthesized LR-activated carbon material exhibited flake like structure along with hydroxyl groups as confirmed by studies by scanning electron microscope (SEM), X-ray diffractometer (XRD), and Fourier transform infrared (FTIR) spectroscope. In addition, the band gap energy (Eg) has been estimated using diffused reflectance spectroscopy (DRS-UV-Vis) and found to be 2.06 eV. The electrochemical property of CFE-electrode was studied utilizing cyclic voltammetric (CV) and electrochemical impedance spectroscopic (EIS) techniques. The galvanostatic charge–discharge tests for this prepared carbon flake electrode demonstrated excellent capacitance performance, making it favorable for the fabrication of supercapacitors. These progressive results could be considered for the enlargement of novel assets to scale for power-storage utility using low-cost carbon materials in various energy storage applications as well.

An economic low-temperature self-ignition solution combustion method was used to synthesize 1–11 mol% chromium ion (Cr3+) doped MgAl2O4 nanoparticles (NPs). The structural, morphological and energy gap variations due to the influence of Cr3+ on the host matrix were evidenced by powder X-ray diffraction (PXRD), Fourier transformed infrared spectroscopy (FTIR), diffuse reflectance spectroscopy (DRS), and transmission electron microscopy (TEM). Under visible light irradiation, the as-prepared NPs showed excellent photocatalytic activities (PCA) for the industrial dye Acid Red-88 (AR-88) and pyrocatechol (PY) - an emerging pollutant (EP). The experiments were carried out at room temperature in an aqueous solution at a concentration of 20 ppm. Among others, MgAl2O4:Cr3+(5 mol%) showed 91.38% degradation within 150 min exhibiting zero-order kinetics and 82% degradation in 6 h displaying the first order kinetics for AR-88 dye and PY EP, respectively. In this case, a greater number of hydroxyl (OH.) radicles dominate over other reactive oxygen species (ROS), such as holes and singlet oxygens (1O2) under different pH conditions. Electrochemical studies have yielded the proton diffusion coefficient (D) value as large as 2.145 × 10−4 cm2s−1 for the optimized NP electrode, which is substantially greater than 1.0935 × 10−5 cm2s−1 for the pure MgAl2O4 one owing to the intercalated anions and structurally disordered density of the electrode material. This superior electrochemical behaviour suggests the potential application of the optimized NP material as an anodic electrode for supercapacitors. Published version This work was supported by the Science and Engineering Research Board, Govt. of India under the ASEAN - India Collaborative R&D Scheme (Project Grant No. CRD/2018/000066 M.S.S) of the ASEAN - India S&T Development Fund (AISTDF)

The current energy situation requires not only enormous energy in a brief period of time but clean energy as well. In this direction, a dye-sensitized solar cell (DSSC)—supercapacitor (SC) integrated energy device has been fabricated. This embedded energy system has a specific advantage such as easy manufacturing, low manufacturing costs, and flexible substrates compatibility. A natural photosensitizer was extracted from readily available beetroots and characterized using ultraviolet (UV)-visible spectroscopy. The zinc oxide semiconductor was synthesized using microwave technique and regarded as the DSSC photoanode material. The ZnO’s phase, purity, and morphology were investigated using X-ray diffraction (XRD) spectroscopy and scanning electron microscope. The iodine-doped cellulose acetate propionate (CAP) biopolymer electrolyte functions as the DSSC and supercapacitor electrolyte. The solid polymer electrolyte conductivity and dielectric studies were performed using electrochemical impedance spectroscopy (EIS). The laser-induced technique was used to synthesize graphene that plays a dual purpose as photocathode in DSSC and supercapacitor electrodes. The embedded energy unit from the DSSC-supercapacitor demonstrates a 6.75% fill factor representing its decent efficiency.

Insulin resistance is considered to be the most common cause of type 2 diabetes (T2D) wherein pancreatic β-cells cosecrete islet amyloid polypeptide (IAPP) with insulin and forms amyloid fibrils at low concentrations. Localization of IAPP between the secretory vesicle membrane and the crystal inhibits IAPP fibrillation. Moreover, inhibition of monomeric insulin and lipid membranes accelerate the fibrillation of IAPP in vitro. The present work investigates the interactions in vitro between lipid-IAPP-insulin under amyloid disease state. Fluorescence microscopy is used to investigate insulin’s effect on fibrillation of IAPP and to study the interactions of crystalline insulin with lipids and IAPP but revealed no significant interaction between IAPP and insulin. However, stable insulin-IAPP interactions are apparent in larger assemblies of crystalline insulin or IAPP fibres favouring the chances of various physiological interactions between these two β-cell hormones. The atomic force microscopy and electron microscopy studies indicate that the assembling process of hIAPP fibre can be tuned by the large surface of insulin. Also, the morphology of self-assembled nanostructures of hIAPP is modulated by the effect of insulin. These results are expected to offer a greater understanding of the interactions between insulin, lipids and peptides paving new dimensions in amyloid disease based therapeutics.

A new nanocomposite has been prepared embedding CuO nanoparticles as an additive into grafted β-nickel hydroxide electrode and their electrochemical performance in KOH electrolyte have been investigated. β-nickel hydroxide (β-Ni(OH)2) has been prepared by a simple precipitation method. Ni(OH)2/NiOOH, the main active materials in the pasted nickel electrode have been prepared using nickel mesh in the form of current collector. A study on the electrochemical performances of the pure β-Ni(OH)2 and CuO added β-Ni(OH)2 electrodes in 6.0 M KOH electrolyte has revealed that CuO embedded β-Ni(OH)2 displays much higher specific capacitance and better cyclability than pure β-Ni(OH)2. In fact, the addition of CuO improves the reversibility of the electrode by reducing the anodic (Epa) and cathodic (Epc) peak potential difference and also increases the separation of the oxygen evolution (EOE) and anodic (Epa) peak potential. Further, CuO nanoparticles grafted β-Ni(OH)2 electrode displays elevated proton diffusion co-efficient (D) and inferior charge transfer resistance. Specifically, CuO embedded β-Ni(OH)2 exhibits 855 F g−1 at 5 Ag-1 and good cycling stability as it maintains more than 90% of its original capacitance even after 3000 cycles. The enhancement may be attributed to the nanosize of CuO and chemical interaction between CuO and β-Ni(OH)2. These results are expected to offer new insight to future researchers who wish to work on the development of novel electrode materials for energy storage applications.

The development of cost-effective and eco-friendly alternatives of energy storage systems is needed to solve the actual energy crisis. Although technologies such as flywheels, supercapacitors, pumped hydropower and compressed air are efficient, they have shortcomings because they require long planning horizons to be cost-effective. Renewable energy storage systems such as redox flow batteries are actually of high interest for grid-level energy storage, in particular iron-based flow batteries. Here we review all-iron redox flow battery alternatives for storing renewable energies. The role of components such as electrolyte, electrode and membranes in the overall functioning of all-iron redox flow batteries is discussed. The effect of iron–ligand chemistry on the performance of battery is highlighted. Additionally, a brief contextual background and fundamentals of redox flow batteries are provided. The design aspects, progress in research, mathematical modeling, cost estimations and future prospects of using all-iron energy systems are discussed in the context of future grid-level energy storage.

Removal of the hazardous and endocrine-disrupting 2,4-dichlorophenol (2,4-DCP) from water bodies is crucial to maintain the sanctity of the ecosystem. As a low bandgap material (1.37 eV), NaBiS2 was hydrothermally prepared and used as a potential photocatalyst to degrade 2,4-DCP under visible light irradiation. NaBiS2 appeared to be highly stable and remained structurally undeterred despite thermal variations. With a surface area of 6.69 m2/g, NaBiS2 has enough surface-active sites to adsorb the reactive molecules and exhibit a significant photocatalytic activity. In alkaline pH, the adsorption of 2,4-DCP on NaBiS2 appeared to decrease whereas, the acidic and neutral environments favoured the degradation. An increase in the photocatalyst dosage enhanced the degradation efficiency from 81 to 86 %, because of higher vacant adsorbent sites and the electrostatic attraction between NaBiS2 and 2,4-DCP. The dominant scavengers degraded 2,4-DCP by forming a coordination bond between chlorine's lone pair of electrons and the vacant orbitals of bismuth, following the order hole> OH > singlet oxygen. Being non-toxic to both natural and aquatic systems, NaBiS2 exhibits antifungal properties at higher concentrations. Finally, the electron-rich NaBiS2 is an excellent electrocatalyst that effectively degrades organic pollutants and is a promising material for industrial and environmental applications.

Fig. 1 and the Graphical Abstract were created by Heno Hwang, scientific illustrator at King Abdullah University of Science and Technology (KAUST). The research reported in this publication was supported by funding from KAUST. The funding support from Department of Science and Technology’s Technology Mission Division (No. OST/TM O(EWO)/OWUIS20IS/TS-03 (G)) under the program “Optimal Water Use in Industrial Sector” is greatly acknowledged.

The dysfunctioning of β-cells caused by the unspecific misfolding of the human islet amyloid polypeptide (hIAPP) at the membrane results in type 2 diabetes mellitus. Here, we report for the first time, the early-stage interaction of hIAPP oligomers on the DMPC (1,2-dimyristoyl-sn-glycero-3-phosphocholine) lipid membrane using electrochemical parameters. Electrochemical techniques are better than other techniques to detect hIAPP at significantly lower concentrations. The surface level interactions between the peptide (hIAPP) and lipid membrane (DMPC) were investigated using atomic force microscopy (AFM), confocal microscopy (CM) and electrochemical techniques such as Tafel polarization, cyclic voltammetry (CV), differential pulse voltammetry (DPV), linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). Inserting IAPP into the fluid domains results in breaking the lipid-to-lipid interaction, leading to restriction of membrane mobility. The SLateral values of the liposome and IAPP co-solubilized liposome indicates the cooperative insertion of IAPP. Further, a new method of immobilizing a membrane to the gold surface has been employed, resulting in an electrical contact with the buffer, preventing the direct utilization of a steady-state voltage across the bilayer. The electrochemical studies revealed that the charge transfer resistance decreased for 3-mercaptopropanoic acid modified gold (MPA-Au) electrode coated with the liposome and after the addition of IAPP, followed by an increase in the capacitance. The present study has opened up new dimensions to the understanding of peptide-membrane interactions and shows different experimental approaches for the future researchers in this domain.

The persistence of hollow centre in the carbon obtained from milkweed floss provides exceptional sorption characteristics, not seen in common biomasses or their derivatives. A considerably high sorption of 320mg of lead per gram of milkweed carbon was achieved without any chemical modification to the biomass. In this research, we have carbonized milkweed floss and used the carbon as a sorbent for lead in waste water. A high surface area of 170m2g-1 and pore volume of 1.07cm3g-1 was seen in the carbon. Almost complete removal (>99% efficiency) of lead could be achieved within 5min when the concentration of lead in the solution was 100ppm, close to that prevailing in industrial waste water. SEM images showed that the carbon was hollow and confocal images confirmed that the sorbate could penetrate inside the hollow tube.

The importance of Ni-based batteries in the present context is extremely valuable, as their electrochemical properties are expected to offer significant insights into their application as battery materials. In this direction, Ni(OH) 2 has been prepared using the co-precipitation method by varying the concentrations of zinc additive (2, 4, 6 & 8 wt%) and pH (8, 9, 10 & 11). The results show that the prepared samples exist in β-phase with flake like structure. The electrochemical properties of b-Ni(OH) 2 have been investigated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements using a paste-type electrode on a nickel mesh as a current collector. The cyclic voltammetry measurements indicate that the reversibility of the electrode reaction increases at pH 10 and 6% Zn additive. Whereas, the EIS measurements reveal that a reduction in the charge transfer resistance increases the double layer capacitance of the nickel electrode.

Nanostructured NiO and Li-ion doped NiO have been synthesized via a facile microwave technique and simulated using the first principle method. The effects of microwaves on the morphology of the nanostructures have been studied by Field Emission Spectroscopy. X-ray diffraction studies confirm the nanosize of the particles and favoured orientations along the (111), (200) and (220) planes revealing the cubic structure. The optical band gap decreases from 3.3 eV (pure NiO) to 3.17 eV (NiO doped with 1% Li). Further, computational simulations have been performed to understand the optical behaviour of the synthesized nanoparticles. The optical properties of the doped materials exhibit violet, blue and green emissions, as evaluated using photoluminescence (PL) spectroscopy. In the presence of Li-ions, NiO nanoparticles exhibit enhanced electrical capacities and better cyclability. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) results show that with 1% Li as dopant, there is a marked improvement in the reversibility and the conductance value of NiO. The results are encouraging as the synthesized nanoparticles stand a better chance of being used as an active material for electrochromic, electro-optic and supercapacitor applications.

Graphene and graphene based composite materials have gained considerable importance in the recent years due the technologically relevant properties exhibited by them. These novel properties stem from the synergistic response, of graphene and the materials which are anchored on them, to a stimulus. Several synthesis methods have therefore been devised, over the years, to produce different graphene based nanocomposite materials which typically are metal nanoparticle-graphene composites or polymer-graphene nanocomposites. This chapter lists several reported methodologies for producing graphene based nanocomposites and also provides information about some interesting and technologically relevant properties exhibited by such composites. Special emphasis is on citing the reports which illustrate the electrochemical sensing application of the composites. The chapter also provides recommendation and future directions that can be followed for comprehensive scientific investigation of the �microstructure� of nanocomposites to further engineering their design in order to harness property windows which still remain unexplored. © 2020 Elsevier B.V.

International audience; Alzheimer's disease (AD) is an incurable neurodegenerative disease characterized by progressive decline of cognitive abilities. Amyloid beta peptides (Aβ), Tau proteins and the phosphorylated form of the Tau protein, p-Tau, are the core pathological biomarkers of the disease, and their detection for the diagnosis of patients is progressively being implemented. However, to date, their quantification is mostly performed on cerebrospinal fluid (CSF), the collection of which requires an invasive lumbar puncture. Early diagnosis has been shown to be important for disease-modifying treatment, which is currently in development, to limit the progression of the disease. Nevertheless, the diagnosis is often delayed to the point where the disease has already progressed, and the tools currently available do not allow for a systematic follow-up of patients. Thus, the search for a molecular signature of AD in a body fluid such as blood or saliva that can be collected in a minimally invasive way offers hope. A number of methods have been developed for the quantification of core biomarkers, especially in easily accessible fluids such as the blood, that improve their accuracy, specificity and sensitivity. This review summarizes and compares these approaches, focusing in particular on their use for Aβ detection, the earliest biomarker to be modified in the course of AD. The review also discusses biomarker quantification in CSF, blood and saliva and their clinical applications.

In this paper, the performance of Fe based redox flow batteries (IRFBs) was dramatically improved by coating N-doped carbon spheres (NDCS) on the graphite felt electrodes. NDCS was synthesized by the single-step hydrothermal method using dextrose and ammonia as a precursor and coated over a graphite felt electrode by electrostatic spraying. The weight of NDCS required for the modification of the electrode to achieve the effective performance of the battery was studied using electrochemical techniques. Cyclic voltammetry (CV) and potentiodynamic polarization study was used to evaluate the kinetic reversibility and linear polarization resistance offered by the electrode towards electrolyte. The characterizing features of the NDCS, untreated graphite felt (UGF) electrode, and optimized modified graphite felt (MGF) electrode were analyzed using SEM, EDAX, XRD, and Raman spectroscopy. The charge-discharge studies were performed for the 132 cm2 IRFB using a 2 mg/cm2 MGF electrode as a positive electrode by varying the current densities from 20 to 60 mA/cm2. The cell resulted in an average coulombic efficiency (CE) of 93%, voltaic efficiency (VE) of 72%, and energy efficiency (EE) of 68% for 15 cycles at the current density of 30 mA/cm2. The improvement in the performance of the IRFB is due to the presence of electrochemically active nitrogen-bearing carbon catalysts. In this paper, the pioneering effort has been made to improve the efficiency of the IRFB with an active area of 132 cm2 using glycine as the ligand.

Dye-sensitized solar cells (DSSCs) are an efficient and versatile method of transforming the clean and most plentiful energy resources available. DSSC is translucent to some extent and relatively inexpensive than the traditional solar cell. Thus, it may be a possible source of electricity for the future. But other things need to be focused on before it is considered a viable commercial product. The review discusses these facets and the numerous changes the DSSC has experienced in the recent years. Photoelectric conversion systems struggle to fulfil the specifications of constant power output owing to the erratic and unstable characteristics of the solar radiation. With the evolution of rechargeable electric energy storage systems (ESSs), the integration of a DSSC and ESSs has developed into a promising approach to solve this issue. Here, we describe the working principle, recent progress of DSSCs, including photoanodes, sensitizers, electrolytes, and counter electrodes, and the use of DSSCs in energy storage, targeting DSSC and supercapacitor (SC) integrated devices. The future prospects for highly effective, reliable DSSC and DSSC-SC development have also been highlighted.

Synthesis based on biomaterial technology has high potential in structural applications. Blending metal oxides with plant extract is an attractive alternative for preparing materials with superior material properties. Here, we report for the first time, the synthesis of NiO bio-composite materials by employing Aloe vera leaf extract. The work mainly highlights the synergistic influence of biomolecules of Aloe vera plant on the electrochemical and photocatalytic properties of NiO. The structure, morphology, band gap and bonding features of NiO bio-composites were characterized by XRD, Electron Microscopy, UV-DRS and FT-IR techniques, respectively. The average crystallite size of the composites was within 60 nm. FT-IR spectra confirmed the strong bonding interactions between biomolecules and NiO. A maximum band gap of 3.88 eV with a good thermal stability for the synthesized composites was observed. The addition of biomolecules to NiO resulted in the improvement of the reversibility of the electrode by reducing the anodic (Epa) and cathodic (Epc) peak potential difference in KOH electrolyte. Also, the composite exhibited greater stability due to recyclability and less resistance even after 1000 charge-discharge cycles, revealing a stable electrode material for supercapacitors applications. The photocatalytic experiments confirmed a maximum of 95% dye degradation efficiency by the composite for AR88 dye. It was also found that 50 % of dye degradation occurred within 74.61 min. The encouraging results project out the potential of the synthesized NiO-biocomposites to be a better supercapacitor and photocatalyst.

Diabetes is a major chronic metabolic disorder globally and around of 285 million people are affected by the disease and the number is expected to double in the next two decades. The major focus of anti-diabetic therapies is to enhance insulin production, sensitivity and/or reduce the blood glucose level. Although several synthetic drugs have been developed as antidiabetic agents but their utility has been hampered due to their side effects and poor efficacy. In this scenario, research on natural products has been gained importance due their safety profile in toxicity studies. Terpenoids belong to an important class of natural products and several terpenoids have been reported as antidiabetic agents. Some of them are under various stages of pre-clinical and clinical evaluation to develop them as antidiabetic agents. These agents can inhibit enzymes responsible for the development of insulin resistance, normalization of plasma glucose and insulin levels and glucose metabolism. Triterpenes can act as promising agents in the treatment of diabetic retinopathy, neuropathy and nephropathy or in impaired wound healing by inhibiting several pathways involved in the diabetes and associated complications. However, efforts in understanding the biological actions and clinical studies involving the applications of triterpenes in treating diabetes are very limited. Hence, special attention is imperative to explore the therapeutic potential of these compounds and provide new information to the scientific community. This review aims to provide the recent advances in triterpenes chemistry, its derivatives, biological interventions and its therapeutic applications with special emphasis on diabetes and its associated disorders.

A custom designed DNA probe against cry1 gene of Bacillus thuringiensis has been used to fabricate a DNA biosensor by self-assembled monolayers of mercaptohexanol (MCH) and thiol-linked custom designed probe (ssDNA-thiol), immobilized on a screen printed gold nanostructured electrode. DNA immobilization and hybridization have been characterized by differential pulse voltammetry (DPV) using methylene blue as an electrochemical hybridization indicator. With this approach, the target DNA could be quantified in the range of 1.0 × 10−6 M to 1.0 × 10−12 M, with a detection limit of 0.997 × 10−12 M by 3σ. Cyclic voltammetry and electrochemical impedance spectroscopy (EIS) have been performed to characterize the sequentially modified electrode. In addition, a non-complementary DNA sequence of Bacillus cereus has been tested as a non-target, that hardly causes any variation in the reduction current of MB reaffirming that the DNA-based biosensor is high selective to Bacillus thuringiensis. The electrochemical detection methods employed in this work can be extended further to develop DNA-based biosensors for the detection of other microorganisms having applications in agriculture, food industries and medical applications.

For large-scale energy storage, iron-based flow batteries (IRFBs) have been considered as a better choice because of their low-cost and use of environmentally friendly iron-based salts. The development of a IRFBs has been limited by the sluggish kinetics of the reaction, especially at the positive electrode during charging. Therefore, it is very important to look for stable electrolytes and superior electrode materials along with their modifications. Carbon-based electrodes are majorly used in IRFBs and these electrodes are feasible to modify using electrocatalysts. In the current study, nitrogen-doped carbon particles (NICaps) derived from Bermuda grass were used to modify graphite felt electrode. SEM, EDAX, Raman, and XPS analysis were used to characterize the modified graphite felt (MGF) electrode. It was observed that the NICaps MGF electrode had a significant improvement in electrochemical properties. The cathodic and anodic peak currents for the MGF electrode (1.55 and 1.63 mA/cm2 respectively) had a remarkable increase in comparison with the untreated graphite felt electrode (UGF) (0.48 and 0.88 mA/cm2 respectively). The Nyquist plot and the data derived from the equivalent circuit indicated lower charge transfer resistance for MGF. The charge-discharge studies carried out using 132 cm2 cell reveals that the modified electrodes result in higher current uptake of 50 mA/cm2 whereas the current uptake from the UGF electrode was limited to 20 mA/cm2. The battery resulted in an average coulombic efficiency of 95%, the peak power density of 60 mW/cm2, and better stability during multiple cycling.

Polyethylene tetraphthalate (PET) bottles, a major environmental pollutant from the food industry, has been used as an activated carbon source in the current work. The specific surface area of the activated carbon has been analyzed using N2 adsorption/desorption isotherms, at different sonication time periods. A high surface area of 899 m2 g-1 with microporosity has been achieved for 20 h sonication followed by activation at 800 °C. To further enhance the material performance, carbon doped MoS2 (MoS2–C), using conventional hydrothermal technique has been synthesized. Different composite ratios of activated carbon and MoS2-C have been tested using electrochemical impedance spectroscopy and the best ratio owing to lesser charge-transfer resistance has been chosen for supercapacitor and HER analysis. The porous network of the plastic derived activated carbon (PAC) with a few layers of MoS2–C contributes significantly to the increase in the power density (469 W kg-1). By inducing defects on the material surface, there has been a significant enhancement in the electrocatalytic activity on PAC and this facilitates HER on its surface. Subsequently, the HER activity of the PDAC/MoS2–C composite has also been reported. Here, the PDAC defective sites along with the hexagonal MoS2–C’s largely exposed reactive edges indicate a reduction in the overpotential and Tafel values of −195 mV and −82 mVdec−1, suggesting that the material under investigation is a good catalyst for electrochemical HER. Also, this article reports for the first-time, HER activity of defect induced plastic derived activated carbon and its excellent catalytic activity.

A new photocatalytic material sodium iron disulfide (NaFeS2) has been synthesized via a hydrothermal method for the degradation of methylene blue (MB) and indigo carmine (IC). This material has been subjected to various analytical, electrochemical and photocatalytic studies to understand its morphology, crystallinity, band gap, oxidation-reduction potential and ability to catalyse the rate of dye degradation. The material exists as nanorods with a thickness of 30–100 nm and a monoclinic phase with an average crystallite size of 25–30 nm. The energy bandgap of the prepared photocatalyst has been calculated using the Kubelka-Munk function and is found to be 2.01 eV. Using a UV light source, the photocatalytic activity of NaFeS2 has been carried out, where the time of irradiation determined the ability of the catalyst to degrade the dye under investigation. With a degradation efficiency of 97% in 105 min for MB and 99% in 45 min for IC, NaFeS2 appears as an excellent photocatalytic material. The electrochemical studies also act as a testament for NaFeS2’sadmirable photocatalytic property. The photocatalytic and electrochemical activities of NaFeS2 offer an innovative platform for the treatment of various other environmental pollutants as well.

Andrographis paniculata Nees is an important medicinal plant found in the tropical regions of the world, which has been traditionally used in Indian and Chinese medicinal systems. It is also used as medicinal food. A. paniculata is found to exhibit anti-inflammatory activities; however, its inhibitory potential on inflammatory Group IIA phospholipases A 2 (PLA 2 ) and its associated inflammatory reactions are not clearly understood. The aim of the present study is to evaluate the inhibitory/neutralizing potential of ethanolic extract of A. paniculata on the isolated inflammatory PLA 2 (VRV-PL-VIIIa) from Daboii rusellii pulchella (belonging to Group IIA inflammatory secretory PLA 2 [sPLA 2 ]) and its associated edema-induced activities in Swiss albino mice. A. paniculata extract dose dependently inhibited the Group IIA sPLA 2 enzymatic activity with an IC 50 value of 10.3 ± 0.5 μg/ml. Further, the extract dose dependently inhibited the edema formation, when co-injected with enzyme indicating that a strong correlation exists between lipolytic and pro-inflammatory activities of the enzyme. In conclusion, results of this study shows that the ethanolic extract of A. paniculata effectively inhibits Group IIA sPLA 2 and its associated inflammatory activities, which substantiate its anti-inflammatory properties. The results of the present study warranted further studies to develop bioactive compound (s) in ethanolic extract of A. paniculata as potent therapeutic agent (s) for inflammatory diseases. SUMMARY This study emphasis the anti-inflammatory effect of A. paniculata by inhibiting the inflammatory Group IIA sPLA2 and its associated inflammatory activities such as edema. It was found that there is a strong correlation between lipolytic activity and pro-inflammatory activity inhibition. Therefore, the study suggests that the extract processes potent anti-inflammatory agents, which could be developed as a potential therapeutic agent against inflammatory and related diseases.

In the recent times, cost-effective and eco-friendly processes of synthesizing nanoparticles (NPs) have emerged as a substitute to conventional synthetic methods. Several research groups in the past have synthesized silver oxide (Ag2O) nanoparticles from various plant extracts and have been extensively reported. A first of its kind facile green combustion method has been adopted here to synthesize Ag2O NPs using Centella asiatica and Tridax plant powder. The unique pentacyclic and triterpene constituents of Centella asiatica and Tridax powder has kindled our curiosity to explore their electrochemical, photocatalytic and biological activities that may contribute to various environmentally benign industrial applications. The cyclic voltammetric studies show that the cathodic and anodic peak potentials for the synthesized Ag2O NPs exhibit hysteresis in the range of 0.3 V to –0.1 V. A high percentage of degradation of acid orange 8 (AO8) dye by the synthesized Ag2O NPs offers new hope on its potential photocatalytic activity. Finally, their anti-bacterial and anti-fungal activities carried out against S. epidermidis and S. aureus and A. fumigates and A. aureus respectively, have shed new light on the ability of the synthesized Ag2O NPs to inhibit the growth of various disease-causing pathogens. Hence, it is believed that this research work will act as a fundamental basis to various researchers and industrialists working in the energy, water and biological fields to carry out advanced studies in the aforementioned domains.