Nanoscale Phase Separations for Versatile Synthesis of Centimeter-Sized Hierarchically Mesoporous Metal-Oxide Films

Hierarchically porous metal-oxide materials have immense potential for many fields, which are highly desired to tackle the limitations of mono-porous architectures, and to combine the advantages of different pore scales. Herein, a simple small-molecule-assisted interfacial assembly strategy, which elegantly combines the mesoscale block copolymers (BCPs)-directed coassembly and nanoscale phase separations of dicyandiamide (DCDA), is developed for the synthesis of centimeter-sized inorganic metal-oxide films with multiscale porosity. The synthetic approach is versatile and can be broadly applied for the fabrication of hierarchically mesoporous metal-oxide films with single (TiO2, ZrO2, Al2O3) or binary components (TiO2-ZrO2 and TiO2-Al2O3) on various substrates ranging from 1D to 3D. The as-prepared films possess ordered structures, uniform thickness, interconnected pores, highly crystallized frameworks, and high surface areas (>200 m(2) g(-1)). As a proof of concept, the photoelectric device assembled by the hierarchically mesoporous TiO2 films (denoted as H-TiO2) shows excellent performance, including a high photocurrent of 0.68 mA cm(-2) and outstanding stability. The presented method may provide new insight into the controllable synthesis of hierarchically porous materials.