Pd functionalized SrTiO3 hollow spheres for humidity-tolerant ethanol sensing

Sensing of gases and volatile organic compounds in harsh humid conditions is a major challenge for any advanced sensing system. SrTiO3 hollow sphere, a cutting edge nanoform in perovskite has been introduced first time in the current study to pursuit humidity independent sensing of ethanol vapor. SrTiO3 (STO) nanospheres were prepared by facile hydrothermal process and later on thermal treatment was carried out at two distinct temperatures i.e., 300 °C (STO-300) and 600 °C (STO-600) to prepare hollow sphere structure with different porosity. Further surface functionalization with Pd nanoparticles (Pd-STO-600) enhanced the overall sensing performance of the STO hollow spheres towards ethanol. The superior hydrophobic property of STO hollow spheres was measured from surface wettability study, envisages outstanding anti-humidity results of the prepared samples to a wide range of humidity (20–80% RH). Apart from this, the Pd-STO-600 sensor exhibited a high response of 7040% ± 80 toward 50 ppm ethanol with excellent selectivity, rapid response/recovery (15 s/37 s), reversibility and long term stability at 150 °C operating temperature under 80% RH (generated at 35 °C). The sensors also exhibited a promising response towards sub-ppm level ethanol, regardless of humidity condition, that opens up new avenues for real-time sensing of VOCs in moistened ambient.