1：Experimental Design and Method Selection:

The study involved a facile, template-free synthesis of S-doped g-C3N4 pinhole nanosheets (SCNPNS) using urea and thiourea precursors, characterized by various analytical techniques to confirm structure and properties.

2：Sample Selection and Data Sources:

Samples were synthesized and tested for fluorescence sensing and photocatalytic degradation using standard metal ions and dyes.

3：List of Experimental Equipment and Materials:

Equipment included XRD (Rigaku D/max-2200pc), TEM (Tecnai G2mF30 S-Twin), FT-IR (Bruker Vertex 70), BET (Micromeritics ASAP-2010), XPS (ESCALAB220i), UV–vis spectrophotometer (Varian Cary 100), fluoroluminescence spectrometer (Quanta Master), zeta-potential analyzer (ELSZ-2000), and others. Materials included urea, thiourea, various metal salts, and dyes from Sigma Aldrich.

4：Experimental Procedures and Operational Workflow:

Synthesis involved heating urea and thiourea at 520°C, followed by dispersion and centrifugation. Fluorescence sensing was performed by adding metal ions to SCNPNS solution and measuring fluorescence. Photocatalysis involved dispersing SCNPNS in dye solutions under visible light and monitoring degradation.

5：Data Analysis Methods:

Data were analyzed using UV–vis spectroscopy, fluorescence measurements, kinetic models (pseudo-first-order), and statistical methods for LOD calculation.