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Updated: Aug 5, 2026

Tuning Oxide Properties by Oxygen Vacancy Control During Growth and Annealing
Published on: June 9, 2023
Oxygen-vacancy-related defects and interfacial electron transfer in SnO2/WO3 heterojunctions for enhanced NO2
Chuan Luo1, Bingqin Lv2, Cheng Xu2
1Faculty of Information Engineering and Automation, Kunming University of Science and Technology, Kunming 650500, China; Yunnan Key Laboratory of Computer Technology Applications, Kunming 650500, China.
Abstract:
Developing low-temperature and high-response NO2 gas sensors is important for environmental monitoring and public health protection. In this study, SnO2/WO3 heterojunction nanocomposites were synthesized by a hydrothermal method and fabricated into gas sensors. Among the investigated samples, SW5 exhibited the highest response of 967 toward 100 ppm NO2 at 130°C, with response/recovery times of 55/80 s and a relative standard deviation of 2.4% over five consecutive cycles. Structural and spectroscopic analyses confirmed the coexistence of SnO2 and WO3, the formation of a SnO2/WO3 heterointerface, interfacial charge redistribution, and a relatively high content of oxygen-vacancy-related defects in SW5. Williamson-Hall and HRTEM analyses further suggested heterointerface-associated structural distortion in the composite. DFT calculations showed that NO2 adsorption at the heterojunction interface was more favorable, with an adsorption energy of -1.97438 eV, and DOS analysis revealed new electronic states near the Fermi level, indicating enhanced adsorption and charge redistribution. The superior NO2 sensing performance of SW5 is attributed to the synergistic effects of relatively abundant oxygen-vacancy-related defects and heterojunction-induced interfacial electron transfer. This work provides a defect/interface co-engineering strategy for developing high-performance metal-oxide NO2 gas sensors.
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