Thin Films and Membranes with Hierarchical Porosity

Thin films and membranes with a hierarchically porous structure are an important class of functional materials; the interconnected pores of different scales have a crucial impact on their properties and functionalities such as adsorption capacity, ionic conductivity, and permeability. Therefore, hierarchically porous thin films and membranes have found a wide variety of applications in areas ranging from catalysis, separation, energy to optics, etc. This article reviews the strategies for the fabrication of hierarchically porous thin films and membranes from a range of materials including polymers, ceramics, carbons, zeolites, metals and metal-organic frameworks, particularly focusing on the template-directed fabrication processes. In addition, the properties and potential applications of these thin films and membranes with a hierarchical porous architecture are highlighted.