Sensors for carbon monoxide based on Pd/SnO2/CNT nanocomposites

This study investigates using a Pd2+-doped Pd/SnO2/CNT nanocomposite (Pd2+/SnO2/CNT) sensor to detect carbon monoxide (CO). Using a simple, controllable sol-gel method, we synthesized a CNT that was coated by Pd2+-doped SnO2 nanoparticles. The prepared materials are highly sensitive to CO at a low temperature and demonstrate a fast response-recovery time. The hybrid Pd2+/SnO2/CNT sensors exhibit high sensitivity, selectivity, repeatability, a low limit of detection (5 ppm, Ra/Rg = 1.95), and a fast response-recovery (t90 ≤2 s) to CO at 100 °C. The sensitivity of the materials was improved to 80 times higher than pure tin oxide at a CO concentration of 500 ppm. Such behaviors may be attributed to the catalytic activity of the PdO nanoparticles, the active reaction site that was generated by the CNT, and the enhanced chemisorption and dissociation of the gas.