Catalytic applications of carbon nanotubes in energy and environmental remediation: multifunctional roles and design strategy

Carbon nanotubes (CNTs) have emerged as highly multifunctional nanomaterials capable of addressing pressing challenges in energy conversion and environmental remediation. Their catalytic role has evolved from passive conductive supports to active, tunable catalytic platforms enabled by good control over nanotube structure, defect chemistry, and electronic properties. Across energy and environmental applications, catalytic performance is governed by unified nanoscale principles, including electronic structure modulation through heteroatom doping, nano-confinement-induced stabilization of active species, and strong interfacial interactions that facilitate efficient charge transfer and dynamic redox processes. Recent advances have demonstrated that CNTs are efficient and durable electrocatalysts and thermally stable supports for hydrocarbon reforming, in which confinement suppresses carbon accumulation. In environmental remediation, CNTs serve as efficient electron acceptors in hybrid photocatalysts, thereby suppressing electron-hole recombination and promoting the degradation of persistent pollutants and inactivation of pathogens. This review critically examines the advances in CNT-based catalysts and the emerging catalytic role of CNTs in these applications. It clarifies the structure-property-function relationships that define CNT catalytic behavior and identifies key challenges and future directions necessary to translate CNT-based catalysts into sustainable energy and environmental remediation technologies.