Raul Zazpe, Bilal Bawab, Jhonatan Rodriguez Pereira, Jan M. Macak, Brno University of Technology, Brno, Czech Republic and University of Pardubice, Pardubice, Czech Republic
Nanomaterials represent a very important class of materials with continuously increasing importance. Due to their intrinsic features, unique properties and diversity of functionalities, they count among the most widely studied materials nowadays. While considerable research efforts have been spent to synthesize various nanomaterials (e.g. nanoparticles, nanopores, nanotubes or nanofibers), limited efforts have been devoted to surface modification and property tailoring of these materials. However, it is their surface that comes into direct contact with various media (air, gases, liquids, solids) and influences the reactivity, stability and biocompatibility of these materials. The surface and aspect ratio (defined as their diameter to length ratio) influence the performance of these materials in various applications. Considering these facts, it is more relevant to tailor the surface of these materials and to be able to influence their properties and reactivity at the nanoscale, rather than to deal with tailoring their own bulk material composition.
The focus of this presentation is the modification of electrochemically active surfaces (in particular of electrodes of Li-ion batteries and of various electrocatalysts) by ultrathin barrier coatings towards more chemically and electrochemically stable surfaces.
Numerous techniques can be utilized for this purpose, such as for example wet chemical or physical deposition techniques. However, it is only the Atomic Layer Deposition (ALD) that is capable of really uniform and homogenous coating of these nanomaterials with precise control of the coating composition.
The presentation will be mainly focused on modification of TiO₂ nanotube layers, porous layers and nanofibers of different aspect ratios via ALD. Experimental details and some very recent application examples of surface protection in Li-ion batteries and of the hematite (α-Fe₂ O₃ ) and Cu₂ O nanostructures for water splitting will be discussed. The mechanism of the stabilization and structural characterizations of these modified materials will be shown.