Designing ZnO-based nano-composites at nanoscale for multifunctional applications

Zinc oxide (ZnO) is unquestionably one of the best known materials for multifunctional nanotechnology development because it is characterized by a large number of interesting end useful physical properties, making it strongly appealing for different applications like optoelectronics, transparent electronics, piezoelectric devices, sensing or catalysis. However, the unique properties of ZnO nanostructures can be further extended by functionalizing their surfaces with different nanostructures, creating active composite nanostructures with properties that combine those of the two or more component with new ones emerging from the formation of new heterostructures or interfaces. In this work authors present an overview on different kinds of surface functionalizations of ZnO nanostructures synthesized in our laboratories, with inorganic and organic semiconductor, super-paramagnetic iron oxide nanoparticles and noble metals by different physical or chemical techniques. Clear enhancements or modifications in their surface reactivity, light absorption, magnetic or other peculiar properties have been obtained. Some examples for gas sensing application, photocatalytic degradation of water pollutants and some new ideas for complex geometries in hybrid photovoltaic applications are presented as case studies in order to show the high potential of this kind of approach.