High‐Performance Humidity Sensors Based on CeO ₂ –Carbon Fiber Hybrid Materials

ABSTRACT Cerium oxide (CeO 2 ) is a promising material for humidity sensing. This study enhances its performance by developing CeO 2 –carbon fiber (CF) composites, with CF contents of 1%, 3%, and 5% by weight. The composites were synthesized via sol–gel and hydrothermal methods and then characterized using XRD, EDX, FTIR, Raman spectroscopy, and SEM to consider structure and composition. These materials were integrated into sensors and tested across a 10%–90% relative humidity range. The best performances were achieved for the CeO 2 –5% CF‐based sensor with an improvement in the response time and the sensitivity measured at 90% relative humidity (RH). These results highlight the potential of CeO 2 –CF hybrid matrices as a promising approach for the development of high‐performance humidity sensors.