Flower-like CeO2/SnO2 Heterostructure for Room-Temperature NH3 Detection

Traditional tin dioxide (SnO2) gas sensors suffer from high operating temperatures and poor sensing response toward ammonia (NH3) at room temperature. Herein, flower-like CeO2/SnO2 n-n heterostructures are fabricated via a facile one-pot solvothermal route followed by high-temperature calcination for ppm-level NH3 detection at room temperature. The CeO2/SnO2 heterostructure calcined at 800 °C presents porous flower microspheres assembled by nanoparticles. Gas-sensing measurements demonstrate that the CeO2/SnO2-800 sensor delivers a high response of 6.5 toward 50 ppm NH3 at room temperature. Moreover, the sensor exhibits outstanding selectivity, reproducibility, and long-term stability over 60 days. Combined XPS, in situ FT-IR, O2-TPD, and EPR characterizations verify that the construction of n-n heterojunctions and abundant oxygen vacancies synergistically boost the concentration of surface-adsorbed oxygen species, thus improving the NH3 sensing performance. The CeO2/SnO2 heterostructure in this work offers a promising strategy for developing low-power room-temperature NH3 gas sensors.