ABSTRACT
Herein, we report the development of a simple and highly sensitive hydroquinone (HQ) chemical sensor based on an electrochemically activated iron-doped (Fe-doped) zinc oxide nanorod (ZnO NR) modified screen-printed electrode (SPE). The Fe-doped ZnO NRs were prepared using a hydrothermal process and their morphological, crystal, compositional and optical properties were characterized in detail. The detailed characterizations showed that the NRs are densely grown, well-crystalline and possess a wurtzite hexagonal phase. The fabricated HQ electrochemical sensor exhibited high sensitivity of 18.60 µA mM(-1) cm(-2) and a very low experimental detection limit of 0.51 µM. Our results demonstrate that simply prepared doped ZnO nanomaterials are promising candidates to fabricate highly sensitive electrochemical sensors.
ABSTRACT
We successfully developed a single-step detection and removal unit for Bi(III) ions based on dithizone (DZ) anchored on mesoporous TiO2 with rapid colorometric response and high selectivity for the first time. [(DZ)3-Bi] complex is easily separated and collected by mesoporous TiO2 as adsorbent and preconcentrator without any color change of the produced complex onto the surface of mesoporous TiO2 (TiO2-[(DZ)3-Bi]) at different Bi(III) concentrations. This is because highly potent mesoporous TiO2 architecture provides proficient channeling or movement of Bi(III) ions for efficient binding of metal ion, and the simultaneous excellent adsorbing nature of mesoporous TiO2 provides an extra plane for the removal of metal ions.
ABSTRACT
Temperature-dependant characteristics of heterojunction diode made by n-ZnO nanorods grown on p-silicon substrates has been characterized and demonstrated in this paper. ZnO nanorods were grown onto the silicon substrate via simple thermal evaporation process by using metallic zinc powder in the presence of oxygen at approximately 550 degrees C without the use of any metal catalysts or additives. The as-grown ZnO nanorods were characterized in terms of their structural and optical properties. The detailed structural studies by XRD, TEM, HRTEM and SAED revealed that the grown nanorods are well-crystalline with the wurtzite hexagonal phase and preferentially grown along the [0001] direction. The as-grown n-ZnO nanorods grown on p-Si substrate were used to fabricate p-n heterojunction diode. The fabricated p-n junction diode attained almost similar turn-on voltage of approximately 0.6 V. The values of turn-on voltage and least current are same with the variations of temperature (i.e., 27 degrees C, 70 degrees C and 130 degrees C).
ABSTRACT
Nanosized niobium oxide powders were synthesized with a yield of approximately 87% using a simple and facile soft-chemical process. Niobium pentachloride (Nb2Cl5) was used as the precursor which was first converted into niobium ethoxide and then hydrolysed with water to synthesize niobia nanopowder. The synthesized powder was calcined at 500 degrees C for phase conversion to end-centered monoclinic as confirmed by diffraction studies and elemental analysis with a chemical composition in the ratio of Nb:O as 1:2.5. The molecular framework of Nb-O-Nb stretching and asymmetric frequency was confirmed by FT-IR, UV-visible and Raman spectroscopic studies. The size, shape and surface morphology of the powders were observed by SEM and TEM which indicated particle sizes of approximately 20 nm. The surface area of 20 m2/g, pore volume of 0.0538 cm2/g and the average pore size of 6.5 nm2 for the calcined sample were obtained with the help of nitrogen adsorption/desorption method using the Barrett-Joyner-Halenda (BJH) method which indicates that the synthesized powder can be used for catalysis and other surface sensitive applications.
ABSTRACT
Flower-shaped ZnO structures composed of hexagonal nanorods were grown in a large-quantity via simple aqueous solution process by using zinc nitrate as a source of zinc ions at low-temperature of approximately 85 degrees C. The as-grown flower-shaped ZnO structures composed of hexagonal nanorods were characterized in terms of their structural, optical and photovoltaic properties by using X-ray diffraction pattern (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED) pattern, FTIR, UV-Vis and Raman-scattering spectroscopy. The detailed structural investigations confirmed that the as-synthesized products are well-crystalline and possessing wurtzite hexagonal phase. For the application point of view, the as-grown flower-shaped ZnO structures composed of hexagonal nanorods were used as photo-anode materials to fabricate the dye sensitized solar cells (DSSCs). An overall light to electricity conversion efficiency of 1.1% with a short-circuit current of 4.34 mA/cm2, open-circuit voltage of 0.554 V and fill factor of 0.45, were achieved for the fabricated solar cell based on flower-shaped ZnO structures composed of hexagonal nanorods.
