Engineering Pore Walls of Mesoporous Tungsten Oxides via Ce Doping for the Development of High-Performance Smart Gas Sensors

Chemiresistive gas sensors are widely used in environmental monitoring and industry production; however, their selectivity and sensitivity are yet to be improved and their working temperature is usually too high (around 250 degrees C), which limit their applications in detecting trace gases at low temperatures due to the low activity of sensitive layers. Herein, novel Ce-doped mesoporous WO3 with high specific surface areas of 59-72 m(2)/g, a stable crystalline framework, and finely tailored pore walls was synthesized via a facile in situ cooperative assembly method combined with a carbon-supported crystallization strategy. The doping of Ce atoms in the mesoporous WO3 pore wall can effectively adjust the coordination environment of W atoms, giving rise to dramatically enhanced oxygen vacancy (O-v) and forming W delta+-O-v sites. As a result, the obtained Ce-doped mesoporous WO3 showed excellent H2S sensing performance at a low working temperature (150 degrees C) with an ultrahigh response value (381 vs 50 ppm), fast response dynamics (6 s), outstanding selectivity, and antihumidity property as well as good long-term stability. The superior gas sensing performance is attributed to the increased O-v density and enhanced conversion of surface-adsorbed H2S into SOx and SOx2- during the surface adsorption-catalysis reaction in the sensitive layer. Density functional theory (DFT) calculations reveal that Ce4+ is embedded into the crystal lattice of WO3 to form an optimal structure rather than atom substitution, and Ce-doped WO3 shows a higher H2S adsorption energy and a larger charge transfer than that in pure WO3, accounting for the better H2S sensing response of Ce4+-doped WO3. Furthermore, a novel gas sensing module and smart portable sensor device based on Ce-doped mesoporous WO3 was developed for efficient real-time monitoring of H2S concentration on a smartphone via Bluetooth communication.

Automated summary

In this research, a novel Ce-doped mesoporous WO3 material was synthesized and showed excellent H2S gas sensing performance at low temperatures. A portable sensor device based on this material was also developed for real-time monitoring of H2S concentration on a smartphone.