Mechanism of laser-induced bulk and surface defect generation in ZnO and TiO_2 nanoparticles: Effect on photoelectrochemical performance

Abstract

We prepd. 70 ZnO and TiO_2 materials to systematically study the effects of laser parameters and adsorbed gold nanoparticles and concomitant changes to bandgap, crystal structure, and bulk and surface defect densities on photocurrent generation of ZnO and TiO_2 photoanodes under simulated sunlight irradn. in neutral aq. electrolytes. We obsd. unambiguous color changes of the ZnO and TiO_2 nanoparticles as a function of laser irradn. and/or AuNP functionalization and were interested in (1) the phys. origin of the individual colors, and (2) a correlation with photoelectrochem. performance. Two-dimensional photoluminescence data allowed us to ext. the effects of surface vs. bulk defects. We obtained key insights about the defect types and mechanisms that laser processing generated and how they affect photoelectrochem. performance.