Preparation of inkjet printed flexible MOF-derived porous ZnO/CuO gas sensor with low operating temperature
| Autor: | Chia-Yu Li, 李佳諭 |
|---|---|
| Rok vydání: | 2018 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 106 In this study, inkjet printing technology was used to prepare a looped electrode composed of silver nanoparticles on a flexible polyimide (PI) film, and a porous semiconductor-type gas-sensing material such as zinc oxide and copper oxide, which were derived from a metal-organic framework material was used as sensing layer, and coated onto nanosilver loop type electrode. To investigate the sensing capability of the homemade gas sensor under reducing gas atmosphere at room temperature with a low wattage UV-LED (10 W) lamp irradiated, to improve the semiconductor gas sensitive materials need to be applied to the limitations of high-temperature environment. Using ethylene glycol as a reducing agent and polyvinylpyrrolidone (PPV) as a protective agent, silver nitrate (AgNO3) was reduced by a simple polyol reduction method to prepare nanosilver particles. X-ray diffraction (XRD) results indicate that the silver nanoparticles are spherical metal silver with face-centered cubic structure. The particle size is approximately 60-80 nm by Scanning Electron Microscope (SEM) and Transmission Electron Microscopy (TEM) and particle size analyzer. The silver nanoparticle was formulated into 5 wt% silver ink, and the ink was filled in a commercially available EPSON T50 printer ink cartridge. The nanosilver loop type electrode is printed on the polyimide film and then coated with a layer of gas sensitive material, wherein the sensing layer is ZnO (N-type) and CuO (P-type), and the formation of heterogeneous interface (P-N Junction) of ZnO mixed with CuO (ZnO/CuO) to complete the preparation of sensors. The sensors are placed in a homemade gas sensing chamber, and the sensing test is carried out under reducing gas atmosphere (0-400 ppm) at room temperature with a low wattage UV-LED (10 W) lamp irradiated. The sensors was connected to a universal meter (Keithley 2400), and the current value was read at different reducing gas concentrations. After the computer software was recorded, the sensing performance of the gas sensor at room temperature was investigated. When the sensor was used to sense 50 ppm acetone at room temperature, the response values of ZnO, CuO, and ZnO/CuO were 34.9, 20.9 and 63.6 respectively. The response time (Tres) was 3, 52 and 5 seconds respectively, the recovery time (Trec) was 5, 14 and 8 seconds, respectively, and the sensed instantaneous current value significantly changed with increasing acetone gas concentration, and was an effective acetone gas sensor. It is worth noting that sensors with heterostructure materials (ZnO/CuO) have obviously synergistic effects. Which show that the sensors can effectively improve the limitations of conventional metal oxide semiconductor gas sensors operating at high operating temperature, and have good sensing ability for the acetone gas with low ppm concentration at room temperature. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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