Chemo-Resistive CeO₂-Decorated Y₂O₃ Heterostructured Nanosensors for Selective Ammonia Detection

Chemoresistive sensing is a predominant tool for detecting and quantifying the presence of environmentally harmful gases, such as NO_x and CO_x, which relies on the gradient in electrical resistance of sensors when they come into contact with these gases. This study introduces a unique CeO₂-decorated Y₂O₃ n–n heterostructured sensor demonstrating significantly enhanced chemo-resistive sensing performance toward NH₃. To realize the potential of metal oxide-based chemical sensors, CeO₂-Y₂O₃ sensors have been successfully constructed via a two-step hydrothermal/calcination methodology in varying compositions, ranging from a low 2.5–10% ceria region. UV-DRS technique revealed the alleviated band energy from 3.51 to 3.32 eV on increasing the concentration of ceria in CeO₂-Y₂O₃ heterojunctions, which improved the sensitivity and selectivity toward NH₃ sensing by influencing their electronic structure, charge transfer kinetics, and interaction with target NH₃ molecules. Physisorption surface studies as curtained the higher specific surface area values of the as-prepared CeO₂-Y₂O₃ nanocomposites as compared to their bare counterparts. Compared to the pure Y₂O₃ sensor (157), the optimized 10% CeO₂-Y₂O₃ nanocomposite displayed enhanced sensing performance (738) at an optimum NH₃ molecules exposure at 275 °C. The improved sensing performance is attributed to the appropriate band energy, remarkable surface area, large oxygen vacancies and the formation of heterojunctions over the interface of the CeO₂-Y₂O₃ sensor. Further, the sensing mechanism participating in the advanced catalytic efficiency of the 10% CeO₂-Y₂O₃ has been comprehensively analyzed.