Insight into the Effect of the Core–Shell Microstructure on the Electrochemical Properties of Undoped 3D-Networked Conductive Diamond/Graphite

Microstructure engineering has aroused tremendous interest to tailor the electrochemical properties of an sp(3)/sp(2)-bonded carbon composite in the chemical sensing field. In this work, the undoped diamond/graphite (D/G) nanoplatelet is controllably synthesized without nitrogen/boron incorporation using microwave plasma chemical vapor deposition. Assisted with high-resolution transmission electron microscopy and conductive atomic force microscopy, it is revealed that the D/G composite is composed of an insulate diamond nanoplatelet stem encapsulated in highly conductive graphite shells. The three-dimensional (3D) conductive graphite edges possess high electrochemica activity, whereas the adjacent inactive diamond core could influence the adsorption of the reactant onto the graphite edges; thus, tunable electrochemical properties from the boron-doped diamond feature to the graphite feature are verified with the thickening of the surrounding graphite shells and the thinning of the diamond stem. Impressively, it is noteworthy that the undoped 3D networked D/G-8% nanoplatelet film, with a thick diamond stem encased into thin graphite shells (similar to 4 nm), demonstrates improved electrochemical activity while retaining the advantages of a wide potential window (3.18 V) and low background currents (127.6 mu F cm(-2)) as much as possible, holding great promise in electrochemical sensing fields. The D/G hybridized methodology herein paves a novel route toward designing a nanocarbon electrode with excellent electrochemical properties.