LAUSR

Abstract A solid fluorescence sensor composed of g-C3N4 nanosheets and chitosan solid film was fabricated by electrostatic interaction. The g-C3N4 nanosheet/chitosan solid film showed selectivity and sensitivity to Cu2+ which was higher than that of other metal ions in common use. Cu2+ ions were found to efficiently bind and quench the fluorescence of the g-C3N4 nanosheet/chitosan solid film. The absorption band of the g-C3N4 nanosheet/chitosan solid film was at 240 nm in the presence of Cu2+, and the maximum emission peak was at 380 nm. Copper ion concentrations were between 0 and 3.1 × 10−5 mol/L at pH 7, the detection limit is 5 nM, compared with previous reports, it was much lower than before. Good linear relationships existed between the metal ion concentration and fluorescence intensity of g-C3N4 nanosheets in the quenching and recovering processes. This is the first study to report on the detection of Cu2+ by utilizing g-C3N4 nanosheet/chitosan composite film. The as-prepared films were conveniently prepared, easy to operate, and recyclable, as well as sensitive and selective to detect Cu2+ in water. All these features indicate the sensor’s potential application in disease diagnosis.