Determination of Tedizolid Phosphate Using Graphene Nanocomposite Based Solid Contact Ion Selective Electrode; Green Profile Assessment by Eco-scale and GAPI Approach

Antibiotics determination plays a major role in minimizing antimicrobial resistance starting from quality control of pharmaceutical formulations to therapeutic drug monitoring. Green modified glassy carbon electrode has been developed for determination of tedizolid phosphate; new antibiotic prodrug; in presence of its active metabolite. The graphene transducer interlayer, dispersed with PVC, improved the electrode stability and standard potential reproducibility. Graphene hydrophobicity prevented the water layer formation between the sensing layers that decreased the potential drift down to 267 μV h⁻¹. Electrochemical impedance showed a low resistance value for graphene containing sensor due to its high electron transfer ability.     

Novel Zn-Fe LDH/MWCNTs and Graphene/MWCNTs Nanocomposites Based Potentiometric Sensors for Benzydamine Determination in Biological Fluids and Real Water Samples

Two sensitive and selective potentiometric sensors based on zinc-iron layered double hydroxides/multiwalled carbon nanotubes (Zn−Fe LDH/MWCNTs) (sensor I) and graphene/multiwalled carbon nanotubes (Gr/MWCNTs) (sensor II) nanocomposites were developed for benzydamine hydrochloride (Benz) determination. The investigated sensors displayed excellent Nernstian slopes 58.5±0.7 and 59.5±0.5 mV decade⁻¹, detection limits 8.3×10⁻⁷ and 1.9×10⁻⁷ mol L⁻¹, long lifetimes, adequate selectivity, high chemical, and thermal stability within pH range of 2.4–8.5 for sensors І and ІІ, respectively. The surface morphology of sensors was analyzed using a Transmission Electron Microscope (TEM). The analytical method was efficiently implemented for Benz determination in biological fluids and surface water samples.     

Hybrid Nanocomposite Based Graphene Sensor for Ultrasensitive Clomipramine HCl Detection

A potentiometric sensor modified with a nanocomposite of montmorillonite sheets decorated with polyaniline nanofibers (MT-PANI-NFs) as an efficient electroactive material and tricresyl phosphate (TCP) as a solvent mediator has been developed for the estimation of clomipramine HCl (CLP.HCl). The optimum potentiometric performance of the sensor was achieved by mixing of MT-PANI-NFs : TCP : graphene with a ratio of 2.69 : 30.11 : 67.20 (% wt/wt). The sensor exhibited a Nernstian slope of 59.0±0.1 mV decade⁻¹ over the concentration range of 1.0×10⁻⁵−1.0×10⁻² mol L⁻¹ with a theoretically calculated detection limit of 5.0×10⁻⁶ mol L⁻¹. The sensor performance was scrutinized in terms of several factors including thermal stability, pH effect, response time and selectivity. As, it displayed a high thermal stability at various temperature degrees (10–60 °C) with pH independency in the range of 3.5–8.5. Additionally, the developed sensor exhibited a very rapid performance for CLP.HCl detection with a fast response time of 4 s and reflecting a superior selectivity towards CLP.HCl over the other interfering species. SEM (scanning electron microscope) was used as a characteristic tool for the investigation of the proposed graphene sensor surface. Furthermore, the graphene sensor has been efficiently used for CLP.HCl estimation in its pharmaceutical formulations.     

A New Comparative Potentiometric Method for Analysis of Omarigliptin Using Three Different Sensors

This work represents first attempt for potentiometric determination of the most recent antidiabetic; omarigliptin. Three sensors, employing potassium tetrakis (p-chlorophenyl) borate as a lipophilic cation exchanger, were developed and compared. One liquid contact ion-selective electrode and two carbon paste-based solid contact ones, plain one and another one modified with polyaniline nanoparticles, were employed. Performances of fabricated sensors were assessed as per IUPAC recommendations. Incorporation of hydrophobic polyaniline nanoparticles as ion-to-electron transducer layer at solid contact/ion-sensitive membrane interface enhanced sensitivity and stability of the third sensor showing LOD of 2.5×10⁻⁷ mol L⁻¹ and slope of 58.57 mV decade⁻¹. The three sensors were applied for omarigliptin determination in presence of its degradation products, in dosage form and spiked human plasma.     

3D Starfish-Like FeOF on Graphene Sheets: Engineered Synthesis and Lithium Storage Performance

To address the problems associated with poor conductivity and large volume variation in practical applications as a conversion cathode, engineering of hierarchical nanostructured FeOF coupled with conductive decoration is highly desired, yet rarely reported. Herein, 3D starfish-like FeOF on reduced graphene oxide sheets (FeOF/rGO) is successfully prepared, for the first time, through a combination of solvothermal reaction, self-assembly, and thermal reduction. Integrating the structural features of the 3D hierarchical nanostructure, which favorably shorten the path for electron/ion transport and alleviate volumetric changes, with those of graphene wrapping, which can further enhance the electrical conductivity and maintain the structural stability of the electrode, the as-prepared FeOF/rGO composite exhibits a superior lithium-storage performance, including a high reversible capacity (424.5 mA h⁻¹ g⁻¹ at 50 mA g⁻¹), excellent stability (0.016 % capacity decay per cycle during 180 cycles), and remarkable rate capability (275.8 mA h⁻¹ g⁻¹ at 2000 mA g⁻¹).     

In Situ Synthesis of CoCeSx Bimetallic Sulfide Nanoparticles on a Bi-Pyrene Terminated Molecular Wire Modified Graphene Surface for Supercapacitors

The excellent electrical conductivity of graphene is due to its highly-conjugated structures. Manipulation of the electronic and mechanical properties of graphene can be achieved by controlling the destruction of its in-sheet conjugation system. Herein, we report the preparation of CoCeS_x−SA@BPMW@RGO through π-π stacking interactions at the molecular level. In this study, sodium alginate was reacted with Co²⁺ and Ce³⁺, and the composite was loaded onto a graphene surface. The graphene sheets were prepared using a bi-pyrene terminated molecular wire (BPMW) to avoid re-stacking of the grapheme sheets, thereby forming nanoscale spaces between sheets. The angle between the BPMW coplanar pyrene group and the phenyl group was 33.2°, and the graphene layer is supported in an oblique direction. Finally, a three-dimensional porous composite was obtained after annealing and vulcanization. The obtained CoCeS_x−SA@BPMW@RGO exhibited excellent electrical conductivity and remarkable cycle stability. When the current density was 1 A g⁻¹, its specific capacitance was as high as 1004 F g⁻¹. BPMW modifies graphene through the synergistic effect of π-π stacking interaction and special structure to obtain excellent electrochemical performance. Moreover, a solid-state asymmetric supercapacitor device was fabricated based on the synthesized CoCeS_x−SA@BPMW@RGO hybrid, which exhibited a power density of 979 W kg⁻¹ at an energy density of 23.96 Wh kg⁻¹.     

Interfacial Coupling of Graphene with Nickel Nanoparticles for Water Splitting and Urea Oxidation: A Spectroelectrochemical Investigation

Nickel nanoparticle and graphene interfaces of various stoichiometries were created through electrodeposition techniques. The catalytic behavior of the electrodeposited films was investigated through spectro-electrochemical methodologies. UV-vis absorbance spectra of the electrodeposited films are significantly different in the air and alkaline medium. Furthermore, UV-vis and Raman spectroscopy confirmed the coupling of Ni nanoparticles (Ni-NP) with the graphene framework, along with NiO and Ni(OH)₂. A combination of Raman and impedance spectroscopy revealed that the surface adsorption and charge transfer properties of the electrodeposited films are entirely dependent on the defects on graphene structure as well as distribution of Ni-NP on graphene. The electrodeposited films possess heterogeneous catalytic properties with a low overpotential of 50 mV (10 mA/cm⁻²) for hydrogen evolution reaction, as well as 601 mV and 391 mV (at 50 mA/cm⁻²) for the oxygen evolution reaction and urea oxidation reaction, respectively. In addition, eelectrodeposited samples show extraordinary overall water splitting performance by achieving a current density of 10 mA/cm² at a very low applied potential of 1.38 V. This synergistic coupling of Ni and graphene renders the electrodeposited samples promising candidates as electrodes for overall water splitting in alkaline and urea-supplemented solutions.     

A Supramolecular Coordination-Polymer-Derived Electrocatalyst for the Oxygen Evolution Reaction

An iron oxide decorated nickel iron alloy nanoparticle/porous graphene hybrid exhibits high electrocatalytic activity and excellent durability toward oxygen evolution reaction (OER). It displays a low overpotential of 274 mV at 10 mA cm⁻², and low Tafel slope of 37 mV dec⁻¹, showing a superior performance to the state-of-the-art RuO₂ OER electrocatalyst.     

CO2 Laser-Induced Graphene with an Appropriate Oxygen Species as an Efficient Electrocatalyst for Hydrogen Peroxide Synthesis

Oxygen species functionalized graphene (O−G) is an effective electrocatalyst for electrochemically synthesizing hydrogen peroxide (H₂O₂) by a 2 e⁻ oxygen reduction reaction (ORR). The type of oxygen species and degree of carbon crystallinity in O−G are two key factors for the high catalytic performance of the 2 e⁻ ORR. However, the general preparing method of O−G by the precursor of graphite has the disadvantages of consuming massive strong oxidant and washing water. Herein, the biomass-based graphene with tunable oxygen species is rapidly fabricated by a CO₂ laser. In a flow cell setup, the laser-induced graphene (LIG) with abundant active oxygen species and graphene structure shows high catalytic performance including high Faraday efficiency (over 78 %) and high mass activity (814 mmolg_catalyst⁻¹ h⁻¹), superior to most of the reported carbon-based electrocatalysts. Density function theory demonstrates the meta-C atoms at nearby C−O, O−C=O species are the key catalytic sites. Therefore, we develop one facile method to rapidly convert biomass to graphene electrocatalyst used for H₂O₂ synthesis.     

Large‐Area,Free‐Standing,Two‐Dimensional Supramolecular Polymer Single‐Layer Sheets for Highly Efficient Electrocatalytic Hydrogen Evolution

The rational construction of covalent or noncovalent organic two‐dimensional nanosheets is a fascinating target because of their promising applications in electronics, membrane technology, catalysis, sensing, and energy technologies. Herein, a large‐area (square millimeters) and free‐standing 2D supramolecular polymer (2DSP) single‐layer sheet (0.7–0.9 nm in thickness), comprising triphenylene‐fused nickel bis(dithiolene) complexes has been readily prepared by using the Langmuir–Blodgett method. Such 2DSPs exhibit excellent electrocatalytic activities for hydrogen generation from water with a Tafel slope of 80.5 mV decade⁻¹ and an overpotential of 333 mV at 10 mA cm⁻², which are superior to that of recently reported carbon nanotube supported molecular catalysts and heteroatom‐doped graphene catalysts. This work is promising for the development of novel free‐standing organic 2D materials for energy technologies.     

Ultrafast Delamination of Graphite into High-Quality Graphene Using Alternating Currents

To bridge the gap between laboratory-scale studies and commercial applications, mass production of high quality graphene is essential. A scalable exfoliation strategy towards the production of graphene sheets is presented that has excellent yield (ca. 75 %, 1–3 layers), low defect density (a C/O ratio of 21.2), great solution-processability, and outstanding electronic properties (a hole mobility of 430 cm² V⁻¹ s⁻¹). By applying alternating currents, dual exfoliation at both graphite electrodes enables a high production rate exceeding 20 g h⁻¹ in laboratory tests. As a cathode material for lithium storage, graphene-wrapped LiFePO₄ particles deliver a high capacity of 167 mAh g⁻¹ at 1 C rate after 500 cycles.     

Crown Ether/Carbon Nanotubes Based Biperiden Disposable Potentiometric Sensor

Sensitive disposable sensors have been constructed for potentiometric determination of Biperiden hydrochloride (BPHCl) based on multi‐walled carbon nanotubes–polyvinylchloride (MWNTs–PVC) composite in presence of dibenzo 24‐crown‐8‐ ether as a molecular receptor. Electrode matrix composition was optimized on the basis of the nature of the electroactive material, ionic sites, membrane plasticizer, and nanomaterial. The fabricated sensors showed improved selectivity and sensitivity towards biperiden hydrochloride with Nernstian cationic compliance of 59.8±1.1 mV decade⁻¹ in the concentration range from 10⁻⁶ to 10⁻² mol L⁻¹. Modification with carbon nanotubes promote electron‐transfer processes and enhanced the stability of potential reading, response time and shelf lifetime of sensors. The proposed method was applied for potentiometric assay of BPHCl in dosage formulation and biological fluids under batch and flow injection analysis (FIA) with average recoveries agreeable with the reported official methods.     

Ion-Selective Electrodes With Sensing Membranes Covalently Attached to Both the Inert Polymer Substrate and Conductive Carbon Contact

The use of solid-contact ion-selective electrodes (ISEs) is of interest to many clinical, environmental, and industrial applications. However, upon extended exposure to samples and under thermal and mechanical stress, adhesion between these membranes and underlying substrates often weakens gradually. Eventually, this results in the formation of a water layer at the interface to the underlying electron conductor and in delamination of the membrane from the electrode body, both major limitations to long-term monitoring. To prevent these problems without increasing the complexity of design with a mechanical attachment, we use photo-induced graft polymerization to simultaneously attach ionophore-doped crosslinked poly(decyl methacrylate) sensing membranes covalently both to a high surface area carbon as ion-to-electron transducer and to inert polymeric electrode body materials (i.e., polypropylene and poly(ethylene-co-tetrafluoroethylene)). The sensors provide high reproducibility (standard deviation of E⁰ of 0.2 mV), long-term stability (potential drift 7 μV h⁻¹ over 260 h), and resistance to sterilization in an autoclave (121 °C, 2.0 atm for 30 min). For this work, a covalently attached H⁺ selective ionophore was used to prepare pH sensors with advantages over conventional pH glass electrodes, but similar use of other ionophores makes this approach suitable to the fabrication of ISEs for a variety of analytes.     

Rational Construction of a N,F Co-doped Mesoporous Cobalt Phosphate with Rich-Oxygen Vacancies for Oxygen Evolution Reaction and Supercapacitors

Transition-metal phosphates have been widely applied as promising candidates for electrochemical energy storage and conversion. In this study, we report a simple method to prepare a N, F co-doped mesoporous cobalt phosphate with rich-oxygen vacancies by in-situ pyrolysis of a Co-phosphate precursor with NH₄⁺ cations and F⁻ anions. Due to this heteroatom doping, it could achieve a current density of 10 mA/cm² at lower overpotential of 276 mV and smaller Tafel slope of 57.11 mV dec⁻¹ on glassy carbon. Moreover, it could keep 92 % of initial current density for 35 h, indicating it has an excellent stability and durability. Furthermore, the optimal material applied in supercapacitor displays specific capacitance of 206.3 F g⁻¹ at 1 A ⋅ g⁻¹ and maintains cycling stability with 80 % after 3000 cycles. The excellent electrochemical properties should be attributed to N, F co-doping into this Co-based phosphate, which effectively modulates its electronic structure. In addition, its amorphous structure provides more active sites; moreover, its mesoporous structure should be beneficial to mass transfer and electrolyte diffusion.     

Application of Precipitation-based and Nanoparticle-based Techniques for Fabrication of Potentiometric Sensors for Nano Molar Determination of Chitosan and Polyvinyl Pyrrolidone in Pharmaceutical Formulations and Biological Fluids

Chitosan (CH) is one of the most abundant biopolymers with multiple applications. Polyvinyl pyrrolidone (PVP) has specific binding and detoxification properties that are of great interest in health care. Hence, it arises a crucial urge to develop economic sensors to analyze CH and PVP in pharmaceutical formulations and biological samples. Two portable sensors were fabricated using precipitation-based technique, and nanoparticles-based technique, for determination of CH and PVP in sensor 1 and 2; respectively. Linear responses of 10⁻⁵ to10⁻⁷ M and 10⁻² to10⁻⁷ M at pH 3.6–4.8 and 7.2–8.4, with ideal Nernstian slopes of 60.00 and 59.83 mV /decade, and nanomolar LODs of 94.90 and 81.20 nM were observed for CH and PVP; respectively. The percentage recoveries were 100.40±1.03 and 100.19±0.64 for sensors 1 and 2; respectively. Both sensors were successfully applied in biological fluids without pre-treatment. Accurate results were obtained using sensor 1, in pure form, pharmaceutical formulations, human plasma, rat liver and rat brain, as well as sensor 2, in pure form, pharmaceutical formulations and urine samples. The results were statistically compared with the reported methods and no significant difference was observed.     

Highly Conductive Cobalt Perthiolated Coronene Complex for Efficient Hydrogen Evolution

Metal-bis(dithiolene) is one of the most promising structures showing redox activity, excellent electron transport and magnetic properties as well as catalytic activities. Perthiolated coronene (PTC), an emerging highly symmetric ligand containing the smallest graphene nanoplate was employed to manufacture a hybrid material with fused metal-bis(dithiolene) and graphene nanoplate, and it has been demonstrated as an efficient strategy for the construction of multifunctional materials recently. Herein, Co-PTC, a 2D MOF containing Co-bis(dithiolene) and coronene units is prepared via a homogeneous reaction for the first time as powder samples, which are bar-shaped microparticles composed of nanosheets. A neutral formula of [Co₃(C₂₄S₁₂)]_n is verified for Co-PTC. Co-PTC plays an ultrahigh conductivity of approximately 45 S cm⁻¹ at room temperature as compressed samples, which is among the highest value ever reported for the compressed powder samples of conducting MOFs. Moreover, Co-PTC exhibits good electrocatalytic performance in the hydrogen evolution reaction (HER) with a Tafel slope of 189 mV decade⁻¹ and an operating overpotential of 227 mV at 10 mA cm⁻¹ with pH=0, as well as a remarkable stability in the extremely acidic aqueous solutions, which is the best hydrogen evolution properties among metal–organic compounds.     

Structural Transformation of SnS2 to SnS by Mo Doping Produces Electro/Photocatalyst for Hydrogen Production

SnS and SnS₂ are layered semiconductors, with potential promising properties for electro- and photocatalytic hydrogen (H₂) production. The vast knowledge in preparation and modification of layered structures was still not employed successfully in this system to fully maximize its potential. Here, the first report of structural transformation of SnS₂ into SnS with Mo-doping as a bifunctional catalyst for the hydrogen evolution reaction (HER) is reported. The structural phase transition optimized the properties of the material, providing a more delicate morphology with additional catalytic sites. The electrochemical studies showed overpotential of 377 mV at 10 mA cm⁻² for HER with Tafel slopes of 100 mV dec⁻¹ in 0.5 m H₂SO₄ for 10 % Mo-SnS. The same structure acts as an efficient photocatalyst in the generation of H₂ from water under visible illumination with rate of 0.136 mmol g⁻¹ h⁻¹ of H₂, which is 20 times higher than pristine SnS₂ under visible light.     

Two-Dimensional LDH Film Templating for Controlled Preparation and Performance Enhancement of Polyamide Nanofiltration Membranes

Tailored design of high-performance nanofiltration membranes that can be used in a variety of applications such as water desalination, resource recovery, and sewage treatment is desirable. Herein, we describe the use of layered double hydroxides (LDH) intermediate layer to control the interfacial polymerization between trimesoyl chloride (TMC) and piperazine (PIP) for the preparation of polyamide (PA) membrane. The dense surface of LDH layer and its unique mass transfer behavior influence the diffusion of PIP, and the supporting role of the LDH layer allows the formation of ultrathin PA membranes. By only changing the concentration of PIP, a series of membranes with controllable thickness from 10 to 50 nm and tunable crosslinking-degree can be prepared. The membrane prepared with a higher concentration of PIP shows excellent performance for divalent salt retention with water permeance of 28 Lm⁻² h⁻¹ bar⁻¹, high rejection of 95.1 % for MgCl₂ and 97.1 % for Na₂SO₄. While the membrane obtained with a lower concentration of PIP can sieve dye molecules of different sizes with a flux of up to 70 Lm⁻² h⁻¹ bar⁻¹. This work demonstrates a novel strategy for the controllable preparation of high-performance nanofiltration membranes and provides new insights into how the intermediate layer affects the IP reaction and the final separation performance.     

Channel regulation of TFC membrane with hydrophobic carbon dots in forward osmosis

Zero-dimensional carbon dots have emerged as important nanofillers for the separation membrane due to their small specific size and rich surface functional groups. This study proposed a strategy based on hydrophobic carbon dots (HCDs) to regulate water channels for an efficient forward osmosis (FO) membrane. Thin-film composite (TFC) membranes with superior FO performance are fabricated by introducing HCDs as the nanofiller in the polyacrylonitrile support layer. The introduction of HCDs promotes the formation of the support layer with coherent finger-like hierarchical channels and micro-convex structure and an integrated polyamide active layer. Compared to the original membrane, TFC-FO membrane with 10 wt% HCDs exhibits high water flux (15.47 L m⁻² h⁻¹) and low reverse salt flux (2.9 g m⁻² h⁻¹) using 1 mol/L NaCl as the draw solution. This improved FO performance is attributed to the lower structural parameters of HCDs-induced water channels and alleviated internal concentration polarization. Thus, this paper provides a feasible strategy to design the membrane structure and boost FO performance.     

Composite nanofiltration membranes prepared by in situ polycondensation of amines in a poly(ethylene oxide-b-amide) layer

Composite membranes for nanofiltration were prepared by a polycondensation reaction between trimesoylchloride and different amines inside a dense layer of poly(ethylene oxide-b-amide). Use of amines containing ethylene glycol blocks resulted in membranes with best performance; hydrophilic membranes with a cut-off as low as 600 g mol⁻¹ and a reasonable water permeability, around 31 h⁻¹ m⁻² bar⁻¹ were produced.