Improvement of the Structural and Chemical Properties of Carbon Nano‐onions for Electrocatalysis

Heteroatom doping of carbon nanostructures is a convenient tool to control their physicochemical properties and to make them suitable for various applications. Carbon nano-onions (CNOs) doped with nitrogen (N-CNOs) have been prepared by annealing aminated-nanodiamond particles (AM-NDs) at different temperatures (1150, 1450 and 1650 °C) in an inert He atmosphere. Their physicochemical properties were compared with those of pristine CNOs obtained from non-functionalized NDs under the same experimental conditions. The carbon nanostructures were characterized using transmission (TEM) and scanning (SEM) electron microscopy, X-ray powder diffraction (XRD), Raman and Fourier transform infrared (FTIR) spectroscopy, porosimetry, and differential-thermogravimetric analyses (TGA-DTG). Their physicochemical properties are systematically discussed for undoped and for the nitrogen-doped CNO samples. The results reveal that the surface morphology and the structure of undoped and nitrogen-doped CNOs vary with the annealing temperature. All of these materials were electrochemically tested as electrode materials for enzyme-free catalysis of hydrogen peroxide. The nitrogen-doped carbon nanostructures have a higher catalytic activity than undoped nanostructures obtained under the same experimental conditions.