Shangguan, Chunmei, Xu, Kai, Dong, Mingli, Ren, Guanghui, You, Rui, Liu, Zhenchen, Ou, Rui, Lu, Lidan, Hu, Yihong, Ma, Qijie, Ha, Nam, Zhang, Bao Yue, Khan, Muhammad Waqas, Mohiuddin, Md, Yang, Yunyi, Zhang, Zhenyue, Zhu, Lianqing, and Ou, Jian Zhen
Nitrogen dioxide (NO2), even at parts-per-billion (ppb) concentrations, can greatly threaten human health. Two-dimensional (2D) nonlayered metal oxides demonstrate the strong potential of detecting ppb-level NO2 gas at low temperatures or room temperature with unique selectivity, owing to their physisorption behaviors of NO2 gas molecules as well as abundant active sites based on dangling bonds and defects. In this work, we reveal the ppb-level NO2 detection capability of 2D nonlayered FeOOH as a derivative of 2D metal oxides, which are synthesized from a facile water-dissolvable template with abundant surface hydroxide groups acting as active sites of NO2 adsorption. 2D FeOOH exhibits large lateral dimensions of ∼1–1.5 μm with thicknesses of ∼4–5 nm. An optical energy band gap of 2.2 eV is found, which is suitable for visible-light-driven optoelectronic NO2 gas sensing. An impressive response factor of 36 for 37.5 ppb NO2 is achieved at 160 °C under blue light excitation with full reversibility, excellent long-term stability in months, unique selectivity, and a detection limit of 0.38 ppb, which is significantly improved over those of ppb-level NO2 sensors based on metal oxides. This work reveals 2D nonlayered metal oxyhydroxides as a group of suitable candidates for future high-performance NO2 gas sensors. [ABSTRACT FROM AUTHOR]