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

In this work, the photo-responsive behaviour of SnO 2 decorated CdO heterostructures-based CO 2 sensor was investigated in irradiation of light. The SnO 2 @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 SnO 2 nanospheres decorated on CdO nanocubes can be observed. The SnO 2 decorated CdO heterostructure detects the CO 2 gas at room temperature. In dark condition, the CO 2 sensing of SnO 2 @CdO heterostructure was poorly observed, although in illumination of visible light the sensing performance were enhanced. The sensor response of SnO 2 @CdO heterostructure in dark and illumination were found to 4.65 and 10.67 respectively at 1400 ppm of CO 2 . 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 SnO 2 @CdO heterostructured film. In this work, SnO 2 decorated CdO heterostructured-based light-induced CO 2 gas sensor has been reported for the first time. Also, the DFT has performed on the optimized SnO 2 @CdO nanocomposite without and with CO 2 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.