Porous AAO template-assisted rational synthesis of large-scale 1D hybrid and hierarchically branched nanoarchitectures

One-dimensional (1D) hybrid and hierarchically branched nanoarchitectures have been the focus of intensive research due to their fascinating size-, shape-, and material-dependent properties, with potential applications in catalysis, biomolecular separation, solar cells, nanoelectronics, nanophotonics, and nanodevices. Up to now, various approaches have been developed for the building of these complex nanoarchitectures, such as chemical vapor deposition, solution-based synthesis, thermal evaporation route, and various combinatorial multi-step approaches. However, the methods mentioned above exhibited limited control over the nanoarchitectural geometry, density, sizes, and locations of the branches. As the nanochannel diameters, lengths, and morphologies inside porous anodic aluminum oxide (AAO) membranes can be tuned by rationally adjusting the anodizing conditions of high-purity Al foils, porous AAO template-assisted synthesis has been considered as a general approach to the large-scale fabrication of 1D hybrid and hierarchically branched nanoarchitectures with controlled geometry, composition of different components and complexity. This review highlights the advances in the porous AAO template-assisted rational synthesis of 1D hybrid and hierarchically branched nanoarchitectures, including axial hetero-nanostructures, coaxial nanocables, hierarchically branched 1D homo-nanostructures, and hierarchically branched 1D hetero-nanostructures. It also discusses the fascinating applications of these complex nanoarchitectures in various fields.