Template-free synthesis of tetragonal Co-doped ZrO2 nanoparticles for applications in electrochemical energy storage and water treatment

Surface engineered recombinant Escherichia coli for the potential application of the cobalt contaminated wastewater treatment and the photocatalytic dye degradation

The novel recombinant Escherichia coli strain was construct through cell surface display for the treatment of cobalt contaminated wastewater and dye contaminated wastewater. First, structural analysis of known cobalt binding peptide was conducted and core binding sites were figured out which showing better cobalt binding ability. The cobalt peptides were attached to OmpC to construct cobalt adsorbing recombinant Escherichia coli. The recombinant strain efficiently absorbed and retrieved cobalt from cobalt wastewater by adsorbing 1895 µmol/g DCW of cobalt. Following adsorption, cobalt nanoparticles were synthesized through thermal decomposition of cobalt adsorbed recombinant strain at 500˚C. The nanoparticles exhibited noteworthy photocatalytic properties, demonstrating a substantial capacity for degrading dyes when used as a catalyst at a concentration of 10 mg/dl. These results presenting potential solutions for effective and environmentally friendly approaches to address cobalt and dye contaminated wastewater treatment process.

3D Hierarchically Structured Tin Oxide and Iron Oxide-Embedded Carbon Nanofiber with Outermost Polypyrrole Layer for High-Performance Asymmetric Supercapacitor

Herein, unique three-dimensional (3D) hierarchically structured carbon nanofiber (CNF)/metal oxide/conducting polymer composite materials were successfully synthesized by combinations of various experimental methods. Firstly, base CNFs were synthesized by carbonization of electrospun PAN/PVP fibers to attain electric double-layer capacitor (EDLC) characteristics. To further enhance the capacitance, tin oxide (SnO₂) and iron oxide (Fe₂O₃) were coated onto the CNFs via facile hydrothermal treatment. Finally, polypyrrole (PPy) was introduced as the outermost layer by a dispersion polymerization method under static condition to obtain 3D-structured CNF/SnO₂/PPy and CNF/Fe₂O₃/PPy materials. With each synthesis step, the morphology and dimension of materials were transformed, which also added the benign characteristic for supercapacitor application. For the practical application, as-synthesized CNF/SnO₂/PPy and CNF/Fe₂O₃/PPy were applied as active materials for supercapacitor electrodes, and superb specific capacitances of 508.1 and 426.8 F g^-1 (at 1 A g^-1) were obtained (three-electrode system). Furthermore, an asymmetric supercapacitor (ASC) device was assembled using CNF/SnO₂/PPy as the positive electrode and CNF/Fe₂O₃/PPy as the negative electrode. The resulting CNF/SnO₂/PPy//CNF/Fe₂O₃/PPy device exhibited excellent specific capacitance of 101.2 F g^-1 (at 1 A g^-1). Notably, the ASC device displayed a long-term cyclability (at 2000 cycles) with a retention rate of 81.1%, compared to a CNF/SnO₂//CNF/Fe₂O₃ device of 70.3% without an outermost PPy layer. By introducing the outermost PPy layer, metal oxide detachment from CNFs were prevented to facilitate long-term cyclability of electrodes. Accordingly, this study provides an effective method for manufacturing a high-performance and stable supercapacitor by utilizing unique 3D hierarchical materials, comprised of CNF, metal oxide, and conducting polymer.

Cobalt-doped V2O5 hexagonal nanosheets for superior photocatalytic toxic pollutants degradation, Cr (VI) reduction, and photoelectrochemical water oxidation performance

The worldwide energy calamity and ecological disturbances demand materials that can remove harmful contaminants from the polluted water. Recently, semiconductor-based catalytic dye removal has created much consideration due to its high efficacy and eco-friendly contaminated water treatment processes. Vanadium oxide (V₂O₅) has attracted superior attention as a catalyst due to its robust oxidation power, chemical inertness, and stability against photodegradation. In this study, pristine and cobalt (Co)-doped V₂O₅ samples were synthesized by solvothermal method and examined for their photo-degradation activity and photoelectrochemical (PEC) water oxidation properties. The orthorhombic crystal phase was confirmed by X-ray diffraction (XRD), hexagonal-shaped morphology was observed by scanning electron microscope (SEM) and reduced optical band gap (2.01 eV) was noticed for doped V₂O₅ catalyst compared to the pristine (2.20 eV) catalyst. The doped V₂O₅ catalyst exhibited enhanced photodegradation of crystal violet CV (92.7%) and Cr (VI) reduction (90.5%) after 100 min of light irradiation. The doped photocatalyst exhibited approximately 2.1 and 1.9-fold enhancement of photodegradation of CV and Cr(VI) reduction, respectively. The doped electrode showed improved photocurrent density (0.54 mA/cm^-2) compared to pristine electrode (0.12 mA/cm^-2). Moreover, the doped electrode showed reduced charge-transfer resistance and enhanced charge-transfer properties compared to those of the pristine electrode. Hence, the prepared hexagonal-shaped V₂O₅ is a suitable material for the elimination of environmental contaminants from the polluted water as well as water splitting for hydrogen generation.

Integrating thermodynamics towards bulk level synthesis of nano Ni catalysts: a green mediated sol–gel auto combustion method

Novel strategy for the environmentally benign bulk level synthesis of nickel nanoparticles.

Facile synthesis of multifunctional C@Fe3O4-MoO3-rGO ternary composite and its versatile roles as sonoadsorbent to ameliorate triphenylmethane textile dye and as potential electrode for supercapacitor applications

The toxic wastewater effluents from textile dyes have been a significant environmental threat worldwide in recent decades. Against this backdrop, this study investigates the performance of C@Fe₃O₄-MoO₃-rGO as a sonoadsorbent to ameliorate crystal violet (CV) dye from the aqua matrix and further explores its potential as an electrode in supercapacitor applications. The phase purity, crystal structure, surface morphology, thermal stability and magnetic behaviour characteristics of the composite were studied using various characterisation techniques such as powder X-ray diffraction (XRD), Raman Spectroscopy, Fourier transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FESEM), High-resolution transmission electron microscopy (HRTEM), Thermogravimetric analysis (TGA) and Vibrating-sample magnetometry (VSM). From the Langmuir isotherm model, the synthesised sonoadsorbent exhibited a maximum adsorption capacity of 1664.26 mg/g for crystal violet, which is remarkably high. Further, to its inherited magnetic characteristics, the composite can be easily separated from the solution by using an external magnet. Furthermore, the working electrode was synthesised with 80% active material, 10% carbon black, and 10% polyvinylidene difluoride to investigate its suitability in supercapacitor applications. The C@Fe₃O₄-MoO₃-rGO composite exhibited an excellent capacitance value of 180.36 F/g with commendable cycling stability, making it suitable as a potential cathode material for the next generation supercapacitors.

Novel g-C3N4/Cu-doped ZrO2 hybrid heterostructures for efficient photocatalytic Cr(VI) photoreduction and electrochemical energy storage applications

Pure ZrO₂, graphitic carbon nitride, Cu-doped ZrO₂ nanoparticles (Cu-Zr), and doped Cu-Zr nanoparticles decorated on the g-C₃N₄ surface (g-CuZr nanohybrids) were successfully prepared by a hydrothermal technique. Synthesized catalysts were examined by XRD, FE-SEM, TEM, UV-Vis spectroscopy, photoluminescence (PL), and BET surface measurements, respectively. The photocatalytic reduction of Cr(VI) photoreduction as well as energy storage supercapacitor applications were thoroughly investigated. The g-CuZr hybrid photocatalyst outperformed other pristine photocatalysts in terms of light absorption and catalytic Cr(VI) reduction performance under stimulated solar light irradiation. Furthermore, methylene blue (MB) was used as a photosensitizer to further improve the Cr(VI) photoreduction performance. In precise, the heterostructured hybrid catalyst exhibited improved photocatalytic Cr(VI) photoreduction activity (∼88.1%) in 5 mg/L MB solution over other catalysts. Moreover, the decoration of Cu-Zr on the surface of g-C₃N₄ enhanced the absorption ability of light and catalytic Cr(VI) photoreduction performance. The PL, EIS, and transient photocurrent analysis demonstrated that the efficiency of the charge carrier's separation in the nanohybrid catalyst was superior over other catalysts. Furthermore, heterostructured g-CuZr nanohybrid electrode exhibited superior specific capacitance (297.2 F/g) over other electrodes, which are 5.5 folds (54.01 F/g), ∼2 folds (144.01 F/g) better than pure ZrO₂ and g-C₃N₄ electrodes. Likewise, the nanohybrid electrode retained about 90% of the capacitive value after 2500 cycles over its initial capacitance.

New lignin-based hybrid materials as functional additives for polymer biocomposites: From design to application

Within this study, the ZrO₂/lignin and ZrO₂-SiO₂/lignin hybrid materials were obtained for the first time. The mechanical grinding method was used for this purpose. In order to determine the properties of obtained lignin-based hybrids and the components used to produce them, as well as to evaluate the efficiency of their preparation, the authors used such research techniques as scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), elemental analysis, porous structure analysis and thermal stability assessment (TGA/DTG). The next step involved using the components and produced hybrid materials as polymer fillers for poly(methyl methacrylate) (PMMA). The obtained lignin-based hybrid biocomposites have then been thoroughly characterized using gel permeation chromatography (GPC), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and hardness testing. All the conducted tests confirm the possibility of using the obtained bio-based products in practice, within the widely understood construction industry, for producing durable building facades or noise barriers, among others.

Novel NiMgOH-rGO-Based Nanostructured Hybrids for Electrochemical Energy Storage Supercapacitor Applications: Effect of Reducing Agents

This paper describes the synthesis and characterization of NiMgOH-rGO nanocomposites made using a chemical co-precipitation technique with various reducing agents (e.g., NaOH and NH4OH) and reduced graphene oxide at 0.5, 1, and 1.5 percent by weight. UV-visible spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, a particle size analyzer, and cyclic voltammetry were used to characterize the composite materials. The formation of the NiMgOH-rGO nanocomposite with crystallite sizes in the range of 10–40 nm was inferred by X-ray diffraction patterns of materials, which suggested interlayers of Ni(OH)2 and Mg(OH)2. The interactions between the molecules were detected using Fourier-transform infrared spectroscopy, while optical properties were studied using UV-visible spectroscopy. A uniform average particle size distribution in the range of 1–100 nm was confirmed by the particle size analyzer. Using cyclic voltammetry and galvanostatic charge/discharge measurements in a 6 M KOH solution, the electrochemical execution of NiMgOH-rGO nanocomposites was investigated. At a 1 A/g current density, the NiMgOH-rGO nanocomposites prepared with NH4OH as a reducing agent had a higher specific capacitance of 1977 F/g. The electrochemical studies confirmed that combining rGO with NiMgOH increased conductivity.

Role of supercritical carbon dioxide (scCO2) in fabrication of inorganic-based materials: a green and unique route

In recent times, the supercritical carbon dioxide (scCO₂) process has attracted increasing attention in fabricating diverse materials due to the attractive features of environmentally benign nature and economically promising character. Owing to these unique characteristics and high-penetrability, as well as diffusivity conditions of scCO₂, this high-pressure technology, with mild operation conditions, cost-effective, and non-toxic, among others, is often applied to fabricate various organic and inorganic-based materials, resulting in the unique crystal architectures (amorphous, crystalline, and heterojunction), tunable architectures (nanoparticles, nanosheets, and aerogels) for diverse applications. In this review, we give an emphasis on the fabrication of various inorganic-based materials, highlighting the recent research on the driving factors for improving the quality of fabrication in scCO₂, procedures for production and dispersion in scCO₂, as well as common indicators utilized to assess quality and processing ability of materials. Next, we highlight the effects of specific properties of scCO₂ towards synthesizing the highly functional inorganic-based nanomaterials. Finally, we summarize this compilation with interesting perspectives, aiming to arouse a more comprehensive utilization of scCO₂ to broaden the horizon in exploring the green/eco-friendly processing of such versatile inorganic-based materials. Together, we firmly believe that this compilation endeavors to disclose the latent capability and universal prevalence of scCO₂ in the synthesis and processing of inorganic-based materials.

Construction of an electrochemical sensor with graphene aerogel doped with ZrO2 nanoparticles and chitosan for the selective detection of luteolin

A simple, fast and sensitive method for the detection of luteolin is proposed based on the chitosan/reduced graphene oxide aerogel with dispersed ZrO₂ nanoparticles modified glassy carbon electrode (ZrO₂/CS/rGOA-GCE) as an electrochemical sensor. The ZrO₂/CS/rGOA composite was prepared by one pot synthesis from a mixture of GO, CS and zirconyl chloride octahydrate, and subsequently be freeze-dried. Scanning electron microscope images showed a typical thin, wrinkled and fluctuant morphology of graphene nanosheets and the polymerized CS and ZrO₂ nanoparticles deposited on the surface of rGOA. Cyclic voltammetry and differential pulse voltammetry were used to measure the electrochemical response of ZrO₂/CS/rGOA composite-based biosensor towards luteolin at the working potential window (-0.8-0.8 V). The improved performance of this biosensor was attributed to efficient electron transfer and large surface area of 3D rGOA, and high specific activity of Zr towards adjacent hydroxyl groups. Under optimized conditions, the analytical performance of this method towards luteolin was investigated with a detection limit of 1 nM and a linear range from 5 nM to 1000 nM.. Finally, the ZrO₂/CS/rGOA-GCE electrochemical method coupled with solid phase extraction was used for the detection of luteolin in real samples. Recoveries of  spiked samples with different concentrations were in the range 78.6-103.3% with a relative RSD lower than 12.0%. Graphical abstract Schematic representation of the preparation of the ZrO₂ nanoparticles and chitosan doped graphene aerogel modified electrode. The electrode was employed for the detection of luteolin coupled with the solid-phase extraction technique.

One-step synthesis of high photocatalytic graphitic carbon nitride porous nanosheets

As a metal-free photocatalyst, graphitic carbon nitride (g-C₃N₄) has attracted tremendous attention. Preparation of porous few-layer g-C₃N₄ nanosheets has been proven to be an effective strategy to obtain high photocatalytic performance. At present, most methods are expensive, time-consuming or complicated. Here, a low-cost, facile and environment-friendly one-step synthesis method of porous few-layer g-C₃N₄ nanosheets is designed by introducing water in the precursor. Straightforward calcination of the precursor, which decomposes to form ammonia, can produce g-C₃N₄ nanosheets with the assistance of water. Under the visible light (>400 nm), the photocatalytic H₂ evolution performance of the so-obtained nanosheets is 3214 μmol · g^-1 · h^-1, which is 17.3 times of the original bulk g-C₃N₄. The apparent quantum yield is 27% under the 380 nm monochromatic light irradiation.

Enhanced catalytic activity of OMS-2 for carcinogenic benzene elimination by tuning Sr2+ contents in the tunnels

Cryptomelane-type manganese oxides (OMS-2) have been intensively investigated for application in the catalytic oxidation of carcinogenic benzene, and doping metal ions in the OMS-2 tunnels are widely used for modifying its catalytic activity. In this study, we reported a novel strategy of enhancing catalytic activity of OMS-2 for carcinogenic benzene elimination by tuning Sr²⁺ concentration in the tunnels. The catalytic activity result revealed that an obvious decrease (△T₅₀ = 27 °C and △T₉₀ = 37 °C) in T₅₀ and T₉₀ (corresponding to benzene conversions at 50 % and 90 %, respectively; initial benzene concentration was 2000 mg m^-3; contact time was 1.5 s) had been observed by increasing the Sr²⁺ concentration in the OMS-2 tunnels. The origin of Sr²⁺ doping effect on catalytic activity was theoretically and experimentally investigated by CO temperature-programmed reduction, ¹⁸O₂ isotope labeling, and density functional theory calculations. The result confirmed that increasing Sr²⁺ concentration in the tunnels not only promoted the lattice oxygen activity, but also facilitated the generation of more oxygen vacancy defects, thus considerably improving the catalytic activity of OMS-2.

Performance of chemically synthesized Mn3O4/rGO nanocomposite for electrochemical supercapacitor: a cost-effective high-performance electrode

The manganese oxide graphene oxide (Mn₃O₄/rGO) composite heterojunction with copper oxide is useful for the production of an electrochemical supercapacitor. The graphene oxide and manganese oxide composite have been synthesized by adopting a method of co-precipitation. The composite of Mn₃O₄/rGO was synthesized with different concentrations of Mn₃O₄ and rGO. The structural, morphological, electrochemical and supercapacitive properties of Mn₃O₄/rGO composite have been examined. The electrochemical and supercapacitive properties have been studied with regard to different substrates. The Mn₃O₄/rGO composite was deposited on different substrates such as steel, copper and brass. The CuO/Mn₃O₄/rGO shows relatively better specific capacitance (856 F g^-1) and better stability (82% retention after 2000 cycles) than other substrates used. The present work describes the development of cost-effective and high-performance CuO/Mn₃O₄/rGO-based nanomaterials for supercapacitors. The CuO/Mn₃O₄/rGO composite can be used as a flexible supercapacitor device.

Synthesis opto-electronic characterization and NLO evaluation of 6-methyl 5-nitro Uracil crystal using XRD, spectroscopic and theoretical tools

The organic composite crystal for 6-methyl 5-nitro Uracil was grown using slow-evaporation method and the crystal quality was checked by observing the peaks in XRD pattern. The molecular structure of 6-methyl 5-nitro Uracil was used to find crystal parameters for determining NLO activity. The appropriate electronic geometrical structure was keenly noted and the transitional energy exchange was studied and thereby fine-tuning of crystal performance was made by adopting suitable electron-accepting and with-drawing substitutional groups. The crystal parameters; a≠b≠c confirmed the orthorhombic lattice pattern. The space group was found as P21/a and Transparency range was observed as 409-1256 nm. The laser measurements were made and laser Damage threshold was estimated at 10 ns[1.08-3 GW/cm2]. The scattering characteristics of bond networks over the molecule were observed by studying vibrational characteristics of elemental bonds. The hybrid calculations on DFT methods were made using B3LYP/6-311++(D,P) basis set. The chemical shift was observed and retracing chemical potential was identified from the parametric oscillation. The frontier molecular interactions between ground and excited orbital lobe overlapping segments were noted and type of interaction system was identified. The electronic and protonic transfer energy was measured and the origination point of equivalent chemical potential was acknowledged. The NBMO profile was keenly grafted and the transitional energy was measured at every consumed electronic energy band. The vibrational circular dichroic image for all vibrational regions was sketched and the rate of transmission and absorption ratio was verified from peak intensity.

ZnO nanosheets-decorated Bi2WO6 nanolayers as efficient photocatalysts for the removal of toxic environmental pollutants and photoelectrochemical solar water oxidation

Herein we report the fabrication of novel Bi₂WO₆/ZnO heterostructured hybrids for organic contaminant degradation from wastewater and photoelectrochemical (PEC) water splitting upon solar illumination. The Bi₂WO₆/ZnO photocatalysts were synthesized using a simple and eco-friendly hydrothermal process without the support of any surfactants. From the photocatalytic experiments, heterostructured Bi₂WO₆/ZnO nanohybrid catalysts exhibited considerably better photocatalytic performance for rhodamine B (RhB) degradation under solar illumination. The BWZ-20 nanocomposite demonstrated superior photodegradation of RhB dye up to 99% in about 50 min. Furthermore, BWZ-20 photoelectrode showeda lower charge-transfer resistance than other samples prepared, suggesting its suitability for PEC water splitting. The photocurrent densities of Bi₂WO₆/ZnO photoelectrodes were evaluated under the solar irradiation. The BWZ-20 photoelectrode exhibited a significant photocurrent density (0.45 × 10^-3A/cm²) at +0.3 V vs. Ag/AgCl, which was~1036-times higher than that of pure Bi₂WO₆, and ~4.8-times greater than the pure ZnO. Such improved photocatalytic and PEC activities are mainly attributed to the formation of an interface between ZnO and Bi₂WO₆, superior light absorption ability, low charge-transfer resistance, remarkable production of charge carriers, easy migration of charges, and suppression of the recombination of photogenerated charge carriers.

Biosynthesis of Copper Oxide Nanoparticles with Potential Biomedical Applications

Introduction

In recent years, the use of cost-effective, multifunctional, environmentally friendly and simple prepared nanomaterials/nanoparticles have been emerged considerably. In this manner, different synthesizing methods were reported and optimized, but there is still lack of a comprehensive method with multifunctional properties.

Materials and Methods

In this study, we aim to synthesis the copper oxide nanoparticles using Achillea millefolium leaf extracts for the first time. Catalytic activity was investigated by in situ azide alkyne cycloaddition click and also A³ coupling reaction, and optimized in terms of temperature, solvent, and time of the reaction. Furthermore, the photocatalytic activity of the synthesized nanoparticles was screened in terms of degradation methylene blue dye. Biological activity of the synthesized nanoparticles was evaluated in terms of antibacterial and anti-fungal assessments against Staphylococcus aureus, M. tuberculosis, E. coli, K. pneumoniae, P. mirabili, C. diphtheriae and S. pyogenes bacteria's and G. albicans, A. flavus, M. canis and G. glabrata fungus. In the next step, the biosynthesized CuO-NPs were screened by MTT and NTU assays.

Results

Based on our knowledge, this is a comprehensive study on the catalytic and biological activity of copper oxide nanoparticles synthesizing from Achillea millefolium, which presents great and significant results (in both catalytic and biological activities) based on a simple and green procedure.

Conclusion

Comprehensive biomedical and catalytic investigation of the biosynthesized CuO-NPs showed the mentioned method leads to synthesis of more eco-friendly nanoparticles. The in vitro studies showed promising and considerable results, and due to the great stability of these nanoparticles in a green media, effective biological activity considered as an advantageous.

NiCo2O4 Nano-/Microstructures as High-Performance Biosensors: A Review

Non-enzymatic biosensors based on mixed transition metal oxides are deemed as the most promising devices due to their high sensitivity, selectivity, wide concentration range, low detection limits, and excellent recyclability. Spinel NiCo2O4 mixed oxides have drawn considerable attention recently due to their outstanding advantages including large specific surface area, high permeability, short electron, and ion diffusion pathways. Because of the rapid development of non-enzyme biosensors, the current state of methods for synthesis of pure and composite/hybrid NiCo2O4 materials and their subsequent electrochemical biosensing applications are systematically and comprehensively reviewed herein. Comparative analysis reveals better electrochemical sensing of bioanalytes by one-dimensional and two-dimensional NiCo2O4 nano-/microstructures than other morphologies. Better biosensing efficiency of NiCo2O4 as compared to corresponding individual metal oxides, viz. NiO and Co3O4, is attributed to the close intrinsic-state redox couples of Ni3+/Ni2+ (0.58 V/0.49 V) and Co3+/Co2+ (0.53 V/0.51 V). Biosensing performance of NiCo2O4 is also significantly improved by making the composites of NiCo2O4 with conducting carbonaceous materials like graphene, reduced graphene oxide, carbon nanotubes (single and multi-walled), carbon nanofibers; conducting polymers like polypyrrole (PPy), polyaniline (PANI); metal oxides NiO, Co3O4, SnO2, MnO2; and metals like Au, Pd, etc. Various factors affecting the morphologies and biosensing parameters of the nano-/micro-structured NiCo2O4 are also highlighted. Finally, some drawbacks and future perspectives related to this promising field are outlined.

An Overview of the Water Remediation Potential of Nanomaterials and Their Ecotoxicological Impacts

Nanomaterials, i.e., those materials which have at least one dimension in the 1–100 nm size range, have produced a new generation of technologies for water purification. This includes nanosized adsorbents, nanomembranes, photocatalysts, etc. On the other hand, their uncontrolled release can potentially endanger biota in various environmental domains such as soil and water systems. In this review, we point out the opportunities created by the use of nanomaterials for water remediation and also the adverse effects of such small potential pollutants on the environment. While there is still a large need to further identify the potential hazards of nanomaterials through extensive lab or even field studies, an overview on the current knowledge about the pros and cons of such systems should be helpful for their better implementation.

Copper-doped ZrO2 nanoparticles as high-performance catalysts for efficient removal of toxic organic pollutants and stable solar water oxidation

Doping effect on the photoelectrochemical (PEC) water splitting efficiency and photocatalytic activities of ZrO₂ under visible light are reported. The XRD analysis revealed that pure, 0.1 and 0.3 mol% doped samples showed mixed crystal phases (tetragonal and monoclinic) and 0.5 mol% doped sample showed a pure tetragonal phase. Under visible light, 90% of methyl orange dye degradation was achieved with in 100 min. Moreover, the optimal doped sample showed a significant degradation rate constant over other samples. The doped photoelectrodes display a better PEC water oxidation performance over pure photoelectrode. Furthermore, the optimal doped (0.3 mol %) electrode shows 0.644 mAcm^-2 photocurrent density, corresponding to an approximate 50-fold enhancement over pure electrode (0.013 mAcm^-2). The optimized doped sample achieved 98% degradation of methyl orange within 100 min of light irradiation. The superior PEC water oxidation and photocatalytic activity of optimal doped samples under visible light are credited to suitable doping content, crystalline size, greater surface area, suitable bandgap, a lower charge carrying resistance, surface properties and the ability for decreasing the charge carrier's recombination rate.

Efficient removal of toxic organic dyes and photoelectrochemical properties of iron-doped zirconia nanoparticles

Iron (Fe)-doped ZrO₂ tetragonal nanoparticles were synthesized by a facile and inexpensive hydrothermal technique, that were doped with Fe³⁺ ions (0.1, 0.3, and 0.5 mol%) into the host lattice without altering the morphology and crystal structure of the nanoparticles. SEM and TEM investigations indicated that the morphology of ZrO₂ nanoparticles did not change even after incorporation of Fe, while the band gap of semiconducting ZrO₂ nanoparticles was reduced from 4.97 to 1.77 eV. Such a in band gap was responsible to harvest more photons to stimulate the generation of more electrons in the valence band, thereby enhancing the photoelectrochemical (PEC) water splitting as well as photocatalytic and photoelectrocatalytic activities in the photodegradation of Rhodamine B. The 0.3 mol%-doped ZrO₂ electrode showed enhanced photocurrent density (0.07 × 10^-3 A/cm²), that was 45-times greater than the pure sample. The electrochemical impedance spectroscopy (EIS) confirmed that 0.3 mol%-doped ZrO₂ exhibited the best charge transfer characteristics, which increased with PEC water splitting activity. The maximum photocurrent density and long-term photo-stability were achieved in the light on-off states.

Casting of carbon cloth enrobed polypyrrole electrode for high electrochemical performances

The present investigation deals with the fabrication of a novel flexible and highly conductive PPy electrode. This was made by festooning PPy nanoparticles on carbon cloth (CC) by using chemical liquid process. The developed porous PPy@CC composite have good flexibility with low weight (1.1 mg) and high electrical conductivity (89 Ω-1cm-1). Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction spectroscopy (XRD) confirmed the formation of PPy on carbon cloth. Scanning electron micrographs (SEM) reveals that the PPy nanoparticles are encapsulated in carbon cloth. The fabricated carbon cloth has been used for solid-state symmetrical supercapacitors (SC) and low-cost material for electrode in potential energy storage devices. These film electrodes showed much superior electrochemical performance i.e. high stability under different current density, encouraging energy density, lower internal resistivity and higher specific capacitance. Synthesized flexible PPy@CC composite electrodes have brilliant applications in various kinds of electrochemical energy storage devices.

Aqueous Cu(ii) ion adsorption by amino-functionalized mesoporous silica KIT-6

After two-step modification, the adsorption capacity of PEI/KIT-6 for Cu²⁺ is significantly improved.

Use of flow field-flow fractionation and single particle inductively coupled plasma mass spectrometry for size determination of selenium nanoparticles in a mixture

Various analytical techniques have been used for size analysis of selenium nanoparticles (SeNPs). These include flow field-flow fractionation (FlFFF), single particle inductively coupled plasma mass spectrometry (SP-ICP-MS), dynamic light scattering (DLS) and transmission electron microscopy (TEM). For hydrodynamic diameter estimation, the FlFFF technique was used and the results were compared with those analyzed by DLS. For core diameter estimation, the results obtained from SP-ICP-MS were compared with those from TEM. Two types of FlFFF channel were employed, i.e., symmetrical FlFFF (Sy-FlFFF) and asymmetrical FlFFF (Asy-FlFFF). Considering the use of FlFFF, optimization was performed on a Sy-FlFFF channel to select the most appropriate carrier liquid and membrane in order to minimize problems due to particle membrane interaction. The use of FL-70 and 10 kDa RC provided an acceptable compromise peak quality and size accuracy for all samples of SeNPs which were coated by proteins (positively charged SeNPs) and sodium dodecyl sulfate (negatively charged SeNPs). FlFFF always yielded the lower estimate of the hydrodynamic size than DLS as a reference method. The results obtained by SP-ICP-MS were consistent with the TEM method for the core diameter estimation. The results from FlFFF and the DLS reference method were significantly different as confirmed by paired t-test analysis, while the results provided by SP-ICP-MS and the TEM reference method were not significantly different. Furthermore, consecutive size analysis by SP-ICP-MS for the fractions collected from FlFFF was proposed for sizing of SeNP mixtures. The combined technique helps to improve the size analysis in the complex samples and shows more advantages than using only SP-ICP-MS.

Various analytical techniques have been used for size analysis of selenium nanoparticles (SeNPs).