Emerging aero-semiconductor 3D micro-nano-architectures: Technology, characterization and prospects for applications

Highly porous, ultra-lightweight materials are widely used in various applications. Aerogels based on both organic and inorganic components have been known for a long period of time as an important class of functional materials. However, a new subclass of ultra-porous inorganic materials prepared by using technologies different from those derived from a gel is nowadays emerging, thereby contributing to a significant expansion of their areas of application. In this review paper, highly porous semiconductor materials prepared on the basis of ZnO sacrificial templates consisting of 3D architectures built up from interconnected microrods, tetrapods or multipods, so called aero-semiconductors, are reviewed from the point of view of technologies applied for their preparation, properties and applications. For the purpose of comparison, other materials prepared on the basis of similar templates are discussed, such as aerographites and other highly porous inorganic nanomaterials and composites containing a semiconductor component. A special focus is put on their applications in sensors, electromagnetic shielding, light emission, microfluidics, microrobotics, biomedicine, photocatalysis and electrochemical applications.