The Use of Anodic Oxides in Practical and Sustainable Devices for Energy Conversion and Storage

Abstract

This review addresses the main contributions of anodic oxide films synthesized and designed to overcome the current limitations of practical applications in energy conversion and storage devices. We present some strategies adopted to improve the efficiency, stability, and overall performance of these sustainable technologies operating via photo, photoelectrochemical, and electrochemical processes. The facile and scalable synthesis with strict control of the properties combined with the low-cost, high surface area, chemical stability, and unidirectional orientation of these nanostructures make the anodized oxides attractive for these applications. Assuming different functionalities, TiO2-NT is the widely explored anodic oxide in dye-sensitized solar cells, PEC water-splitting systems, fuel cells, supercapacitors, and batteries. However, other nanostructured anodic films based on WO3, CuxO, ZnO, NiO, SnO, Fe2O3, ZrO2, Nb2O5, and Ta2O5 are also explored and act as the respective active layers in several devices. The use of AAO as a structural material to guide the synthesis is also reported. Although in the development stage, the proof-of-concept of these devices demonstrates the feasibility of using the anodic oxide as a component and opens up new perspectives for the industrial and commercial utilization of these technologies.

Nanoporous Anodic Alumina Photonic Crystals for Sunlight Harvesting Applications: A Perspective

“…To this end, different semiconductors such as copper(I) oxide (Cu 2 O), [ 203,204 ] copper tungsten oxide (CuWO 4 ), [ 205 ] copper bismuth oxide (Cu 2 BiO 4 ), [ 206 ] copper indium selenide (CuInSe 4 ), [ 207 ] iron(III) oxide, [ 208 ] silver metal (Ag), [ 209 ] and also heterostructures of Fe 2 O 3 –Cu 2 O, [ 210 ] and nickel–bismuth–vanadate (BiVO 4 ) [ 211 ] have been deposited as nanowires or nanorods by electrodeposition into NAA structures featuring straight pores. Additionally, nanowire and nanotube arrays made of Cu 2 ZnSnS 4 [ 212 ] and iron titanate (Fe 2 TiO 5 ), [ 213 ] respectively, have been deposited by solution‐based techniques within NAA. In all these studies, arrays of free‐standing nanowires, nanorods, and nanotubes were obtained upon selective dissolution of the NAA template.…”

Fabrication, Characterization and Photocatalytic Activity of Copper Oxide Nanowires Formed by Anodization of Copper Foams

“…Recent emerging issues such as water purification, filtration, and materials for renewable energy harvesting and storage, as well as carbon dioxide reduction, increase demand for novel nanostructured materials [ 1 ]. Research on the nanostructures materials will have an invaluable impact on the progress in catalysts performance, device miniaturization, and assembly or energy harvesting and storage [ 2 ]. Nanostructures, such as nanorods, nanowires, and nanotubes made of metallic and semiconducting materials, have attracted much interest because of their technological applications in different fields such as nanoelectronics, optoelectronics, sensors, energy, and magnetic storage [ 3 ].…”

“…One of the key materials that served as a template in these nanostructures fabrication is porous anodic alumina (PAA) [2][3][4][5][6][7][8]. Porous anodic alumina is formed by electrochemical oxidation of aluminum that results in the formation of porous oxide.…”

“…Anodization of aluminum with the formation of nanostructures triggered research on the electrochemical oxidation of other metals such as titanium, iron, hafnium, tungsten, zirconium, zinc, etc., [2][3][4][5][6][7][8]. In general, the majority of the anodic oxides have fixed stoichiometry, are amorphous, and are made of nanopores or nanotubes.…”

Peculiar Porous Aluminum Oxide Films Produced via Electrochemical Anodizing in Malonic Acid Solution with Arsenazo-I Additive

“…The ratio of simultaneously occurring self-organized processes of metal oxidation with the formation of oxide and dissolution plays an important role in the formation of porous and tubular anodic oxides of valve metals. Different kinds of metal dissolution during anodic oxidation of aluminum and other valve metals lead to the formation of oxide films with different morphologies: barrier layers, quasi-regular porous layers, high degree self-ordering porous layers as well as tubular and nanocomposite structures [ 6 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 ]. The anodizing electrolyte is, aside from other process parameters, the main factor that determines this morphology.…”