Synergistic charge separation via S-scheme and Schottky junctions in Ni-decorated melem hydrate/g-C3N5 for enhanced photocatalytic tetracycline hydrochloride degradation

Abstract

Interface engineering plays pivotal role in enhancing the photocatalytic degradation efficiency of organic pollutants using solar irradiation. In this study, we report the design and fabrication of a dual heterojunction S-scheme/Schottky photocatalyst, Ni-decorated melem hydrate/g-C₃N₅, via a straightforward photodeposition method. Experimental investigations demonstrated that the introduction of Ni nanoparticles significantly enhanced both light-harvesting capability and photocatalytic efficiency toward tetracycline hydrochloride (TCH) degradation. The optimized ternary composite achieved ~ 98% removal efficiency, whereas the pristine melem hydrate/g-C₃N₅ achieved only ~ 61%. This remarkable enhancement is attributed to the synergistic effect of the S-scheme and Schottky heterojunction, which promotes efficient charge separation and provides additional active sites for photocatalytic reactions. The proposed S-scheme/Schottky charge transfer mechanism was elucidated through trapping experiments and X-ray photoelectron spectroscopy analysis. Furthermore, possible TCH degradation pathways were proposed based on the identification of intermediate species formed during the photocatalytic process. This study highlights a promising approach for the rational design of advanced S-scheme/Schottky hybrid photocatalysts, offering an effective strategy for the photocatalytic treatment of antibiotic contaminants and other organic pollutants.

Graphical abstract