Hydrothermally Synthesized ZnSnO3 Nanoflakes Based Low-Cost Sensing Device for High Performance CO2 Monitoring

Abstract

This work reports a room temperature operative ZnSnO _3 nanoflakes-based CO _2 gas sensor. The perovskite ZnSnO _3 nanoflakes are synthesized by a one-pot hydrothermal technique. The prepared material was characterized via XRD, SEM, UV-visible spectroscopy, and DLS measurement for confirming the crystal structure, surface morphology, optical properties, and size distribution. The X-ray diffraction pattern revealed that ZnSnO _3 was in the orthorhombic phase and average crystallite size examined by the Scherrer formula was 8.05 nm. Optical studies were done by the UV–vis spectroscopy and a direct optical band gap was found to be 3.27 eV. The surface morphology of ZnSnO _3 was found to nanoflakes are almost uniform dimensions. The fabricated sensor device of ZnSnO _3 detected the CO _2 gas at room temperature (RT) for different concentrations. The best sensor response was found to be 4.93 for 1000 ppm of CO _2 whereas at 200 ppm the response and recovery times were found to be 5.92 s and 7.23 s respectively. HOMO-LUMO gap energy of ZnSnO _3 without and with interaction from CO _2 molecule was found 1.165 eV and 1.577 eV, respectively. DFT studies are used for a better understanding of sensing mechanisms.