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This study explores a water‐splitting activity using a biphasic electrodeposited electrode on nickel foam (NF). The *Ni9S8/Cu7S4/NF electrode with citric acid reduction exhibits superior OER (oxygen evolution reaction) and HER (hydrogen evolution reaction) performance with reduced overpotential and a steeper Tafel slope. The *Ni9S8/Cu7S4/NF electrode displays the ultra‐low overpotential value of 212 mV for OER and 109 mV for HER at the current density of 10 mA cm−2. The Tafel slope of 25.4 mV dec−1 for OER and 108 mV dec−1 for HER was found from that electrode. The maximum electrochemical surface area (ECSA), lowest series resistance and lowest charge transfer resistance are found in citric acid reduced electrode, showing increased electrical conductivity and quick charge transfer kinetics. Remarkably, the *Ni9S8/Cu7S4/NF electrode demonstrated excellent stability for 80 hours in pure water splitting and 20 hours in seawater splitting. The synergistic effect of using bimetallic (Cu&Ni) sulfide and enhanced electrical conductivity of the electrode are caused by reduction of metal sulfide into metallic species resulting in improved water splitting performance. [ABSTRACT FROM AUTHOR]

Electrocatalytic water splitting is a promising solution to resolve the global energy crisis. Tuning the morphology and elemental composition is a crucial aspect in designing highly-efficient nanomaterials based electrocatalyst for water splitting. Herein, green synthesis using phytochemicals from aloe vera leaves extract was employed to hydrothermally synthesize copper oxide/cobalt oxide nanostructures on nickel foam. The reaction medium was performed in presence of mineralizers of different pH; hydrochloric acid (HCl), citric acid (CA), urea, diethyl amine (DEA) and sodium hydroxide (NaOH) to produce five different compositions of copper oxide/cobalt oxide on nickel foam. Based on FESEM and EDS analysis, it was verified that the plant mediated hydrothermal process yielded interesting morphologies and the elemental composition of the synthesized metal oxide nanostructures distinctly varied with effect to the different mineralizers used. Use of acidic mineralizers such as hydrochloric acid and citric acid favoured formation of copper oxide whereas basic mineralizers such as urea, diethyl amine and sodium hydroxide favoured formation of cobalt oxide. The green synthesis of metal oxide electrode in presence of urea exhibits the best OER electrocatalytic performance with an overpotential of 390 mV, and 453 mV for a current density of 50 mA cm−2 and 100 mA cm−2 respectively. The sample also exhibited sustained stability over 70 h, hence proving that the proposed electrode can serve as an efficient catalyst for electrocatalytic OER. • Green synthesis using aloe vera leaves extract to hydrothermally synthesize nanostructures. • Use of acidic mineralizers favoured formation of copper oxide. • Basic mineralizers favoured formation of cobalt oxide. • Best OER electrocatalytic performance of 453 mV overpotential for 100 mA cm−2. [ABSTRACT FROM AUTHOR]

This study explores green-synthesized delafossite CuAlO2 as a hole transport layer (HTL) in a CH3NH3SnI3-based perovskite solar cells (PSCs) with an FTO/CuAlO2/CH3NH3SnI3/WO3/Au structure. The performances of the cell have been theoretically investigated using SCAPS-1D. Interface defects significantly impact cell efficiency, as defect density increases from 1014 cm−3 to 1020 cm−3 efficiency reducing from 25.3% to 24.45% in the HTL/perovskite junction and from 25.2% to 17.8% in the perovskite/electron transport layer (ETL) interface. PCBM as buffer layer at perovskite/ETL interface compensates for power conversion efficiency (PCE) losses. Optimizing parameters reveals the delafossite CuAlO2-based, lead-free perovskite solar cell achieving peak efficiency at 26.74%, with VOC, JSC, and FF values of 0.99 V, 33.43 mA cm−2, and 81.05%, respectively. This research underscores delafossite CuAlO2 as a promising HTL for eco-friendly, stable CH3NH3SnI3-based perovskite solar cells, emphasizing its potential in enhancing device performance. [ABSTRACT FROM AUTHOR]

Electrocatalytic water splitting is a promising alternative to produce high purity hydrogen gas as the green substitute for renewable energy. Thus, development of electrocatalysts for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are vital to improve the efficiency of the water splitting process particularly based on transition metals which has been explored extensively to replace the highly active electrocatalytic activity of the iridium and ruthenium metals‐based electrocatalysts. In situ growth of the material on a conductive substrate has also been proven to have the capability to lower down the overpotential value significantly. On top of that, the presence of substrate has given a massive impact on the morphology of the electrocatalyst. Among the conductive substrates that have been widely explored in the field of electrochemistry are the copper based substrates mainly copper foam, copper foil and copper mesh. Copper‐based substrates possess unique properties such as low in cost, high tensile strength, excellent conductor of heat and electricity, ultraporous with well‐integrated hierarchical structure and non‐corrosive in nature. In this review, the recent advancements of HER and OER electrocatalysts grown on copper‐based substrates has been critically discussed, focusing on their morphology, design, and preparation methods of the nanoarrays. [ABSTRACT FROM AUTHOR]

In the recent past, there has been an increase in the use of semiconductor nanostructures that convert solar energy to electrical energy. This has encouraged the development of better and more efficient solar cells (SCs). Numerous investigations have been conducted into synthesizing novel semiconductor materials and tuning the electronic properties based on the shape, size, composition, and assembly of the quantum dots to improve hybrid assemblies. Recent studies that are determining the prospects of quantum dot SCs can form the basis for improving photovoltaic efficiency. Here, we have reviewed studies that investigated the sensitization methods for fabricating highly efficient SCs. We also discussed some examples that would help other researchers who want to sensitize quantum dot (QD) SCs. Thereafter, we analyzed the main and popular strategies that can be used for sensitizing the QD SCs within the limitations, advantages, and prospects of fabricating high-efficiency and stable QDs. During this work, we offered strong technical support and a theoretical basis for improving the industrial applications of QD. In addition, we provide a reference that can inspire other researchers who aim to improve the performance of SCs. [ABSTRACT FROM AUTHOR]

Synthesis of copper oxide (CuO) nanostructures via biological approach has gained attention to reduce the harmful effects of chemical synthesis. The CuO nanostructures were synthesized through a green approach using the Garcinia mangostana L. leaf extract and copper (II) nitrate trihydrate as a precursor at varying calcination temperatures (200–600 °C). The effect of calcination temperatures on the structural, morphological and optical properties of CuO nanostructures was studied. The red shifting of the green-synthesized CuO nanoparticles' absorption peak was observed in UV-visible spectrum, and the optical energy bandgap was found to decrease from 3.41 eV to 3.19 eV as the calcination temperatures increased. The PL analysis shown that synthesized CuO NPs calcinated at 500 °C has the maximum charge carriers separation. A peak located at 504–536 cm−1 was shown in FTIR spectrum that indicated the presence of a copper-oxygen vibration band and become sharper and more intense when increasing the calcination temperature. The XRD studies revealed that the CuO nanoparticles' crystalline size was found to increase from 12.78 nm to 28.17 nm, and dislocation density decreased from 61.26 × 1014 cm−1 to 12.60 × 1014 cm−1, while micro strain decreased from 3.40 × 10−4 to 1.26 × 10–4. From the XPS measurement, only CuO single phase without impurities was detected for the green-mediated NPs calcinated at 500 °C. The morphologies of CuO nanostructures were examined using FESEM and became more spherical in shape at elevated calcination temperature. More or less spherical nanostructure of green-mediated CuO calcinated at 500 °C were also observed using TEM. The purity of the green-synthesized CuO nanoparticles was evaluated by EDX analysis, and results showed that increasing calcination temperature increases the purity of CuO nanoparticles. [ABSTRACT FROM AUTHOR]

Tungsten oxide (WOx) thin films were synthesized through the RF magnetron sputtering method by varying the sputtering power from 30 W to 80 W. Different investigations have been conducted to evaluate the variation in different morphological, optical, and dielectric properties with the sputtering power and prove the possibility of using WOx in optoelectronic applications. An Energy Dispersive X-ray (EDX), stylus profilometer, and atomic force microscope (AFM) have been used to investigate the dependency of morphological properties on sputtering power. Transmittance, absorbance, and reflectance of the films, investigated by Ultraviolet-Visible (UV-Vis) spectroscopy, have allowed for further determination of some necessary parameters, such as absorption coefficient, penetration depth, optical band energy gap, refractive index, extinction coefficient, dielectric parameters, a few types of loss parameters, etc. Variations in these parameters with the incident light spectrum have been closely analyzed. Some important parameters such as transmittance (above 80%), optical band energy gap (~3.7 eV), and refractive index (~2) ensure that as-grown WOx films can be used in some optoelectronic applications, mainly in photovoltaic research. Furthermore, strong dependencies of all evaluated parameters on the sputtering power were found, which are to be of great use for developing the films with the required properties. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study is to modify guar gum (GG) into guar gum acetate (GGA) and phthaloyl guar gum (PHGG) by transesterification and phthaloylation, respectively. Design/methodology/approach: GG has been modified into GGA through transesterification reaction between GG and vinyl acetate and PHGG through esterification reaction with phthalic anhydride. The modified GG was characterized by solubility test, Fourier-transform infra-red (FTIR) spectroscopy, proton nuclear magnetic resonance (1H NMR) spectroscopy, X-ray diffractometry (XRD) and thermogravimetric analysis. Swelling properties of GGA and PHGG hydrogels in water were evaluated. Findings: These two types of modified GG have better solubility such as in dimethyl sulfoxide and N,N-dimethylformamide but no true organosolubility was achieved. The modifications were confirmed through FTIR with new absorption peaks at 1,733 cm−1 for GGA and 1,709 cm−1 for PHGG coupled with observed substitution peaks at 1.80 to 2.20 ppm and 7.40 to 7.90 ppm, respectively, from 1H NMR spectroscopies. XRD revealed both GGA and PHGG are less crystalline than native GG. GGA was found to be more thermally stable than native GG, whereas PHGG was slightly less thermally stable than native GG. The swelling property in distilled water for native GG, PHGG and GGA was 918.43 ± 46.62%, 537.04 ± 2.87% and 393.04 ± 13.42%, respectively. Research limitations/implications: The GGA and PHGG hydrogels are expected to be useful for biomedical fields such as tissue engineering and drug-delivery. Originality/value: Modifications of native GG into GGA using vinyl acetate and PHGG using phthalic anhydride are novel. [ABSTRACT FROM AUTHOR]

Generation of energy across the world is today reliant majorly on fossil fuels. The burning of these fuels is growing in line with the increase in the demand for energy globally. Consequently, climate change, air contamination, and energy security issues are rising as well. An efficient alternative to this grave hazard is the speedy substitution of fossil fuel-based carbon energy sources with the shift to clean sources of renewable energy that cause zero emissions. This needs to happen in conjunction with the continuing increase in the overall consumption of energy worldwide. Many resources of renewable energy are available. These include thermal, solar photovoltaic, biomass and wind, tidal energy, hydropower, and geothermal. Notably, tidal energy exhibits great potential with regard to its dependability, superior energy density, certainty, and durability. The energy mined from the tides on the basis of steady and anticipated vertical movements of the water, causing tidal currents, could be converted into kinetic energy to produce electricity. Tidal barrages could channel mechanical energy, while tidewater river turbines can seize the energy from tidal currents. This study discusses the present trends, ecological effects, and the prospects for technology related to tidal energy. [ABSTRACT FROM AUTHOR]

Guar gum succinate (GGS) was chemically modified by reacting guar gum with succinic anhydride in the presence of 4-dimethylaminopyridine. Succination was confirmed by Fourier transform infrared (FTIR) spectroscopy with carbonyl bands at 1724 cm−1 and ester linkage at 1567 cm−1 of the succinate group. The resulting amorphous, GGS was used as a polymer host to prepare cost-effective solid polymer electrolyte (SPE) films via incorporating a blend of ethylene carbonate (EC), carboxymethyl cellulose (CMC), lithium triflate (LiTf) and lithium iodide (LiI). SPE system for GGS:EC (1.0:0.6) with 30 wt% LiTf showed highest conductivity of 6.29 × 10−5 S cm−1 and GGS:CMC:EC (0.5:0.5:0.6) with 25 wt% LiI showed highest conductivity of 2.10 × 10−4 S cm−1. FTIR revealed multiple complexation sites for ion mobility indicating that GGS possesses high prospects as a conductive SPE. [ABSTRACT FROM AUTHOR]

ABSTRACT Electrospun materials have a number of applications in the tissue engineering field. However, the limited solubility of chitosan (CS), especially in organic solvents, makes its electrospinning with other synthetic organosoluble polymers impossible. In this article, we report the synthesis of a novel organosoluble derivative of CS through the application of a simple synthetic methodology. CS was reacted with 1,3-diethyl-2-thiobarbituric acid (DETBA) with triethylorthoformate in the presence of methanol and acetic acid (4:1). The functional groups in the synthesized materials were confirmed by Fourier transform infrared and solid-state NMR spectroscopy, whereas X-ray diffraction revealed the level of crystallinity. The CS derivative (CS-DETBA) was tested for its cytotoxic effects on human gastric adenocarcinoma AGS cells and was found to be nontoxic. The prepared derivative showed a much enhanced inhibitory effect on the growth of three bacterial strains, Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus, over that of CS itself. Overall, CS-DETBA showed good solubility in a range of organic solvents, such as dimethyl sulfoxide and N,N-dimethylformamide, and was blended with polycaprolactone (PCL) to form films and electrospun nanofibers. The morphologies of the synthesized materials were analyzed by field emission scanning electron microscopy, and the fiber diameter was 360 nm under optimum conditions. This study demonstrated that the CS-DETBA-PCL blend could be a potential material for tissue engineering and biomedical applications. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45905. [ABSTRACT FROM AUTHOR]

Improving the safety efficacy ratio of existing drugs is a current challenge to be addressed rather than the development of novel drugs which involve much expense and time. The efficacy of drugs is affected by a number of factors such as their low aqueous solubility, unequal absorption along the gastrointestinal (GI) tract, risk of degradation in the acidic milieu of the stomach, low permeation of the drugs in the upper GI tract, systematic side effects, etc. This review aims to enlighten readers on the role of pH sensitive hydrogels in drug delivery, their mechanism of action, swelling, and drug release as a function of pH change along the GI tract. The basis for the selection of materials, their structural features, physical and chemical properties, the presence of ionic pendant groups, and the influence of their pKa and pKb values on the ionization, consequent swelling, and targeted drug release are also highlighted. [ABSTRACT FROM AUTHOR]

A gel polymer electrolyte system based on phthaloylchitosan was prepared. The effects of process variables, such as lithium iodide, caesium iodide, and 1-butyl-3-methylimidazolium iodide were investigated using a distance-based ternary mixture experimental design. A comparative approach was made between response surface methodology (RSM) and artificial neural network (ANN) to predict the ionic conductivity. The predictive capabilities of the two methodologies were compared in terms of coefficient of determination R2 based on the validation data set. It was shown that the developed ANN model had better predictive outcome as compared to the RSM model. [ABSTRACT FROM AUTHOR]

Electrocatalytic water splitting is a promising solution to resolve the global energy crisis. Tuning the morphology and particle size is a crucial aspect in designing a highly efficient nanomaterials-based electrocatalyst for water splitting. Herein, green synthesis of nickel oxide nanoparticles using phytochemicals from three different sources was employed to synthesize nickel oxide nanoparticles (NiOx NPs). Nickel (II) acetate tetrahydrate was reacted in presence of aloe vera leaves extract, papaya peel extract and dragon fruit peel extract, respectively, and the physicochemical properties of the biosynthesized NPs were compared to sodium hydroxide (NaOH)-mediated NiOx. Based on the average particle size calculation from Scherrer's equation, using X-ray diffractograms and field-emission scanning electron microscope analysis revealed that all three biosynthesized NiOx NPs have smaller particle size than that synthesized using the base. Aloe-vera-mediated NiOx NPs exhibited the best electrocatalytic performance with an overpotential of 413 mV at 10 mA cm−2 and a Tafel slope of 95 mV dec−1. Electrochemical surface area (ECSA) measurement and electrochemical impedance spectroscopic analysis verified that the high surface area, efficient charge-transfer kinetics and higher conductivity of aloe-vera-mediated NiOx NPs contribute to its low overpotential values. [ABSTRACT FROM AUTHOR]

In this study, phytochemical assisted nanoparticle synthesis was performed using Muntingia calabura leaf extracts to produce copper oxide nanoparticles (CuO NPs) with interesting morphology. Scanning electron microscope (SEM) and transmission electron microscope (TEM) analysis of the biosynthesized CuO NPs reveal formation of distinct, homogeneous, and uniform sized CuO nanorods structure with thickness and length of around 23 nm and 79 nm, respectively. Based on Fourier-transform infrared (FTIR) analysis, the unique combinations of secondary metabolites such as flavonoid and polyphenols in the plant extract are deduced to be effective capping agents to produce nanoparticles with unique morphologies similar to conventional chemical synthesis. X-ray diffraction (XRD) analysis verified the monoclinical, crystalline structure of the CuO NPs. The phase purity and chemical identity of the product was consolidated via X-Ray photoelectron spectroscopy (XPS) and Raman spectroscopic data which indicate the formation of a single phase CuO without the presence of other impurities. The direct and indirect optical band gap energies of the CuO nanorods were recorded to be 3.65 eV and 1.42 eV. [ABSTRACT FROM AUTHOR]

This study explores the possibility of transforming lignocellulose-rich agricultural waste materials into value-added products. Cellulose was extracted from an empty fruit bunch of oil palm and further modified into carboxymethyl cellulose (CMC), a water-soluble cellulose derivative. The CMC was then employed as the polymeric content in fabrication of solid polymer electrolyte (SPE) films incorporated with lithium iodide. To enhance the ionic conductivity of the solid polymer electrolytes, the compositions were optimized with different amounts of glycerol as a plasticizing agent. The chemical and physical effects of plasticizer content on the film composition were studied by Fourier transform infrared (FTIR) and X-ray diffraction (XRD) analysis. FTIR and XRD analysis confirmed the interaction plasticizer with the polymer matrix and the amorphous nature of fabricated SPEs. The highest ionic conductivity of 6.26 × 10−2 S/cm was obtained with the addition of 25 wt % of glycerol. By fabricating solid polymer electrolytes from oil palm waste-derived cellulose, the sustainability of the materials can be retained while reducing the dependence on fossil fuel-derived materials in electrochemical devices. [ABSTRACT FROM AUTHOR]

A starch-resorcinol-formaldehyde (RF)-lithium triflate (LiTf) based biodegradable polymer electrolyte membrane was synthesized via the solution casting technique. The formation of RF crosslinks in the starch matrix was found to repress the starch's crystallinity as indicated by the XRD data. Incorporation of the RF plasticizer improved the conductivity greatly, with the highest room-temperature conductivity recorded being 4.29 × 10−4 S cm−1 achieved by the starch:LiTf:RF (20 wt.%:20 wt.%:60 wt.%) composition. The enhancement in ionic conductivity was an implication of the increase in the polymeric amorphous region concurrent with the suppression of the starch's crystallinity. Chemical complexation between the plasticizer, starch, and lithium salt components in the electrolyte was confirmed by FTIR spectra. [ABSTRACT FROM AUTHOR]

This work is a pioneer attempt to fabricate quasi-solid dye-sensitized solar cell (QSDDSC) based on organosoluble starch derivative. Rheological characterizations of the PhSt-HEC blend based gels exhibited viscoelastic properties favorable for electrolyte fabrication. From amplitude sweep and tack test analyses, it was evident that the inclusion of LiI improved the rigidity and tack property of the gels. On the other hand, the opposite was true for TPAI based gels, which resulted in less rigid and tacky electrolytes. The crystallinity of the gels was found to decline with increasing amount of salt in both systems. The highest photoconversion efficiency of 3.94% was recorded upon addition of 12.5 wt % TPAI and this value is one of the highest DSSC performance recorded for starch based electrolytes. From electrochemical impedance spectroscopy (EIS), it is deduced that the steric hindrance imposed by bulky cations aids in hindering recombination between photoanode and electrolyte. [ABSTRACT FROM AUTHOR]

Several images are presented in support of a study which examined artificial neural networks, phthaloylchitosan-based gel polymer electrolyte, and ionic conductivity.