Abstract
One of the characteristics of molecular (and enzymatic) catalysts is that they are made up of a very limited number of metal atoms (usually just one), whereas solid catalysts are made up of a very large number of metal atoms. Recently, it has been shown that it is possible to synthesize heterogeneous catalysts containing isolated metal atoms within a solid matrix, usually carbonaceous, which obviously plays a very important role in the reactivity of these isolated sites. This structuring brings them close to molecular catalysts. What's more, these compounds appear to be endowed with specific catalytic properties that are currently the subject of a huge number of studies. These are the catalysts presented in this lecture. In particular, the following are discussed : (i) synthesis methods, which are delicate in the sense that the isolated sites must not be contaminated by small quantities of metal nanoparticles with different catalytic properties ; (ii) various methods for characterizing these isolated sites (microscopies, X-ray spectroscopy, etc.) ; (iii) recent studies aimed at characterizing their performance and catalytic specificities, in particular those of nickel- and cobalt-based compounds forCO2 reduction.
