Construction of hierarchical NiCo2 S4 /2D-Carbyne nanohybrid onto nickel foam for high performance supercapacitor and non-enzymatic electrochemical glucose sensor applications.

Synthesising and designing pseudocapacitive material with good electrochemical and electrocatalytic behaviour is essential to use as supercapacitor as well as non-enzymatic glucose sensor electrode. In this work, NiCo2 S4 nanoparticles decorated onto the 2D-Carbyne nanosheets are achieved by the solvothermal process. The as-prepared NiCo2 S4 @2D-Carbyne provides rich reaction sites and better diffusion pathways. On usage as an electrode for supercapacitor application, the NiCo2 S4 @2D-Carbyne exhibits the specific capacitance of about 2507 F g-1 at 1 A g-1 . In addition, the fabricated hybrid device generates an energy density of 52.2 Wh kg-1 at a power density of 1.01 kW kg-1 . Besides, the glucose oxidation behaviour of NiCo2 S4 @2D-Carbyne modified GCE has also been performed. The diffusion of glucose from the electrolyte to the electrode obeys the kinetic control process. Furthermore, the fabricated NiCo2 S4 @2D-Carbyne non-enzymatic glucose sensor exhibits a limit of detection of about 34.5 µM with a sensitivity of about 135 µA mM-1 cm-2 . These findings highlight the need to design and synthesis electrode materials with adequate electrolyte-electrode contact, strong structural integrity, and rapid ion/electron transport.

NiCo2O4/Ti2NbC2 (double MXene) nanohybrid-based non-enzymatic electrochemical biosensor for the detection of glucose in sweat.

The non-enzymatic electrochemical sensors are attractive due to their high sensitivity, quick detection, low cost, and simple construction. Hence, in this work, a non-enzymatic biosensor was constructed with NiCo2O4 nanoparticles (~ 82 nm) decorated over Ti2NbC2 nanosheets by an in-situ method. The crystal structure, phase purity, morphology and elemental composition of the synthesized NiCo2O4/Ti2NbC2 nanohybrid was investigated using XRD, Raman and FESEM analysis. The electrocatalytic and electrochemical behaviour of the prepared nanohybrid was investigated using cyclic voltammetry and amperometry analysis. Hybrid of NiCo2O4/Ti2NbC2 produces a biocompatible, electrochemically active surface with enhanced electrical conductivity. The enhanced surface area of NiCo2O4 and superior electrical conductivity of Ti2NbC2 nanosheets helped to develop non-enzymatic electrochemical glucose sensor with enhanced sensitivity (425.6 µA mM-1cm-2), low limit of detection and quick response time that satisfy glucose detection applications. Thus, the developed non-enzymatic electrochemical glucose sensor has excellent electrochemical properties and making it as a strong candidate for the detection of glucose concentration in sweat.

Supramolecular assembly of benzocaine bearing cyclodextrin cavity via host-guest complexes on polyacrylonitrile as an electrospun nanofiber.

Nanofibers (NFs) can be encapsulated with cyclodextrins (CDs) based host-guest complexes (HCs) in order to enable many biological applications. Here, benzocaine (BNZ) forms HCs with ß-cyclodextrin (ß-CD) that are co-precipitated and further added to polyacrylonitrile (PAN) solution for making BNZ:ß-CD-HCs/PAN NFs material with the aid of electrospinning technique. The marginal increase in absorbance and fluorescence intensity along with the shift in spectral maxima of BNZ in the presence of ß-CD suggested the host-guest interaction between BNZ and ß-CD. NFs showed a uniform and clean morphology in SEM images and interestingly, the ICs revealed that significantly thinner in terms of average fiber diameter (AFD) than those of free BNZ on PAN medium. BNZ molecule is completely included in the PAN surface as the result of NFs and thus, the original sharp peaks for the BNZ have vanished and the peaks are much broader for the BNZ and BNZ:ß-CD-HCs. BNZ is also found to be a good candidate for anti-inflammatory, anti-oxidant, and anti-diabetic. The results showed an improved activity when it is in the form of HCs on a PAN medium. Making HCs of drugs could be significant in biological applications.

Recent Advances and Challenges in Light Conversion Phosphor Materials for Third-Generation Quantum-Dot-Sensitized Photovoltaics.

Photovoltaic (PV) technologies have received tremendous attention for producing clean and renewable energy from the Sun. Third-generation quantum-dot-sensitized solar cells (QDSCs) present promising alternatives to conventional silicon solar cells due to their unique properties such as simplicity in fabrication, lower processing temperature, high flexibility, semitransparent nature, and a theoretical conversion efficiency of up to 44%. However, the light-harvesting QD materials used in these SCs allow for the absorption of a small portion (from 300 to 800 nm) of the solar spectrum due to their narrow band gap. The nonabsorption of UV and near-infrared (NIR) light limits the power conversion efficiency (PCE) of these SCs. Hence, a PV technique that efficiently uses the entire solar spectrum becomes essential. The incorporation of light conversion phosphor materials (LCs) in QDSCs is a promising technology to absorb the whole part of the solar spectrum and enhance the PCE of these SCs. This review presents an overview of the advantages and limitations of QDSCs, different types of lanthanide-based light conversion phosphor materials, their synthesis and light conversion mechanism, and their influence on QDSCs.

Facile synthesis of reduced graphene oxide using Acalypha indica and Raphanus sativus extracts and their in vitro cytotoxicity activity against human breast (MCF-7) and lung (A549) cancer cell lines.

In the present study, an eco-friendly approach is adapted for the synthesis of reduced graphene oxide (rGO's) by a simple hydrothermal reaction using two plant extracts namely Acalypha indica and Raphanus sativus. After the hydrothermal reaction, GO turns into a black color from brown color, which indicates the successful reduction of graphene oxide. Further, various characterization techniques such as UV-Vis spectroscopy, Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction is used to confirm the physicochemical properties of synthesized rGO's. Raman analysis confirms the reduction of GO by noticing an increase in the ID/IG ratio significantly. Field emission scanning electron microscopy and transmission electron microscopy clearly show the morphology and crystalline nature of rGO's. FT-IR spectrum confirms that the bioactive molecules of the plant extract (i.e. polyphenols, flavonoids, terpenoids, etc.) playing a key role in the elimination of oxygen groups from the GO surface. Further, the synthesized rGO's are tested for their potential against human lung and breast cancer cell lines. A significant cancer cell inhibition activity is obtained even in the less concentration of rGO's with IC50 values for lung cancer cell lines are 38.46 µg/mL and 26.69 µg/mL for AIrGO and RSrGO, respectively. Similarly, IC50 values for breast cancer cell lines are 35.97 µg/mL and 33.22 µg/mL for AIrGO and RSrGO, respectively.

Anti-bacterial and anti-biofilm properties of green synthesized copper nanoparticles from Cardiospermum halicacabum leaf extract.

In the present study, a copper nanoparticle (Cu NPs) was synthesized by a green synthesis method with Cardiospermum halicacabum leaf extract. The surface area of Cu NPs was measured with dynamic light scattering (DLS). UV-Vis spectrum clearly illustrates the typical absorption peak of Cu NPs. The crystalline property of Cu NPs was confirmed from the XRD pattern. TEM analysis clearly indicates the average particle size of synthesized Cu NPs was in the range of 30-40 nm with hexagonal shape. Energy-dispersive spectroscopy confirms the major strong peaks of Cu NPs. FTIR analysis confirms the existence of various functional biomolecules over the metal nanoparticles and they are playing an important role in the formation of Cu NPs. The antibacterial and anti-biofilm analyses were carried out to confirm their aptitude for biomedical applications. Interestingly, Cu NPs control the development of biofilm by attaching over the cell wall and disturb their growth and development.

Morphology restrained growth of V2O5 by the oxidation of V-MXenes as a fast diffusion controlled cathode material for aqueous zinc ion batteries.

Herein, we report morphology controlled growth of layered V2O5 on V2C by the oxidation of V-MXenes at different temperatures and used it as a cathode material for Zn-ion batteries (ZIBs). Hence, the V2O5 nanoparticles are uniformly grown on the V2C nanosheets with interlinked disordered carbon which provide fast diffusion and high rate performance in aqueous zinc-ion batteries.

Optimizing graphene content in a NiSe/graphene nanohybrid counter electrode to enhance the photovoltaic performance of dye-sensitized solar cells.

Nickel selenide (NiSe) nanoparticles were grown on graphene nanosheets (GN) with different mass ratios to obtain their corresponding NiSe/GNx (x = 0.25 to 1.00) nanohybrids by a facile in situ hydrothermal process to integrate the advantages of the high specific surface area of graphene and the homogeneously immobilized catalytic sites of NiSe. The nanohybrid with a mass ratio of 1 : 0.50 (i.e., NiSe/GN0.50) exhibited higher electrocatalytic activity and electrolyte diffusion. Thus, NiSe/GN0.50 exhibited an improved photo-conversion efficiency (PCE) of 12% (η = 8.62%) compared to a standard Pt (η = 7.68%)-based dye-sensitized solar cell (DSSC). This improved PCE mainly originated from the catalytic ability of NiSe and the multiple interfacial electron transfer pathways of graphene, resulting in enhanced charge transfer and fast tri-iodide reduction kinetics at the counter electrode/electrolyte interface. The results obtained from the cyclic voltammetry (CV), electrochemical AC-impedance (EIS) and Tafel polarization studies validated the synergistic effects of NiSe and GN and the high potential of this nanohybrid as an efficient counter electrode (CE) for DSSCs.

Hydrothermally Synthesized Li4Ti5O12 Nanotubes Anode Material with Enhanced Li-Ion Battery Performances.

Hollow Li4Ti5O12 nanotubes were synthesized by stirring in a heated oil bath using P25 as titanium source and lithium hydroxide as lithium source. The as-prepared samples displayed a nanotube structure, with diameter of about 20~50 nm and length of 0.4 µm. The specific surface area of as-prepared samples reached 153.2 m²g-1. It is demonstrated that the Li4Ti5O12 nanotubes with improved performance can be obtained by hollow structure and high specific surface area. In consequence, it delivered a high reversible initial discharge capacity of 174.2 mAh g-1 at 0.5 C rate. A stable capacity of 170.9 mAh g-1 was delivered when the rate was reduced back to 0.5 C, suggesting good structural stability of the nanocable, high reversibility even after high rate charge- discharge, and good cycle stability. In addition, a capacity of 134.9 mAh g-1 and 98 mAhg-1 could be retained at a high rate of 5 C and 10 C, indicating excellent rate performances.

Constructing efficient mixed-ion perovskite solar cells based on TiO2 nanorod array.

Oriented TiO2 nanorod array (TiO2 NA) is very attractive in the fields of halide perovskite solar cells (PSCs) due to its fewer grain boundaries and high crystallinity for effective charge collection. The optimization of TiO2 nanostructures has been proved to be an effective approach for efficient PSCs. On the other hand, tuning the crystallization of perovskite films on top of the TiO2 NA is very important for efficient TiO2-NA based PSCs. Herein, scanning electron microscopy (SEM) and X-ray powder diffraction (XRD) were used to study the crystallization of different mixed-ion Cs0.1(FA0.83MA0.17)0.9Pb(I0.83Br0.17)3 perovskite (in which MA = CH3NH3+, and FA = CH(NH2)2+) films, from different perovskite precursor concentrations, on the TiO2 nanorod arrays. A mechanism was proposed to reveal the inherent connection between the precursor concentration and the crystallite growth of the perovskite film prepared with anti-solvent quenching process. Meanwhile, both faster charge separation at perovskite/TiO2 NA interface and longer charge transport were observed on thicker perovskite film with larger grains, revealed by the time-resolved method. However, atomic force microscopy (AFM) results indicated that too thick perovskite film impaired the charge collection owing to the increased recombination. By balancing the charge collection and film thickness, highly efficient PSCs were prepared with a champion power conversion efficiency (PCE) of 19.33% with little hysteresis. The study highlights a great potential of incorporating oriented one-dimensional electron extraction materials in high-performance PSCs and other applications.

Progress on the Photocatalytic Reduction Removal of Chromium Contamination.

Rapid industrialization leads to increased wastewater discharge encompassing hexavalent chromium (Cr(VI)), which leads to serious environmental problems of toxicity and potential carcinogenicity. Removal of these species is normally carried out by ion-exchange, precipitation, membrane filtration, sorption, photocatalytic reduction, etc. This review mainly focuses on the photocatalytic and photoelectrocatalytic (PEC) reduction of Cr (VI), because of their advantages over other methods such as reduced risk of secondary pollution by non-reduced Cr (VI), no sludge formation, no need for a large amount of chemical reagents, clean and easy installation. The main factors influencing the photocatalytic reduction efficiency of Cr (VI) such as catalyst activity, solution pH, Cr adsorption on the catalyst and additives, are briefly discussed. Finally, a special emphasis is provided to the photoelectrocatalytic (PEC) reduction of Cr (VI).

In situ grown nickel selenide on graphene nanohybrid electrodes for high energy density asymmetric supercapacitors.

Nickel selenide (NiSe) nanoparticles uniformly supported on graphene nanosheets (G) to form NiSe-G nanohybrids were prepared by an in situ hydrothermal process. The uniform distribution of NiSe on graphene bestowed the NiSe-G nanohybrid with faster charge transport and diffusion along with abundant accessible electrochemical active sites. The synergistic effect between NiSe nanoparticles and graphene nanosheets for supercapacitor applications was systematically investigated for the first time. The freestanding NiSe-G nanohybrid electrode exhibited better electrochemical performance with a high specific capacitance of 1280 F g-1 at a current density of 1 A g-1 and a capacitance retention of 98% after 2500 cycles relative to that of NiSe nanoparticles. Furthermore, an asymmetric supercapacitor device assembled using the NiSe-G nanohybrid as the positive electrode, activated carbon as the negative electrode and an electrospun PVdF membrane containing 6 M KOH as both the separator and the electrolyte delivered a high energy density of 50.1 W h kg-1 and a power density of 816 W kg-1 at an extended operating voltage of 1.6 V. Thus, the NiSe-G nanohybrid can be used as a potential electrode material for high-performance supercapacitors.

Dimensional stability and electrochemical behaviour of ZrO2 incorporated electrospun PVdF-HFP based nanocomposite polymer membrane electrolyte for Li-ion capacitors.

Different weight percentages of ZrO2 (0, 3, 5, 7 and 10 wt%) incorporated electrospun PVDF-HFP nanocomposite polymer membranes (esCPMs) were prepared by electrospinning technique. They were activated by soaking in 1 M LiPF6 containing 1:1 volume ratio of EC : DMC (ethylene carbonate:dimethyl carbonate) to get electrospun nanocomposite polymer membrane electrolytes (esCPMEs). The influence of ZrO2 on the physical, mechanical and electrochemical properties of esCPM was studied in detail. Finally, coin type Li-ion capacitor cell was assembled using LiCo0.2Mn1.8O4 as the cathode, Activated carbon as the anode and the esCPME containing 7 wt% of ZrO2 as the separator, which delivered a discharge capacitance of 182.5 Fg-1 at the current density of 1Ag-1 and retained 92% of its initial discharge capacitance even after 2,000 cycles. It revealed that the electrospun PVdF-HFP/ZrO2 based nanocomposite membrane electrolyte could be used as a good candidate for high performance Li-ion capacitors.