Anodization of FeAl intermetallic alloys for bandgap tunable nanoporous mixed aluminum-iron oxide

Nanoporous Anodic Aluminum-Iron Oxide with a Tunable Band Gap Formed on the FeAl3 Intermetallic Phase

“…The parameters that determine the morphology of the anodic oxide produced include the type of aqueous or non-aqueous electrolyte solutions and their concentration and temperature as well as the potential and duration of the electrochemical anodization process [13]. Parameters that describe the geometry of nanostructured anodic oxides, include the average pore diameter, average distance between pore centers, thickness of the oxide coating, and thickness of the barrier layer, which separates the bottom of the resulting pores from the substrate material; this is especially true for anodic aluminum oxide, which is a typical material produced by anodization [14][15][16]. Nanolayers owe their great interest to their specific functional properties, classifying them to the group of engineering nanomaterials, which is widely used in many branches of technology and industry.…”

Review of Fabrication Methods, Physical Properties, and Applications of Nanostructured Copper Oxides Formed via Electrochemical Oxidation

“…The most frequently studied anodic oxides are hexagonally arranged anodic aluminum oxide (AAO) [ 1 ] and nanoporous or nanotubular anodic titanium oxide (ATO) [ 2 ]. Intensive research on those two nanostructured materials has incited significant progress in: electrochemical and optical sensing [ 3 , 4 ], nanofabrication [ 5 ], photonic crystals [ 6 ], information optical coding [ 7 ], filtration and kidney dialysis [ 8 ], drug releasing platforms [ 9 ], biomaterials performance [ 10 ], renewable energy harvesting [ 11 , 12 ], the removal of greenhouse gases [ 13 ], magnetic materials [ 14 ], surface-enhanced Raman spectroscopy [ 15 ], plasmonic materials [ 16 ], structural color generation [ 17 ], tunable contact angle surfaces [ 18 , 19 ], and tunable band gap materials [ 20 ].…”

“…Currently, the majority of transition metals have been tested as substrates for anodizing. Researchers have obtained nanostructured anodic oxides as the result of the electrochemical oxidation of: W [ 21 , 22 ], Sn [ 23 ], Zr [ 24 , 25 ], Zn [ 26 , 27 ], Nb [ 28 , 29 ], Fe [ 30 ], and FeAl [ 20 , 31 ]. The majority of the nanostructures obtained by transition metals anodization are composed of oxide, where the metallic element is at one fixed oxidation state.…”

“…Morphological features of nanostructured anodic oxides are tailored by operating conditions. For example, the pore diameter and intepore distance of anodic alumina and titania are linear functions of the applied voltage [ 1 , 2 , 20 ]. Additionally, electrochemical in situ doping of anodic oxides, due to the application of various additives in the electrolyte, allows one to dope the growing nanostructures [ 37 ].…”

“…Therefore, self-organized anodization seems to be a promising method in copper oxides formation, providing high-surface area nanostructures with a band gap tunable by operating conditions (size of the nanostructures) and chemical composition (in situ doping). Per analogiam to the anodization of Al and Ti [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 ], it can be expected that the morphology of the nanostructures formed by copper anodization can be tailored after the optimization of the operating conditions. Moreover, recent advances in Al and Ti anodization, as well as recent high-tech applications, may provide some inspiration for electrochemical copper oxidation.…”