Single-step Anodization Research Articles

Facile Fabrication of Indium-Doped TiO2 Via Anodization As Photoanodes for Photoelectrochemical Water Splitting Under Visible Light

Directionality of Nanostructured forms of TiO2 prepared through electrochemical anodization as photoanodes in photoelectrochemical (PEC) water splitting benefits the efficient e- and h+ separation. However, a large band gap hinders using such nanostructures in the presence of visible light. Doping with metals can be one of the strategic ways to reduce band gaps. In the present work, single-step anodization of titanium foils in the viscous electrolyte containing different concentrations of indium metal salt is used to fabricate Indium-doped TiO2 nanostructures. The anodization samples are annealed to obtain the photoactive anatase phase of TiO2. As prepared, Indium-doped TiO2 structures are characterized by field emission scanning electron microscope, X-ray diffraction, and UV-Vis light diffuse absorbance spectroscopy. PEC water splitting activity of Indium-doped TiO2 nanostructures is tested in 1 M KOH using a Xe-arc lamp equipped with an AM1.5 G filter under 1 sun. Indium doping enhances the photocurrent, photostability, and charge separation properties compared to the bared TiO2 nanostructures. This work shows that doping the optimum amount of Indium affects the PEC activity of the photoanodes through increased TiO2 lattice defects, and electrical conductivity.

Effect of Bath Composition on Titanium Anodization Using the Constant-Current Approach: A Crystallographic and Morphological Study

Porous TiO2 thin films were prepared via electrochemical anodization of commercial-grade titanium foils in baths containing variable amounts of ethylene glycol. X-Ray diffraction, scanning electron microscopy, and UV/visible spectroscopy were employed to assess the effect of ethylene glycol on the nature of TiO2 layers. Emphasis is given to the modification of pore size and anatase-to-rutile ratio since these characteristics strongly affect the catalytic performance of TiO2. To simplify the scaling up of the process, a single-step anodization process was employed on a commercial grade 2 titanium foil in constant-current mode without the use of fluorides—conditions that are easily replicable on an industrial scale. We point out some interesting relationships among operating parameters, such as bath composition and current densities, and the characteristics of the anodization layers evidence that the pore size and anatase-to-rutile ratio can be strictly controlled. Increasing the amount of ethylene glycol stimulated the formation of a thinner and less porous TiO2 layer, richer in rutile phase, and characterized by reduced-diameter pores. These results demonstrate the effectiveness and, to some extent, the tunability of the morphology and mineralogic composition of titanium anodization in fluoride-free and ethylene-glycol-bearing acidic solutions.

Antibacterial and biocompatible polyaniline-doped titanium oxide layers.

Titanium anodization has been shown to produce crystalline oxides exhibiting photocatalytic reactions that form reactive oxygen species (ROS) when exposed to UV light. The ROS subsequently attack bacteria cells, and thus reduce bacteria attachment on titanium implant surfaces. Polyaniline (PANI) is a conductive polymer that has shown antibacterial properties when electropolymerized onto titanium. Our research group hypothesized the addition of PANI to crystalline titanium oxide surfaces would increase the available free electrons and thus increase photocatalytic activity (PCA). This research led to the development of a novel single-step anodization approach for PANI doping crystalline titanium oxide layers. The objective of the present study was to determine the proper aniline electrolyte concentration needed to maximize the PCA and reduce bacterial attachment on the formed oxides. Aniline concentrations up to 1 M were added into a 1 M sulfuric acid electrolyte. The formed oxides exhibited increased PANI surface coverage but decreased anatase and rutile crystalline titanium oxide phase formation with increasing aniline electrolyte concentrations. Despite exhibiting the lowest levels of anatase and rutile formation, the 0.75 M and 1M aniline oxides with the greatest PANI surface coverage also exhibited the highest PCA levels. 1 M aniline oxides showed significantly higher PCA under UVA irradiation compared to oxides formed from aniline concentrations up to 0.5M (p < 0.001). 0.75 M aniline oxides exhibited significant reductions in Staphylococcus aureus attachment with or without UVA irradiation compared to control oxides without PANI. MTT and live/dead assays confirmed cytocompatibility and nearly 100% cell viability for the PANI doped oxides.

Fabrication of Mo-doped TiO2 nanotube arrays photocatalysts: The effect of Mo dopant addition time to an aqueous electrolyte on the structure and photocatalytic activity

Molybdenum-doped TiO2 nanotubes (TNTs) samples were synthesized in two routes by a single-step anodization method for a sustainable photocatalytic process. This study aimed to evaluate the effectiveness of dopant adding time on the photocatalytic activity of TiO2 nanotubes. In the first route, molybdenum dopant with three initial concentrations of 0.02, 0.06, and 0.1 M was added to the electrolyte at the beginning of the anodizing process, while in the second route, molybdenum precursors were added to the electrolyte after 30 min from the beginning of anodization (after the formation of nanotubes). The structural characteristics of Mo-doped TNTs in both routes were compared with non-doped nanotubes using field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) techniques. The optical properties and efficiency of electron-hole pairs separation and charge transfer kinetics were evaluated by diffuse reflectance spectroscopy (DRS) and electrochemical impedance spectroscopy (EIS) methods. Moreover, methylene blue (MB) degradation under visible light was performed to investigate the photocatalytic activity. The results indicate that the second route of synthesis causes the formation of well-aligned TNTs while increasing the Mo concentration will destroy the tube structure in some places on the surface and cause the loss of structural order, in the first path. By Mo doping into TiO2 nanotubes, the optical properties are improved and the absorption edge of TiO2 nanotubes was extended to the visible region. The Mo-doped samples in the second route with concentrations of 0.1 M exhibited the highest visible light absorption and charge transfer rate among all the Mo-doped samples. Also, Mo-doped samples had better photocatalytic activity than non-doped samples in MB degradation and the highest photocatalytic efficiency was related to the Mo-doped sample synthesized in the second route with a Mo concentration of 0.1 M.

A novel single-step anodization approach for pani-doping oxide surfaces to improve the photocatalytic activity of titanium implants

Crystalline titanium oxides have shown photocatalytic activity (PCA) and the formation of antibacterial reactive oxygen species (ROS) when stimulated with UV light. Polyaniline (PANI) is a conductive polymer that has shown antibacterial effects. Previously, titanium oxides have been PANI-doped using a multi-step approach. In the present study, we compared PANI-doped specimens produced with a two-step method (ACV), to PANI-doped specimens produced by a novel single-step direct anodization (AAn) method, and a control group of anodized un-doped specimens. The surface morphology, oxide crystallinity, surface elemental composition, surface roughness, surface wettability, oxide adhesion, corrosion resistance, PCA, and ROS generation of each oxide group were evaluated. All groups exhibited mixed anatase and rutile phase oxides. The AAn group revealed less anatase and rutile, but more PANI-surface coverage. The AAn group exhibited significantly increased PCA after 60 min of direct UVA illumination compared to the ACV group, despite containing lower amounts of anatase and rutile. The ACV and AAn groups showed significant increases in ROS production after 4 h UVA illumination while the control group showed similar ROS production. These findings suggested that PANI doping using the novel direct anodization technique significantly improved PCA even for oxides containing less crystallinity. The S. aureus attachment response to each oxide group was also compared under UVA pre-illumination, UVA direct illumination, and no illumination (dark) lighting conditions. Although no significant differences were shown in the bacterial response, both PANI-doped groups exhibited less average bacterial attachment compared to the control group. The response of MC3T3-E1 pre-osteoblast cells to each oxide group was evaluated using MTT and live/dead assays, and no evidence of cytotoxicity was found. Since many, if not most, titanium implant devices are routinely anodized as a part of the manufacturing processes, these study findings are applicable to a wide variety of implant applications.

Novel photoanodes based on (Mo-Cr) co-doped titania nanotube for highly efficient photocathodic protection performance of stainless steel

Mo-doped, Cr-doped, and Mo-Cr co-doped titania nanotube arrays were synthesized through the single step anodization of titanium. Mo-Cr co-doped titania nanotubes prepared showed great improvement on photocatalytic activity in the protection of stainless steel (403SS) under visible light irradiation compared with Mo and Cr mono-doped titania. The open-circuit potential (OCP) of 403SS (in 3.5 wt% aqueous NaCl) coupled with the best co-doped sample (Cr50:Mo50-TNT) was reduced from −240 to −690 mV, while the electrode potential was maintained at −320 mV even upon turning the light off. This study also identified the effect of the addition of sulfur compounds as hole scavengers on the photoelectrochemical (PEC) properties and photoelectrochemical cathodic protection (PCP) by the best Mo-Cr co-doped titania nanotube. Sodium sulfate and sulfite, sodium thiosulfate, sodium sulfide, potassium metabisulfite and thiourea have been used as hole scavengers. The order of photocurrent is as follows: Na2S > K2S2O5 > CS(NH2)2 > Na2S2O3 > no hole scavengers > Na2SO4 > Na2SO3. Mo-Cr co-doped titania nanotube show much more favorable PCP impact on 403SS than the pure titania sample, according to the results of the changes in the potentials and current densities. Furthermore, the results finally proved that sodium sulfide is the most appropriate hole scavenger.

A Study on Functional Hydrophobic Stainless Steel 316L Using Single-Step Anodization and a Self-Assembled Monolayer Coating to Improve Corrosion Resistance

Stainless steel fabricated using chromium is widely being used in various industries due to its superior corrosion resistance compared to light metals such as aluminum, titanium, and magnesium. However, despite its excellent properties, a problem of poor corrosion resistance in harsh environments remains. In this study, an economical and environmentally friendly anodizing process was applied to the surface of stainless steel (SUS 316L) to create porous nanostructures to improve its water-repellent properties. In these experiments, voltages of 30, 50, 70, and 90 V were applied to stainless steel for 3 h to form an oxide film, prior to immersion in 0.1 M phosphoric acid for 10 min to expand the oxide pores. In addition, the change of the oxide structure was observed through field-emission scanning electron microscopy (FE-SEM). In terms of the contact angle, hydrophilicity was observed at applied voltages of 70 and 90 V, in which a porous film was formed; the best water repellency was observed at a 90 V applied voltage, after the application of an FDTS (1H,1H,2H,2H-perfluorodecyltrichlorosilane) coating, a self-assembled monolayer. Finally, the corrosion behavior of a hydrophobic specimen was tested using potentiodynamic polarization (PDP) experiments. The hydrophobic SUS 316L alloy subsequently displayed improved corrosion resistance in a 3.5 wt% NaCl solution.

Influence of sterilization on the performance of anodized nanoporous titanium implants

Towards clinical translation of bioactive nano-engineered titanium implants, achieving appropriate sterilization and understanding its influence on the modified implant characteristics is essential. With limited studies exploring the influence of sterilization techniques on electrochemically anodized titanium with TiO2 nanostructures, we aimed to advance this domain by performing an in-depth evaluation of the influence of common sterilization techniques (ethanol immersion, various UV irradiation times, gamma irradiation, and dry/wet autoclaving) on TiO2 nanopores fabricated on micro-rough Ti surfaces (dual micro-nano) via single step anodization. Various sterilized surfaces were systematically compared in terms of topographical, chemical, crystalline, wettability and mechanical characteristics. Next, we investigated the protein adhesion capacity and functions of primary gingival fibroblasts (proliferation, adhesion/alignment and spreading morphology) to compare the bioactivity of the sterilized nanopores. Ethanol immersion, gamma irradiation and UV irradiation conserved the topography of the fabricated nanopores, while autoclave sterilization (both dry and wet) compromised the nanoporous structures. Various duration of UV-sterilization resulted in no significant changes in the surface topography and chemistry of the fabricated TNPs. Our findings revealed that UV irradiation is the most appropriate technique to sterilize nano-engineered titanium implants for appropriate wettability, protein adhesion capacity and enhanced metabolism and proliferation of human gingival fibroblasts (hGFs). This study systematically investigated the influence of sterilization on anodized nano-engineered titanium implants towards achieving reproducible outcomes (in terms of topography, chemistry and bioactivity), and found that UV irradiation holds great promise for application across different nano-engineered metal surfaces.

Chromium-doped titanium oxide nanotubes grown via one-step anodization for efficient photocathodic protection of stainless steel

Single-step anodization of titanium foils in ethylene glycol based electrolytes , which contain chrome alum (KCr(SO 4 ) 2 ) as the source of chromium, has been used to synthesize chromium doped TiO 2 nanotubes with efficient photocathodic protection of 403 stainless steel. Chrome alum is a non-toxic source of Cr 3+ ions. In addition, the effect of various chrome alum concentrations in the anodizing solution on the photocathodic protection behavior have also been investigated. Chrome alum concentration in the electrolyte affected the performance of the prepared photoelectrodes. The photocurrent density of the best chromium doped TiO 2 nanotube electrode was up to 2.4 times higher than the undoped sample. The open-circuit potential of the synthetic films coupled with 403 stainless steel was shifted to more negative values and provided efficient photocathodic protection of stainless steel under light irradiation. In addition, the light absorption and photoelectrochemical behavior of chromium doped TiO 2 nanotube samples was improved under light irradiation in comparison with undoped TiO 2 nanotubes. • Chromium doped TiO 2 nanotube films were prepared by one-step anodization of titanium. • Chrome alum was used as a non-toxic chromium ion (Cr 3+ ) source. • The effects of various Cr 3+ concentrations on photocathodic protection behavior was studied. • The photocurrent density of chromium doped TiO 2 electrodes was enhanced up to 2.4 times compared to the undoped sample

Aluminium-doped TiO2 nanotubes with enhanced light-harvesting properties

Titanium dioxide (TiO2) application in light-harvesting processes is hindered by its wide band gap. Strategies such as morphology shifts from nanoparticles to nanotubes and doping of fabricated nanostructures are widely used to address this issue. Combining both approaches, this work successfully synthesizes, for the first time, aluminium-doped TiO2 nanotubes via a single-step anodization method at three distinct potentials (20, 40 and 60 V). SEM images revealed the successful formation of remarkably thin layers of TiO2 nanotubes produced at 40 and 60 V. X-ray diffractograms and Raman spectra suggest the successful insertion of aluminium into the anatase lattice. Diffuse reflectance confirmed the doping process through a marked effect on the absorbance of visible light for the higher voltages, as well as through a reduction in the optical band gap. For utilization purposes, the photoelectrochemical performance of 40 V Al–TiO2 was able to deliver a comparable response to that of a compact TiO2 layer of the same thickness. The current density developed by the 60 V sample was increased by 120% in comparison to the undoped material, despite having an absorbance much lower than that of the latter. Overall, synthesizing an Al-doped TiO2 nanotubular structure has proven to be a great strategy in the development of materials for application in advanced light-harvesting electrodes.

Optimization of photocatalytic performance of a gC3N4–TiO2 nanocomposite for phenol degradation in visible light

In the current study, response surface method (RSM) was used to optimize the photocatalytic performance of a graphitic carbon nitride (gC3N4)–TiO2 nanocomposite, which was fabricated in a single step anodization technique. The RSM statistically established the optimal conditions for the assessment and design of the experiments. We examined the effect of different operating parameters of gC3N4–TiO2 nanocomposites (such as melamine dose, annealing temperature, and annealing time) on phenol degradation in visible-light. From RSM results, the optimum synthesis condition was observed when gC3N4–TiO2 nanocomposite was fabricated at a melamine dose of 2.08 g, annealing temperature 575.4 °C, and annealing time 2.93 h. This optimum sample showed 3.9 times higher phenol degradation efficiency than pristine TiO2 nanotubes. The gC3N4–TiO2 nanocomposite was characterized with field emission scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, and UV–Vis diffuse reflectance spectroscopy. From recycling results, it was observed that the gC3N4–TiO2 nanocomposite was stable for many cycles. We observed that the RSM model predicted data are in a good agreement with phenol degradation experimental data with R2 value of 0.988. It was established that the RSM is a viable technique for optimal synthesis of a nanocomposite that can effectively degrade the pollutant.

Trace amounts of Ru-doped Ni–Fe oxide bone-like structures via single-step anodization: a flexible and bifunctional electrode for efficient overall water splitting

A trace amount of Ru-doped Ni–Fe oxide film with an in situ formed 3D bone-like structure is an outstanding, efficient, durable, and flexible bifunctional catalyst for water splitting.

Electrodeposition Assisted Formation of Anodized TiO2-CuO Heterojunctions for Solar Water Splitting

The anatase phase titanium dioxide nanotubes (ATNTs) is investigated for photocatalytic water splitting in pristine form and after copper oxide (CuO) incorporation. ATNTs are grown using titanium substrate by one and two step anodization followed by annealing at 450 ºC for transformation to anatase phase. Both of the anodization steps are performed by electrochemical process using ammonium fluoride, ethylene glycol and deionized water as electrolyte. The ATNTs are then modified with CuO nanoparticles, electrochemically and also through dip-coating process. The growth of ATNTs and deposition of CuO nanoparticles is confirmed with X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and energy dispersive X-ray (EDX) spectroscopy. Well organized and vertically aligned nanotubes are confirmed under FESEM. Linear Sweep Voltammetry (LSV) technique is performed for photocurrent responses in distilled water in the dark environment as well as in the light of solar simulator at applied potential of 1.0V. ATNTs grown with two steps anodization offered promising results for photocatalytic water splitting compared to single step anodization. The CuO modification in ATNTs shown a reasonable increase in photocurrent densities compared to pristine ATNTs. Moreover, the ATNTs modified with CuO through electrochemical deposition exhibited greater photocurrent responses than the dip coating method. Figure 1

Single-step synthesis of Fe-TiO2 nanotube arrays with improved light harvesting properties for application as photoactive electrodes

Research on TiO2 nanotubes gained prominence in the past years due to their photoelectrochemical behavior. Metallic ion doping via a simple and fast method of production can dictate a path in order to achieve and improve such application. This work reports an innovative single-step anodization synthesis of iron-doped TiO2 nanotubes. Titanium foils were anodized at three potentials (20, 40 and 60 V) for 1 h. The resulting arrays were characterized by scanning electron microscopy, X-ray diffraction, Raman, XPS and UV–Vis diffuse reflectance spectroscopy. SEM images showed that higher anodization potentials successfully produced Fe-TiO2 nanotubes without a passivating top-layer. XRD and Raman results indicate that Fe ions were introduced in the anatase framework. Fe-doping produced a shift in the UV–Vis absorption edge towards the visible region, which reflected onto the photoelectrochemical performance of the electrodes. The Fe-TiO2 sample anodized at 60 V developed a current density of 1.9 × 10−4 A·cm−2, i.e., 2.5 times greater than that of the undoped TiO2 sample. The results indicate that the obtained Fe-TiO2 nanotube arrays are promising materials for application as photoactive electrodes.

Electrodeposition-assisted formation of anodized TiO2–CuO heterojunctions for solar water splitting

The anatase phase titanium dioxide nanotubes (ATNTs) are investigated for photocatalytic water splitting with and without the formation of copper oxide (CuO) heterojunctions. ATNTs have been grown on titanium substrate by one- and two-step anodization, followed by annealing at 450 oC for transformation to anatase phase. Anodization was performed in an electrolyte containing ammonium fluoride, ethylene glycol and deionized water. The ATNTs were then modified with CuO nanoparticles by dip-coating and electrochemical deposition. The growth of ATNTs and incorporation of CuO nanoparticles in it were confirmed with X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and energy-dispersive X-ray (EDX) spectroscopy. Well-organized and vertically aligned nanotubes were observed in the FESEM results. Contact angle measurements proved that the thin film of nanotubes is hydrophilic in nature. Linear sweep voltammetry (LSV) technique was performed for photocurrent responses, using distilled water in the dark environment as well as in the light of solar simulator at applied potential of 1.0 V. The photocurrent densities in the dark were negligible, while it became significant under the influence of simulated visible light. The ATNTs grown with two-step anodization offered promising results for photocatalytic water splitting compared to single-step anodization. The CuO modification in ATNTs exhibited a reasonable increase in photocurrent densities compared to pristine ATNTs. Furthermore, the electrochemical deposition process for modification of ATNTs with CuO afforded much better photocurrent responses compared to the dip coating method. The electrochemical deposition of CuO in ATNTs was performed at 0.7 V, 0.9 V and 1.1 V, among which the sample prepared at 0.7 V exhibited the highest photocurrent densities.

High-efficiency photoelectrochemical cathodic protection performance of the iron-nitrogen-sulfur-doped TiO2 nanotube as new efficient photoanodes

Novel iron-nitrogen-sulfur-tridoped titanium dioxide nanotubes (Fe-N-S-TiO2 NTs) have been synthesized via single step anodization of titanium using potassium ferricyanide, as a suitable additive, in dimethyl sulfoxide (DMSO) electrolyte and applied as photoanodes in the photocathodic protection of stainless steel 403 (SS403). Photocurrent density, open circuit potential and Tafel polarization curves have been used to study the photocathodic protection effect of the samples prepared. Upon the addition of potassium ferricyanide to the anodizing electrolyte and titanium dioxide nanotube doping, the light absorption of the Fe-N-S-TiO2 NTs were increased to the visible region, comparable with pure TiO2 NTs, according to the results obtained. Enhanced photoelectro-response activity and photocathodic protection performance for 403 stainless steel are exhibited by Fe-N-S-TiO2 NTs under light illumination. In addition, the optimal sample electrode (FT4) potentials shifted negatively to −683 mV under illumination.

Hematite (α-Fe2O3) nanosheets with enhanced photo-electrochemical ability fabricated via single step anodization

In the present study, synthesis of hematite nanosheets and their photocurrent response have been reported. The nanosheets are fabricated through a single step-anodization technique at room temperature. Light absorption study of nanosheets, using diffuse-reflectance-spectroscopy, depicts the band gap of ~2.16 eV. Photocurrent density of as-fabricated nanosheets is found to be ~0.72 mA cm−2. The enhanced photocurrent density as compared to iron oxide based photoelectrodes can be attributed to high surface area for light absorption and good crystallinity. These features improve the charge separation to overcome charge carrier recombination which favours their preference as a promising candidate for visible-light driven applications.

Formation of a self-organized nanoporous structure with open-top morphology on 304L austenitic stainless steel

A novel and simple method is reported for producing a self-organized nanoporous structure on austenitic stainless steel (SUS-304L) with open-top morphology. Uniform nanopores with a quasi-hexagonal arrangement were obtained on a very large scale with no crack formation by using single-step anodization. Electropolishing of SUS-304L in ethylene glycol monobutyl ether and perchloric acid electrolyte prior to anodization was the key factor to obtain self-organized and regularly ordered nanopores. Under optimized electropolishing conditions, a honeycomb-like patterned morphology of shallow nanopores was developed on the surface of SUS-304L. Anodization of the patterned morphology in ethylene glycol-based electrolyte generated self-organized and ordered nanopores. Morphology, structure and chemical analyses of the samples were carried-out using FESEM, EDAX, XRD, XPS and ToF-SIMS. FESEM images revealed the formation of hexagonal and ordered nanopores with uniform diameter. EDAX analysis confirmed that the nanoporous oxide layer is composed of iron, chromium, nickel and oxygen. A blue energy shift in the XPS spectra was observed after annealing, which is attributed to the absence of F-species. ToF-SIMS depth profile analysis confirmed the high content of chromium oxide on the surface of the nanoporous oxide layer. The hexagonal nanoporous ordered morphology is useful in anti-corrosion and decoration applications.

Effect of wettability on the water entry problem of aluminum spheres

We investigated the hydrodynamics of water entry by aluminum spheres varying in wettability, assisted by nano/microscaled surface morphology. A wide range of contact angle (C.A.: 0° ≤ θ0 < 170°) on the test spheres was prepared via inexpensive single-step anodization method. The water entry events: Splash and cavity formation, were visualized by a high-speed camera to understand the fast transient features affected by the surface wettability. In terms of hydrodynamics, cavity formation and air entrainment during the water entry were analyzed via dynamic wetting of liquid film flow along the sphere surface. It was confirmed that wettability was a determinant factor of both splash shape and cavity formation, especially in hydrophobic condition (90° ≤ θ0). Furthermore, the analysis of dynamic contact angle of liquid film front in this study was able to classify the water entry events more detail than previous literature. In addition, we also recorded audio signals to evaluate acoustic pressures produced by the impact between spheres and water pool. The audio signals, which are expected to be proportional to acoustic pressures, differed when hydrophilic and hydrophobic spheres entered water.

RuO2-Doped TiO2 Nanotube Membranes Prepared via a Single-Step/Potential Shock Sequence

Anodic TiO2 nanotubes were simultaneously grown and doped with RuO2 by single-step anodization in a negatively-charged RuO4&lt;sup&gt;−&lt;/sup&gt; precursor. Subsequently, a high positive voltage was imposed on the nanotubes in an F&lt;sup&gt;−&lt;/sup&gt;-based electrolyte (a process referred to as potential shock), which led to the formation of a through-hole RuO2-doped TiO2 nanotube membrane without significant loss of the RuO2 catalyst. XPS results confirmed that the doped Ru metal was converted into RuO2 as the potential shock voltage increased. Further increases in the potential shock voltage led to the formation of RuOx/Ru in the TiO2 nanotubes. All of our results clearly showed that a through-hole catalyst-doped TiO2 nanotube membrane can be produced by a sequence consisting of single-step anodization and the potential shock process.