Mechanistic Insights and Interface Engineering in Bi₂O₃/Ti₃C₂T_X Nanohybrid for Enhanced CO₂ Sensor Performance

Carbon dioxide emissions pose a significant threat to human health and the environment, necessitating improvements in CO 2 sensing devices. Current infrared detection sensors are complex and large, limiting their practical applications due to their high-power consumption and large size. To overcome this problem, we report herein a CO 2 -sensitive Bi 2 O 3 /Ti 3 C 2 T x film based sensing device fabricated using a drop casting method. As-synthesized materials were analyzed for crystal structure and size, surface morphology, and composition using XRD, SEM, EDS, and UV-visible spectroscopy. The Bi 2 O 3 nanoparticles were decorated on the surface of Ti 3 C 2 T x MXene sheets resulting in the formation of a nanocomposite. At room temperature, Bi 2 O 3 /Ti 3 C 2 T x nanocomposite exhibits a sensor response of 1.43 at 250 ppm, which is better than the sensor response of pristine Ti 3 C 2 T x MXene i.e. 1.35 at the same concentration of 250 ppm. When Bi 2 O 3 /Ti 3 C 2 T x nanocomposite was exposed to 250 ppm of CO 2 , it exhibited a response and recovery times of 6.01 s and 8.52 s, respectively. The Bi 2 O 3 /Ti 3 C 2 T x nanocomposite sensor showed excellent selectivity and good repeatability. This improvement is due to the formation of junction at the interface of Bi 2 O 3 /Ti 3 C 2 T x nanocomposite, which is explained with a detailed sensing mechanism. These exceptional performances of Bi 2 O 3 /Ti 3 C 2 T x nanocomposite highlight their potential for gas sensing applications.