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

Abstract 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 (TiO 2 , ZrO 2 , Al 2 O 3 ) or binary components (TiO 2 –ZrO 2 and TiO 2 –Al 2 O 3 ) 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 TiO 2 films (denoted as H–TiO 2 ) 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.