Selective and Reversible Sensing of Low Concentration of Carbon Monoxide Gas Using Nb-Doped OMS-2 Nanofibers at Room Temperature

A reversible and selective resistive gas sensor using Nb-doped cryptomelane octahedral molecular sieves (Nb-OMS-2) nanofibers for room-temperature CO gas detection was developed. The electrical resistance of the Nb-OMS-2 nanofibers decreases on exposure to CO gas. The sensor displayed response of 22% for 2 ppm and 91% for 400 ppm of CO gas in air. The average detection and recovery time were similar to 15 s for 200 ppm of CO at room temperature. The substitution of Mn with Nb in the OMS-2 framework, the formation of Nb-O-Mn bridge, and the reaction of CO with bridge oxygen are proposed to be responsible for high sensitivity and selectivity for CO gas in air.