Strong Electrochemiluminescence Emission from Oxidized Multiwalled Carbon Nanotubes

: Carbon nanotubes (CNTs) as well-known nanomaterials are extensively studied and widely applied in various fields. Nitric acid (HNO3 ) is often used to treat CNTs for purification purposes and preparing oxidized CNTs for various applications. However, too little attention is paid to investigating the effect of HNO3 treatment on the optical properties of CNTs. In this work, it is observed for the first time that HNO3 -oxidized multiwalled carbon nanotubes (ox-MWCNTs) have strong electrochemiluminescence (ECL) activity, which enables ox-MWCNTs to become new and good ECL carbon nanomaterials after carbon quantum dots (CQDs) and graphene quantum dots (GQDs). Various characterization technologies, such as transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy, are used to reveal the relationship between ECL activity and surface states. The ECL behaviors of ox-MWCNTs are investigated in detail and a possible ECL mechanism is proposed. Finally, the new ECL nanomaterials of ox-MWCNTs are envisioned to have promising applications in sensitive ECL sensing and in the study of CNT-based catalysts.