Protonation of g-C3N4 and its temperature-sensing properties

Graphitic carbon nitride (g-C 3 N 4 ) was obtained through heat treatment of melamine and the g-C 3 N 4 flakers were then protonated with sulfuric acid. Their crystalline structure, microstructure, and optical properties were systematically studied. Our results show that protonation treatment did not change the crystal structure of g-C 3 N 4 but mitigated the agglomeration problem (i.e., decrease of the particle size), and resulted in certain degree of exfoliation. A blue shift in the ultraviolet–visible absorption measurement was observed. Temperature-dependent photoluminescence measurements were carried out on the protonated g-C 3 N 4 sample, where a linear temperature-dependent behavior was observed in a wide temperature range with a sensitivity of 0.83%K −1 . Our results showed that the protonated g-C 3 N 4 is a promising material for temperature sensors.