Under UV–vis light irradiation, the degradation curves of dye
MB using ZnO, Cu2O and ZnO/Cu2O CSNCs as photocatalysts are
shown in Fig. 4a. ZnO/Cu2O CSNCs evidently demonstrates the
highest photocatalytic activity, compared with pure ZnO and pure
Cu2O. It could be deduced that the high photocatalytic activity of
ZnO/Cu2O CSNCs was due to the special n-ZnO/p-Cu2O core-shell
structure which easily forms a p-n heterojunction. The p-Cu2O/n-