Carbon atoms trapped in cages: Metal carbide clusterfullerenes

•An exhaustive survey of recent research progress of metal carbide clusterfullerenes (MCCFs).•A detailed enumeration of structural establishments of representative MCCFs.•Novel structures, intriguing cluster–cage interplays, and exohedral reactivity.•Fascinating properties and potential applications.

Metal carbide clusterfullerenes (MCCFs), which trap two carbon atoms together with metal atom(s) inside the fullerene cage, are a novel branch of endohedral metallofullerenes (EMFs). This review presents an exhaustive survey of recent research progress in MCCFs. After a detailed enumeration of the structural establishments of representative MCCFs, their novel structures, intriguing cluster–cage interplays, fascinating properties, and potential applications are highlighted. Moreover, a variety of new MCCF members are suggested for future identification.