A new type of p-type NiO/n-type ZnO nano-heterojunctions with enhanced photocatalytic activity

A new type of NiO/ZnO nano-heterojunction was developed by the template-assisted approach. The p–n nano-heterojunctions were formed between the NiO and ZnO nanoparticles in the ultrathin shell of the NiO/ZnO hollow nanospheres. The grain size of the NiO/ZnO nano-heterojunctions is in the 10 nm scale, and the specific surface area is higher than 100 m2 g−1. Moreover, the ultrathin shell makes the distribution of the NiO/ZnO nano-heterojunctions to arrange in a single-layer structure rather than a stacking arrangement. Therefore, this new type of the NiO/ZnO nano-heterojunctions could almost completely separate the electron and hole to the surface rather than being wasted in the materials. As a result, the photocatalytic activity of the p-type NiO/n-type ZnO nano-heterojunctions for the degradation of rhodamine B (RhB) was much higher than that of ZnO. In particular, the p-type NiO/n-type ZnO hollow nanospheres with different Ni/Zn molar ratios exhibited diverse catalytic activity, the mechanism of which has been discussed in detail.