Nanostructured Anodic Oxides: Fabrication & Applications

摘要： The special issue of Current Nanoscience entitled “Nanostructured Anodic Oxides: Fabrication & Applications” comprises review papers focused on various aspects of these nanostructures. Nanostructured anodic oxides are awaking high hopes in the research community due to the solutions of emerging problems they offer. Classically, the anodic oxides on aluminum and its alloys are a protective coating, providing improved corrosion resistance [1-5], adhesion of primer to metallic substrate [6] and hardness of the anodized surface [7-10]. However, since two-step self-organized anodization was invented in 1995, allowing to form highly-ordered honey-comb ordering of the nanopores (Fig. 1a), numerous researches have been triggered. On one hand, still new electrolytes, operating conditions and electrolyte additives are being researched, providing new ranges of the applied voltages and consequently new ranges of oxides pore diameter and interpore distance [11-17]. On the other hand, research on anodic aluminum oxide is so mature, that already significant achievements in nanofabrication [18-22] (Figs. 1b-1c), surfaces with tunable wetting angle [23-27], cells culturing platforms [28, 29], biomaterials performance [29], sensing [30, 31], structural color generation [31, 32], photocatalysis [33], renewable energy harvesting [34-36], photonic crystals [37] and plasmonic materials [38] have been reported. Moreover, also other metals are being researched. Numerous achievements in anodization of Ti [39-45] W [46], Zr [47, 48], Cu [49-51], Fe [52], Sn [53], Zn [54] and stainless steel [55] allowed to make progress in renewable energy harvesting [43, 44, 51] (especially in the assembly of dye-sensitized solar cells [44] and photoelectrochemical water splitting [43, 51]), CO2 reduction to hydrocarbons [45], drug delivery systems [41], improvement in biomaterials performance [40] and photocatalysis [46]. Moreover, also intermetallic alloys, like FeAl [56, 57] and bimetallic, layered systems like Al-Ti [58] were anodized in order to form nanoporous oxides with tunable band gap and to ease the nanofabrication, respectively.