Doped Gs. Properties and Interest in Catalysis

In this sense, XPS provides information not only on the total content of the dopant element, but also on the different types of families of the dopant elements, depending on the position of the element on the G sheet and on the coordination sphere. Typically, experimental XPS peaks for a dopant element are broad and with different shapes. By deconvolution of the experimental peak in much narrower components corresponding to 

From the catalytic point of view, it is relevant not only the presence of dopant elements but also their distribution in different famihes. For instance, for certain reaction such as the aerobic oxidation of benzyl alcohol a linear correlation between the population of graphenic N with the catalytic activity has been foimd [15]. Apparently, the other types of 

N atoms do not correlate with the catalytic activity. This experimental linear relationship has been taken as evidence in support that the active sites are not really any type of nitrogen, but only those nitrogens on gra-phenic positions. 

One problem related with doping in catalysis is stability of the material, meaning that doped G should not xmdergo any variation during the catalytic cycle. It is very common that since the dopant element is involved in the catalysis, a proportion of it can become detached from the G and can be transformed into a different species. This leaching of the dopant element due to the instability of the doped G in the catalysis can be a cause of deactivation of the material upon recycling of the catalyst. 

Besides doping, co-doping in where two or more elements are present on the G sheet is also interesting from the point of view of using Gs as catalysts. One case that could be of interest is the presence of electron deficient atoms such as B and heteroatoms with excess of electrons such as N. In a certain way the simultaneous presence of B and N could be similar to the introduction of acid and basic Lewis sites. The concept of bifunctional acid-base solid catalyst has found wide application in heterogeneous catalysis of solids such as aluminophosphates containing NH groups (ALPONs) due to the cooperative activity of both sites in the reaction mechanism. 

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