Boosting photocatalytic performance in Cu doped ZnO nanocomposites : Investigation of Exciton-free carrier conversion and oxygen vacancy dynamics.

The production of photocatalytic materials with strong light absorption ability and high quantum efficiency by simple means is a long-term goal of photocatalytic technology. In this work, we have synthesized Cu doped ZnO nanoparticles by a facile sol-gel method. By introducing Cu impurities, it is shown that the excitons in ZnO have been efficiently separated into free carriers, leading to optimized photocatalytic performance. The surface amorphous layers of the nanoparticles grew thicker at the introduction of Cu atoms into ZnO lattice, which boosted the photocatalytic ability due to the increase of surface oxygen vacancy concentration. This finding provides a direct evidence of quasi-particle-free carrier conversion in Cu doped ZnO, as well as a guidance for fabricating high efficiency ZnO based nano-photocatalysts.