Catalytic Properties of Nitrogen‐Containing Carbons

Tuning CNT Properties for Metal-Free Environmental Catalytic Applications

“…Considering that CNTs present a non-microporous Figure 1. Oxygen, nitrogen and sulfur surface groups incorporated on carbon nanotubes (CNTs) by post-synthesis treatments, and techniques for their identification/quantification [9][10][11][12][13][14][15][16][17].…”

“…The exceptional electronic properties and catalytic performances of N-doped carbon nanotubes are attracting much interest [11,25,40,41]. The incorporation of nitrogen atoms onto the carbon structure is relatively easy due to the similar sizes of the nitrogen and carbon atoms [42,43], providing additional electrons for the graphitic lattice [44].…”

“…Regarding post-treatments, the incorporation of nitrogen can be achieved either by treating the carbon materials with ammonia or using nitrogen-containing carbon precursors, such as urea, melamine, polyacrylonitriles, polyvinylpyridine, and quinoline-containing pitch [31,46,47]. Generally, the incorporation of pyridinic-like (N-6), pyrrolic-like (N-5), and graphitic-like (N-Q) structures enhances the basicity of the CNTs [10,11,48,49].…”

“…The modification of metal-free carbon materials by tailoring textural and surface chemical properties can play an important role in their catalytic performance; in particular, N-doping was demonstrated to increase the activity of carbon catalysts in oxidation reactions [11,31,51,52,56,85,86]. Regarding the use of N-doped CNTs in oxalic acid oxidation by CWAO, CNTs modified with nitric acid, urea and gas-phase thermal treatment showed the highest basic character and also the highest catalytic activity, but the performance is similar to that observed with the original CNTs after cyclic runs [31].…”

“…Compared to traditional catalysts (noble metals or metal oxides), the N-species are well anchored into the catalyst structure and, as a result, the drawbacks related to loss of active phase are improbable to occur even under severe reaction conditions [45]; in addition, the stability and electron transfer rate are improved, leading to a higher durability of the catalysts during the catalytic processes [11,87]. transfer rate are improved, leading to a higher durability of the catalysts during the catalytic processes [11,87]. Besides all the research studies already published regarding the kind of functionalities on CNTs that allow high activity and stability of metal-free CNTs on CWAO and COZ, the reaction pathways involved in those reactions are still in doubt.…”