Rapid Self-Assembly-Driven Fabrication of 3D Porous Macroscopic Architectures from Manganese Dioxide Nanowire Building Blocks for Enhanced Air Pollutants Abatement

Abstract

The development of 3D macroscopic architectures assembled from inorganic nanoparticles with tailored porous frameworks has garnered substantial attention across academic and industrial domains. These hierarchical structures combine the advantageous features of nanoscale building blocks with macroscopic functionality, offering enhanced surface accessibility and interconnected pathways while preventing nanoparticle reaggregation. This study presents an innovative cross-linker-free assembly strategy that enables the rational organization of 1D nanowires into 3D macroscopic architectures, effectively preserving the intrinsic structural advantages of both nanoscale and macroscale components. This methodology employs metal-cation-mediated assembly of hydroxylated α-MnO₂ nanowires, where controlled introduction of cations disrupts electrostatic repulsion between nanowires while facilitating interwire connections through cation-hydroxyl coordination. The strong coordination interaction between metal cations and surface hydroxyl groups on α-MnO₂ nanowires drives the formation of 3D interconnected network architecture, resulting in stable hydrogel formation. Subsequent freeze-drying of these hydrogels yields aerogel materials demonstrating exceptional adsorption capacities for common indoor air pollutants, achieving 34.1 mg g⁻¹ for ammonia and 21.5 mg g⁻¹ for formaldehyde. This cation-coordination-driven assembly approach not only establishes a generalizable framework for designing functional macroscopic assemblies from nanowire building blocks but also expands the potential application landscape for such hierarchical architectures, particularly in environmental remediation technologies.