e. when the particle size decreased, the band-gap energy increased.ZnO is an interesting chemically and thermally stable n-type semiconductor of wurtzite structure with a large-band selleck chemicals Ruxolitinib gap energy of 3.37 eV at low temperature and 3.3 eV at room temperature [3�C6], and with high sensitivity to toxic and combustible gases. It is sensitive to many gases at moderate temperature, especially H2 gas [7�C12]. For comparison with Inhibitors,Modulators,Libraries the same doping material there were many reports of other preparation methods. Xu et al.  prepared pure ZnO powder by chemical precipitation. The response characteristics of 0.5 wt% Pt/ZnO nanoparticles to 0.2% H2 in air at 330 ��C was reported with the sensitivity of 2. Moreover, Rout et al.  reported ZnO nanowires/nanotubes prepared by electrochemical deposition on alumina membranes.
The response characteristics for 1 at.% Pt/ZnO nanoparticles Inhibitors,Modulators,Libraries were obtained. The sensitivity of ZnO nanowires without and with Pt impregnation for 1,000 ppm of H2 were 43 and 825 at 150 ��C, respectively, indicating the enhancement in sensitivity by incorporating Pt into the ZnO nanowires. The response time for the as-prepared and the Pt-impregnated ZnO were 54 and 42 s respectively with the recovering times of 5 and 4 s respectively. In addition, Wang et al.  reported ZnO nanorods deposited by Molecular Beam Epitaxy (MBE) and detection of hydrogen at room temperature with catalyst-coated multiple ZnO nanorods. The Pt metal catalyst coating deposited on multiple ZnO nanorods were compared for their effectiveness in enhancing sensitivity for detecting hydrogen at room temperature.
Pt-coated nanorods showed a relative response of up to 8% in room temperature Inhibitors,Modulators,Libraries resistance upon exposure to a hydrogen concentration in N2 of 500 ppm. Tien et al.  reported that ZnO nanorods were deposited by Molecular Beam Epitaxy (MBE) and hydrogen sensing at room temperature with Pt-coated ZnO thin films and nanorods. A comparison of the sensitivities was reported for detecting hydrogen with Pt-coated single ZnO nanorods and thin films. The Pt-coated single nanorods showed a current response of approximately a factor of 3 larger at room temperature upon exposure to 500 ppm H2 in N2 than the thin films of as-prepared ZnO. For comparison with other Inhibitors,Modulators,Libraries doping materials, Xu et al.  reported that a Ru-doped ZnO gas sensor showed the selectivity of 0.
2% H2 at 230 ��C and 400 ��C were 6 and 2, respectively. The Rh-doped ZnO gas sensor had good gas selectivity for 0.2% H2 of 115 at 300 ��C. A Ag-doped ZnO gas sensor showed characteristic response of 9 for 0.2% H2 at 400 ��C. A summary comparing H2 sensing Carfilzomib with metal-doped ZnO prepared by several synthetic methods is shown in Table selleck chem 1. ZnO is one of the most widely applied oxide-gas sensor. ZnO gas sensing materials owe to their high chemical stability, low cost, and good flexibility in fabrication.