A unique 2D/2D g-C3N4/UiO-66 S-scheme nano-heterojunction was successfully developed via a straightforward hydrothermal approach to enhance the photocatalytic decomposition of organic contaminants under visible light. Comprehensive characterization techniques were employed to systematically examine the properties of the individual semiconductors and the newly synthesized heterostructure. PL, EIS and PR analyses confirmed that the photo-generated charge carries in 2D/2D nano-heterojunction/visible-light system have been efficiently separated. The improved photocatalytic performance could be ascribed to the strong contact between nanosheets of two semiconductors, uniform dispersion of UiO-66 nanosheets on the surface of large g-C3N4 nanosheets and synergistic effect of S-scheme electron-hole migration. The nano-heterojunction synthesized at the mass ratio of 0.2:1 of UiO-66 nanosheets to g-C3N4 nanosheets, g-C3N4/UiO-66/20, exhibited the highest MB photo-degradation rate (70.19% and 98.25% at catalyst dosages of 0.1 and 0.3 g/L, respectively), where the kinetic constant is 2.53 and 4.10 times of pristine g-C3N4 and UiO-66, respectively. Quenching experiments identified 〖.O〗_2^-, .OH and h^+ as the predominant active species, in descending order of importance. g-C3N4/UiO-66/20 nano-heterojunction indicated tremendous reusability and consistency, and it can be employed to successively uptake pollutant molecules from wastewater. This paper paves the way to construction of new visible-light driven 2D/2D nano-heterojunctions for the wastewater treatment process.
