Bi2O2CO3/ZnWO4 composite photocatalysts have been successfully synthesized by a mixed calcination method after hydrothermal process. The catalysts were characterized by powder x-ray diffraction, scanning electron microscopy, transmission electron microscopy, high resolution transmission electron microscopy, x-ray photoelectron spectroscopy, and UV-vis diffuse reflectance spectrum. The results showed that the hierarchical Bi2O2CO3/ZnWO4 nanocomposites were obtained by mixed grinding calcination method and Bi2O2CO3 nanospheres grow on the primary ZnWO4 particles. The Bi2O2CO3/ZnWO4 composites exhibit higher photocatalytic activities compared to pure ZnWO4 and Bi2O2CO3 particles under UV light irradiation. Furthermore, the excellent photocatalytic efficiency of the Bi2O2CO3/ZnWO4 composite was deduced closely related to Bi2O2CO3/ZnWO4 heterojunctions whose presence is generally regarded to be a favorable factor for the separation of photogenerated electrons and holes.

By controlling the morphology of organic and inorganic semiconductors on a molecular scale, nanoscale p–n junctions can be generated in a bulk composite. Such a composite is typically called a bulk heterojunction composite, which can be considered as one virtual semiconductor combining the electrical and optical properties of the individual components. Solar cells are one attractive application for bulk heterojunction composites. Conjugated polymers or oligomers are the favorite p-type semiconducting class for these composites, while for the n-type semiconductor, inorganic nanoparticles as well as organic molecules have been investigated. Due to the solubility of the individual components, printing techniques are used to fabricate them.