Abstract
NiO-loaded g-C₃N₄ photocatalysts (1.5–13.5 wt %) were successfully synthesized. • 5.5NiO/g-C₃N₄ achieved the highest activity with 98 % CR degradation in 1 h. • NiO incorporation shifted the CB from −0.58 V to −0.68 V, improving charge transfer. • Band gap decreased from 2.91 eV (GCN) to 2.80 eV (5.5NiO/GCN). • Co-contaminants (NaCl, Na₂SO₄) reduced degradation efficiency to 80-93 %. In this work, NiO with various mass percentages (1.5%, 3.5%, 5.5%, 7.5%, 9.5%, 13.5%) was loaded on GCN to improve the photocatalytic degradation of CR and BPA. Among all prepared samples, the 5.5NiO/GCN composite displayed the highest photocatalytic activity, achieving 98% degradation of CR and 91% degradation of BPA within 1 h. Mott-Schottky analysis revealed a conduction band potential of -0.58 V for pristine GCN and -0.68 V for the optimized 5.5NiO/GCN composite. Band gap energies obtained from the Tauc plot were 2.91 eV for GCN and 2.80 eV for 5.5NiO/GCN, confirming that NiO incorporation narrowed the band gap and enhanced photocatalytic properties. Furthermore, the influence of co-existing pollutants was also investigated. Inorganic salts (NaCl and Na₂SO₄) reduced degradation efficiencies to 93% for CR and 84% for BPA, whereas organic co-contaminants (PVA and acetone) decreased them to 80% and 77%, respectively, under identical conditions. Total organic carbon (TOC) analysis demonstrated 91% mineralization for CR and 87% for BPA over 1 h, indicating that the photocatalyst achieved significant mineralization, not just superficial degradation. Overall, these findings establish 5.5NiO/GCN as a highly efficient photocatalyst for both dye and organic pollutant removal and emphasize the critical role of co-contaminants in real wastewater scenarios. Download: Download high-res image (257KB) Download: Download full-size image