Plasmon Effect of Ag Nanoparticles on TiO2/rGO Nanostructures for Enhanced Energy Harvesting and Environmental Remediation.

We report Ag nanoparticles infused with mesosphere TiO2/reduced graphene oxide (rGO) nanosheet (TiO2/rGO/Ag) hybrid nanostructures have been successfully fabricated using a series of solution process synthesis routes and an in-situ growth method. The prepared hybrid nanostructure is utilized for the fabrication of photovoltaic cells and the photocatalytic degradation of pollutants. The photovoltaic characteristics of a dye-sensitized solar cell (DSSC) device with plasmonic hybrid nanostructure (TiO2/rGO/Ag) photoanode achieved a highest short-circuit current density (JSC) of 16.05 mA/cm2, an open circuit voltage (VOC) of 0.74 V and a fill factor (FF) of 62.5%. The fabricated plasmonic DSSC device exhibited a maximum power conversion efficiency (PCE) of 7.27%, which is almost 1.7 times higher than the TiO2-based DSSC (4.10%). For the photocatalytic degradation of pollutants, the prepared TiO2/rGO/Ag photocatalyst exhibited superior photodegradation of methylene blue (MB) dye molecules at around 93% and the mineralization of total organic compounds (TOC) by 80% in aqueous solution after 160 min under continuous irradiation with natural sunlight. Moreover, the enhanced performance of the DSSC device and the MB dye degradation exhibited by the hybrid nanostructures are more associated with their high surface area. Therefore, the proposed plasmonic hybrid nanostructure system is a further development for photovoltaics and environmental remediation applications.

Growth of large-scale MoS2 nanosheets on double layered ZnCo2O4 for real-time in situ H2S monitoring in live cells.

There is an urgent need to develop in situ sensors that monitor the continued release of H2S from biological systems to understand H2S-related pathology and pharmacology. For this purpose, we have developed a molybdenum disulfide supported double-layered zinc cobaltite modified carbon cloth electrode (MoS2-ZnCo2O4-ZnCo2O4) based electrocatalytic sensor. The results of our study suggest that the MoS2-ZnCo2O4-ZnCo2O4 electrode has excellent electrocatalytic ability to oxidize H2S at physiological pH, in a minimized overpotential (+0.20 vs. Ag/AgCl) with an amplified current signal. MoS2 grown on double-layered ZnCo2O4 showed relatively better surface properties and electrochemical properties than MoS2 grown on single-layered ZnCo2O4. The sensor delivered excellent analytical parameters, such as low detection limit (5 nM), wide linear range (10 nM-1000 µM), appreciable stability (94.3%) and high selectivity (2.5-fold). The practicality of the method was tested in several major biological fluids. The electrode monitors the dynamics of bacterial H2S in real-time for up to 5 h with good cell viability. Our research shows that MoS2-ZnCo2O4-ZnCo2O4/carbon cloth is a robust and sensitive electrode to understand how bacteria seek to adjust their defense strategies under exogenously induced stress conditions.

Sono-synthesis approach of reduced graphene oxide for ammonia vapour detection at room temperature.

In this paper, we report the sono-synthesis of reduced graphene oxide (rGO) using polyethyleneimine (PEI), and its performance for ammonia vapour detection at room temperature. Graphene oxide (GO) and reduced graphene oxide (rGO) were prepared by sonication method by using low-frequency ultrasound under ambient condition and films were deposited by Doctor Blade method. The rGO, which has vapour accessible structure showed a good sensing response with a minimum detection limit of 1 ppm and the detection range from 1 ppm to 100 ppm. The sensing response was found to be 2% at 1 ppm and 34% at 100 ppm of ammonia and the developed sensor operated at room temperature. The sensor displays a response time of 6 s and a recovery time of 45 s towards 100 ppm of ammonia vapour. The source for the highly sensitive, selective and stable detection of ammonia with negligible interference from other vapours is discussed and reported. We believe reduced graphene oxide (rGO) could potentially be used to manufacture a new generation of low-power portable ammonia sensors.

Alkyd resin based hydrophilic self-cleaning surface with self-refreshing behaviour as single step durable coating.

Herein, we reported the photo-catalytic degradation/anti-bacterial property of Ag-doped ZnO nanoparticles (SDZO Nps) prepared by a facile gel-combustion technique and its self-cleaning/self-refreshing/self-disinfectant behaviour while on impregnating as pigment into the alkyd resin based coating. The influence of doping Ag (1% & 2%) with ZnO has been evaluated in terms of crystal structure, morphology, optical properties, etc. using X-ray diffraction analysis, Field Emission Scanning Electron Microscope, UV-Vis analysis, and Photoluminescence spectra. The photo-catalytic degradation of crystal violet solution by SDZO Nps is spectroscopically followed employing UV-Vis spectroscopy. From the obtained results, the rate of degradation of 1% SDZO Nps is found higher than that of other samples under sunlight illumination; degrading 1 mg of crystal violet in 30 min. Thus, implementing the synergic effect of nano ZnO and the doped Ag provides a suitable pathway for the development of high efficient photo-catalyst. Further, alkyd resin based self-cleaning coating is formulated using 1% SDZO Nps as pigment along with other additives; the contents are milled to form a homogeneous mixture by high energy ball milling technique. Crystal violet solution coated over dried alkyd coating gets decolorized on exposure to sunlight indicating the mineralization of pollutants and proves the fact that the as obtained coating possess self-cleaning nature. Besides the self-cleaning property, the coating exhibits self-refreshing property which is essential for the long lasting self-cleaning activity. Further, the disinfectant properties of 1% SDZO Nps and 1% SDZO Nps impregnated coating have been evaluated against gram negative Escherichia coli bacterial strain. The acquired experimental outcomes suggest the potential use of self-cleaning coating to keep the environment clean and hygienic economically.

Incorporation of ZnO and their composite nanostructured material into a cotton fabric platform for wearable device applications.

The central idea of this paper is to innovate a new approach for the development of wearable device materials through the coating of cotton fabric with ZnO and Sb-/Ag-/ZnO composites. The study was designed in order to have a clear understanding of the role of ZnO as well as the modified composite thereof under investigation. Cotton fabric with uniform ZnO/ZnO-composite layers on the surface was successfully synthesized via a solvothermal method. The growth behaviors were investigated by comparing ZnO and ZnO-composites. The structural, morphological, chemical states, optical, electrical and thermopower properties of these fabrics were studied. Nanostructured ZnO-composite fabric had enhanced UV shielding with a value of 83.96. It is found that the ZnO-composite fabrics have increased electrical conductivity. The thermopower value of the ZnO-composite fabric could reach 471.9µVK-1. Such materials are anticipated to be worthwhile as wearable electronic devices and as protective textiles.