A photocatalytic system designed based on heterojunction formation can be successful in the degradation of pollutants by separating and transporting charge carriers. For this purpose, high performance g-C3N4-nanosheets/Ni3V2O8 n-p heterojunction with different weight percentages of Ni3V2O8 was achieved by calcination-hydrothermal method. Various descriptive properties including morphology, crystallinity, functional groups, optical interaction, elemental composition, electron-hole separation, and energy band structure were analyzed by SEM, TEM, HRTEM, XRD, FT-IR, UV-vis DRS, EDX, XPS, PL, EIS, photocurrent, and Mott-Schottky. Photocatalytic tests were performed by degrading tetracycline in the visible spectrum. The best efficiency is attributed to the g-C3N4-nanosheets/Ni3V2O8 (30%) nanocomposite, which can degrade 97.5% of tetracycline within 40 min. The results show that n-p heterojunction formation with improving the separation and migration of charge carriers led to an increase in photocatalytic activity compared to g-C3N4-nanosheets and Ni3V2O8. The obtained nanocomposite was recycled 4 times without significant loss of photocatalytic performance, which is a confirmation of the high stability of the photocatalyst. The results of trapping experiments and Mott-Schottky analysis were used to propose a possible mechanism by combining g-C3N4-nanosheets and Ni3V2O8 components with matching energy band structures. This paper presents an idea for fabricating g-C3N4-nanosheets-based heterogeneous photocatalysts for tetracycline degradation using visible spectrum light
