Direct pyrolysis and ultrasound assisted preparation of N, S co-doped graphene/Fe3C nanocomposite as an efficient electrocatalyst for oxygen reduction and oxygen evolution reactions.

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.

Ultrasound-induced radicals initiated the formation of inorganic-organic Pr2O3/polystyrene hybrid composite for electro-oxidative determination of chemotherapeutic drug methotrexate.

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.

Biocompatible chitosan-pectin polyelectrolyte complex for simultaneous electrochemical determination of metronidazole and metribuzin.

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.

Effect of Ammonium Salts on the Hydrothermal Synthesis of TiO2 Nanocubes for Dye-Sensitized Solar Cells.

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%.

Enhanced photovoltaic performance of dye-sensitized solar cells based on nickel oxide supported on nitrogen-doped graphene nanocomposite as a photoanode.

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.

Economically applicable Ti(2)O(3) decorated m-aminophenol-formaldehyde resin microspheres for dye-sensitized solar cells (DSSCs).

In this present study, we focus on economically applicable polymeric material as photo-anode for dye-sensitized solar cells (DSSCs). Water droplets on grass like Ti2O3 decorated m-aminophenol-formaldehyde resin microspheres (mAPFR@Ti2O3) synthesized by surfactant-free and template-free hydrothermal method. The synthesized mAPFR@Ti2O3 material morphology was characterized by field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). From that results, it was found in uniform arrangements with excellent thermal stability. As we know from the literature we are the first to report the mechanism about mAPFR microspheres formations. Owing to the low temperature processing, cheap cost and easy preparation in this current study we propose to use mAPFR@Ti2O3 microspheres as an active material for the preparation of doped photo-anode in DSSCs exhibited the short-circuit photocurrent density (Jsc) of 18.14mAcm-2, open circuit voltage (Voc) of 0.70V, fill factor (FF) of 0.62, power conversion efficiency is 7.90% which is 84% greater than that of DSSCs with conventional TiO2 electrode.

Enhancement of Power Conversion Efficiency of TiO2-Based Dye-Sensitized Solar Cells on Various Acid Treatment.

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 400­600 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.