CeO₂/In₂O₃ Hollow Nanosphere Heterojunction for Real-Time CO Monitoring under High Humidity

Abstract

Real-time monitoring of carbon monoxide (CO) is crucial for ensuring human safety. However, the accuracy of the CO detection is significantly diminished by high ambient humidity. This study focuses on synthesizing CeO 2 /In 2 O 3 hollow nanospheres with varying CeO 2 contents (0, 1, 2, 3 mol %) using a twostep method. Testing under different humidity conditions demonstrates that incorporating CeO 2 not only amplifies the response rate of pure In 2 O 3 sensors (from 1.4 to 1.65 at 100 ppm of CO) but also curtails the response and recovery times (from 11 s/27 s to 6 s/23 s) at 280 °C. Furthermore, CeO 2 /In 2 O 3 composite sensors exhibit improved selectivity, repeatability, and long-term stability. Notably, the robust CO detection performance under high humidity verifies that the fabricated CeO 2 /In 2 O 3 sensors can monitor CO in humid environments. The enhanced performance stems from the unique hollow structure, abundant mesopores on the surface, and the heterojunction between CeO 2 and In 2 O 3 .