Over the last two decades, preparations of nanoparticles have advanced from simple shape and size control of single component materials, to the more recent developments of binary and hybrid nanoparticles containing two or more disparate materials.
It is an exciting period in the study of nanomaterials and nanoparticles; we are at the cusp of being able to design nanoparticles with a specific function and application in mind and synthesize them. And it is through the process of striving for these grand goals that we learn more about growth behavior and can then build nanoparticles with increasing complexity.
Nanoparticles have several distinct characteristics and advantages that make them potentially revolutionary materials in applications such as clean energy, medical diagnostics, drug delivery, chemical manufacture, environmental remediation of pollutants and opto-electronics.
As chemists, the Macdonald group is interested in the synthesis of nanoparticles in order to harness their large surface area for enhanced reactivity and size-dependent light absorption for solar energy applications. The Macdonald group re-explores long ignored materials as nanoparticles, studies their size and shape dependent reactivity and uses their previously un-tapped catalytic potential as electrocatalysts with applications in solar cells and sensors.
Re-exploring lost materials
Some materials considered inert at the bulk scale have been shown to be highly catalytically active at the nanoscale. The key is the enhanced reactivity of nanoparticles due to their large surface area to volume ratio. Whereas an iron thumb tack presents perhaps a postage stamp worth of surface area, the same weight in iron nanoparticles has a total surface area added up to that of a football field. Consequently reactions at surfaces, of which many catalytic processes are, are greatly enhanced.
Unexpectedly enhanced reactivity has been shown in particular for the metal oxides and sulfides, many of which are considered “poisoned” or inactive at the bulk scale but highly active when in the nanoscale.
Solar energy capture
The second main interest of our group is the study of semiconductor hybrid nanoparticles for solar energy applications. Under illumination, these multi-component nanoparticles undergo charge separation, the basic requirement for light harvesting technologies such as photovoltaics and photocatalysis.
The interest in the Macdonald group is to develop syntheses of hybrid nanoparticles in new material combinations and to understand and exploit their growth behaviour to prepare novel and functional structures. We study the optical and electronic properties of these new nanoparticles and their use as catalysts and photocatalysts. Our ultimate goal is the efficient capture of sunlight for sustainable energy applications such as hydrogen gas production from water splitting and photovoltaic cells.