Rare Earth-Driven Photogenerated Charge Separation in SnO2@Y2O3 Heterojunctions for Enhanced H2S Sensing at Room Temperature

Although conventional heat-activated gas sensors effectively detect air pollutants such as highly toxic H2S and NO2, 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 SnO2@Y2O3 synthesized using an electrospinning-solvothermal method. This is the first demonstration of gas sensing at room temperature using SnO2@Y2O3 heterostructures under low-power ultraviolet light. This heterostructure has excellent H2S sensing performance, thanks to its rich adsorbed oxygen species [21.01%, significantly higher than pure SnO2 (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 SnO2@Y2O3 sensor's response to 10 ppm of H2S under UV irradiation is 318.3% higher than that of the pure SnO2 sensor. In addition, the sensor has excellent selectivity to H2S 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 H2S on the SnO2@Y2O3 heterojunction is significantly higher than that on the SnO2 (110) surface. In addition, the electron transfer amount of H2S on the SnO2@Y2O3 heterojunction (0.385 e) is 218.2% higher than that on the SnO2 (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 H2S.