Zn2+-decorated porous g-C3N4 with nitrogen vacancies: Synthesis, enhanced photocatalytic performance and mechanism in degrading organic contaminants

Photocatalytic degradation is an effective and challenging strategy in purifying wastewaters containing organic pollutants. Thus, developing a suitable photocatalyst and clarifying the degradation mechanism are extremely worthwhile. In this work, Zn²⁺-decorated porous g-C₃N₄ with nitrogen vacancies (g-C₃N_4-δ) is prepared with the facile sonication-calcination method. Benefitting from the modified geometric structure and electronic properties, compared with g-C₃N_4-δ, the resulting composites deliver reduced micropore percentage, enhanced separation and migration of photogenerated carriers, narrowed band gap, and improved reducing capacity of photoinduced electrons, favoring the photocatalytic reaction. Particularly, Zn²⁺(2)-g-C₃N_4-δ (10 mg) displays the highest photocatalytic activity toward eliminating tetracycline (TC, 10 mg L^-1, 50 mL), and the degradation efficiency (63.9%) within 30 min is 3.4 times that of g-C₃N_4-δ (18.9%) irradiated by visible light. Moreover, the optimal composite demonstrates satisfactory recyclability and excellent universality. This study suggests a novel way to construct g-C₃N₄-based photocatalysts for efficiently degrading organic contaminants in water.