Fig. 1From: Hierarchical Heterostructure of ZnO@TiO2 Hollow Spheres for Highly Efficient Photocatalytic Hydrogen Evolution a A low-magnified SEM image of ZnO@TiO2 hollow spheres; the inset shows the statistical analysis of diameter distribution of the samples. b A high-magnified SEM image of a single broken ZnO@TiO2 sphereBack to article page