S-scheme heterojunction ZnO/g-C3N4 shielding polyester fiber composites for the degradation of MB

Solar-driven nano-semiconductor catalysts have shown great potential in solving environmental pollution and energy issues. They convert solar energy into chemical energy, release strong oxidizing hydroxyl radicals (OH·), and thoroughly degrade organic pollutants. However, these photocatalysts in turn may also damage some organic carriers. Therefore, we have used graphite phase carbon nitride (g-C3N4) as the isolation layer to prevent the carrier polyester fiber (PET) from being oxidized by zinc oxide (ZnO). ZnO-g-C3N4@PET composite has been prepared by hydrothermal method, photoluminescence results indicated that ZnO-g-C3N4@PET has a low photo-generated charge recombination rate, while g-C3N4 improves the visible light response of the composite and exhibits an obvious photocatalytic enhancement effect. In the experiment of degrading methylene blue (MB), the degradation efficiency of ZnO-g-C3N4@PET composite has been significantly improved compared with ZnO@PET and g-C3N4@PET alone. In addition, the prepared photocatalyst also has good reusability and still maintains a high degradation rate after five cycles of tests. In the end, a possible mechanism and a pathway of photocatalytic degradation of MB were proposed. All in all, this is a feasible way to build a highly efficient, environmentally friendly and sustainable supported photocatalyst.