Room-Temperature NO<sub>2</sub> Sensor Based on Oxygen Vacancy-Rich SnO Nanosheets
Wen Zhang, S. Wang, Tao Tang, Yin Cheng, Yi Liang, Jing Hao Zhuang, Xin Hu, Min Zhang, Yao Yang Liu, Jie Qi, Baoyue Zhang, Azmira Jannat, Jian Zhen Ou, Zhong Li
Abstract
Nitrogen dioxide (NO 2 ) is a hazardous air pollutant that poses significant threats to both human health and the environment. The development of NO 2 sensors with high sensitivity, exceptional selectivity, and ultralow detection limits is of critical scientific and practical importance. However, conventional metal oxide-based NO 2 sensors often suffer from inherent limitations, including high operating temperatures and relatively low sensitivity. Given that oxygen vacancies in metal oxides serve as active sites for NO 2 adsorption and facilitate charge transfer at the gas–solid interface, this study demonstrates the room-temperature sensing capabilities of two-dimensional (2D) SnO nanosheets with a high concentration of oxygen vacancies, achieved without external excitation (e.g., light). Notably, the sensor exhibits n-type behavior, attributed to free electrons originating from oxygen vacancies. More importantly, the proposed sensor outperforms pure SnO and other metal oxide-based sensors, achieving a remarkably low detection limit of 10 ppb and a record-high response value of 136.43 toward 800 ppb of NO 2 . Furthermore, it demonstrates outstanding repeatability, exceptional selectivity, and long-term stability over two months. These findings highlight the feasibility of achieving ppb-level NO 2 detection at room temperature through morphological control and defect engineering, paving the way for the development of ultrasensitive and high-performance NO 2 sensors.