LAUSR

Abstract Graphitic carbon nitride (g-C3N4) is an interesting material used for fluorescence sensing of metal ions due to its high photoluminescence response, chemical and thermal stability as well as low toxicity. In this work, we report the fluorescence sensing of Fe3+ ions by using g-C3N4 synthesized by thermal polycondensation of nitrogen-rich precursors such as melamine and urea, without any additional chemical treatment. Furthermore, the influence of these commercial precursors on the chemical structure and optical properties of g-C3N4 has been investigated in detail. The XRD, FTIR, DRS, SEM, TEM, elemental analysis and XPS characterization techniques have confirmed that the synthesis of g-C3N4 from urea precursor yields an exfoliated material with lower condensation degree than the material synthesized from melamine, but a low photoluminescence (PL) emission. In contrast, the use of melamine as precursor produces well-condensed g-C3N4 sheets, favoring the σ* to nitrogen lone-pair state transition in the obtained material, which is involved in the fluorescence sensing of the metal ions. In this sense, the g-C3N4 synthesized from melamine showed a good linearity over the Fe3+ concentration range from 0 to 100 μM and a limit of detection of 8.7 μM.