Selective detection of carbon dioxide using LaOCl-functionalized SnO₂ nanowires for air-quality monitoring

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• 作者：Do Dang Trung^a ; Le Duc Toan^a ; Hoang Si Hong^b ; Tran Dai Lam^c ; Tran Trung^d ; ^{trantrung@utehy.edu.vn} ; Nguyen Van Hieu^a ; ^{hieu@itims.edu.vn}
• 关键词：SnO2 nanowires ; LaOCl ; CO2 sensor
• 刊名：Talanta
• 出版年：2012
• 出版时间：15 January, 2012
• 年：2012
• 卷：88
• 期：Complete
• 页码：152-159
• 全文大小：1412 K

文摘

In spite of the technical important of monitoring CO₂ gas by using a semiconductor-type gas sensor, a good sensitive and selective semiconductor CO₂ sensor has been not realized due to the rather unreactive toward CO₂ of conventional semiconductor metal oxides. In this work, a novel semiconductor CO₂ sensor was developed by functionalizing SnO₂ nanowires (NWs) with LaOCl, which was obtained by heat-treating the SnO₂ NWs coating with LaCl₃ aqueous solution at a temperature range of 500-700 ¡ãC. The bare SnO₂ NWs and LaOCl-SnO₂ NWs sensors were characterized with CO₂ (250-4000 ppm) and interference gases (100 ppm CO, 100 ppm H₂, 250 ppm LPG, 10 ppm NO₂ and 20 ppm NH₃) at different operating temperatures for comparison. The SnO₂ NWs sensors functionalized with different concentrations of LaCl₃ solution were also examined to find optimized values. Comparative gas sensing results reveal that LaOCl-SnO₂ NWs sensors exhibit much higher response, shorter response-recovery and better selectivity in detecting CO₂ gas at 400 ¡ãC operating temperature than the bare SnO₂ NWs sensors. This finding indicates that the functionalizing with LaOCl greatly improves the CO₂ response of SnO₂ NWs-based sensor, which is attributed to (i) p-n junction formation of LaOCl (p-type) and SnO₂ nanowires (n-type) that led to the extension of electron depletion and (ii) the favorable catalytic effect of LaOCl to CO₂ gas.