Active Sites in Carbocatalysis: Tuning Their Activity

Carbocatalysis, i.e., catalysis by metal-free carbon-based materials, has recently emerged as a “green” alternative for several thermal-, electric-, and solar-driven chemical processes in the gas phase and in the liquid phase. Indeed, and in addition to their more common role as a catalyst support, carbon materials can promote a large variety of reactions, replacing metal or metal oxide catalysts. However, the active sites are seldom identified and properly quantified, making it impossible to calculate turnover frequencies to benchmark the novel metal-free catalysts with those traditionally used. In order to advance the field, it is essential to correlate the catalytic properties of the carbon materials with their surface chemistry. In this work, we review a small selection of reactions catalyzed by metal-free carbon materials, emphasizing synthesis methodologies and characterization techniques used to identify the active sites, where relevant structure-activity relationships could be established.