Wang, H.; Lichao, J.; Bogdanoff, P.; Fiechter, S.; Möhwald, H.; Shchukin, D.: Size-related native defect engineering in high intensity ultrasonication of nanoparticles for photoelectrochemical water splitting. Energy & Environmental Science 6 (2013), p. 799-804

Manipulation of electronic structures in nanostructured semiconductors is a key issue for improving their performance in optics, magnetics, electronics, and optoelectronics. We present in this paper that microscopically localized annealing by high intensity acoustic cavitation makes possible an interesting size-related native defect engineering in ZnO nanoparticles, which have been further adopted in photoelectrochemical (PEC) water splitting and achieved successfully tunable PEC performance. Since the critical particle size for nuclei of cavitation bubble is hundreds of nanometers, particle size dependent cavity nucleation is proposed for understanding the observed size-related variation of native defects. Furthermore, the tunable PEC performance can be explained by the sonication induced uctuation of shallow/deep energy level defect concentrations, which can be applied for designing future high performance PEC devices. We believe that the sonication induced native defect engineering presented in this study will provide a new alternative for improving semiconductor electronic structures and will advance the study of nanoparticle based PEC water splitting.