Core-shells particles grown in a tubular reactor: Influence of the seeds nature and MPCVD conditions on boron-doped diamond crystalline quality

A trend in the synthesis of Boron Doped Diamond (BDD) materials resides in increasing surface areas to exalt reactivity at the BDD/electrolyte interface. This can be achieved either by surface structuration of BDD films or conformal growth on 3D substrates. Another strategy considers isolated BDD particles, mainly obtained by milling of BDD layers that can be further deposited on surfaces or embedded in a conductive matrix. Here, we propose an alternative method to obtain boron-doped diamond particles using a core-shell approach, which consists in growing diamond coatings on spherical silica templates seeded with nanodiamonds. We investigated the effects of the nature and the density of diamond seeds as well as growth parameters on the crystalline quality of the coatings. The microstructure and the boron incorporation in the diamond shell was investigated by combining Scanning Electron Microscopy (SEM), UV Raman and X-ray Photoemission Spectroscopy (XPS) investigations. Such characterizations were compared to Scanning TEM (STEM) imaging, Energy Dispersive Spectroscopy (EDS) and Electron energy loss spectroscopy (EELS) performed on thin cross-sections of core-shells prepared by focused ion beam (FIB) milling.