Facile synthesis of pseudo-peanut shaped hematite iron oxide nano-particles and their promising ethanol and formaldehyde sensing characteristics

Herein, pseudo-peanut shaped hematite iron oxide nano-particles are prepared through a facile cost effective wet chemical synthesis route. The synthesized particles are characterized in terms of their phase formation behavior, morphological features and also used for sensing ethanol and formaldehyde vapors. The sensing characteristics (response %, response time, recovery time, selectivity coefficient) are investigated by varying the operating temperature (300-375 degrees C) of the sensor and concentration (20200 ppm) of the studied vapors. The sensor shows promising response towards ethanol and formaldehyde vapors. In the studied operating temperature range, the response of the sensor towards ethanol is found to be better than formaldehyde. The cross-selectivity issue of the sensor has been addressed using the variation of selectivity coefficient with the exposure time of the vapors. For sensing ethanol and formaldehyde vapors, the response of the pseudo-peanut shaped particles is compared with poly-disperse type hematite particles. As compared to the poly-disperse particles, peanut like structures are found to be superior for sensing the studied vapors.