Ultrasensitive Electrochemical Detection and Plasmon-Enhanced Photocatalytic Degradation of Rhodamine B Based on Dual-Functional, 3D, Hierarchical Ag/ZnO Nanoflowers.

The sensitive detection and degradation of synthetic dyes are pivotal to maintain safety owing to the adverse side effects they impart on living beings. In this work, we developed a sensitive electrochemical sensor for the nanomolar-level detection of rhodamine B (RhB) using a dual-functional, silver-decorated zinc oxide (Ag/ZnO) composite-modified, screen-printed carbon electrode. The plasmon-enhanced photocatalytic degradation of organic pollutant RhB was also performed using this nanocomposite prepared by embedding different weight percentages (1, 3, and 5 wt%) of Ag nanoparticles on the surface of a three-dimensional (3D), hierarchical ZnO nanostructure based on the photoreduction approach. The structure and morphology of an Ag/ZnO nanocomposite were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), elemental mapping, ultraviolet-visible (UV-vis) spectroscopy, and X-ray diffraction (XRD). The electrochemical sensor exhibited a very high sensitivity of 151.44 µAµM-1cm-2 and low detection limit of 0.8 nM towards RhB detection. The selectivity, stability, repeatability, reproducibility, and practical feasibility were also analyzed to prove their reliability. Furthermore, the photocatalysis results revealed that 3 wt% of the Ag/ZnO hybrid nanostructure acquired immense photostability, reusability, and 90.5% degradation efficiency under visible light. Additionally, the pseudo-first-order rate constant of Ag-3/ZnO is 2.186 min-1 suggested promising activity in visible light photocatalysis.

Nanomolar detection of food additive tert-butylhydroquinone in edible oils based on novel ternary metal oxide embedded ß-cyclodextrin functionalized carbon black.

It is pivotal to precisely detect food preservatives to ascertain food quality and safety. In this work, we report the sensitive electrochemical detection of widely used cytotoxic food preservative tert-butylhydroquinone (TBHQ). A novel nanocomposite was sonochemically prepared by embedding ternary metal oxide (TMO) comprising ZnO, CuO, and MgO in ß-cyclodextrin (ß-CD) functionalized carbon black (CB). The properties of the prepared nanocomposite were evaluated by employing multiple characterization methods. The nanocomposite fabricated on a screen printed carbon electrode exhibited exceptional electrocatalytic activity towards TBHQ detection, evident from the resultant very low detection limit of 1 nM and high sensitivity of 22.67 µA µM-1 cm-2. Moreover, the developed TBHQ sensor evinced all the important traits of a good electrochemical sensor including excellent selectivity, stability, reproducibility, and repeatability. Furthermore, for validating practical feasibility of TBHQ detection, we successfully determined this food additive in edible oils.

Synthesis of amine-functionalized multi-walled carbon nanotube/3D rose flower-like zinc oxide nanocomposite for sensitive electrochemical detection of flavonoid morin.

A novel composite consisting of three dimensional (3D) hierarchical rose flower-like zinc oxide decorated with amine-functionalized multi-walled carbon nanotubes (NH2-MWCNT/ZnO) was synthesized and applied to the effective electrochemical detection of morin, a flavonoid with health-promoting and therapeutic activities. We have used a hydrothermal technique to synthesize the 3D rose flower-like ZnO, which was then composited with NH2-MWCNT through a sonochemical method. The morphology and structure of the prepared materials were characterized using scanning electron microscopy (SEM), elemental mapping, X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area analysis, Fourier-transform infrared spectroscopy (FT-IR), and Raman spectroscopy. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques were employed for the evaluation of electrochemical properties of the NH2-MWCNT/ZnO nanocomposite. Under optimal conditions, the NH2-MWCNT/ZnO modified screen printed carbon electrode (SPCE) exhibits a broad linear response from 0.2 to 803.4 µM, excellent selectivity of 2.71 µAµM-1cm-2, and a very low limit of detection (LOD) of 0.002 µM. The practicability of the fabricated sensor has been confirmed by selectivity and real sample analyses. Furthermore, the developed sensor also shows good operational and storage stability.

Sonochemical synthesis of iron-graphene oxide/honeycomb-like ZnO ternary nanohybrids for sensitive electrochemical detection of antipsychotic drug chlorpromazine.

We report a novel electrochemical sensor for the sensitive and selective determination of the antipsychotic drug chlorpromazine (CPZ) based on the iron (Fe) nanoparticles-loaded graphene oxide (GO-Fe)/three dimensional (3D) honeycomb-like zinc oxide (ZnO) nanohybrid modified screen printed carbon electrode (SPCE). The 3D hierarchical honeycomb-like ZnO was synthesized using a novel aqueous hydrothermal method and the GO-Fe/ZnO nanohybrid was prepared based on an inexpensive and fast sonochemical method using a high-intensity ultrasonic bath (Delta DC200H, 200 W, 40 KHz). Characterizations including scanning electron microscopy, elemental mapping, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy were carried out as part of this work. The electrocatalytic oxidation behavior of CPZ at various electrodes was investigated using the cyclic voltammetry technique, through which the GO-Fe/ZnO modified SPCE was identified as the best performing electrode. The quantitative determination of CPZ was then performed using the differential pulse voltammetry technique. The as-prepared GO-Fe/ZnO/SPCE sensor exhibited a quick and sensitive response towards the oxidation of CPZ with linear concentration ranges from 0.02 to 172.74 µM and 222.48 to 1047.74 µM. The modified SPCE sensor displayed a low detection limit (LOD) of 0.02 µM and a high sensitivity of 7.56 µA µM-1 cm-2. The proposed sensor also showed remarkable operational and storage stability, reproducibility, and repeatability. Furthermore, the practicability of the GO-Fe/ZnO/SPCE sensor has been verified with real sample analysis using commercial antipsychotic CPZ tablets and human urine samples, and adequate recovery has been achieved.

Electrochemical Deposition of ZnO Porous Nanoplate Network for Dye-Sensitized Solar Cells.

Mesoporous ZnO films composed of interconnected porous nanoplates were prepared by an electrochemical deposition-pyrolytic conversion approach and constructed into the photoanodes of dyesensitized solar cells (DSSCs). Precursor nanoplates grown on conducting glass substrates were transformed into ZnO porous nanoplates by calcination at 400 °C for 1 h. Correlations between the ZnO film thickness and the electrochemical deposition time were determined in order to prepare ZnO films of various thicknesses and to study the effect of the film thickness on the photovoltaic performance of DSSCs. The optimal film thickness was determined to be approximately 27 µm, and the best performing cell reached an energy conversion efficiency of 2.91%. The results show that the ZnO porous nanoplate network so prepared is suitable for DSSC applications.

Enhancing performance of ZnO dye-sensitized solar cells by incorporation of multiwalled carbon nanotubes.

A low-temperature, direct blending procedure was used to prepare composite films consisting of zinc oxide [ZnO] nanoparticles and multiwalled carbon nanotubes [MWNTs]. The mesoporous ZnO/MWNT films were fabricated into the working electrodes of dye-sensitized solar cells [DSSCs]. The pristine MWNTs were modified by an air oxidation or a mixed acid oxidation treatment before use. The mixed acid treatment resulted in the disentanglement of MWNTs and facilitated the dispersion of MWNTs in the ZnO matrix. The effects of surface property and loading of MWNTs on DSSC performance were investigated. The performance of DSSCs was found to depend greatly on the type and the amount of MWNTs incorporated. At a loading of 0.01 wt%, the acid-treated MWNTs were able to increase the power conversion efficiency of fabricated cells from 2.11% (without MWNTs) to 2.70%.

Optimization of dye adsorption time and film thickness for efficient ZnO dye-sensitized solar cells with high at-rest stability.

Photoelectrodes for dye-sensitized solar cells were fabricated using commercially available zinc oxide (ZnO) nanoparticles and sensitized with the dye N719. This study systematically investigates the effects of two fabrication factors: the ZnO film thickness and the dye adsorption time. Results show that these two fabrication factors must be optimized simultaneously to obtain efficient ZnO/N719-based cells. Different film thicknesses require different dye adsorption times for optimal cell performance. This is because a prolonged dye adsorption time leads to a significant deterioration in cell performance. This is contrary to what is normally observed for titanium dioxide-based cells. The highest overall power conversion efficiency obtained in this study was 5.61%, which was achieved by 26-µm-thick photoelectrodes sensitized in a dye solution for 2 h. In addition, the best-performing cell demonstrated remarkable at-rest stability despite the use of a liquid electrolyte. Approximately 70% of the initial efficiency remained after more than 1 year of room-temperature storage in the dark. To better understand how dye adsorption time affects electron transport properties, this study also investigated cells based on 26-µm-thick films using electrochemical impedance spectroscopy (EIS). The EIS results show good agreement with the measured device performance parameters.

Functional and physical interactions between components of the Prp19p-associated complex.

The Prp19p-associated complex is essential for the yeast pre-mRNA splicing reaction. The complex consists of at least eight protein components, but is not tightly associated with spliceosomal snRNAs. By a combination of genetic and biochemical methods we previously identified four components of this complex, Ntc25p, Ntc85p, Ntc30p and Ntc20p, all of them being novel splicing factors. We have now identified three other components of the complex, Ntc90p, Ntc77p and Ntc31p. These three proteins were also associated with the spliceosome during the splicing reaction in the same manner as Prp19p, concurrently with or immediately after dissociation of U4 snRNA. Two-hybrid analysis revealed that none of these proteins interacted with Prp19p or Ntc25p, but all interacted with Ntc85p. An interaction network between the identified components of the Prp19p-associated complex is demonstrated. Biochemical analysis revealed that Ntc90p, Ntc31p, Ntc30p and Ntc20p form a subcomplex, which, through interacting with Ntc85p and Ntc77p, can associate with Prp19p and Ntc25p to form the Prp19p-associated complex. Genetic analysis suggests that Ntc31p, Ntc30p and Ntc20p may play roles in modulating the function of Ntc90p.