Catalytic Decomposition of 2% Methanol in Methane over Metallic Catalyst by Fixed-Bed Catalytic Reactor

The structure and performance of promoted Ni/Al2O3 with Cu via thermocatalytic decomposition (TCD) of CH4 mixture (2% CH3OH) were studied. Mesoporous Cat-1 and Cat-2 were synthesized by the impregnation method. The corresponding peaks of nickel oxide and copper oxide in the XRD showed the presence of nickel and copper oxides as a mixed alloy in the calcined catalyst. Temperature program reduction (TPR) showed that Cu enhanced the reducibility of the catalyst as the peak of nickel oxide shifted toward a lower temperature due to the interaction strength of the metal particles and support. The impregnation of 10% Cu on Cat-1 drastically improved the catalytic performance and exhibited 68% CH4 conversion, and endured its activity for 6 h compared with Cat-1, which deactivated after 4 h. The investigation of the spent carbon showed that various forms of carbon were obtained as a by-product of TCD, including graphene fiber (GF), carbon nanofiber (CNF), and multi-wall carbon nanofibers (MWCNFs) on the active sites of Cat-2 and Cat-1, following various kinds of growth mechanisms. The presence of the D and G bands in the Raman spectroscopy confirmed the mixture of amorphous and crystalline morphology of the deposited carbon

One- and two-dimensional nanostructures for chemical- and biosensing

Nanostructures have been very popular for several years to do research on sensing. In this paper we will demonstrate the advantage of using nanowires of zinc oxide (ZnO) as one dimensional structure for potentiometric measurements in biological environments. The developed procedures show suitability for the accurate determination of most of the important metal ions and to characterize cells and thin bio-layers. We will also show how to use these structures for biosensing of glucose, cholesterol, and the application of extended gate metal oxide semiconductor field effect transistors as the signal transducer. In the second part, we will show how to use a two-dimensional nanostructure, specifically graphene, for cholesterol and glucose biosensing

Zinc Oxide-Based Self-Powered Potentiometric Chemical Sensors for Biomolecules and Metal Ions

Advances in the miniaturization and portability of the chemical sensing devices have always been hindered by the external power supply problem, which has focused new interest in the fabrication of self-powered sensing devices for disease diagnosis and the monitoring of analytes. This review describes the fabrication of ZnO nanomaterial-based sensors synthesized on different conducting substrates for extracellular detection, and the use of a sharp borosilicate glass capillary (diameter, d = 700 nm) to grow ZnO nanostructures for intracellular detection purposes in individual human and frog cells. The electrocatalytic activity and fast electron transfer properties of the ZnO materials provide the necessary energy to operate as well as a quick sensing device output response, where the role of the nanomorphology utilized for the fabrication of the sensor is crucial for the production of the operational energy. Simplicity, design, cost, sensitivity, selectivity and a quick and stable response are the most important features of a reliable sensor for routine applications. The review details the extra- and intra-cellular applications of the biosensors for the detection and monitoring of different metallic ions present in biological matrices, along with the biomolecules glucose and cholesterol

Flow Potentiometric Injection Analysis of Uric Acid Using Lipid Stabilized Films with Incorporated Uricase on ZnO Nanowires

A novel potentiometric uric acid biosensor was fabricated by immobilization of uricase into stabilized lipid films using zinc oxide (ZnO) nanowires as measuring electrode. Uricase was incorporated into the lipid film prior polymerization on the surface of well aligned ZnO nanowires resulting in a sensitive, selective, stable and reproducible uric acid biosensor. The potentiometric response was twice as large from previously reported values due to the presence of a cationic lipid in the lipid film. The sensor response had no interferences by normal concentrations of ascorbic acid, glucose, urea, proteins and lipids. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Luminescence from Zinc Oxide Nanostructures and Polymers and their Hybrid Devices

Zinc oxide (ZnO) is a strong luminescent material, as are several polymers. These two materials have distinct drawbacks and advantages, and they can be combined to form nanostructures with many important applications, e. g., large-area white lighting. This paper discusses the origin of visible emission centers in ZnO nanorods grown with different approaches. White light emitting diodes (LEDs) were fabricated by combining n-ZnO nanorods and hollow nanotubes with different p-type materials to form heterojunctions. The p-type component of the hybrids includes p-SiC, p-GaN, and polymers. We conclude by analyzing the electroluminescence of the different light emitting diodes we fabricated. The observed optical, electrical, and electro-optical characteristics of these LEDs are discussed with an emphasis on the deep level centers that cause the emission

Indirect optical transition due to surface band bending in ZnO nanotubes

ZnO nanotubes (ZNTs) have been successfully evolved from ZnO nanorods (ZNRs) by a simple chemical etching process. Two peaks located at 382 nm and 384 nm in the UV emission region has been observed in the room temperature photoluminescence (PL) 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.Original Publication:Li Li Yang, Qingxiang Zhao, Muhammad Qadir Israr, Jamil Rana Sadaf, Magnus Willander, Galia Pozina and J. H. Yang, Indirect optical transition due to surface band bending in ZnO nanotubes, 2010, Journal of Applied Physics, (108), 10, 103513.http://dx.doi.org/10.1063/1.3511345Copyright: American Institute of Physicshttp://www.aip.org

High-responsivity broadband photodetection of an ultra-thin In2S3/CIGS heterojunction on steel

Cu(In,Ga)Se2 (CIGS) is a promising light harvesting material for large-area broadband photodetection, but it has been rarely studied up to now. Here an In2S3/CIGS heterojunction photodiode on steel is shown to be highly broadband photo-sensitive, with a photoresponsivity over 0.8 A/W, an external quantum efficiency over 100%, and a detectivity over 8×1010 Jones from 505 to 910nm under a reverse bias of 1 V. Moreover, the CIGS photodiode exhibits an outstanding weak light detection ability (i.e., at light power density of 20µW/cm2), reaching a record responsivity of 2.06 A/W, an impressive EQE of 293%, and a good detectivity of 2.3×1011 Jones at 870 nm under 1 V reverse bias. Importantly, the CIGS photodiode, working as a self-powered photodetector, under 0 V, shows a record detectivity of ∼3.4×1012 Jones with a high responsivity of ∼0.44A/W and a high EQE of ∼63%, at 870 nm