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 <i>Y</i> 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 <i>Y</i> and light excitation, providing a low-temperature, safe, and highly selective sensing platform for toxic gases such as H₂S.