CVD diamond growth on non-diamond substrates has to be initiated by the presence of nuclei at the surface. On conductive and flat substrates, bias enhanced nucleation (BEN) can be efficiently applied to create in-situ nuclei. On non-conductive or 3D-shaped substrates, an
alternative approach relies on the dispersion of diamond nanoparticles (NDs), so called the nanoseeding technique. Here, NDs will act as seeds for the CVD growth. Several nanoseeding techniques have been proposed in the literature, for instance using spin-coating and spontaneous
adsorption on a surface by dip-coating. Here, we choose to fabricate the ND coating using a layer-by-layer coating process as described elsewhere [27]. Briefly, to ensure the electrostatic immobilization of NDs on a substrate, a cationic polymer is first deposited, allowing the spontaneous immobilization of negatively charged NDs. In a previous work [23], we detailed how this method can be successfully applied to get an efficient nanoseeding even on nanometric 3D structures. In the present work, we adapted this approach to ensure an efficient nanoseeding of all the silica fibers through the filter. Indeed, this process is usually performed by simple successive dipping of the sample in the solutions of polyelectrolytes and NDs. Here, in order to improve the seeding density on the entire membrane thickness, a Buchner filtration process has been chosen to ensure the diffusion of the polymer and the NDs all over the filter. The seeding conditions are detailed in the Experimental part. The seeding and filtration device is illustrated in the Supporting information. The SEM images of Fig. 1a, b illustrate the seeding density at the upstream and the downstreampart of the membrane. One can note that all the membranes are homogenously seeded; the upstream as well as the downstream fibers show the same nanodiamond densities.