Engineering exfoliated bentonite as a multifunctional matrix for g-C3N4/Ag3PO4 composites with enhanced adsorptive-photocatalytic performance

Visible-light-driven bentonite-based adsorptive–photocatalytic composites were successfully synthesized through bentonite exfoliation (EB), followed by in-situ crystallization and co-precipitation with g-C 3 N 4 and Ag 3 PO 4 (CN/AP). The effect of synthesis parameters, including pH (3, 8, 11) and hydrothermal temperature (100 and 200 °C), on structural evolution and photocatalytic performance was systematically investigated. Structural, morphological, and electronic properties were analyzed using XRD, FTIR-ATR, BET, DRS, SEM-EDS, TEM, TG-DTA, PL, XPS, EIS, and Mott-Schottky techniques. The results indicate significant structural improvement after composite formation, with the surface area increasing to 47.3 m 2 /g in EB/CN/AP11.200 (11 times higher than pristine EB) and band-gap narrowing to 2.62 eV in EB/CN/AP3.200. XPS analysis confirmed the successful formation of the CN/AP heterostructure and strong interfacial interactions within the EB-supported structure. Photocatalytic evaluation using Rhodamine B (RhB) and nitrogen oxides (NO x ) as model pollutants demonstrated superior bifunctional performance, achieving up to 98.85% RhB degradation with EB/CN/AP8.200 and approximately 20% de-NO x with EB/CN/AP3.200 under visible-light irradiation. Radical scavenging experiments identified photogenerated holes (h⁺) as the dominant reactive species. Reduced photoluminescence intensity and electrochemical analyses (EIS and Mott-Schottky) further confirmed improved charge separation and favorable band alignment in the composite system. The optimized composite maintained 81.35% of its RhB degradation efficiency after five cycles, indicating good stability. These results demonstrate the strong potential of EB/CN/AP composites for visible-light-driven environmental remediation in aqueous and gaseous systems. • Ternary structure enables dual adsorption-photocatalysis on modified bentonite. • Surface area increases 11 × to 47.3 m 2 /g, creating abundant active sites. • Controlled structure achieves 98.85% dye and 20% NO x degradation efficiency. • Composite remains stable and effective for dye removal over five reuse cycles.