Browsing by Author "Tsai, Cheng-Yu"

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Acetone sensing mechanism of PdO at temperatures below 250 degrees C
(2017-04-02)
Tsai, Cheng-Yu
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Chen, Yi Sheng
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Cheng, I-Kai
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Pan, Fu-Ming
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交大名義發表
Correlation of surface processes with characteristic sensing responses of PdO thin films to ethanol
(2019-04-15)
Cheng, I-Kai
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Wang, Jeng-Han
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Tsai, Cheng-Yu
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Chen, Yi-Sheng
;
Pan, Fu-Ming
Gas sensing characteristics of PdO nanoflake thin films exposed to ethanol (EtOH) at temperatures below 250 degrees C was studied. The PdO thin film responses distinctly to 0.15 ppm EtOH in dry air at temperatures above 100 degrees C. A characteristic valley-shaped response feature develops in the early stage of the exposure to EtOH at 150 degrees C and above. Formation of the valley feature is a result of the combined effects of two types of surface processes, which successively modify the sensor conductance in the opposite way. Dehydrogenation of adsorbed EtOH induces reduction of preadsorbed oxygen anions and the PdO substrate, resulting in the drop of the conductance. On the other hand, subsequent adsorption of EtOH and oxygen on newly growing Pd nanoclusters, which develop due to the reduction of the PdO substrate, causes the increase in the conductance. The Pd nanoclusters can be later reoxidized in the EtOH gas mixture, thereby modifying the sensing behavior of the PdO sensor. X-ray photoelectron spectroscopy (XPS), diffusive reflectance infrared Fourier transform spectroscopy (DRIFTS) and temperature programmed desorption (TPD) were used to study adspecies and gaseous species formed in the EtOH gas sensing reactions. On the basis of the characteristic electrical response and chemical characterizations, we proposed the formation mechanism for the characteristic response feature.
Effect of carriers on the performance of anaerobic sequencing batch biofilm reactor treating synthetic municipal wastewater
(2014-11-01)
Dutta, Kasturi
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Tsai, Cheng-Yu
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Chen, Wen-Hsing
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Lin, Jih-Gaw
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環境工程研究所
In this study, effects of granular activated carbon (GAC) and natural zeolite as attached carriers for microbes on anaerobic treatment of synthetic municipal wastewater were evaluated in laboratory scale anaerobic sequencing batch biofilm reactors (ASBBRs). An anaerobic sequencing batch reactor (ASBR) and three ASBBRs, individually named ASBR-1 without any carrier (control), ASBBR-2 with GAC, ASBBR-3 with zeolite, ASBBR-4 with both GAC and zeolite, were operated at 2.5 d HRT with non-fat dry milk to mimic municipal wastewater. The four reactors were successfully started up and attained steady state within two weeks of operation. Total COD and soluble COD removal efficiencies of more than 93% and 98%, respectively, were observed in the four reactors during steady-state. The average biogas productions for ASBR-1, ASBBR-2, ASBBR-3 and ASBBR-4 were 229, 246, 238 and 278 mI/d, respectively. Addition of carriers improved both the COD removal efficiency and biogas production. Apparently GAC improved COD removal efficiency and zeolite improved gas production. SEM results suggested higher number of biomass attached to GAC than zeolite. (C) 2014 Elsevier Ltd. All rights reserved.
Ethanol gas sensing mechanism of PdO nanoflake thin film at temperatures below 250 degrees C
(2017-04-02)
Cheng, I-Kai
;
Wang, Jeng-Han
;
Tsai, Cheng-Yu
;
Chen, Yi-Sheng
;
Pan, Fu-Ming
Growth and properties of single-crystalline Ge nanowires and germanide/Ge nano-heterostructures
(2012)
Tsai, Cheng-Yu
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Yu, Shih-Ying
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Hsin, Cheng-Lun
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Huang, Chun-Wei
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Wang, Chun-Wen
Single-crystalline Ge nanowires have been synthesized on Au-coated Si substrates through a thermal evaporation, condensation method and vapor-liquid-solidmechanism. The [111] growth direction of the Ge nanowires was analyzed using HRTEM and fast Fourier transform diffraction patterns. Global back-gated Ge nanowire field-effect transistors (FETs) on the Si3N4 dielectrics were fabricated and studied, showing p-type behavior and a field effect hole mobility of 44.3 cm(2) V-1 s(-1). The Ge channel length could be well controlled through the annealing process. After a rapid thermal annealing (RTA) process, Ni2Ge/Ge/Ni2Ge nano-heterostructures were formed. The electrical transport properties were effectively improved by the heterojunction rather than the metal contact. The epitaxial relationship between Ge and orthorhombic Ni2Ge was Ge [110]//Ni2Ge[110] and Ge(-11-1)//Ni2Ge(1-1-2). From electrical transport properties, the measured resistivity of the Ge nanowires was much lower than intrinsic bulk Ge material. A room temperature photoluminescence spectrum of the Ge nanowires possessed a broad blue emission with a peak at 462 nm in wavelength, which was attributed to the oxide-related defect states. Due to the existence of the defects, a Ge nanowire FET was able to detect visible light and serve as a nanowire photodetector.
The influence of UV filter and Al/Ag moisture barrier layer on the outdoor stability of polymer solar cells
(2020-03-15)
Weng, Chia-Ning
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Yang, Hao-Chun
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Tsai, Cheng-Yu
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Chen, Szu-Han
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Chen, Yan-Syun
The degradation of the polymer solar cells in the outdoor condition was studied. It was found that the devices with normal structure (ITO/PEDOT:PSS/PBDTTT-EFT:PC71BM/ZrOx/Al) show better stability than those with inverted device structure (ITO/ZnO/PBDTTT-EFT:PC71BM/MoO3/Ag). PBDTTT-EFT is poly[4, 8-bis(5-(2-ethylhexyl) thiophen-2-yl) benzo [1,2-b;4,5-b] dithiophene-2, 6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno [3,4-b] thiophene-) - 2-carboxylate-2-6-diyl)] and PC71BM is [6,6]-phenyl-C71-butyric acid methyl ester. The major cause of degradation was attributed to the ultraviolet (UV) part of the sunlight. When the UV filter with cut-off wavelength of 400 nm was used to protect the device, the decay rate was improved by 50 times and the protected device retains 95% of their initial power conversion efficiency after 13 days outside. In the meanwhile, the decay of device fabricated by toluene was found 8 times faster than device by chlorobenzene. Thin 20 nm of Ag capping layer can further improve the stability. Degradation under water immersion indicates that the major effect of Ag is to protect against the residual moisture inside the encapsulation.
Treatment of campus domestic wastewater using ambient-temperature anaerobic fluidized membrane bioreactors with zeolites as carriers
(2019-01-01)
Chen, Wen-Hsing
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Tsai, Cheng-Yu
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Chen, Shen-Yi
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Sung, Shihwu
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Lin, Jih-Gaw
An anaerobic fluidized-bed bioreactor (AFBR) connected with an anaerobic fluidized membrane bioreactor (AFMBR) in series with natural zeolites as carriers was used to treat the campus domestic wastewater (chemical oxygen demand (COD) of 130 +/- 38 mg/L) at ambient temperature (20-35 degrees C) in this study. Results indicate that the attached growth of anaerobic microbes was observed on the surface of zeolite and 95% of COD were removed in the AFBR after 30 days of batch operation. When the AFBR-AFMBR system was run with a HRT from 3 to 4 h, the COD, biochemical oxygen demand (ROD), and suspended solid (SS) were removed by 84, 87, and 96%, respectively, with the corresponding effluent COD, BOD, and SS of 20, 8, and 2 mg/L, respectively. Overall, 41% of the COD removal was attributed to coupling with sulfate reduction by sulfate-reducing bacteria in this study. In the AFMBR, the transmembrane pressure remained lower than 0.2 bar at the membrane flux of 10 L/m(2)-h. The membrane module was operated consecutively for 333 days without chemical cleaning. In addition, the maximum substrate utilization rate of 37 g/L-d determined based on the modified Stover-Kincannon equation elucidates that the organics in the campus domestic wastewater were readily biodegraded. This facilitated the AFBR-AFMBR system removing the organics to the levels lower than the discharging limits.