Fullerenes and derivatives as electrocatalysts: Promises and challenges

Carbon-based metal-free nanomaterials are promising alternatives to precious metals as electrocatalysts of key energy storage and conversion technologies. Of paramount significance are the establishment of design principles by understanding the catalytic mechanisms and identifying the active sites. Distinct from sp2-conjugated graphene and carbon nanotube, fullerene possesses unique characteristics that are growingly being discovered and exploited by the electrocatalysis community. For instance, the well-defined atomic and molecular structures, the good electron affinity to tune the electronic structures of other substances, the intermolecular self-assembly into superlattices, and the on-demand chemical modification have endowed fullerene with incomparable advantages as electrocatalysts that are otherwise not applicable to other carbon materials. As increasing studies are being reported on this intriguing topic, it is necessary to provide a state-of-the-art overview of the recent progress. This review takes such an initiative by summarizing the promises and challenges in the electrocatalytic applications of fullerene and its derivatives. The content is structured according to the composition and structure of fullerene, including intact fullerene (e.g., fullerene composite and superlattices) and fullerene derivatives (e.g., doped, endohedral, and disintegrated fullerene). The synthesis, characterization, catalytic mechanisms, and deficiencies of these fullerene-based materials are explicitly elaborated. We conclude it by sharing our perspectives on the key aspects that future efforts shall consider.