Atmospheric-pressure chemical purification of detonation-synthesized nanodiamond by using perchloric acid: Intensive parametric study to control sp3/sp2carbon ratio

Controlled- and high-sp3/sp2 carbon ratio of the detonation-synthesized nanodiamond (DND) may play a very important role in many applications. Here, we demonstrated an atmospheric-pressure process of chemical purification using perchloric acid (HClO4) and intensively studied the control parameters including the reaction temperature, DND loading amount, and processing time. The sp3/sp2 carbon ratio was characterized using UV-Raman spectroscopy (325 nm) and is evaluated based on the intensity ratio (IDia/IG) of the diamond peak and G band peak at 1325 cm− 1 and 1590 cm− 1, respectively. Through the combination of control parameters, we successfully controlled the intensity ratio of IDia/IG at the range from 0.28 to 1.5 and achieved 15.5% higher than compared with commercial DND. In addition, we also investigated the electrical conductivity of DND vs. intensity ratio of IDia/IG and the results show that lower intensity ratio of IDia/IG have higher electrical conductivity because of non-diamond carbon.