Polyol-assisted functionalization of carbon nanotubes-a perspective

Since the 1991 rediscovery of carbon nanotubes (CNTs), methods to decorate these materials with well-dispersed, functional nanoparticles have been greatly pursued. Nanoparticle-functionalized carbon nanotubes (CNTs) have potential applications within advanced high-strength materials, sensors, and catalysis. However, CNTs generally have to be surface-activated, using complex and time-consuming treatments, before they can be decorated with nanoparticles via traditional methods like wet impregnation, which in itself has additional drawbacks (mainly the energy penalty from the drying step). Polyol-mediated functionalization is a viable, economical alternative, as it is a rapid and simple technique that uses biocompatible solvents that are available in large industrial quantities. Additionally, although they are sometimes implemented, strong surface activation treatments are not necessarily required to get even distributions of functional nanoparticle on CNTs. Further, polyols are good dispersion media and have the ability to dissolve a variety of metal salt precursors, a definite advantage that allows the method to be used in the synthesis of various target functional metal nanoparticles. Current research in this field is mainly focused on functionalizing CNTs with metallic and metal-oxide nanoparticles. A perspective of the current literature shows varying deposition results and a lack of continuity across reports, though process metrics like temperature and pH clearly impact supported-nanoparticle morphology. This review describes some of the advances in this field, as well as the significant drawbacks that currently restrict the widespread implementation of polyol-mediated CNT functionalization.