Ultrahigh photoactivity of ZnO nanoparticles for decomposition of high‑concentration microcystin‑LR in water environment

Use of highly photoactive materials is critical for applicability of photocatalysis in large-scale water treatment facilities. Unfortunately, in a real setting, the performance of existing photocatalysts is not as good as expected. Therefore, finding a truly photoactive material is of great importance. Herein, ZnO nanoparticles prepared through a simple solid-state route at moderate temperatures in the absence of oxygen are demonstrated to be a suitable option for environmental photocatalysis. Within only 8 min of UVA irradiation at pH 6, the degradation efficiency for 2 mg/L of microcystin-LR using 0.5 g/L of ZnO synthesized at 350°C reaches as high as 97%. Hydroxyl radicals and valence band holes are found to be responsible for such a high degradation of microcystin-LR. The photocatalytic activity can also be maintained after six successive uses.