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Abstract Highly exposed surface area CeO 2 polyhedral nanostructures were successfully prepared via a two-step hydrothermal route for gas-sensing applications. The surface chemistry and formation of polyhedral nanostructures was attributed to the interaction between polyvinylpyrrolidone and ammonium bicarbonate surfactants with parent ceria. The synthesized polyhedron CeO 2 structures were characterized using XRD, XPS, BET, SEM, EDS and TEM, respectively. The polyhedrons exhibited a high specific surface area 98.76 m2/g. For gas-sensing applications, the CeO 2 polyhedrons were exposed to different gases at various temperatures, from a low to high concentration range (1–150 ppm). At an optimal temperature 220 °C, superior gas-sensing response towards formaldehyde was observed than other target gases. The enhanced sensor response was attributed to multifaceted polyhedral nanostructures. The polyhedral structure based sensors have great potential in industrial sensing applications. Graphical abstract fx1 [ABSTRACT FROM AUTHOR]

Following sol-gel route, hierarchical mesoporous nanostructures of lanthanum chromates (LaCrO 3) perovskite oxides are successfully synthesized for supercapacitor applications. The structural behaviors of nano perovskite oxides are investigated using X-rays diffraction, low and high resolution scanning and transmission electron microscopes, photoelectron X-ray spectroscopy, and Brunauer-Emmett-Teller (BET). The as-prepared LaCrO 3 powders is mingled with activated carbon and subsequently glazed on a flexible carbon cloth current collector (LCO@CC). The electrochemical capabilities of LCO@CC based electrode, such as: cyclic voltammetry, galvanostatic charge:discharge and electrochemical impedance spectroscopy are investigated in neutral M LiCl aqueous solutions. Moreover, the fabricated LCO@CC electrode achieves maximum capacitance of 1268 F/g at 2 A/g and retains excellent cyclic ability of 91.5% after 5000 charge:discharge cycles. The efficient electrochemical performances of carbon cloth decorated LaCrO 3 electrode are credited to dynamic charge storage mechanism by fast redox reaction of electrolyte-electrode interactions with extremely low charge transfer resistance. Image 1 [ABSTRACT FROM AUTHOR]

Wurtzite zero dimensional ZnS nanospheres and random-shaped nanoparticles successfully synthesized via a low temperature hydrothermal route. The formation of nanostructures is attributed due to PVP and thiourea and discussed in details. The as-prepared nanostructures were characterized by XRD, EDS, SEM and HRTEM. Based on experimental results, a plausible growth mechanism is also proposed along with crystal structure of ZnS. The gas–sensing properties of as–prepared ZnS products are tested using efficient substrate sensors via an intelligent gas testing system. Both at room and 100–400 °C temperature, high response and selectivity towards formaldehyde than other gases is observed. Comparative studies of ZnS nanostructures for different concentrations of formaldehyde gas and definite sensor-stability for different gases is studied, as well. [ABSTRACT FROM AUTHOR]

Low-cost dynamic materials for Faradaic redox reactions are needed for high-energy storage supercapacitors. A simple and cost-effective hydrothermal process was employed to synthesize amaryllis-like NiCo 2 S 4 nanoflowers. The sample was characterized by X-ray powder diffraction, Brunauer–Emmett–Teller method, scanning electron microscopy, and transmission electron microscopy. NiCo 2 S 4 nanoflowers were coated onto carbon fiber fabric and used as a binder-free electrode to fabricate a solid-state supercapacitor compact device. The solid-state supercapacitor exhibited excellent electrochemical performance, including high specific capacitance of 360 F g −1 at scan rate of 5 mV s −1 and high energy density of 25 W h kg −1 at power density of 168 W kg −1 . In addition, the supercapacitor possessed high flexibility and good stability by retaining 90% capacitance after 5000 cycles. The high conductivity and Faradic-redox activity of NiCo 2 S 4 nanoflowers resulted in high specific energy and power. Thus, NiCo 2 S 4 nanoflowers are promising pseudocapacitive materials for low-cost and lightweight solid-state supercapacitors. [ABSTRACT FROM AUTHOR]

Regular hexagonal embedded ZnO nanorods were successfully prepared by a simple hydrothermal method. The addition of urea as a homogeneous precursor was found to play a vital role in the embedding of secondary nanorods. The nanostructures were characterized by XRD, SEM, and EDS. The gas-sensing properties of secondary grown embedded nanorods were reported for formaldehyde, ethanol, methanol, acetone, and ammonia at different concentrations and temperatures. A higher response and greater selectivity toward formaldehyde than other gases was observed. A sharp response with the best recovery time was achieved at an optimum temperature of 200 °C. [ABSTRACT FROM AUTHOR]