A theoretical study on sensing performance of ZnO (101 ̅0) surface for the detection of CO and HCHO: Effects of Metal Dopants

• Main Authors: En-Wei Chou, 周恩韋
• Other Authors: Jyh-Chiang Jiang
• Format: Others
• Language: en_US
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/26v74z

碩士 === 國立臺灣科技大學 === 化學工程系 === 105 === Nowadays controlling indoor air quality is attracting immense research attention since humans are spending more time in the indoor activities. Carbon monoxide (CO) and Formaldehyde (HCHO) is the most common highly toxic gases, which are found in many households and offices. Sensing the toxic gases from atmosphere, which helps us to monitor and obtain more response time to avoid from continuous exposure of CO and HCHO. Therefore in this study, we have performed density functional theory calculations with the generalized gradient approximation for designing the efficient ZnO based sensor. Further, we have considered the different metal atoms such as Cr, Ti, Ni, and Al for doping on the ZnO surface and investigated their electronic and magnetic properties for the detection of CO and HCHO. Our results indicate that the both adsorbents have interacted with surface metal atoms via either dative bond or π-back donation and combination of both. We found that these types of interaction controls their sensing ability. We also analyzed the interaction between adsorbents and the surface metal atoms using density of states (DOS), electron density difference (EDD) contour plots, and change in magnetic moments and compared how the doping of metal atoms affects both electronic and magnetic properties. Our DFT results show that the location of the d band center determines the types of CO interaction for different metal doped ZnO surface and we found that the Ti doped ZnO surface will be the good sensing material for CO compared to others. In the case of HCHO, a cooperative interaction such as C-H⋯O hydrogen bond and dative bond formed between HCHO and different metal doped ZnO surface, except Ti doped surface. Our results proved that the sensing properties of an oxide material can be modified by means of suitable doping. Based on our results we expect that Ti and Al doped ZnO surface will be the suitable material to enhance the sensitivity to detect CO and HCHO at room temperature, respectively.