Temperature-Induced Conversion of 2D Vanadium-Doped MoSe2 Nanosheets to 1D V2MoO8 Rods: Enhanced Performance in Electrochemical Antibiotic Detection in Biological and Environmental Samples.

In this work, new strategies were developed to prepare 1D-V2MoO8 (VMO) rods from 2D V-doped MoSe2 nanosheets (VMoSe2) with good control over morphology and crystallinity by a facile hydrothermal and calcination process. The morphological changes from 2D to 1D rods were controlled by changing the calcination temperature from 300 to 600 °C. The elimination of Se and the incorporation of O into the V-Mo structure were evaluated by TGA, p-XRD, Raman, FE-SEM, EDAX, FE-TEM, and XPS analyses. These results prove that the optimization of the physical parameters leads to changes in the crystal phase and textural properties of the prepared material. The VMoSe2 and its calcined products were investigated as electrochemical sensors for the detection of the antibacterial drug nitrofurantoin (NFT). At a calcination temperature of 500 °C, the modified screen-printed carbon electrodes (SPCE) proved to be an excellent electrochemical sensor for the detection of NFT in neutral media. Under the optimized conditions, VMO-500 °C/SPCE exhibits low detection limit (LOD) (0.015 µM), wide linear ranges (0.1-31, 47-1802 µM), good sensitivity, and selectivity. The proposed sensor was successfully used for the analysis of NFT in real samples with good recovery results. Moreover, the reduction potential of NFT agreed well with the theoretical analysis using quantum chemical calculations, with the B3LYP with 6-31G(d,p) basis set predicting an E0 value of -0.45 V. The interaction between the electrode surface and NFT via the LUMO diagram and the electrostatic potential surface is also discussed.

Ti3C2Tx Filled in EMIMBF4 Semi-Solid Polymer Electrolytes for the Zinc-Metal Battery.

Zinc-ion batteries (ZIBs) are promising candidates for safe energy storage applications. However, undesirable parasitic reactions such as dendrite growth, gas evaluation, anode corrosion, and structural damage to the cathode under an acidic microenvironment severely affected cell performance. To resolve these issues, an MXene entrapped in an ionic liquid semi-solid gel polymer electrolyte (GPE) composite was explored. The molecular-level mixing of poly(vinylidene fluoride-co-hexafluoropropylene) (PVHF), zinc trifluoromethanesulfonate (Zn(OTF)2), 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF4) ionic liquid, and Ti3C2Tx MXene provided a controlled Zn2+ shuttle toward the anode/cathode. Ti3C2Tx/EMIBF4/Zn(OTF)2/PVHF exhibited a breaking strength of 0.36 MPa with an associated extension of 23%. The Zn//Ti3C2Tx/EMIBF4/Zn(OTF)2/PVHF//Zn symmetric cell with continuous zinc plating/stripping exhibited excellent Zn2+ ion mobility toward the anode and cathode without undesired reactions. This was confirmed by post-mortem analysis after a symmetric cell compatibility test. The as-prepared GPE with a Na3V2(PO4)3 (NVP) cathode exhibited a high chemical diffusion coefficient of 1.14 × 10-7. It also showed an outstanding reversible capacity of 89 mAh g-1 at C/10 with an average discharge plateau voltage of 1.45 V, cycle durability, and controlled self-discharge. These results suggested that the Zn2+ ions in the Ti3C2Tx/EMIBF4/Zn(OTF)2/PVHF composite are reversibly labile in the anode and cathode directions.

Electrochemical detection of sulfanilamide using tannic acid exfoliated MoS2 nanosheets combined with reduced graphene oxide/graphite.

Sulfonamides are a family of synthetic drugs with a broad-spectrum of antimicrobial activity. Like other antimicrobials, they have been found in aquatic environments, making their detection important. Herein, an electrochemical sensor was designed using tannic acid exfoliated few-layered MoS2 sheets, which were combined with a mixture of reduced graphene oxide (rGO) and graphite flakes (G). The rGO/G was formed using electrodeposition, by cycling from -0.5 to -1.5 V in an acidified sulfate solution with well dispersed GO and G. The exfoliated MoS2 sheets were drop cast over the wrinkled rGO/G surface to form the final sensor, GCE/rGO/G/ta-MoS2. The mixture of rGO/G was superior to pure rGO in formulating the sensor. The fabricated sensor exhibited an extended linear range from 0.1 to 566 µM, with a LOD of 86 nM, with good selectivity in the presence of various salts found in water and structurally related drugs from the sulfonamide family. The sensor showed very good reproducibility with the RSD at 0.48 %, repeatability and acceptable long term stability over a 10-day period. Good recovery from both tap and river water was achieved, with recovery ranging from 90.4 to 98.9 % for tap water and from 83.5 to 94.4 % for real river water samples.

Development of an Amorphous Nickel Boride/Manganese Molybdate Heterostructure as an Efficient Electrode Material for a High-Performance Asymmetric Supercapacitor.

The exploration of heterostructure materials with unique electronic properties is considered a desirable platform for fabricating electrode/surface interface relationships for constructing asymmetric supercapacitors (ASCs) with high energy density. In this work, a heterostructure based on amorphous nickel boride (NiXB) and crystalline square bar-like manganese molybdate (MnMoO4) was prepared by a simple synthesis strategy. The formation of the NiXB/MnMoO4 hybrid was confirmed by powder X-ray diffraction (p-XRD), field emission scanning electron microscopy (FE-SEM), field-emission transmission electron microscopy (FE-TEM), Brunauer-Emmett-Teller (BET), Raman, and X-ray photoelectron spectroscopy (XPS). In this hybrid system (NiXB/MnMoO4), the intact combination of NiXB and MnMoO4 leads to a large surface area with open porous channels and abundant crystalline/amorphous interfaces with a tunable electronic structure. This NiXB/MnMoO4 hybrid shows high specific capacitance (587.4 F g-1) at 1 A g-1, and it even retains a capacitance of 442.2 F g-1 at 10 A g-1, indicating superior electrochemical performance. The fabricated NiXB/MnMoO4 hybrid electrode also exhibited an excellent capacity retention of 124.4% (10000 cycles) and a Coulombic efficiency of 99.8% at a current density of 10 A g-1. In addition, the ASC device (NiXB/MnMoO4//activated carbon) achieved a specific capacitance of 104 F g-1 at 1 A g-1 and delivered a high energy density of 32.5 Wh.kg-1 with a power density of 750 W·kg-1. This exceptional electrochemical behavior is due to the ordered porous architecture and the strong synergistic effect of NiXB and MnMoO4, which enhances the accessibility and adsorption of OH- ions that improve electron transport. Moreover, the NiXB/MnMoO4//AC device exhibits excellent cyclic stability with a retention of 83.4% of the original capacitance after 10000 cycles, which is due to the heterojunction layer between NiXB and MnMoO4 that can improve the surface wettability without causing structural changes. Our results show that the metal boride/molybdate-based heterostructure is a new category of high-performance and promising material for the growth of advanced energy storage devices.

Synthesis of active-site rich molybdenum-doped manganese tungstate nanocubes for effective electrochemical sensing of the antiviral drug (COVID-19) nitazoxanide.

Nitazoxanide (NTZ), a promising antiviral agent, is currently being tested in clinical trials as a potential treatment for novel coronavirus disease 2019 (COVID -19). This paper describes a one-pot hydrothermal synthesis to prepare molybdenum (Mo)-doped manganese tungstate nanocubes (Mo-MnWO4 NCs) for the electrochemical sensing of NTZ. The as-prepared Mo-MnWO4 NCs were characterized using various techniques such as XRD, Raman, FE-SEM, FE-TEM, and XPS to confirm the crystal structure, morphology, and elemental composition. The obtained results demonstrate that Mo doping on MnWO4 generates many vacancy sites, exhibiting remarkable electrochemical activity. The kinetic parameters of the electrode modified with Mo-MnWO4 NCs were calculated to be (Ks) 1.1 × 10-2 cm2 s-1 and (α) 0.97, respectively. Moreover, a novel electrochemical sensor using Mo-MnWO4 NCs was fabricated to detect NTZ, which is used as a primary antibiotic to control COVID-19. Under optimal conditions, the electrochemical reduction of NTZ was determined with a low detection limit of 3.7 nM for a linear range of 0.014-170.2 µM with a high sensitivity of 0.78 µA µM-1 cm-2 and negligible interference with other nitro group-containing drugs, cations, and anions. The electrochemical sensor was successfully used to detect NTZ in the blood serum and urine samples and achieved high recoveries in the range of 94-99.2% and 95.3-99.6%, respectively. This work opens a way to develop high-performance sensing materials by exploring the introduction of defect engineering on metal tungstates to detect drug molecules for practical applications.

SARS-CoV-2 main protease (3CLpro) interaction with acyclovir antiviral drug/methyl-ß-cyclodextrin complex: Physiochemical characterization and molecular docking.

During the current outbreak of the novel coronavirus disease 2019 (COVID-19), researchers have examined several antiviral drugs with the potential to inhibit the proliferation of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The antiviral drug acyclovir (AVR), which is used to treat COVID-19, in complex with methyl-ß-cyclodextrin (Mß-CD) was examined in the solution and solid phases. UV-visible and fluorescence spectroscopic analyses confirmed that the guest (AVR) was included inside the host (Mß-CD) cavity. A solid inclusion complex of AVR was prepared by co-precipitation, physical mixing, kneading, and bath sonication methods at a 1:1 ratio of Mß-CD:AVR. The prepared Mß-CD:AVR inclusion complex was characterized using Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM) analysis. Phase solubility studies indicated the Mß-CD:AVR inclusion complex exhibited a higher stability constant and linear enhancement in AVR solubility with increasing Mß-CD concentrations. In silico analysis of the Mß-CD/AVR inclusion complex confirmed that AVR drugs show potential as inhibitors of SARS-CoV-2 3C-like protease (3CLpro) receptors. Results obtained using the PatchDock and FireDock servers indicated that the most favorable docking ligand was Mß-CD:AVR, which interacted with SARS-CoV-2 (3CLPro) protease inhibitors with high geometric shape complementarity scores (2522 and 5872) and atomic contact energy (-313.77 and -214.70 kcal mol-1). Our results suggest that the Mß-CD/AVR inclusion complex inhibits the main protease of SARS-CoV-2, although further wet-lab experiments are needed to verify these findings.

Facile synthesis of neodymium stannate nanoparticles an effective electrocatalyst for the selective detection of dimetridazole in biological samples.

In this work, pyrochlore neodymium stannate nanoparticles (Nd2Sn2O7 NP) have been synthesized by a facile co-precipitation technique and employed as an electrode material on GCE for the determination of dimetridazole (DM) drug. The physical properties and texture of the Nd2Sn2O7 NP were characterized by PXRD, Raman spectroscopy, FE-SEM, EDX mapping, XPS, and HR-TEM analytical studies. The electrocatalytic investigation of Nd2Sn2O7 NP/GCE was carried out by CV, and DPV techniques. The fabricated Nd2Sn2O7 NP/GCE shows a lower LOD of 6 nm towards the determination of DM and the calculated sensitivity is 0.61 µA µM-1 cm-2. In addition to that, the constructed sensor delivers notable repeatability, reproducibility, and superior selectivity with the existence of metal ions, biological molecules, and nitro compounds, enabling the electrochemical detection of DM. Furthermore, Nd2Sn2O7 NP/GCE sensor displays acceptable recovery results in the real sample analysis in biological fluids such as human blood serum and human urine.

Fabrication of a Selective Sensor Amplification Probe Modified with Multi-Component Zn2SnO4/SnO2 Heterostructured Microparticles as a Robust Electrocatalyst for Electrochemical Detection of Antibacterial Drug Secnidazole.

In this study, we synthesized heterostructured zinc stannate/tin oxide microparticles (ZTO/TO MPs) by a simple coprecipitation method and used them as an effective electrode material for the electrochemical detection of the antibacterial drug secnidazole (SCZ). The as-prepared ZTO/TO MPs were characterized by XRD, Raman, FE-SEM, HR-TEM, EDX, and XPS analyses. The physiochemical studies clearly proved that the fabricated ZTO/TO MPs were formed in a heterostructure phase without other impurities. A glassy carbon electrode modified with the synthesized ZTO/TO MPs showed an excellent and improved electrocatalytic activity in the electrochemical reduction of SCZ. Using differential pulse voltammetry (DPV), an impressive linear calibration range, extending from 0.01 to 193 µM, was observed, coupled with a detection limit of 0.0054 µM and a sensitivity of 0.055 µA/µM. In addition, the ZTO/TO MPs/GCE showed very good selectivity for the detection of SCZ in the presence of a number of biological, inorganic, and structurally related compounds. Finally, the ZTO/TO MPs/GCE was investigated for the analysis of SCZ in human blood serum samples. A very good recovery was obtained when spiking the blood serum with SCZ, highlighting the good applicability of the ZTO/TO MPs/GCE for the electrochemical analysis of SCZ in complex biological samples.

Synthesis and Characterization of Pyrochlore-Type Praseodymium Stannate Nanoparticles: An Effective Electrocatalyst for Detection of Nitrofurazone Drug in Biological Samples.

Apart from perovskites, the development of different types of pyrochlore oxides is highly focused on various electrochemical applications in recent times. Based on this, we have synthesized pyrochlore-type praseodymium stannate nanoparticles (Pr2Sn2O7 NPs) by using a coprecipitation method and further investigated by different analytical and spectroscopic techniques such as X-ray diffraction, Raman spectroscopy, field emission-scanning electron microscopy, high resolution-transmission electron microscopy, and X-ray photoelectron spectroscopy analysis. Followed by this, we have designed a unique and novel electrochemical sensor for nitrofurazone detection, by modifying the glassy carbon electrode (GCE) with the prepared Pr2Sn2O7 NPs. For that, the electrochemical experiments were performed by using cyclic voltammetry and differential pulse voltammetry techniques. The Pr2Sn2O7 NPs modified GCE exhibits high sensitivity (2.11 µA µM-1 cm-2), selectivity, dynamic linear ranges (0.01-24 µM and 32-332 µM), and lower detection limit (4 nM). Furthermore, the Pr2Sn2O7 NPs demonstrated promising real sample analysis with good recovery results in biological samples (human urine and blood serum) which showed better results than the noble metal catalysts. Based on these results, the present work gives clear evidence that the pyrochlore oxides are highly suitable electrode materials for performing outstanding catalytic activity toward electrochemical sensors.

Amorphous cobalt boride nanosheets anchored surface-functionalized carbon nanofiber: An bifunctional and efficient catalyst for electrochemical sensing and oxygen evolution reaction.

Development of new metal boride with carbon composite is an emerging class of catalyst and it brings enormous curiosity in the material community because of their potential intriguing properties. Here, we describe a new type of amorphous cobalt boride (A-CoB) nanosheet anchored on the surface of functionalized carbon nanofiber (A-CoB/ƒ-CNF) by a simple method. The emerged A-CoB/ƒ-CNF composite was demonstrated to possess great bifunctional electrocatalytic activity for the electrochemical sensing of antibiotic drug nitrofurantoin (NFT) and oxygen evolution reaction (OER). The prepared A-CoB/ƒ-CNF composite was characterized by various analytical and spectroscopic techniques such as XRD, FE-SEM, HR-TEM, Raman, and XPS analysis. The result from the electrochemical impedance spectroscopy confirms that the A-CoB/ƒ-CNF composite shows high electrical conductivity and the number of electron transferability for the NFT sensor and OER which is due to the presence of abundant active sites/large surface area in A-CoB, and synergistic effect between the A-CoB and ƒ-CNF. As an electrochemical sensor, the A-CoB/ƒ-CNF modified electrode shows substantial sensitivity (3.13 µA µM-1 cm-2), wider linear response range (0.01- 527 µM), and lower detection limit (0.003 µM) as-compared to the previously reported noble and non-noble metal-based electrocatalyst for NFT sensor. As well, the A-CoB/ƒ-CNF composite demonstrates superior OER activity with low overpotential and small Tafel slope value of 0.35 V and 173 mV/dec, respectively, which shows advanced kinetics than noble metal catalysts. Based on the results, we believed that the present work gives clear evidence for the preparation of transition metal boride anchored carbon material with an outstanding catalytic activity, and hence, it can be also extended to further electrochemical applications.

Ultrasound supported synthesis of tantalum carbide integrated functionalized carbon composite for the voltammetric determination of the antibacterial drug nitrofurantoin in pharmaceutical samples.

The synthesis and fabrication of oval-shaped tantalum carbide (Ta-C) integrated functionalized-multiwalled carbon nanotube (Ta-C/f-MWCNT) as an electrocatalyst for the electrochemical determination of nitrofurantoin (NFT) is described. The Ta-C/f-MWCNT composite was prepared using the soft-template method followed by the ultrasonication process. The as-prepared Ta-C/f-MWCNT composite was characterized using powder X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FESEM), scanning transmission electron microscopy (STEM), and X-ray photoelectron spectroscopy (XPS) analysis. The electrochemical properties of Ta-C/f-MWCNT were investigated by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and linear sweep voltammetry (LSV). The Ta-C/f-MWCNT-modified glassy carbon electrode (Ta-C/f-MWCNT/GCE) was successfully utilized as an active electrocatalyst for the detection of NFT in the presence of 0.384 mM NFT containing 0.05 M phosphate buffer (pH 7) at a scan rate of 50 mV/s. The Ta-C/f-MWCNT/GCE exhibited a wide linear response range (0.04-1047 µM) and a low detection limit (0.0011 µM). Further, the Ta-C/f-MWCNT/GCE showed appreciable results for repeatability, reproducibility, and long-term cyclic stability towards NFT sensing. The Ta-C/f-MWCNT/GCE was applied to real sample analysis such as a commercial tablet and human urine samples. The Ta-C/f-MWCNT/GCE exhibited good recovery values for the tablet (105 to 115%) and urine (101-107%) samples. The above electrochemical results suggest that the Ta-C/f-MWCNT is a promising electrocatalyst for the electrochemical sensing of NFT drug. Graphical abstract .

Ultrasound treated cerium oxide/tin oxide (CeO2/SnO2) nanocatalyst: A feasible approach and enhanced electrode material for sensing of anti-inflammatory drug 5-aminosalicylic acid in biological samples.

In this work, we developed cerium oxide/tin oxide (CeO2/SnO2) nanocatalyst with the assistance of urea by a simple sonochemical method and utilized as an efficient electrode material for electrochemical sensing of anti-inflammatory drug 5-aminosalicylic acid (Mesalamine, MES). The CeO2/SnO2 nanoparticles (NPs) were systematically characterized in terms of their crystal structure, morphologies, and physicochemical properties using XRD, Raman, FESEM, HR-TEM, EDX, mapping, and XPS analysis. The characterization results clearly confirmed that the prepared NPs was formed in the phase of CeO2/SnO2 without any other impurities. The electrochemical properties of CeO2/SnO2 NPs were investigated by EIS, CV, and DPV techniques. The CeO2/SnO2 NPs (9.6 µA) modified GCE demonstrated an excellent and improved electrocatalytic activity in terms of higher anodic peak current and lower peak potential when compared to bare GCE (6.7 µA) and CeO2 NPs/GCE (8.2 µA) for the sensing of MES. The CeO2/SnO2 NPs/GCE shows broader linear response range and lower detection limit of 0.02-1572 µM and 0.006 µM, respectively. Moreover, other potentially interfering compounds such as a similar functional group containing biological substances and inorganic species have no interference effect towards MES sensing. In addition, the practicability of the CeO2/SnO2 NPs/GCE was tested by real sample analysis in commercial MES tablet, human urine, and serum samples with the appreciable recovery results.

Electrochemical detection of toxic anti-scald agent diphenylamine using oxidized carbon nanofiber encapsulated titanium carbide electrocatalyst.

Two dimensional (2D) titanium carbide (Ti-C) is an analogues of graphene have tremendous attention in recent years due to their high electrical conductivity and catalytic activity. Herein, we have synthesized Ti-C micro particles based on the template-assisted method and subsequently integrated with oxidized carbon nanofiber (f-CNF) through ultrasonication technique. The prepared Ti-C/f-CNF composite was subjected to various structural and morphological characterization techniques including the X-ray diffraction (XRD), scanning electron microscope (SEM), Energy Dispersive X-ray (EDX) and X-ray photoelectron spectroscopy (XPS). The all followed studies confirmed the formation and crystalline nature of prepared Ti-C/f-CNF nanocomposite. Further, the proposed Ti-C/f-CNF composite modified electrode was successfully applied as an electrocatalyst for the electrochemical detection of diphenylamine (DPA) in food. DPA is known as an anti-scald agent used to post harvest treatment of fruits. However, the higher concentration of DPA causes some hazardous side effects to human. Thus, the detection of DPA is an important concern in healthcare research. Eventually, the proposed Ti-C/f-CNF/SPCE exhibited ultra-low detection limit of (0.003 µM) with a linear range of 0.04-56.82 µM towards the detection of DPA. Moreover, the practicability of the proposed sensor was tested by real sample analysis by using fresh apple extract. Remarkably, the proposed sensor showed an excellent recovery range from 106.8% to 108% for the detection of DPA in spiked apple extract. Finally, we concluded that the integration of f-CNF with Ti-C is significantly enhanced both electrical conductivity and electrocatalytic activity for sensor application.

Synthesis and Characterization of Samarium-Substituted Molybdenum Diselenide and Its Graphene Oxide Nanohybrid for Enhancing the Selective Sensing of Chloramphenicol in a Milk Sample.

The electronic conductivity and electrocatalytic activity of metal chalcogenides are normally enhanced by following the ideal strategies such as substitution/doping of heterogeneous atoms and hybridization of highly conductive carbon supportive materials. Here, a rare earth element (samarium) was substituted with MoSe2 using the simple hydrothermal method. The lattice distortion due to the substitution of Sm3+ with MoSe2 was clearly observed by using high-resolution transmission electron microscopy analysis. As a consequence, the prepared SmMoSe2 nanorod was encapsulated with graphene oxide (GO) sheets by using ultrasonication process. Furthermore, the GO-encapsulated SmMoSe2 nanocomposite modified glassy carbon electrode (GO@SmMoSe2/GCE) was used for the sensing of chloramphenicol. The results showed that the GO@SmMoSe2/GCE revealed the superior electrocatalytic activity with low detection (5 nM) and sensitivity (20.6 µA µM-1 cm-2) to electrochemical detection of proposed analyte. It indicates that the substitution of Sm3+ and encapsulation of GO significantly increased both the electrical conductivity and electrocatalytic activity of MoSe2.

Synthesis and characterization of manganese diselenide nanoparticles (MnSeNPs): Determination of capsaicin by using MnSeNP-modified glassy carbon electrode.

A new type of manganese diselenide nanoparticles (MnSeNPs) was synthesized by using a hydrothermal method. Their surface morphology, crystallinity and elemental distribution were characterized by using transmission electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy which scrutinize the formation of the NPs. The NPs were coated on a glassy carbon electrode (GCE), and electrochemical impedance spectroscopy, cyclic voltammetry and differential pulse voltammetry were applied to study the electroanalytical properties towards the oxidation of the food additive capsaicin. The modified GCE displays lower charge transfer resistance (R ct = 29.52 Ω), a larger active surface area (0.089 cm2/g, and more efficient electrochemical oxidation of capsaicin compared to a MnS2/GCE and a bare GCE. The oxidation peak potential is 0.43 V (vs. Ag/AgCl) which is lower than that of previously reported GCEs. The sensor has a detection limit as low as 0.05 µM and an electrochemical sensitivity of 2.41 µA µM-1 cm-2. The method was applied to the determination of capsaicin in pepper samples. Graphical abstract Electrochemical determination of capsaicin in pepper extract by using MnSeNPs modified electrode.