Facile and size-controllable fabrication of copper nanoparticles on nitrogen-doped carbon dots using an N,N-dimethylformamide-based reduction approach

Abstract

Nitrogen-doped carbon dots (NCDs) have been recognized as a promising supporting material for stabilizing metal nanoparticles. In this study, copper nanoparticles (CuNPs) decorated onto NCDs were easily prepared under mild conditions. Two types of Cu fabricated NCDs were prepared by using different Cu precursors – CuCl2 and N,N-dimethylformamide (DMF)-protected CuNPs, where DMF was employed as a multifunctional reagent serving as a reducing agent, stabilizer, and solvent for the synthesis of the CuNPs. The resulting NCDs with Cu species were characterized using ICP-AES, FT-IR, XPS, XRD, and STEM. We found that the Cu precursor greatly influence the fabrication of Cu species on NCDs, with the Cu content of the CuNPs/NCDs being almost twice that of CuCl2/NCDs. Furthermore, when DMF-protected CuNPs were used, nano-sized Cu particles ranging from 4 to 11 nm were immobilized on NCDs surface, whereas single-atom Cu were observed when using CuCl2. This indicates that DMF-protected CuNPs are a suitable source of Cu for the preparation of nano-sized Cu on NCDs.