Nanoporous silicon structure with graphene coating

A technique has been developed for the formation of porous silicon structures with a variable pore morphology along the layer depth. The technology allows to create filtering nanoporous layers that are located on a macroporous frame, the thickness of which provides strength, which allows the use of membranes in various filtering devices. In the structure of GPSi-var, pores with diameters from 33 nm to 80 nm were more than 97.8%. Modifying the characteristics of membranes based on GPSi-var structures, we propose coating the inner and outer pore surfaces with graphene layers. An original CVD synthesis process is developed in the so-called “sharp pressure drop” (SPD) mode in the reactor working zone. For the synthesis of graphene coatings in layers with a closed pore structure, the cyclic SPD mode was used. The depth of graphene synthesis in this mode is determined by the number of SPD cycles. It was also determined that, as a result of the synthesis of graphene on pore walls, the properties of porous layers are significantly improved. In addition to the previously identified decrease in electrical resistance (by 2–3 orders of magnitude) and increased chemical resistance to weakly alkaline solutions, a significant increase in the specific surface area has been experimentally established, which significantly expands the scope of application of this nanostructured material.