Method as well as resulting electrode and capacitor. The method includes the following process steps: •. in a surface of a metal film substrate, etching microstructures with a predetermined roughness, •. depositing in said microstructures a metal or compound layer, •. converting said metal or compounds layer into metal nanoparticles, constituting a catalyst, •. growing cross linked nanotubes in said microstructures at said metal nanoparticle acting as catalysts.