The effect of Ag loading on gas sensor properties of TiO2 nanorods

Highlights: • Ag loaded TiO₂ nanorods were fabricated by hydrothermal and thermal evaporation. • Ag loading enhanced the sensing performance of TiO₂ nanorods. • Functionalized sensors showed selective behavior against acetone at 100°C. • Ag loading exhibited superior acetone sensitivity at 200°C. • Gas sensing performance was discussed with X-ray photoelectron spectroscopy. In this work, volatile organic compounds gas sensing properties of Ag loaded n-type TiO₂ nanorods (NRs) were investigated. TiO₂ NRs were grown by facile and cost-effective seed mediated hydrothermal process on alumina substrates. Ag loading on TiO₂ NRs was performed by thermal evaporation technique with three evaporation durations (30, 45, and 90 s). Morphological and structural characterizations were carried out by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy (XPS). Sensor characteristics of pristine and Ag loaded TiO₂ NRs were investigated for the detection of acetone, ethanol, hydrogen cyanide, and hydrogen sulfide gases. The gas sensing mechanism highlighting the enhanced sensitivity to acetone with Ag loading is discussed in correlation with detailed XPS studies. Gas sensing measurements show that the Ag loading substantially enhanced the sensitivity and selectivity against acetone. Also, the catalytic effect of Ag on TiO₂ NRs surface reduced the operating temperature. Ag loaded TiO₂ NRs sensor offered a sensor response for 65 ppb (particle per billion) acetone while there was not any observed response for pristine TiO₂ NRs at optimal operating temperature (200^C). Moreover, Ag loaded TiO₂ NRs provided highly selective and sensitive acetone sensing performance at 100^C.