In situ optical sub-wavelength thickness control of porous anodic aluminum oxide

• Aleksandrs Dutovs,
• Raimonds Popļausks,
• Oskars Putāns,
• Vladislavs Perkanuks,
• Aušrinė Jurkevičiūtė,
• Tomas Tamulevičius,
• Uldis Malinovskis,
• Iryna Olyshevets,
• Donats Erts and
• Juris Prikulis

Beilstein J. Nanotechnol. 2024, 15, 126–133, doi:10.3762/bjnano.15.12

• consistently manufacturing PAAO with the targeted thickness. An electrochemical cell with an optical window was designed for reflectance spectroscopy of PAAO during anodization. Real-time fitting of spectra to a transfer-matrix model enabled continuous monitoring of the thickness growth of the PAAO layer

• . Automation software was designed to terminate the anodization process at preset PAAO thickness values. While the concept was illustrated using the widely used method of anodization in a 0.3 M oxalic acid electrolyte with a 40 V potential, it can be readily customized for other protocols. PAAO layers with

• effective thickness below 300 nm could be produced with a few nanometers accuracy using single-crystal aluminum substrates. The results were confirmed using spectroscopic ellipsometry. The method for controlling the thickness during anodization eliminates the necessity of sample sectioning for electron

Hierarchically patterned polyurethane microgrooves featuring nanopillars or nanoholes for neurite elongation and alignment

• Lester Uy Vinzons,
• Guo-Chung Dong and
• Shu-Ping Lin

Beilstein J. Nanotechnol. 2023, 14, 1157–1168, doi:10.3762/bjnano.14.96

• fabrication. For instance, traditional techniques, such as electron-beam lithography, laser writing, and cleanroom photolithography, have flexibility in design but require costly equipment [13][14]. Relatively cheaper techniques, such as anodization, electroplating, and electrospinning, are limited by the

Biomimetic chitosan with biocomposite nanomaterials for bone tissue repair and regeneration

• Se-Kwon Kim,
• Sesha Subramanian Murugan,
• Pandurang Appana Dalavi,
• Sebanti Gupta,
• Sukumaran Anil,
• Gi Hun Seong and
• Jayachandran Venkatesan

Beilstein J. Nanotechnol. 2022, 13, 1051–1067, doi:10.3762/bjnano.13.92

• delivery system in synthetic bone implants can stimulate bone regeneration while preventing bacterial infection. Furthermore, coating materials containing TiO2 can help drug stabilisation producing a long-term drug release profile [119]. The electrochemical anodization process was used by Lai et al. (2018

An overview of microneedle applications, materials, and fabrication methods

• Zahra Faraji Rad,
• Philip D. Prewett and
• Graham J. Davies

Beilstein J. Nanotechnol. 2021, 12, 1034–1046, doi:10.3762/bjnano.12.77

• porous silicon structures [40][41], for example arrays with biodegradable macroporous silicon tips produced using electrochemical anodization. A disadvantage is that the tips of the microneedles may break off and remain in the skin during the drug delivery process where they will be biodegraded only

Comprehensive review on ultrasound-responsive theranostic nanomaterials: mechanisms, structures and medical applications

• Sepand Tehrani Fateh,
• Lida Moradi,
• Elmira Kohan,
• Michael R. Hamblin and
• Amin Shiralizadeh Dezfuli

Beilstein J. Nanotechnol. 2021, 12, 808–862, doi:10.3762/bjnano.12.64

Antimicrobial metal-based nanoparticles: a review on their synthesis, types and antimicrobial action

• Matías Guerrero Correa,
• Fernanda B. Martínez,
• Cristian Patiño Vidal,
• Camilo Streitt,
• Juan Escrig and
• Carol Lopez de Dicastillo

Beilstein J. Nanotechnol. 2020, 11, 1450–1469, doi:10.3762/bjnano.11.129

• , chemical vapor deposition, electrochemical anodization method, hydrolysis, hydrothermal method, precipitation–hydrothermal method, reverse micellar route, sol–gel method, solution-based synthesis, solvothermal synthesis, and the sonochemical method. The most relevant ones, along with the typical resulting

• -condensation of the vapors on the cold surface of the vacuum reactor. Sergeev et al. [45] obtained Ag nanoparticles with sizes ranging from 20 to 150 nm using this technique. The electrochemical anodization method is based on the reactions that occur between the electrode and the electrolyte. In this method

Electrochemical nanostructuring of (111) oriented GaAs crystals: from porous structures to nanowires

• Elena I. Monaico,
• Eduard V. Monaico,
• Veaceslav V. Ursaki,
• Shashank Honnali,
• Vitalie Postolache,
• Karin Leistner,
• Kornelius Nielsch and
• Ion M. Tiginyanu

Beilstein J. Nanotechnol. 2020, 11, 966–975, doi:10.3762/bjnano.11.81

• , Chisinau MD-2001, Republic of Moldova Leibniz IFW Dresden, Helmholtzstr. 20, 01069 Dresden, Germany 10.3762/bjnano.11.81 Abstract A comparative study of the anodization processes occurring at the GaAs(111)A and GaAs(111)B surfaces exposed to electrochemical etching in neutral NaCl and acidic HNO3 aqueous

• electrolytes is performed in galvanostatic and potentiostatic anodization modes. Anodization in NaCl electrolytes was found to result in the formation of porous structures with porosity controlled either by current under the galvanostatic anodization, or by the potential under the potentiostatic anodization

• . Possibilities to produce multilayer porous structures are demonstrated. At the same time, one-step anodization in a HNO3 electrolyte is shown to lead to the formation of GaAs triangular shape nanowires with high aspect ratio (400 nm in diameter and 100 µm in length). The new data are compared to those

Atomic layer deposition for efficient oxygen evolution reaction at Pt/Ir catalyst layers

• Stefanie Schlicht,
• Korcan Percin,
• Stefanie Kriescher,
• André Hofer,
• Claudia Weidlich,
• Matthias Wessling and
• Julien Bachmann

Beilstein J. Nanotechnol. 2020, 11, 952–959, doi:10.3762/bjnano.11.79

• of the salts followed by their thermal decomposition. In the alternative method, more academic in nature, atomic layer deposition (ALD) is applied to the felts after anodization. ALD allows for a controlled coating with ultralow noble-metal loadings in narrow pores. In acidic electrolyte, the ALD

• the Ti support and subsequent thermal decomposition to the corresponding elements [16][17][18]. As an academic method yielding better control of the electrode surface geometry, we perform an “anodization” of the Ti fibers to generate an ordered porous layer, followed by atomic layer deposition (ALD

• homogeneous mixing of both elements in small nanoparticles, the coating of deep pores with them, and the adequacy of anodization with ALD as a surface treatment of Ti felts have all been demonstrated in the recent past [22][23]. Anodization is performed by applying a large positive voltage (+40 V) to the felt

A set of empirical equations describing the observed colours of metal–anodic aluminium oxide–Al nanostructures

• Cristina V. Manzano,
• Jakob J. Schwiedrzik,
• Gerhard Bürki,
• Laszlo Pethö,
• Johann Michler and
• Laetitia Philippe

Beilstein J. Nanotechnol. 2020, 11, 798–806, doi:10.3762/bjnano.11.64

• .11.64 Abstract Structural colours have received a lot of attention regarding the reproduction of the vivid colours found in nature. In this study, metal–anodic aluminium oxide (AAO)–Al nanostructures were deposited using a two-step anodization and sputtering process to produce self-ordered anodic

• (AAO) films; anodization; structural colours; reflectance; polar coordinates; plasmonic effects; Introduction Recently, the reproduction of the vivid colours found in nature has received increasing interest [1]. These colours appear when light interacts with periodic structures. With regard to this

• , anodic aluminium oxide films play an important role. There are different approaches in obtaining brilliant colours using AAO films, such as the use of new anodization electrolytes (etidronic acid) [2], the use of pulsed anodization [3], and the deposition of a metal layer onto the surface of AAO–Al films

Effect of Ag loading position on the photocatalytic performance of TiO₂ nanocolumn arrays

• Jinghan Xu,
• Yanqi Liu and
• Yan Zhao

Beilstein J. Nanotechnol. 2020, 11, 717–728, doi:10.3762/bjnano.11.59

• preparation of 1D TiO2 nanostructures is mainly performed by using anodization [17], hydrothermal [18] and template [19] methods. Meanwhile, the most common methods for the combination with precious metals are chemical deposition [20] and physical deposition [21]. The development of anodized aluminum oxide

• photolithography and the template method by Sung et al. [30]. In this case, Ag particles were loaded on the outside of the nanocolumns by magnetron sputtering, and the catalysis was carried out at a sputtering time of 30 min. Besides, Jani et al. [31] studied the preparation of TiO2 nanotube arrays by anodization

• aluminum template preparation: Highly pure aluminum sheets (purity >99.9%, 20 × 20 × 0.5 mm) were subjected to secondary anodization to prepare highly ordered AAO templates. Thus, each aluminum sheet was annealed prior to oxidation and then electrochemically polished using a 1:4 volume ratio of HClO4 and

Nanostructured and oriented metal–organic framework films enabling extreme surface wetting properties

• Andre Mähringer,
• Julian M. Rotter and
• Dana D. Medina

Beilstein J. Nanotechnol. 2019, 10, 1994–2003, doi:10.3762/bjnano.10.196

• example, sol–gel synthesis, electrochemical deposition, anodization, electrochemical polymerization, electrospinning, plasma treatment, chemical or hydrothermal methods, vapor deposition, layer-by-layer assembly or laser ablation [19][27][28][29][30][31][32][33][34][35][36][37][38][39]. However, the

An iridescent film of porous anodic aluminum oxide with alternatingly electrodeposited Cu and SiO₂ nanoparticles

• Menglei Chang,
• Huawen Hu,
• Haiyan Quan,
• Hongyang Wei,
• Zhangyi Xiong,
• Jiacong Lu,
• Pin Luo,
• Yaoheng Liang,
• Jianzhen Ou and
• Dongchu Chen

Beilstein J. Nanotechnol. 2019, 10, 735–745, doi:10.3762/bjnano.10.73

• oxide (AAO) films with different thicknesses were generated by anodization for different durations. Subsequently, the electrodeposition of Co and Cu were performed. Under irradiation of natural light perpendicular to the surface, different colors (including purple, blue, blue-green, green, and yellow

• ) appeared in the Co/AAO films depending on the anodization duration, and another set of colors (including purple, indigo, blue, blue-green, and green) also appeared in the Cu/AAO films depending on the oxidation time. This colorful AAO composite film with the electrodeposited metal was a result of an

• was deposited via sputtering, yielding a colorful filter material. Different structural colors could be obtained via changing the anodization time [17]. In this context, instead of using high-purity aluminum foils and titanium foils as the substrate for the anodization treatment, which have been

Widening of the electroactivity potential range by composite formation – capacitive properties of TiO₂/BiVO₄/PEDOT:PSS electrodes in contact with an aqueous electrolyte

• Konrad Trzciński,
• Mariusz Szkoda,
• Andrzej P. Nowak,
• Marcin Łapiński and
• Anna Lisowska-Oleksiak

Beilstein J. Nanotechnol. 2019, 10, 483–493, doi:10.3762/bjnano.10.49

• , Poland 10.3762/bjnano.10.49 Abstract Composites based on the titania nanotubes were tested in aqueous electrolyte as a potential electrode material for energy storage devices. The nanotubular morphology of TiO2 was obtained by Ti anodization. TiO2 nanotubes were covered by a thin layer of bismuth

• nanotubular morphology of TiO2 was obtained by Ti plate anodization. The nanostructure of TiO2 provides a high specific surface area that is crucial for energy storage devices based on pseudocapacitance and electrochemical double-layer capacitance. TiO2 nanotubes were covered by a nanometric layer of bismuth

• /discharge tests were equal to jk = ja = 0.5 mA·cm−2. All values expressed by a surface containing unit are divided by the geometrical area of the electrode. Electrode preparation Titania nanotubes Titania nanotube synthesis was based on a two-stage anodization process in water/ethylene glycol (5%/95

Nanoporous water oxidation electrodes with a low loading of laser-deposited Ru/C exhibit enhanced corrosion stability

• Sandra Haschke,
• Dmitrii Pankin,
• Vladimir Mikhailovskii,
• Maïssa K. S. Barr,
• Adriana Both-Engel,
• Alina Manshina and
• Julien Bachmann

Beilstein J. Nanotechnol. 2019, 10, 157–167, doi:10.3762/bjnano.10.15

• the anodization conditions used here, the pitch P and diameter D are set to approx. 425 nm and 370 nm, respectively. This value of D is the maximum possible given a set P. It maximizes the specific surface area and thereby the electrocatalytic current density reachable [43]. The pore length is varied

• cover glasses (borosilicate glass, 18 × 18 mm2, 0.13–0.16 mm thickness) were purchased from Marienfeld-Superior. Aluminum plates (99.99%) for the anodization procedure were supplied by Smart-Membranes. The indium tin oxide sputter target (99.99%) was purchased from AEM. Preparation of planar samples For

• isopropanol. Preparation of nanostructured samples Nanostructured Ru/C electrodes were prepared in several steps as illustrated in Figure 5. A standard two-step anodization of aluminum (represented as (a) in Figure 5) delivered the nanoporous aluminum oxide membranes further used as templates [35]. Aluminum

Amorphous Ni_xCo_yP-supported TiO₂ nanotube arrays as an efficient hydrogen evolution reaction electrocatalyst in acidic solution

• Yong Li,
• Peng Yang,
• Bin Wang and
• Zhongqing Liu

Beilstein J. Nanotechnol. 2019, 10, 62–70, doi:10.3762/bjnano.10.6

• unstable under acidic conditions. One effective way to improve their stability is with an appropriate support material. Compared to the nickel foam or other substrates [19][23][24], TiO2 nanotube arrays prepared by anodization are favorable for the loading of catalysts and the fast transfer of electrons

• aqueous solution, the NixCoyP/TNAs electrodes presented enhanced electrocatalytic activity and robust stability after incorporating Co into NiP. Experimental Preparation of NixCoyP/TNA electrodes The TiO2 nanotube arrays used here were prepared using an electrochemical anodization technique according to

Nanostructure-induced performance degradation of WO₃·nH₂O for energy conversion and storage devices

• Zhenyin Hai,
• Mohammad Karbalaei Akbari,
• Zihan Wei,
• Danfeng Cui,
• Chenyang Xue,
• Hongyan Xu,
• Philippe M. Heynderickx,
• Francis Verpoort and
• Serge Zhuiykov

Beilstein J. Nanotechnol. 2018, 9, 2845–2854, doi:10.3762/bjnano.9.265

• applications [24][33][34]. Oriented WO3·H2O sheets were hydrothermally grown in mixed acids at 80 °C for 17 h, followed by sintering at 500 °C in order to obtain crystalline WO3 for the photoelectrochemical water oxidation [35]. A 2D WO3 nanosheet sensor fabricated by high-temperature anodization of tungsten

Impact of the anodization time on the photocatalytic activity of TiO₂ nanotubes

• Jesús A. Díaz-Real,
• Geyla C. Dubed-Bandomo,
• Juan Galindo-de-la-Rosa,
• Luis G. Arriaga,
• Janet Ledesma-García and
• Nicolas Alonso-Vante

Beilstein J. Nanotechnol. 2018, 9, 2628–2643, doi:10.3762/bjnano.9.244

• Columbia, V6T 1Z4, Canada 10.3762/bjnano.9.244 Abstract Titanium oxide nanotubes (TNTs) were anodically grown in ethylene glycol electrolyte. The influence of the anodization time on their physicochemical and photoelectrochemical properties was evaluated. Concomitant with the anodization time, the NT

• anodization produces vertically oriented, well-ordered nanotubular arrays with high aspect ratio. TiO2 nanotubes (TNTs) produced in this way have been preferred by several groups since they are expected to exhibit better photocatalytic properties than nanoparticles, due to the short electron-diffusion path

• , high specific surface area, high mass-transport rate, and remarkable light-harvesting properties [17][18]. Generally, the electrochemical anodization process implies that the anodic polarization of a mechanically/chemically prepared Ti sheet induces the growth of TNTs using an etching agent (typically

A visible-light-controlled platform for prolonged drug release based on Ag-doped TiO₂ nanotubes with a hydrophobic layer

• Caihong Liang,
• Jiang Wen and
• Xiaoming Liao

Beilstein J. Nanotechnol. 2018, 9, 1793–1801, doi:10.3762/bjnano.9.170

• -layer titania nanotubes (TNTs) fabricated using by an in situ voltage up-anodization process. The visible-light photocatalytic activity is improved by loading Ag onto the TNTs by NaBH4 reduction. Then, the TNTs containing Ag nanoparticles were modified with dodecanethiol (NDM) to create a hydrophobic

• ] created two-layer TNTs with a pear-like structure which has a smaller upper layer diameter (60–80 nm) and a larger lower layer diameter (180–200 nm) by a novel in situ voltage up-anodization method to prolong the release of drugs. Gulati et al. [16] used an altered periodic voltage in the anodization

• structural modification of TiO2 nanotubes. We decorated AgNPs onto two-layer TNTs fabricated by an in situ voltage up-anodization technique to improve the availability of visible light. In addition, we coated a hydrophobic organic layer (dodecanethiol) directly onto the hydrophilic surface of the nanotubes

Preparation and morphology-dependent wettability of porous alumina membranes

• Dmitry L. Shimanovich,
• Alla I. Vorobjova,
• Daria I. Tishkevich,
• Alex V. Trukhanov,
• Maxim V. Zdorovets and
• Artem L. Kozlovskiy

Beilstein J. Nanotechnol. 2018, 9, 1423–1436, doi:10.3762/bjnano.9.135

• it is possible to develop a template that is suitable for various membrane technologies. Experimental In this study, various membranes were fabricated based on porous anodic alumina, prepared via a two-step anodization of Al foil using three distinct sets of conditions: type I – in an aqueous

• solution of oxalic acid (0.3 M H2C2O4) at 15 °C, 50 V; type II – in an aqueous solution of oxalic acid (0.3 M H2C2O4) at 15 °C, 40 V (as previously described in detail [31]); type III – in an aqueous solution of sulfuric acid (1.5 M H2SO4) at 15 °C, 20 V. Before anodization, a technological frame was

• ), respectively. Here, k is a constant of proportionality for the diluted water electrolytes on the basis of acids and Ua is the voltage of anodization (i.e., forming voltage) for the Al foil [35]. The same values were found from the SEM images of the experimental samples (Table 1). Table 1 lists other important

A comparative study of the nanoscale and macroscale tribological attributes of alumina and stainless steel surfaces immersed in aqueous suspensions of positively or negatively charged nanodiamonds

• Colin K. Curtis,
• Antonin Marek,
• Alex I. Smirnov and
• Jacqueline Krim

Beilstein J. Nanotechnol. 2017, 8, 2045–2059, doi:10.3762/bjnano.8.205

• and the sample was then immersed into 4 wt % oxalic acid solution maintained at 0 °C. A cathode was placed in the bath and an electric potential of 40 V was applied between the anode and the cathode. Anodization was halted at 3 min yielding an approximately 100 nm thick Al2O3 layer. After the

• anodization procedure, the samples were thoroughly rinsed with DI water before mounting the sample within the flow cell. Macroscale friction measurements Macroscopic scale friction coefficient measurements were performed with a MTM2 Mini-Traction Machine (PCS Instruments, London, UK). The apparatus is capable

Liquid permeation and chemical stability of anodic alumina membranes

• Dmitrii I. Petukhov,
• Dmitrii A. Buldakov,
• Alexey A. Tishkin,
• Alexey V. Lukashin and
• Andrei A. Eliseev

Beilstein J. Nanotechnol. 2017, 8, 561–570, doi:10.3762/bjnano.8.60

• reported by Mardilovich et al. (pH 5.0–8.2) for the membranes obtained by anodization at 40 V [17]. Alterations of the pH stability ranges might be explained by the difference in chemical composition of membranes obtained in “mild” and “hard” anodization conditions. The membranes obtained at high voltages

• by mild anodization and this membrane after water filtration illustrates very close profiles with the only difference represented by a peak at ≈7 ppm (Figure 4). The difference spectrum (Figure 4b) is fitted well by a single component with an asymmetric resonance signal shape centered at 7.5 ppm. The

• in the case of the AAO_120V membrane (pore diameter 90 ± 10 nm) obtained by hard anodization, which corresponds with the quantity of weakly bounded water (see Supporting Information File 1, Figure S1). Thus 27Al NMR indicates the removal of aluminum atoms partially coordinated by oxalic acid or water

Anodization-based process for the fabrication of all niobium nitride Josephson junction structures

• Massimiliano Lucci,
• Ivano Ottaviani,
• Matteo Cirillo,
• Fabio De Matteis,
• Roberto Francini,
• Vittorio Merlo and
• Ivan Davoli

Beilstein J. Nanotechnol. 2017, 8, 539–546, doi:10.3762/bjnano.8.58

• anodization of the NbN films were used, respectively, to define the main trilayer geometry and/or to separate electrically, different areas of the trilayers. The anodized films were characterized by using Auger spectroscopy to analyze compounds formed on the surface and by means of a nano-indenter in order to

• overall fabrication recipe with existing processes and literature. Along with the optimal and controlled film growth we also carried out an investigation of the anodization of these films since this technique is necessary for the most of the procedures leading to the patterning of tunnel junctions. The

• processes for defining patterns on NbN thin films are typically based on ion etching and subsequent deposition of insulating layers [9][10][11]. We have tried to limit our fabrication recipe instead to minimal procedures, namely just lift-off lithography and selective anodization. By using lift-off

Phosphorus-doped silicon nanorod anodes for high power lithium-ion batteries

• Chao Yan,
• Qianru Liu,
• Jianzhi Gao,
• Zhibo Yang and
• Deyan He

Beilstein J. Nanotechnol. 2017, 8, 222–228, doi:10.3762/bjnano.8.24

• obtained by dehydration treatment of Cu(OH)2 nanorods at 150 °C in vacuum for 10 min. The Cu(OH)2 nanorods were prepared by the galvanostatic electrochemical anodization of a Cu plate in a two-electrode system via a DC power supply (ITECH IT6123B). Typically, a copper foil (20 mm × 20 mm × 25 µm, 99%, back

• side covered by insulating type) was pretreated in alcohol and then used as the anode. The cathode was a graphite rod with 55 mm length and 5 mm diameter, and was kept 25 mm away from the anode. The anodization process was carried out in 0.8 M NaOH aqueous solution, and a constant current of 6 mA was

Surface-enhanced Raman scattering of self-assembled thiol monolayers and supported lipid membranes on thin anodic porous alumina

• Marco Salerno,
• Amirreza Shayganpour,
• Barbara Salis and
• Silvia Dante

Beilstein J. Nanotechnol. 2017, 8, 74–81, doi:10.3762/bjnano.8.8

• anodic porous alumina (tAPA) was fabricated from a 500 nm thick aluminum (Al) layer coated on silicon wafers, through single-step anodization performed in a Teflon electrochemical cell in 0.4 M aqueous phosphoric acid at 110 V. Post-fabrication etching in the same acid allowed obtaining tAPA surfaces

• ; SERS; nanopores; supported lipid bilayers; thiols; Introduction Anodic porous alumina (APA) is a layered material usually obtained in thick form (≈10 µm thickness scale) from electrochemical anodization in the acidic aqueous electrolyte of aluminum (Al) foils [1]. In APA, the control of pore size

• , pore density and porosity is achieved by changing the anodization voltage during the fabrication and the etching parameters during the post-fabrication treatment [2]. It is widely recognized that the APA surface is biocompatible with practically all cell types and provides a means of controlling the

Nanostructured TiO₂-based gas sensors with enhanced sensitivity to reducing gases

• Wojciech Maziarz,
• Anna Kusior and
• Anita Trenczek-Zajac

Beilstein J. Nanotechnol. 2016, 7, 1718–1726, doi:10.3762/bjnano.7.164

• deposition [24][25], and thermal, chemical, and electrochemical (anodization) oxidation [26][27][28][29]. Thermal and chemical oxidation seem to be the easiest to perform, the least expensive, and have interlaboratory reproducibility as an additional advantage. TiO2 is obtained mainly in form of thin film