The present invention relates to a structure including a layer including titanium (di)oxide nanostructures, such as titania nanotubes, in contact with a membrane layer including a proton-conducting polymer. A process for preparing the structures of the invention is presented wherein titanium (di)oxide nanostructures on a first substrate are transferred to an ion-conducting polymer membrane by pressing using a hot press, and then detaching the nanostructures from the first substrate.