Dual-template derived Ce-doped WO3 nanosheets with enhanced surface reactivity for low-temperature NO2 detection

Dual-template hydrothermal synthesis of high-area WO 3 nanosheets. • Ce doping tunes WO 3 with optimal NO 2 sensing at 3% doping level. • Fivefold higher response (189.6 toward 10 ppm NO 2 at 150 °C) vs WO 3 . • Detection limit of 25 ppb with fast response/recovery (28/37 s). Nitrogen dioxide (NO 2 ) is a hazardous air pollutant, necessitating the development of highly sensitive sensors operating at low temperatures. Herein, Ce-doped WO 3 nanosheets with enhanced surface reactivity were fabricated via a dual-template hydrothermal strategy using PVP and P123. The dual-template approach enables the formation of uniform nanosheets with enlarged specific surface area and abundant accessible active sites, thereby boosting surface adsorption and reaction kinetics. Ce doping further tailors the surface and electronic structures by introducing abundant oxygen vacancies and defect levels that reduce the apparent optical bandgap from 2.45 to 2.37 eV, which enhances charge transfer and adsorption capability. As a result, the 3% Ce-WO 3 sensor exhibits optimal performance at 150°C, delivering a high response of 189.6 toward 10 ppm NO 2 , nearly five times higher than that of pristine WO 3 , along with a low detection limit of 25 ppb, excellent selectivity, and long-term stability. Mechanistic analysis reveals that the synergistic effects of dual-template-derived surface reactivity and Ce-induced electronic modulation reduce the activation energy from 0.57 to 0.31 eV, thereby facilitating NO 2 adsorption and surface redox reactions at low temperatures. This work provides an effective strategy for the rational design of high-performance gas sensors for low-temperature NO 2 detection. Download: Download high-res image (91KB) Download: Download full-size image In summary, we have successfully synthesized Ce-doped WO 3 nanosheets via a dual-template hydrothermal method and systematically investigated their NO 2 sensing performance. Among the investigated samples, the sensor with 3% Ce doping exhibited the optimal NO 2 sensing performance, delivering a high response of 189.6 toward 10 ppm NO 2 at 150°C, which is approximately five times higher than that of pristine WO 3 under identical conditions. In addition, a low detection limit of 25 ppb was achieved, along with rapid response and recovery times of 28 s and 37 s, respectively. Mechanistic investigations reveals that Ce doping introduces abundant surface oxygen vacancies, narrows the apparent optical bandgap from 2.45 to 2.37 eV, and shifts the Fermi level upward, as confirmed by XPS, UV-Vis, and Mott-Schottky measurements. These electronic structure modifications significantly reduce the activation energy and promote surface redox kinetics, thereby enabling highly efficient NO 2 detection at relatively low operating temperatures. This work demonstrates that rare-earth doping, combined with rational morphology engineering, is an effective strategy for regulating the electronic structure and surface properties of WO 3 , providing a promising approach for the development of high-performance gas sensors for next-generation environmental monitoring applications.