Pt-decorated hierarchical SiC nanofibers constructed by intertwined SiC nanorods for high-temperature ammonia gas sensing
In this work, novel hierarchical SiC nanofibers (HSiC) constructed by intertwined SiC nanorods were fabricated through electrospinning and catalyst-assisted pyrolysis routes. HSiC possessed a high surface area of 108.7 m2 g-1 and interconnected porous structure. Platinum nanoparticles with size of 2-3 nm were homogeneously deposited onto SiC nanorods (Pt/HSiC) via ethylene glycol reduction method. When applied to detect 500 ppm NH3 at 500 °C, the sensor based on Pt/HSiC demonstrated a sensitivity of 9.1% and short response/recovery time of 2 s/5 s. Moreover, the sensor exhibited a low detection limit of 1 ppm NH3 and excellent repeatability. The outstanding performance is attributed to the hierarchically interconnected macro-meso-porous structure, which provides more effective active sites and facilitates the gas diffusion. A proposed mechanism for the increasing resistance under NH3 atmosphere was based on the stronger spill-over mechanism and dipolar layer effect. The successful synthesis of HSiC may provide a potential catalyst support for applications in high-temperature and corrosive environments.