Design and fabrication of g-C3N4 nanosheets decorated TiO2 hybrid sensor films for improved performance towards CO2 gas

The g-C3N4 decorated titanium dioxide (TiO2) porous nanospheres composites thin films were successfully synthesized via a spray pyrolysis technique. The structural, morphological and textural properties of the fabricated thin film sensors were analyzed through X-ray diffraction (XRD), electron microscopy (SEM and TEM), Raman and N-2 adsorption-desorption analysis. The incorporation g-C3N4 in to TiO2 matrix was also confirmed through Energy dispersive spectra (EDS) and X-ray photoelectron microspore (XPS) analysis. Gas-sensing properties of the pure and g-C3N4/TiO2 hybrid thin film sensors were investigated towards H2S and CO2 gases with various ppm levels (0-1500). The results illustrates that 10 wt.% g-C3N4 decorated TiO2 composite film show outstanding sensing response (88%) and high stability (only loss 2.5% of its initial response value) towards CO2 gas at 1500 ppm (450 degrees C), which is comparatively high response towards H2S gas (67%) under same ppm level. The improved sensing response is due to the incorporated g-C3N4 could provide high conductivity, large surface area (108.5 m(2)/g) with porous nature (15.7 nm), which is consists of interconnection between g-C3N4 nanosheets and TiO2 spheres. The improved mechanism of the proposed sensor was also discussed in detail.