Nanostructural evolution of hydrothermally grown SrTiO₃ perovskite and its implementation in gaseous phase detection of ethanol

Abstract

A group of SrTiO3 nanostructures with unique nano-architecture have been synthesized in the current study. Sol-gel derived TiO2 nanoparticles along with Sr(OH)2 solution was processed with facial hydrothermal reaction at 180⁰C and highly stable and distinct morphologies of SrTiO3 were developed after different reaction time. Nanobush, nanograss, nanorod and nanosphere morphologies were created after 10, 14, 18 and 24 h of hydrothermal reaction. SrTiO3 nanosphere was transformed into nano-hollow sphere morphology after thermal annealing at 600 ⁰C. Detailed morphological, structural and chemical characterizations were carried out for all the distinct nanoforms of SrTiO3 where they exhibited high crystallinity, chemical stability along with excellent surface properties like high porosity, roughness, and large effective surface area. Due to having rich surface properties, all the SrTiO3 morphologies were then implemented for gaseous phase detection of multiple volatile organic compounds (VOCs). However, all the SrTiO3 nanoforms showed ethanol selective behavior among all the VOCs. Nanograss and nano-hollow spheres exhibited excellent ethanol sensing with 69 and 78 response value (Rv/Ra) in 50 ppm ethanol at 150 °C with appreciably fast response/recovery time of 36 s/34 s and 150 s/ 58 s, respectively. Additionally, all the SrTiO3 nanostructures exhibited anti-humidity characteristics and potential sensing in humid ambient (up to 80% RH). Later, the ethanol selective behavior of SrTiO3 was established by density functional theory (DFT) simulations which envisaged the highest negative adsorption energy and smallest distance (r) for ethanol molecule, implying stable adsorption with SrTiO3 (110) system.