Incorporation of dopants into the lattice of ZnO nanoparticles to control photoactivity

Using a similar production process, a series of doped and undoped ZnO nanoparticles has been tested for photoactivity, using chemical methods, when exposed to UV radiation. Parameters such as crystallite size, dopant type and concentration were considered. It was confirmed that photoactivity increased significantly by a factor of 2 to 3 as the mean crystallite size was decreased from 100 to 20 nm. Analysis of a further series of materials doped with metal cations showed that, depending on the dopant type and concentration, photoactivity could be reduced by more than an order of magnitude. A variant of the method of atom location by channelling-enhanced microanalysis (ALCHEMI) was applied to these crystal systems to determine whether or not dopant atoms at a concentration of less than 1 at.% were incorporated on the cation sublattice site within the nanoparticles. This technique is described and discussed in some detail.