Bulk materials synthesis metal colloids

Whichever method is followed, a protective agent able to induce a repulsive force opposed to the van der Waals forces is generally necessary to prevent agglomeration of the formed particles and their coalescence into bulk material. Since aggregation leads to the loss of the properties associated with the colloidal state, stabilization of metallic colloids - and therefore the means to preserve their finely dispersed state - is a cmcial aspect for consideration during their synthesis. 

Usually there is a lot of effort required to make nanomaterials by electrochemical means. In aqueous solutions the electrodeposition of nanocrystalline metals requires pulsed electrodeposition and the addition of additives whose reaction mechanism hitherto has only been partly understood (see Chapter 8). A further shortcoming is that usually a compact bulk material is obtained instead of isolated particles. The chemical synthesis of metal or metal oxide nanoparticles in aqueous or organic solutions by colloidal chemistry, for example, also requires additives and often the desired product is only obtained under quite limited chemical conditions. Changing one parameter can lead to a different product. 

Thus the first section to follow pertains to the synthesis of bulk materials including amorphous and mesoporous oxide supports (chapters 1 ), heteropolyacids (chapter 5), and colloidal metals (chapter 6). The second section covers the synthesis of heterogeneous materials, and has been divided into syntheses in nanoscale domains (chapters 7-10) and those based on two-dimensional metal complex-substrate interactions (chapters 11-14), or a clever way around noninteracting precursors via viscous drying (chapter 15). Effects of drying (chapter 16) and pretreatment (chapter 17) comprise the third section of the book. 

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