Photo-responsive highly sensitive CO2 gas sensor based on SnO2@CdO heterostructures with DFT calculations

Abstract

In this work, the photo-responsive behaviour of SnO2 decorated CdO heterostructures-based CO2 sensor was investigated in irradiation of light. The SnO2@CdO heterostructures were synthesized by a hydrothermal process. The crystal structure, surface morphology, composition, and optical properties of as-synthesized materials were examined by XRD, Raman, FESEM, EDS, HRTEM, XPS, and UV-Vis analyses. From the FESEM and TEM analysis, the SnO2 nanospheres decorated on CdO nanocubes can be observed. The SnO2 decorated CdO heterostructure detects the CO2 gas at room temperature. In dark condition, the CO2 sensing of SnO2@CdO heterostructure was poorly observed, although in illumination of visible light the sensing performance were enhanced. The sensor response of SnO2@CdO heterostructure in dark and illumination were found to 4.65 and 10.67 respectively at 1400 ppm of CO2. Whereas for 200 ppm the sensor response was found to 4.20 with 4 and 6 s response and recovery times. Since in illumination of light, the photo-generated carriers are suggested to be responsible for the enhancement of the sensing characteristics of SnO2@CdO heterostructured film. In this work, SnO2 decorated CdO heterostructured-based light-induced CO2 gas sensor has been reported for the first time. Also, the DFT has performed on the optimized SnO2@CdO nanocomposite without and with CO2 interaction. Some electronic parameters like band gap, electron affinity, and ionization potential were calculated for optimized composite and suggested for better understanding of the sensing phenomenon.