Catalysis by hybrid sp2/sp3 nanodiamonds and their role in the design of advanced nanocarbon materials

Hybrid sp2/sp3 nanocarbons, in particular sp3-hybridized ultra-dispersed nanodiamonds and deriv. materials, such as the sp3/sp2-hybridized bucky nanodiamonds and sp2-hybridized onion-like carbons, represent a rather interesting class of catalysts still under consideration. Their characteristics, properties and catalytic reactivity are presented, with an anal. of the state-of-the-art of their use in gas- and liq.-phase reactions, including photo- and electro-catalysis. It is remarked that intrinsic differences exist between these and other nanostructured carbon catalysts. The anal. shows how different features make nanocarbons unique with respect to other types of catalysts and are the bases for an advanced design of nanocarbon-type catalysts. The aspects discussed regard the presence of hybrid sp2/sp3 configurations, nano-engineering related to the role of defects and vacancies in their catalytic behavior, the creation of active sites by modification in the charge d. at carbon atoms or C-C bonds, the generation of strained C-C bonds by curvature and other mechanisms, and the formation of semiconducting areas and defect sites at the interface with supported nanoparticles. The advanced strategies for identifying and quantifying active sites of carbon catalysts are highlighted. [on SciFinder(R)]