One-pot titration methodology for the characterization of surface acidic groups on functionalized carbon nanotubes

Abstract

Functionalization is one of the key procedures for real applications of carbon nanotubes (CNTs) as it involves the generation of the acidic functional groups on their surfaces. In these procedures, precise elucidation of these surface acidic groups is significant for the proper utilization of the functionalized CNTs. For easy characterization of the practical acidic groups on CNTs, one-pot titration methodology is developed, breaking the boundary between the conventional indirect and direct titration methods. The practical acidic functional groups including carboxylic, lactonic, and phenolic groups were successfully computed from the acid ionization constant (pKa) distribution from the direct titration of nitric acid-oxidized multi-walled CNTs by means of a one-pot titration methodology. These results were fairly identical to the results of the popular indirect titration method, showing that the developed methodology is essentially applicable for the surface characterization of acidic groups on CNTs and potentially extended to the other carbon nanomaterials.