Catalysis with carbon nanoparticles

Abstract

Carbon nanoparticles (CNPs) represent a recent class of nanomaterials, based on carbon sp² atoms in the inner core. These new nano-dots cover a wide range of application fields: analytical, sensing and biosensing, bioimaging, theranostic, and molecular communication. However, their use as nanocatalysts is relatively new. Although CNPs can be easily synthesized and obtained in good amounts, few reports on their catalytic applications have been reported. This minireview collects the use of these nanoparticles as catalysts highlighting the improvements with respect to the classic catalytic systems. In particular, due to their unique optical and electrical properties, and due to the possibility to cover the external shell with a wide variety of functional groups, CNPs have found catalytic applications in three main classes of reactions: (i) photocatalysis, (ii) acid-base catalysis and (iii) electro catalysis.

Fig. 1. Most common carbon nanostructures.

Scheme 1. (a) One-pot synthesis of CNPs; (b) covalent functionalization of the external shell.

Fig. 2. Representation of solar H₂ production using the hybrid CNPs (reproduced from ref. 15, Copyright 2019 American Chemical Society).

Scheme 2. Ring opening reaction catalyzed by CNPs.

Scheme 3. Hydroxylation of aromatic compounds catalysed by CNPs in polymer matrix and hydrogen peroxide.

Scheme 4. Conversion of dopamine into aminochrome by using Cu²⁺–CNPs functionalized with β-cyclodextrin.

Scheme 5. Enantioselective epoxidation of CN–chromene by using chiral CNPs.

Fig. 3. Electrocatalytic water oxidation catalysed by CNPs/SnO₂/Co₃O₄ (adapted from ref. 22, with permission of Elsevier Ltd.).

Fig. 4. Schematic representation of the catalyst used in the methanol oxidation (adapted from ref. 24, with permission of Elsevier).

Fig. 5. Schematic representation of the catalyst for the oxygen reduction reactions (adapted from ref. 25, with permission of Elsevier).