Unraveling the promoted nitrogen dioxide detection performance of N-doped SnO2 microspheres at low temperature

• Published in: Journal of alloys and compounds 2020-09, Vol.834, p.155209, Article 155209
• Main Authors: Du, Wenjing, Si, Wenxu, Du, Wenzheng, Ouyang, Tianhong, Wang, Fenglong, Gao, Mengjiao, Wu, Lili, Liu, Jiurong, Qian, Zhao, Liu, Wei
• Format: Article
• Language: English
• Subjects: Ammonia; Detection; DFT calculations; Doping; Electron transfer; Electronic structure; Energy bands; Free electrons; Gas sensing; Low temperature; Metal oxides; Microspheres; Nitrogen dioxide; Nitrogen doping; Selectivity; Tin dioxide; Vacancies
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2020.155209

Nitrogen doping has been proven an efficient strategy to modulate the electronic structure of metal oxides to tune their properties. Herein, we report the synthesis of N-doped SnO2 microspheres through calcining the pristine SnO2 in NH3 atmosphere. Texture characterizations show that N–SnO2 microspheres exhibit 3D-porous architectures with a diameter of ca. 300–500 nm. After NH3 treatment, the SnO2 exhibits the formation of the N-doping and oxygen vacancies on the surface of the material, rich free-electrons and the narrow energy band. It is found that the as-prepared N-doped SnO2 microspheres at 200 °C (N–SnO2-200), show superior selectivity and high response (S = 155 to 5 ppm NO2) compared with its counterparts. DFT calculations and experimental results illustrate that N impurities and oxygen vacancies as N-induced active sites favor the adsorption of NO2 molecules; rich free-electrons increase the amount of adsorbed NO2 molecules; and the narrow energy band promotes the effectively electron transfer during the sensing reaction. Therefore, in this work we unravel the improved NO2 gas-sensing performances of the N-doped SnO2 and provide new guidance for the development of highly efficient metal oxide sensing materials for NO2 detection. •The N-doped SnO2 nanospheres were synthesized via NH3 heat treatment of the pristine SnO2.•The correlation between the content of N doping and the gas-sensing property was further studied.•The N–SnO2 nanospheres obtained at 200 °C shows improved response and selectivity to NO2 at 80 °C.•The improved sensing mechanism of the N–SnO2 sensor to NO2 was further studied via DFT calculation.