CO2 gas sensing properties of graphitic carbon nitride (g-C3N4) thin films

In this work, thin films of graphitic carbon nitride (g-C3N4) obtained at different thermal oxidation temperatures were studied for CO2 sensing abilities. Polycondensation of melamine , simultaneous thermal oxidation were employed to obtain bulk and exfoliated g-C3N4 respectively. Thin films of g-C3N4 for CO2 gas sensing studies were developed by drop casting method. XRD confirms the g-C3N4 structure with specialIntscript preferential orientation and the exfoliation of g-C3N4 was evidenced with the corresponding peak shift. FTIR analysis demonstrated the presence of higher number of amino group functionalization resulted from the exfoliation. 2D lamellar structures resulted from thermal oxidation possess high surface area, pore size and pore volume compared to bulk g-C3N4. Upon exfoliation, a nearly two-fold increase in the Carbon dioxide (CO2) gas sensing response was observed. Highly exfoliated g-C3N4 based sensor registered 80 and 60 s response and recovery times, respectively. CO2 gas sensing mechanism of g-C3N4 sensors was proposed based on the obtained structural and morphological char-acteristics. Considering the results obtained in this study such as high sensing response, stability , good repeatability, g-C3N4 in its exfoliated form will be a competitive candidate for future CO2 sensor applications.