Improved photocatalytic activity for water splitting over MFe2O4-ZnO (M = Cu and Ni) type-II heterostructures

Novel heterostructures based on spinel-structured ferrites (CuFe2O4 and NiFe2O4) coupled to ZnO were prepared to enhance the photocatalytic activity of the pure materials for hydrogen evolution from water splitting. The loading of ZnO played a determinant role in the enhancement of the photocatalytic activity, being 3% the optimal amount. The heterostructures exhibited suitable photocatalytic activity and stability under UV light. The catalytic activity of CuFe2O4-ZnO 3% was 1.3 times higher than the activity of CuFe2O4, while the performance of NiFe2O4-ZnO3% was 1.6 times higher than NiFe2O4. This improvement in the activity was attributed to an appropriate coupling of the electronic bands of the semiconductors to form the heterostructure, allowing enhanced charge transference in the interface of the semiconductors and a reduction in the recombination, which lead to a higher photocatalytic activity.