Rapid and ultrahighly sensitive ethanol sensing in p-type SrTi1-xFexO3

Abstract

Gas sensors based on p-type semiconducting metal oxides have recently received significant attention due to their superior gas selectivity compared to those based on n-type metal oxides. Nevertheless, p-type metal oxides-based gas sensors have limitations such as low sensitivity and slow response. Herein, we present highly sensitive and fast responding ethanol (C2H5OH) gas sensors that are composed of p-type SrTi1_ xFexO3 (STF) with various Fe compositions deposited on vertically aligned SiO2 nanorods (NRs) with a larger surface-to-volume ratio than STF thin films. As the Fe content increases, the charge transfer energy between adsorbed oxygen species and transition cations decreases, and the amount of oxygen vacancy increases, This results in the acceleration of charge transfer and the generation of active sites. The fabricated STF on SiO2 NRs exhibited gas responses ranging from 74 to 528 for 50 ppm ethanol gas depending on the Fe content with fast response and recovery time, overcoming the low sensitivity and slow response of previously reported p-type gas sensors. The observed unprecedented synergistic effects of STF on SiO2 NRs for highly selective ethanol sensing establish a new perspective on quaternary p-type perovskites for selective gas sensing in which n-type metal oxides have been used.