Rare Earth-Driven Photogenerated Charge Separation in SnO<sub>2</sub>@Y<sub>2</sub>O<sub>3</sub> Heterojunctions for Enhanced H<sub>2</sub>S Sensing at Room Temperature
Yanhui Sun, Jiawen Cui, Shouhang Fu, Shupeng Sun, Kehan Qian, Zhixin Luo, Dong Han
Abstract
Although conventional heat-activated gas sensors effectively detect air pollutants such as highly toxic H 2 S and NO 2, their high operating temperatures increase the risk of explosions in flammable gas environments, limiting their applications. In this study, we report a novel composite material of SnO 2 @Y 2 O 3 synthesized using an electrospinning-solvothermal method. This is the first demonstration of gas sensing at room temperature using SnO 2 @Y 2 O 3 heterostructures under low-power ultraviolet light. This heterostructure has excellent H 2 S sensing performance, thanks to its rich adsorbed oxygen species [21.01%, significantly higher than pure SnO 2 (11.55%)] and enhanced interfacial charge transfer. The introduction of the Y element greatly reduces the photogenerated electron–hole recombination efficiency of the composite material under UV light. Furthermore, the SnO 2 @Y 2 O 3 sensor’s response to 10 ppm of H 2 S under UV irradiation is 318.3% higher than that of the pure SnO 2 sensor. In addition, the sensor has excellent selectivity to H 2 S due to the interface potential barrier between the two, and the response is at least 6.8 times that of other interfering gases. DFT calculations further show that the adsorption energy of H 2 S on the SnO 2 @Y 2 O 3 heterojunction is significantly higher than that on the SnO 2 (110) surface. In addition, the electron transfer amount of H 2 S on the SnO 2 @Y 2 O 3 heterojunction (0.385 e) is 218.2% higher than that on the SnO 2 (110) surface (0.121 e). This work proposes a new strategy for improving the performance of gas sensors by introducing element Y and light excitation, providing a low-temperature, safe, and highly selective sensing platform for toxic gases such as H 2 S.