Study on surface sensitization of g-C3N4 by functioned different aggregation behavior porphyrin and its optical properties

Tetracarboxyl-phenyl porphyrin (TCPP) hybridized graphitic carbon nitride (g-C3N4) composites have been facilely synthesized through grinding method and ethanol dispersion. TCPP molecules as a sensitizer could easily assemble on the surface of g-C3N4 nanosheets mainly through π–π stacking interaction. The TCPP-g-C3N4 composite is employed to optical waveguide (OWG) gas sensor, and its aggregation behaviors in different pH condition are studied by UV–vis spectroscopy and the corresponding morphologies are observed by SEM. It is found that the TCPP-g-C3N4 film under basic condition (pH = 11), where TCPP formed H - type aggregation on the film surface, has fine response to SO2 (0.1–100 ppm) and H2S (1–100 ppm). The gas-sensitive mechanism is protonation and deprotonation process, in terms of UV–vis spectroscopy.