Extrinsic oxygen defects in SnO/SnO2 heterostructure for efficient NO2 gas detection

• Published in: Sensors and actuators. B, Chemical Vol. 399; p. 134751
• Main Authors: Kim, Jihee, Nazarian-Samani, Masoud, Lee, Jihyun, Lee, Sang-kil, Pi, Ji Hee, Lee, Kyu Hyong, Kim, Yu Jin, Lee, Sanghyeon, Lee, Wooyoung
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.01.2024
• Subjects: NO2 gas sensor; NO2 selectivity; Oxygen vacancy; SnO/SnO2 heterostructure; Tin-oxide gas sensor; Tin-oxide gas sensor; NO2 selectivity; NO2 gas sensor; SnO/SnO2 heterostructure; Oxygen vacancy
• ISSN: 0925-4005; 1873-3077
• DOI: 10.1016/j.snb.2023.134751

High selectivity and fast response in the detection of NO2 are key factors in protecting human health in life-threatening environments. The p-n SnO/SnO2 heterostructure is a promising material as a metal oxide for effective chemical reactions with a target gas. It has a synergistic effect on the intrinsic semiconducting properties and the formation of an interfacial electric field in the heterojunction. The extrinsic oxygen vacancies in the SnO/SnO2 structure enhance the chemical reaction in the sensing property. In this study, we developed a defect-SnO/SnO2 heterostructure-based NO2 gas sensor. It shows excellent sensing performances with a high response of 100.86, fast response time of 5.83 s, and superior selectivity (approximately 23 times higher than those of other target gases) in the detection of 50 ppm NO2 at 150 °C. Raman and electron paramagnetic resonance (EPR) results supported the presence of oxygen vacancies in the defect-rich SnO/SnO2 crystal and X-ray photoelectron spectroscopy (XPS) and time-of flight secondary ion mass spectrometry (ToF-SIMS) analyses described the role of SnO/SnO2 heterostructure with oxygen defects as an effective electron donor for the adsorbed oxygen molecules and NO2 target gas. We believe that the direct formation of oxygen vacancies in the SnO/SnO2 heterostructures is a significant reference for the development of high-performance NO2 gas sensors. [Display omitted] •A SnO/SnO2 heterostructure with extrinsic oxygen defects was designed.•The defect-SnO/SnO2 crystal allows a reduction of the band gap and easier electron transition.•It enables effective chemical interaction with NO2 molecules by the adsorbed oxygen species.•The sensor device shows superior NO2 sensing performances with a fast response and high selectivity.