Nb 2 O 5 Microcolumns for Ethanol Sensing.

Pseudohexagonal Nb 2 O 5 microcolumns spanning a size range of 50 to 610 nm were synthesized utilizing a cost-effective hydrothermal process (maintained at 180 °C for 30 min), followed by a subsequent calcination step at 500 °C for 3 h. Raman spectroscopy analysis unveiled three distinct reflection peaks at 220.04 cm -1 , 602.01 cm -1 , and 735.3 cm -1 , indicative of the pseudohexagonal crystal lattice of Nb 2 O 5 . The HRTEM characterization confirmed the inter-lattice distance of 1.8 Å for the 110 plain and 3.17 Å for the 100 plain. The conductometry sensors were fabricated by drop-casting a dispersion of Nb 2 O 5 microcolumns, in ethanol, on Pt electrodes. The fabricated sensors exhibited excellent selectivity in detecting C 2 H 5 OH (ΔG/G = 2.51 for 10 ppm C 2 H 5 OH) when compared to a variety of tested gases, including CO, CO 2 , NO 2 , H 2 , H 2 S, and C 3 H 6 O. The optimal operating temperature for this selective detection was determined to be 500 °C in a dry air environment. Moreover, the sensors demonstrated exceptional repeatability over the course of three testing cycles and displayed strong humidity resistance, even when exposed to 90% relative humidity. This excellent humidity resistance gas sensing property can be attributed to their nanoporous nature and elevated operating temperature.