Activation Strategies for Enhancement the Catalytic Activity of Gold Nanocatalysts

Recent advances in nanoscience have led to the development of numerous methodologiesfor controlled synthesis of mono dispersed nanoparticles and/or nanoclusters via surface stabilization by organic capping ligands. The application of these nanoparticles in catalysis and other fields often requires the removal of organic ligands. It is known that the removal of organic capping agents or organic residues on gold nanoparticles is necessary for achieving high activity of the catalyst and should ensure the particle remains isolated on the surface without agglomeration. The nanoparticles are deposited on a support and the stabilizing ligands-capped metal particles are then removed to activate the catalyst because in the surface chemistry, clean metal surfaces are more active than “dirty” surfaces, which are passivated by organic fragments. There are many ways to activated supported noble metals particles or clusters like gold including washing procedure, heat treatment, combination of washing procedure and thermal treatment, plasma, ozonolysis and permanganate or even potassium manganite. The gold nanocatalysts activation helps to determine both the physical and chemical nature of the active species and can play an important role in controlling the activity and the selectivity of supported noble metals nanoparticles and nanoclusters.