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Flufenamic acid (FFA) has anti-inflammatory, analgesic and antipyretic properties. We describe herein the preparation of a nanoribbon-like copper metal–organic framework (CuMOF) with an average length of 10 ± 5 μm and a width of 100 ± 50 nm via a simple hydrothermal approach. An amperometric sensor based on the activated carbon (AC)-supported ribbon-like CuMOF-modified electrode has been constructed for the detection of FFA. The AC–CuMOF nanostructure was characterized using scanning electron microscopy (SEM), electron diffraction X-ray spectroscopy (EDX) and X-ray diffraction (XRD) spectroscopy techniques. The peak current confirmed the excellent electrooxidation of FFA at the AC–CuMOF-modified glassy carbon electrode (GCE) and peak potential values resulting from cyclic voltammetry (CV) and amperometric (i–t) studies. The estimated values of the linear range (0.01 μM to 2210 μM), limits of detection (1.09 nM) and quantification revealed the enhanced electrocatalytic activity of the AC–CuMOF-modified GCE as compared to only CuMOF and AC. AC–CuMOF/GCE also possesses better repeatability and reproducibility along with good sensitivity (13.75 μA μM−1 cm−2). Even in the presence of other common potential interferents, our fabricated electrode displayed high selectivity towards FFA. The practicability demonstration of our sensor has been done in urine samples. Thus, AC–CuMOF/GCE can be a crucial platform in the determination of FFA.

To dates, the facile synthesis of inorganic–coated organic polymer composite has received greater attention in the order of research fields including advanced materials and electrochemical analysis owing to the complementary or synergistic effects. In this context, Pr2O3 and Pr2O3 coated polystyrene (Pr2O3/PS) inorganic–organic colloidal composite were prepared via ultrasound-induced radicals initiated precipitation and dispersion polymerization methods. The synthesized Pr2O3/PS composite was systematically studied by FE-SEM, TEM, EDX, FT-IR, XRD, and XPS analysis. This composite modified glassy carbon electrode (Pr2O3/PS GCE) was utilized to construct a novel electrochemical sensor for the detection assay of chemotherapy agent methotrexate (MTA). Under optimal condition, the designed sensor showed outstanding performance for MTA trace level detection over the linear concentration range of 0.01–236 µM with a detection limit of 0.8 nM for MTA. Furthermore, the prepared sensor accomplished excellent stability and relevant reproducibility, in addition to reliable practical assay in real human blood serum and urine samples. Besides, the possible MTA sensing mechanism of Pr2O3/PS GCE has been deliberated in detail. Our finding suggested that the developed Pr2O3/PS composite might be a favorable material for the fabrication of the high-performance electrochemical sensor.

In this study, a novel polystyrene:β-cyclodextrin inclusion complex-supported yttrium oxide (Y2O3)-modified glassy carbon electrode (PS:β-CD IC/Y2O3/GCE) was developed for the simultaneous determination of selected drugs, 4-aminoantipyrine (4-AAP) and acyclovir (ACV) for the first time. The results showed that PS:β-CD IC/Y2O3/GCE exhibits well-defined oxidation peak currents with a lower positive shift in peak potential in the simultaneous determination of 4-AAP and ACV compared to the bare GCE, demonstrating the superior catalytic activity. The fabricated sensor showed the linear ranges of 0.01–655 and 0.01–918 μM with low detection limits of 0.01 and 0.02 μM for the determination of 4-AAP and ACV, respectively. Further, the as-prepared PS:β-CD IC/Y2O3/GCE has been applied to the simultaneous and individual determination of 4-AAP and ACV in human urine and commercial ACV tablet samples with satisfactory recovery (98–99.3 and 88–96.6%), thereby showing a notable potential for extensive applications in the...

TiO2 nanocubes were synthesized via hydrolysis condensation of titanium tetra-isopropoxide (TTIP) in aqueous media, followed by hydrothermal treatment with ammonium salts. Various ammonium salts with different alkyl chain such as ammonium hydroxide (NH4OH), tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH) and tetrabutylammonium hydroxide (TBAH) were investigated. The crystalline phase, shape, and morphology of TiO2 nanocubes were studied by XRD, TEM, and SEM analysis. These TiO2 nanocubes were pure anatase phase and tended to assemble with well-ordered and close-packed domains. Both alkyl chain length of ammonium salts and hydrothermal duration affected the TiO2 nanocube formation process. The ammonium salts with longer alkyl chain formed TiO2 nanocubes in shorter hydrothermal time and offered the smallest particle size. The above TiO2 nanocubes were applied as photoanode materials in N719 anchored dye-sensitized solar cells and one of the cells exhibited the maximum power conversion efficiency of 7.85%.

Herein, we are reporting carboxylic acid-functionalized multi-walled carbon nanotubes-polyindole/Ti2O3 hybrid nanocomposite (f-MWCNTs-PIN/Ti2O3) synthesis, phase structure and morphology studies with extended applications. FE-SEM, and TGA results shows that the hybrid nanocomposite having good thermal stability. This hybrid nanocomposite is utilized to prepare a photo-anode of dye-sensitized solar cells (DSSCs). Interestingly, the doped with TiO2 (f-MWCNTs-PIN/Ti2O3/TiO2) hybrid nanocomposite based photo-anode for DSSC reported power conversion efficiency (PCE) of 8.6% and it is about 6% higher than that of un-doped TiO2 photo-anode. The corresponding short-circuit photocurrent density (Jsc) of 18.30 mA cm−2, open circuit voltage (Voc) of 0.71 V, fill factor (FF) of 0.66, and dye absorption amount is 0.16 × 10−6 mol cm−2 respectively. The obtained results suggest that the hybrid nanocomposite is a suitable photo-anodic material for DSSCs applications.

We applied the nitrogen-doped graphene@nickel oxide (NGE/NiO) nanocomposite doped TiO2 as a photo-anode for dye-sensitized solar cells (DSSCs) on fluorine-doped tin oxide (FTO) substrates by screen printing method. Power conversion efficiency (PCE) of 9.75% was achieved for this DSSCs device, which is greater than that of DSSCs devices using GO/TiO2, and NiO/TiO2 based photo-anodes (PCE=8.55, and 9.11%). Also, the fill factor (FF) of the DSSCs devices using the NGE/NiO/TiO2 nanocomposite photo-anode was better than that of other photo-anodes. The NGE/NiO/TiO2 short-circuit photocurrent density (Jsc) of 19.04mAcm-2, open circuit voltage (Voc) of 0.76V, fill factor (FF) of 0.67 and dye absorption rate 0.21×10-6molcm-2. The obtained results suggest that as-prepared NGE/NiO/TiO2 nanocomposite is suitable photo-anode for DSSCs application.

Bifunctional electrocatalysts to enable efficient oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are essential for fabricating high performance metal-air batteries and fuel cells. Here, a defect rich nitrogen and sulfur co-doped graphene/iron carbide (NS-GR/Fe

The surface modification of the TiO2 photoelectrode film is one of the promising ways to improve the photovoltaic performance of dye-sensitized solar cell (DSSC). In this work for the acid treatment of TiO2 powder, fluorine containing compounds such as trifluoroacetic acid was carried out to enhance the properties of photoanode. In order to investigate the effect of trifluoroacetyl group, the TiO2 nanopowders were also treated with different acids such as acetic acid, nitric acid, hydrochloric acid, and sulfuric acid and their properties were compared. The TiO2 powders treated with both acetic acid and TFA have possessed smooth surface morphologies as well as enhanced particle dispersions with reduced particle sizes. Photoelectrodes prepared for these two kinds of TiO2 powders accommodated high amounts of dye loading and exhibited excellent light transmittance (wavelength region of 400–600 nm). Electrochemical impedance spectroscopy analysis showed the smallest radius of the semicircle which indicates the enhanced rate of electron transport for the cell based photoelectrode with trifluoroacetic acid treated TiO2 powder. The solar cell from the untreated TiO2 film showed the power conversion efficiency of 8.86% and the highest efficiency of 9.51% was achieved by the cell fabricated from trifluoroacetic acid treated TiO2 film.

A sensitive and selective hydrazine sensor was developed by β-cyclodextrin modified palladium nanoparticles decorated reduced graphene oxide (PdNPs-β-CD/rGO) nanocomposite. The PdNPs-β-CD/rGO hybrid material was prepared by simple electrochemical method. The hydrophobic cavity of β-CD ineracts with palladium nanoparticles by hydrophobic interaction and further it is uniformly assembled on the rGO surface through hydrogen bond formation, which is clearly confirmed by FT-IR, FESEM and TEM. The high electrocatalytic activity of hydrazine oxidation was observed at −0.05 V (vs. Ag/AgCl) on PdNPs-β-CD/rGO modified electrode; due to the excellent stabilization, high catalytic activity and large surface area of the PdNPs-β-CD/rGO composite. The PdNPs-β-CD/rGO fabricated hydrazine sensor exhibited an excellent analytical performance, including high sensitivity (1.95 μA μM−1 cm−2), lower detection limit (28 nM) and a wide linear range (0.05 to 1600 μM). We also demonstrated that the PdNPs-β-CD/rGO nanocomposite modified electrode is a highly selective and sensitive sensor towards detection of hydrazine among the various interfering species. Hence, the proposed hydrazine sensor is able to determine hydrazine in different water samples.

The controlled morphological TiO 2 particles have gained great importance in a wide variety of applications due to their promising physico-chemical properties. In this study, TiO 2 microstructures with various shapes to utilize as scattering layer in dye-sensitized solar cell (DSSC) applications were successfully synthesized via different hydrothermal conditions. The effects of the versatile preparation parameters including the amount of titania precursor and surfactant, the addition of ethanol/water, and the hydrothermal process temperature and time on the TiO 2 morphology were investigated. The structural and morphological analysis clearly shown that the preparation conditions played crucial roles in the morphology, particle size, and crystalline phase of the TiO 2 microparticles. Different kinds of shapes such as rice- (∼1.10 μm (l) and ∼0.41 μm (w)), star- (∼3.60 μm) and flower-like (3.75 μm) TiO 2 morphological structures were obtained. The morphology and size of the TiO 2 particles were mainly governed by the concentrations of titanium tetraisopropoxide (TTIP) precursor, amounts of tetramethylammonium hydroxide (TMAH) surfactant and hydrothermal temperatures and durations. The as-prepared rice-shaped TiO 2 was composed of mixed anatase and brookite binary phases, whereas the star- and flower-shaped TiO 2 microstructures were consisted of ternary anatase, rutile, and brookite crystalline TiO 2 phases. The three different rice-, star-, and flower-shaped TiO 2 microstructures were employed as scattering layers for photoanodes in DSSCs. Among them, the star-like TiO 2 photoanode based DSSC exhibited the highest power conversion efficiency of 9.56%, which was also better than those of the devices fabricated without scattering layer (a-TiO 2 , 8.38%) and with commercial P25 as scattering layer (a-TiO 2 /P25-TiO 2 , 8.52%) at the same film thickness of ∼14 μm.

Bifunctional electrocatalysts to enable efficient oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are essential for fabricating high performance metal–air batteries and fuel cells. Here, a defect rich nitrogen and sulfur co-doped graphene/iron carbide (NS-GR/Fe3C) nanocomposite as an electrocatalyst for ORR and OER is demonstrated. An ink of NS-GR/Fe3C is developed by homogeneously dispersing the catalyst in a Nafion containing solvent mixture using an ultrasonication bath (Model-DC150H; power − 150 W; frequency − 40 kHz). The ultrasonically prepared ink is used for preparing the electrode for electrochemical studies. In the case of ORR, the positive half-wave potential displayed by NS-GR/Fe3C is 0.859 V (vs. RHE) and for the OER, onset potential is 1.489 V (vs. RHE) with enhanced current density. The optimized NS–GR/Fe3C electrode exhibited excellent ORR/OER bifunctional activities, high methanol tolerance and excellent long-term cycling stability in an alkaline medium. The observed onset potential for NS–GR/Fe3C electrocatalyst is comparable with the commercial noble metal catalyst, thereby revealing one of the best low-cost alternative air–cathode catalysts for the energy conversion and storage application.

Development of novel biocompatible sensor material suitable for modest, cost-effective, and rapid practical application is a demanding research interest in the field of electroanalytical chemistry. In this context, for the first time, we utilized biocompatible chitosan-pectin biopolyelectrolyte (CS-PC BPE) complex for the simultaneous electroreduction of an important antibiotic drug (metronidazole-MNZ) and herbicide (metribuzin-MTZ). This sensor reveals an attractive welfares such as simplicity, biocompatibility, and low production cost. Under optimized experimental conditions, the electroanalytical investigation confirmed that CS-PC BPE modified glassy carbon electrode (CS-PC BPE/GCE) was found to sense MNZ and MTZ in the nanomolar range. Moreover, as-prepared CS-PC BPE/GCE exhibited prominent selectivity, stability, and reproducibility. Additionally, the possible MNZ and MTZ sensing mechanism of CS-PC BPE/GCE have been discussed in detail. Lastly, real sample analysis was also carried out and revealed from several investigations that the CS-PC BPE/GCE is a good electrochemical sensor system for the detection of targeted analytes.

TiO2 nanocubes were synthesized via hydrolysis condensation of titanium tetra-isopropoxide (TTIP) in aqueous media, followed by hydrothermal treatment with ammonium salts. Various ammonium salts with different alkyl chain such as ammonium hydroxide (NH4OH), tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH) and tetrabutylammonium hydroxide (TBAH) were investigated. The crystalline phase, shape, and morphology of TiO2 nanocubes were studied by XRD, TEM, and SEM analysis. These TiO2 nanocubes were pure anatase phase and tended to assemble with well-ordered and close-packed domains. Both alkyl chain length of ammonium salts and hydrothermal duration affected the TiO2 nanocube formation process. The ammonium salts with longer alkyl chain formed TiO2 nanocubes in shorter hydrothermal time and offered the smallest particle size. The above TiO2 nanocubes were applied as photoanode materials in N719 anchored dye-sensitized solar cells and one of the cells exhibited the maximum power conversion efficiency of 7.85%.