Multifunctional carbon nanotube (CNT)-based ZnO composite structures for photocatalytic and sensing applications: A review

The development of multifunctional nanomaterials has gained considerable attention due to their wide-ranging applications in environmental remediation and sensing technologies. Nitrogen-doped zinc oxide (N–ZnO) integrated with carbon nanotubes (CNTs) has emerged as a promising hybrid nanocomposite system with enhanced physicochemical properties. Nitrogen doping narrows the band gap of ZnO and enables visible-light activation, while CNTs provide conductive pathways that facilitate rapid electron transport and suppress charge recombination. These synergistic effects significantly enhance photocatalytic degradation of organic pollutants and improve sensitivity toward chemical and biological analytes. This review presents a comprehensive overview of synthesis strategies, structural and electronic properties, photocatalytic mechanisms, and sensing applications of N–ZnO/CNT nanocomposites. Recent advances, challenges, and future prospects for large-scale and multifunctional applications are also critically discussed.