UV‐Enhanced, Humidity‐Tolerant Formaldehyde Chemiresistor Based on Ce‐MOF‐Derived CeO ₂ Nanospheres Decorated 1D/2D Polyaniline Nanohybrid

Abstract Formaldehyde (HCHO), a widespread indoor contaminant suspected of being carcinogenic, endangers both human and environmental health when the concentration reaches 20 ppm. Therefore, the development of HCHO gas sensors with high sensitivity, selectivity, and room temperature (RT) operability is of great significance. However, achieving excellent sensitivity and selectivity under RT conditions remains challenging, particularly due to the influence of ambient moisture. Herein, a Ce‐metal‐organic framework (MOF) derived CeO 2 /polyaniline (PANI) nanocomposite is synthesized by oxidative polymerization techniques. The CeO 2 /PANI‐based sensor exhibits superior HCHO‐gas‐sensing performance compared to sensors based on pristine PANI and CeO 2 . The highest sensor response of CeO 2 /PANI sensor is 28.34 to 35 ppm, which is 5.18 and 1.75 times higher than those of the PANI and CeO 2 sensors at RT, respectively. Under UV light irradiation, the sensor response of the CeO 2 /PANI nanocomposite further increases to 43.72, representing 5.08 and 1.80 fold enhancements, respectively. Furthermore, the sensor demonstrates rapid response and recovery times of 4.42 and 5.57 s at 1 ppm with illumination of light. The gas‐sensing performance of the CeO 2 /PANI nanocomposite is enhanced by p‐n heterojunctions, oxygen vacancies, a high surface area, and a synergistic interaction between CeO 2 nanoparticles and PANI.