Colloidal Nanometals as Fuel Cell Catalyst Precursors
Read full article onlineFull Article
The goal of this article is to highlight the incentives and methods that are typically used for using nanomaterials as precursors of fuel cell catalysts. Our “precursor” concept for the manufacturing of heterogeneous metal colloid catalysts was developed in the last decade. This method facilitates ready accessibility to homogeneous alloys, segregated alloys, layered bimetallics, or “decorated” metal particles and because of which it is now possible to tailor the precursor metallic colloids with controlled structures and metal interfaces. The advantage here is one can preprepare and thoroughly characterize active components of the electrocatalysts using modern analytical tools.
Nanostructured metal particles were considered potential catalysts essentially because of their unique electronic structures combined with extremely large surface areas. In general, isolable particles between 1 and 50 nm that are prevented from agglomeration by protective shells are termed “nanostructured metal colloids.” These colloids can be redispersed in both water (“hydrosols”) and organic solvents (“organosols”) depending on the nature of the protecting shell used. A wealth of knowledge has been acquired about these materials over the past decades. Highly dispersed mono- and bimetallic colloids have been used as precursors for a variety of catalysts applicable in chemical catalysis. This contribution, however, will deal only with those applications significant to fuel cell technology.