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In the current investigation, zinc oxide (ZnO) nanoparticles and Fe-doped ZnO nanoparticles were sustainably synthesized utilizing an extract derived from the Rumex dentatus plant through a green synthesis approach. The Scanning electron microscope (SEM), X-ray diffraction (XRD), Energy-dispersive x-ray spectroscopy (EDX), Ultra-violet visible spectroscopy (UV–vis) spectroscopy, Fourier-transform infrared spectroscopy (FTIR), and Thermogravimetric analysis (TGA) techniques were used to examine the compositional, morphological, optical, and thermal properties of both samples. The doping of iron into ZnO NPs has significantly influenced their properties. The analysis firmly established that both ZnO NPs and Fe-doped ZnO NPs have hexagonal wurtzite structures and spherical shapes by XRD and SEM. The EDX analysis suggests that iron atoms have been successfully integrated into the ZnO lattice. The change in color observed during the reaction indicated the formation of nanoparticles. The UV–vis peaks at 364 nm and 314 nm confirmed the presence of ZnO NPs and Fe-doped ZnO NPs, respectively. The band gap of ZnO NPs by Fe dopant displayed a narrowing effect. This indicates that adding iron ions to ZnO NPs offers a control band gap. The thermal study TGA revealed that Fe-doped ZnO NPs remain stable when heated up to 600 °C. The antibacterial efficacy of ZnO NPs and Fe-doped ZnO NPs was evaluated against several bacterial strains. The evaluation is based on the zone of inhibition (ZOI). Both samples exhibited excellent antibacterial properties as compared to conventional pharmaceutical agents. These results suggest that synthesizing nanoparticles through plant-based methods is a promising approach to creating versatile and environmentally friendly biomedical products. [ABSTRACT FROM AUTHOR]

For modern high‐tech flexible energy storage devices, it becomes important to synthesize micro‐/nanostructures as per the required shape and morphology with superior physical and electro‐active characteristics. This work shares the fabrication and characterization of ZnSn(OH)6 (Zinc hydroxystannate [ZHS]) prepared by facile microwave‐assisted technique and furthermore converted into flexible sheets by employing lignocelluloses (LC) known as natural fibers, collected from Carica papaya leaf petiole as a substrate to provide the flexible matrix. X‐ray diffraction measurements confirm the successful crystalline structure of ZHS. Scanning electron microscopy and transmission electron microscopy showed the solid spherical structure of ZHS microspheres. Fourier transform infrared spectrometry and Raman spectroscopy confirmed the composite formation of ZHS and LC‐based composite sheets (ZHS/LC sheets). Electrochemical measurements that is, cyclic voltammetry (CV), Galvanostatic charge/discharge, and electrochemical impedance (EIS) spectroscopy revealed the electroactive behavior of ZHS/LC paper sheets as working electrode for energy storage applications. CV measurements revealed the specific capacitance of 100 F/g and EIS measurements confirmed the decrease in the resistance of LC fiber after the growth of ZHS microspheres. Presented flexible ZHS based paper sheets will be highly feasible for the modern bendable/flexible/disposable energy storage applications. [ABSTRACT FROM AUTHOR]

Tremendous efforts have been directed to developing reliable electrocatalysts to gain clean hydrogen energy from water splitting and encounter energy challenges. The morphology at the nanoscale of electrocatalysts has also a significant influence on hydrogen evolution reaction. An alkaline-based electrocatalyst, strontium hydroxide hydrate, has been synthesized at temperatures of 80, 140, and 200 °C using the hydrothermal process. The employed growth temperature capably influences the morphology and intrinsic characteristics of the strontium hydroxide hydrate for the hydrogen evolution reaction. The mesoporous nature, greater electrochemical and specific surface area of nanorods, and facile proton donation by the acid jointly enhance the HER activity. Hy-Sr-(OH)2-200 nanorods have exhibited a good overpotential of 84 mV in 0.5 M H2SO4 at the current density of 10 mA cm–2, which is better than the nanopallets (Hy-Sr-(OH)2-80) and the hybrid morphology consisting of nanopallets and nanorods (Hy-Sr-(OH)2-140). The mesoporous nature, greater electrochemical and specific surface area, and nanorod-like morphology have promoted and facilitated the adsorption and desorption of the active hydrogen atoms at the active sites inside the Hy-Sr-(OH)2-200 nanorods. As a result, Hy-Sr-(OH)2-200 nanorods exhibit the Tafel slope of 81 mV dec–1 in 0.5 M H2SO4 and follow the Volmer–Heyrovsky phenomena. Moreover, Hy-Sr-(OH)2-200 nanorods show a good turnover frequency of 142.84 ms–1 at the fixed reversible hydrogen potential of 0.5 V, which is better than the other employed electrolytes and electrocatalysts fabricated at temperatures of 80 and 140 °C. The symmetric system, consisting of Hy-Sr-(OH)2-200 nanorods, shows a good overpotential of 240 mV at a current density of 10 mA cm–2, along with a Tafel slope of 79 mV dec–1 in 0.5 M H2SO4. The electrocatalyst of Hy-Sr-(OH)-2-200 nanorods comprehensively exhibits good performance for the hydrogen evolution reaction. [ABSTRACT FROM AUTHOR]

Functional materials, in the combination of lignocelluloses, known as natural fibers, with oxide materials, can result in cultivating functional properties such as flexibility, relativity good electrical conduction, good electrical charge storage capacity, and tunable electric permittivity. This study presents the morphological, dielectric, and impedance properties of lignocellulose–lead oxide (LC/PbO2) composite sheets electrodeposited with silver metallic nanoparticles for various time spans. The uncoated samples show a rather simple behavior where the impedance data fit well to the two-system model with different relaxation times. On the other side, the impedance spectra of the electrodeposited sample have varying features, which mainly depend upon the deposition thickness of the Ag particles. The common feature is the drift of conductive species, as seen from the straight-line behavior in the Nyquist plots, which were fitted using a Warburg element in the equivalent circuit model. [ABSTRACT FROM AUTHOR]

The past one and a half decades have witnessed the tremendous progress of two-dimensional (2D) crystals, including graphene, transition-metal dichalcogenides, black phosphorus, MXenes, hexagonal boron nitride, etc., in a variety of fields. The key to their success is their unique structural, electrical, mechanical and optical properties. Herein, this paper gives a comprehensive summary on the recent advances in 2D materials for optoelectronic approaches with the emphasis on the morphology and structure, optical properties, synthesis methods, as well as detailed optoelectronic applications. Additionally, the challenges and perspectives in the current development of 2D materials are also summarized and indicated. Therefore, this review can provide a reference for further explorations and innovations of 2D material-based optoelectronics devices. [ABSTRACT FROM AUTHOR]

Composite materials and their applications constitute a hot field of research nowadays due to the fact that they comprise a combination of the unique properties of each component of which they consist. Very often, they exhibit better performance and properties compared to their combined building blocks. Graphene oxide (GO), as the most widely used derivative of graphene, has attracted widespread attention because of its excellent properties. Abundant oxygen-containing functional groups on GO can provide various reactive sites for chemical modification or functionalization of GO, which in turn can be used to develop novel GO-based composites. This review outlines the most recent advances in the field of novel dyes and pigments encompassing GO as a key ingredient or as an important cofactor. The interactions of graphene with other materials/compounds are highlighted. The special structure and unique properties of GO have a great effect on the performance of fabricated hybrid dyes and pigments by enhancing the color performance of dyes, the anticorrosion properties of pigments, the viscosity and rheology of inks, etc., which further expands the applications of dyes and pigments in dyeing, optical elements, solar-thermal energy storage, sensing, coatings, and microelectronics devices. Finally, challenges in the current development as well as the future prospects of GO-based dyes and pigments are also discussed. This review provides a reference for the further exploration of novel dyes and pigments. [ABSTRACT FROM AUTHOR]

A non-enzymatic dopamine electrochemical sensing probe was developed. A hexagonal shape zinc-doped cobalt oxide (Zn-Co2O4) nanostructure was prepared by a facile hydrothermal approach. The combination of Zn, which has an abundance of electrons, and Co3O4 exhibited a synergistically electron-rich nanocomposite. The crystallinity of the nanostructure was investigated using X-ray diffraction. A scanning electron microscope (SEM) was used to examine the surface morphology, revealing hexagonal nanoparticles with an average particle size of 400 nm. High-resolution transmission electron microscopy (HR-TEM) was used to confirm the nanostructure of the doped material. The nanostructure's bonding and functional groups were verified using Fourier transform infrared spectroscopy (FTIR). The electrochemical characterization was conducted by using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and amperometry. The resistivity of the electrode was confirmed through EIS and showed that the bare glassy carbon electrode (GCE) exhibited higher charge transfer resistance as compared to modified Zn-Co2O4/GCE. The sensing probe was developed by modifying the surface of GCE with Zn-Co2O4 nanostructure and tested as an electrochemical sensor for dopamine oxidation; it operated best at a working potential of 0.17 V (vs Ag/AgCl). The developed sensor exhibited a low limit of detection (0.002 µM), a high sensitivity (126 µA. µM−1 cm−2), and a wide linear range (0.2 to 185 µM). The sensor showed a short response time of < 1 s. The sensor's selectivity was investigated in the presence of coexisting species (uric acid, ascorbic acid, adrenaline, epinephrine, norepinephrine, histamine, serotonin, tyramine, phenethylamine, and glucose) with no effects on dopamine determination results. The developed sensor was also successfully used for determining dopamine concentrations in a real sample. [ABSTRACT FROM AUTHOR]

Tungstate nanorods (WO3 -NRs) were synthesized by a facile hydrothermal method using sodium tungstate as a precursor while sodium sulfate and hydrochloric acid were used as stabilizing agents. Scanning electron microscopy (SEM) images showed outstanding growth of WO3-NRs with uniform surface morphology. The X-ray diffraction (XRD) analysis confirmed the purity and crystalline nature of the synthesized material. The material was further characterized by different tools such as TEM, EDX, FTIR, XPS, BET, and Raman spectroscopy. For the electrochemical response of WO3-NRs, cyclic voltammetry measurements were performed for the detection of vitamin C (ascorbic acid). The designed sensor shows a limit of detection of 0.56 µM and higher selectivity in the presence of its structural and functional analogs such as uric acid and lauric acid. Improved sensing properties of WO3-NRs are attributed to the synergistic effects involving the quantum effect, high surface area, fast electron transfer, and highly ordered 1-D nanostructure. Among them, the highly arranged 1-D growth of WO3 nanorods has a greater impact on the efficiency of the biosensor. These results provide a new insight for the synthesis of 1-D nanostructures of transition metal oxides for contributions in sensor devices, solar cells, and capacitor applications. [ABSTRACT FROM AUTHOR]

Zinc oxide (ZnO) nanostructures were synthesized via a one‐step solid‐state reaction approach in ammonia (NH3) gas environment with different temperature ramp rates. The so‐formed nanostructures were characterized using X‐ray diffraction (XRD) for phase identification, where the typical wurtzite hexagonal structure was observed. Scanning electron microscopy (SEM) confirmed the particle size to be in the range 45–50 nm, the same as calculated by the XRD pattern for the ramp rate of 10 °C/min. Energy dispersive X‐ray (EDX) spectroscopy and X‐ray photoelectron spectroscopy (XPS) confirmed the chemical purity of the samples. The photoluminescence (PL) spectrum indicated multiple near‐band‐edge emissions and energy‐band emissions. Then, these ZnO nanomaterials were used for the degradation of crystal violet (CV) dye under UV light irradiation. The CV solution was completely degraded in 2 hr. The initial photocatalyst and dye amounts of 0.2 g/100 ml and 0.5 mg/L, respectively, were found to be the optimum values for maximum degradation efficiency. The ZnO‐based photocatalyst was stable up to three cycles of reuse. These results indicate that the high surface area and porosity of the nanomaterials are responsible for the high efficiency, which was confirmed by specific surface area analysis. [ABSTRACT FROM AUTHOR]