The development of highly active and stable bifunctional noble-metal-based electrocatalysts for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) is a crucial goal for clean and renewable energy, which still remains challenging. Herein, we report an efficient and stable catalyst comprising a Co single atom incorporated in an RuO 2 sphere for HER and OER, in which the Co single atom in the RuO 2 sphere was confirmed by XAS, AC-STEM, and DFT. This tailoring strategy uses a Co single atom to modify the electronic structures of the surrounding Ru atoms and thereby remarkably elevates the electrocatalytic activities. The catalyst requires ultralow overpotentials, 45 mV for HER and 200 mV for OER, to deliver a current density of 10 mA cm À 2 . The theoretical calculations reveal that the energy barriers for HER and OER are lowered after incorporation of a cobalt single atom.

The present article describes a miniaturized potentiometric urea lipid film based biosensor on graphene nanosheets. Structural characterization of graphene nanosheets for miniaturization of potentiometric urea lipid film based biosensors have been studied through atomic force microscopy (AFM) and transmission electron microscopy (TEM) measurements. UV‐Vis and Fourrier transform IR (FTIR) spectroscopy have been utilized to study the pre‐ and postconjugated surfaces of graphene nanosheets. The presented potentiometric urea biosensor exhibits good reproducibility, reusability, selectivity, rapid response times (∼4 s), long shelf life and high sensitivity of ca. 70 mV/decade over the urea logarithmic concentration range from 1×10−6 M to 1×10−3 M.

Highly oriented ZnO nanotubes were fabricated on a silicon substrate by aqueous chemical growth at low temperature (<100 °C) by trimming of ZnO nanorods. The yield of nanotubes in the sample was 100%. Photoluminescence spectroscopy of the nanotubes reveals an enhanced and broadened ultraviolet (UV) emission peak, compared with the initial nanorods. This effect is attributed to whispering gallery mode resonance. In addition, a redshift of the UV emission peak is also observed. Enhancement in the deep defect band emission in the nanotubes compared to nanorods was also manifested as a result of the increased surface area.

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A novel potentiometric cholesterol biosensor was fabricated by immobilization of cholesterol oxidase into stabilized lipid films using zinc oxide (ZnO) nanowalls as measuring electrode. Cholesterol oxidase was incorporated into the lipid film prior polymerization on the surface of ZnO nanowalls resulting in a sensitive, selective, stable and reproducible cholesterol biosensor. The potentiometric response was 57 mV/ decade concentration. The sensor response had no interferences by normal concentrations of ascorbic acid, glucose, and urea, proteins and lipids. The present biosensor could be implanted in the human body because of the biocompatibility of the lipid film.

ZnO nanotubes ͑ZNTs͒ have been successfully evolved from ZnO nanorods ͑ZNRs͒ by a simple chemical etching process. Two peaks located at 382 and 384 nm in the UV emission region has been observed in the room temperature photoluminescence ͑PL͒ spectrum of ZNTs since the surface band bending in ZNTs induces the coexistence of indirect and direct transitions in their emission process. In addition, a strong enhancement of total luminescence intensity at room temperature in ZNTs has also be observed in comparison with that of ZNRs. Both temperature-dependent PL and time-resolved PL results not only further testify the coexistence of indirect and direct transitions due to the surface band bending but also reveal that less nonradiative contribution to the emission process in ZNTs finally causes their stronger luminescence intensity.

Chemically fashioned zinc oxide (ZnO) nanowalls on aluminum wire have been characterized and utilized to fabricate a potentiometric cholesterol biosensor by an electrostatic conjugation with cholesterol oxidase. The sensitivity, specificity, reusability, and stability of the conjugated surface of ZnO nanowalls with thickness of similar to 80 nm have been investigated over a wide logarithmic concentrations of cholesterol electrolyte solution ranging from 1x10(-6)-1x10(-3) M. The presented biosensor illustrates good linear sensitivity slope curve (similar to 53 mV/decade) corresponding to cholesterol concentrations along with rapid output response time of similar to 5 s.Original Publication:M.Q. Israr, J.R. Sadaf, Omer Nur, Magnus Willander, S. Salman and B. Danielsson, Chemically fashioned ZnO nanowalls and their potential application for potentiometric cholesterol biosensor, 2011, Applied Physics Letters, (98), 25, 253705.http://dx.doi.org/10.1063/1.3599583Copyright: American Institute of Physicshttp://www.aip.org