Covalent Fullerene Networks: Preparation, Properties and Catalytic Applications

Covalent fullerene networks (CFNs), formed by interlinking fullerene cages through diverse bonding patterns, represent an emerging class of functional carbon nanomaterials with tunable dimensionality and properties. In this review, we systematically summarize recent advances in the preparation, structural characteristics, properties and catalytic applications of versatile CFNs, including one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D) architectures. Various preparation methods are discussed, including alkali/alkaline-earth metal doping, photo-, pressure-, and temperature-induced polymerization, as well as template-directed assembly and chemical vapor transport. Dimensionality engineering markedly influences the electronic structure, carrier transport, mechanical strength, and surface reactivity of CFNs. In specific, 1D CFNs exhibit quasi-1D quantum confinement and anisotropic charge transport; 2D monolayer CFNs possess high specific surface area and in-plane anisotropy; while 3D CFNs display ultra-hardness, plasticity, and metallic conductivity. Owing to their adjustable bandgaps, efficient charge separation, and rich active sites, CFNs have demonstrated potential applications in photocatalytic water splitting, CO 2 reduction and oxygen reduction/evolution reactions electrocatalytic systems. Furthermore, covalent functionalization, heteroatom doping, and metal-nanoparticle loading provide feasibility for enhancing the catalytic activity and stability of CFNs. Finally, we present an outlook regarding future research directions of CFNs, such as controllable and scalable preparation, in-situ characterization of the relationship between structural changes and energy band structures of CFNs to achieve different catalytic performance and applications in other fields especially energy conversion and storage.