Czech Republic;
708 00 Ostrava-Poruba;
17. listopadu 2172/15;
Palacky University;
783 71;
Slechtiteki 27;
Czech Republic ||Department of Chemistry and Physico-Chemical Processes;
Czech Republic ||Institute of Environmental Technology;
Centre for Advanced Innovation Technologies;
Faculty of Materials Science and Technology;
VSB - Technical University of Ostrava;
Olonwuc;
Department of Chemistry and Physico-Chemical Processes;
VSB-Technical University of Ostrava;
Nanotechnology Centre;
Centre for Energy and Environmental Technologies;
17. Ustopadu 2172/15;
Regional Centre of Advanced Technologies and Materials;
Faculty of Science;
The previous studies on K-doped g-C_3N_4 suggest a simple correlation between the increased potassium content and the improved photocatalytic activity due to a shift of the valence band potential to more positive values, leading to the direct oxidation of hydroxyl ions to hydroxyl radicals by holes. In this study, we investigated the influence of different potassium precursors on the properties and photocatalytic efficiency of K-modified g-C_3N_4 materials in Rhodamine B degradation. Detailed characterization revealed that the choice of precursor significantly affects the structural and optoelectronic properties with complex correlations rather than superficial relationships between potassium content and photocatalytic activity. Notably, KCl-based samples, despite having a lower specific surface area, exhibited enhanced photocatalytic properties due to prolonged carrier lifetimes and improved charge transfer efficiency compared to KOH-based samples. Higher precursor concentrations resulted in more recombination centers, increasing Urbach energy and reducing photocatalytic activity. These findings underscore the importance of precise synthesis control, revealing that both K and Cl atoms act as charge transfer bridges, improving the material's photocatalytic properties beyond mere surface area enhancement. In addition, even smaller amounts of Cl atoms in g-C_3N_4 showed much higher impact on the final position of conduction and valence band potentials than K atoms.