TiO2 Nanotube Layers Research Articles

Surface Wettability of ZnO-Loaded TiO2 Nanotube Array Layers

Herein we report on the synthesis and the effects of gradual loading of TiO2 nanotube array layers with ZnO upon surface wettability. Two-step preparation was chosen, where TiO2 nanotube layers, grown in a first instance by anodization of a Ti foil, were gradually loaded with controlled amounts of ZnO using the reactive RF magnetron sputtering. After crystallization annealing, the formerly amorphous TiO2 nanotubes were converted to predominantly anatase crystalline phase, as detected by XRD measurements. The as-prepared nanotubes exhibited a well-aligned columnar structure, 1.6 μm long and 88 nm in diameter, and a small concentration of oxygen vacancies. Ti2+ and Ti3+ occur along with the Ti4+ state upon sputter-cleaning the layer surfaces from contaminants. The Ti2+ and Ti3+ signals diminish with gradual ZnO loading. As demonstrated by the VB-XPS data, the ZnO loading is accompanied by a slight narrowing of the band gap of the materials. A combined effect of material modification and surface roughness was taken into consideration to explain the evolution of surface super-hydrophilicity of the materials under UV irradiation. The loading process resulted in increasing surface wettability with approx. 33%, and in a drastic extension of activation decay, which clearly points out to the effect of ZnO-TiO2 heterojunctions.

Visible Light-Enhanced Antibacterial and Osteogenic Functionality of Au and Pt Nanoparticles Deposited on TiO2 Nanotubes

This study aimed at evaluating the visible light mediated antimicrobial and osteogenic applications of noble metal, such as gold (Au) and platinum (Pt) coated titania (TiO2) nanotubes (NTs). In this study, the Au and Pt nanoparticles (NPs) were deposited on anodized 100 nm TiO2 NTs by ion plasma sputtering. The Au and Pt NPs were mainly deposited on the top surface layer of TiO2 NTs and showed light absorbance peaks around the 470 and 600 nm visible light region used in this study, as seen from the surface characterization. From the results of antibacterial activity test, Au and Pt NPs that were deposited on TiO2 NTs showed excellent antibacterial activity under 470 nm visible light irradiation due to the plasmonic photocatalysis based on the localized surface plasmon resonance effect of the Au and Pt NPs. In addition, alkaline phosphate activity test and quantitative real-time PCR assay of osteogenic related genes resulted that these NPs promoted the osteogenic functionality of human mesenchymal stem cells (hMSCs) under 600 nm visible light irradiation, because of the synergic effect of the photothermal scattering of noble metal nanoparticles and visible light low-level laser therapy (LLLT). Therefore, the combination of noble metal coated TiO2 NTs and visible light irradiation would be expected to perform permanent antibacterial activity without the need of an antibacterial agent besides promoting osteogenic functionality.

Thin TiO2 Coatings by ALD Enhance the Cell Growth on TiO2 Nanotubular and Flat Substrates.

The present work exploits Ti sheets and TiO2 nanotube (TNT) layers and their surface modifications for the proliferation of different cells. Ti sheets with a native oxide layer, Ti sheets with a crystalline thermal oxide layer, and two kinds of TNT layers (prepared via electrochemical anodization) with a defined inner diameter of 12 and 15 nm were used as substrates. A part of the Ti sheets and the TNT layers was additionally coated by thin TiO2 coatings using atomic layer deposition (ALD). An increase in cell growth of WI-38 fibroblasts (>50%), MG-63 osteoblasts (>30%), and SH-SY5Y neuroblasts (>30%) was observed for all materials coated by five cycles ALD compared to their uncoated counterparts. The additional ALD TiO2 coatings changed the surface composition of all materials but preserved their original structure and protected them from unwanted crystallization and shape changes. The presented approach of mild surface modification by ALD has a significant effect on the materials' biocompatibility and is promising toward application in implant materials.

The Influence of a Surface Treatment of Metallic Titanium on the Photocatalytic Properties of TiO2 Nanotubes Grown by Anodic Oxidation

Titanium dioxide (TiO2) nanotubes obtained by the anodic oxidation of titanium metal foils can be used for the photocatalytic degradation of organic pollutants. The aim of our study was to determine the influence of the titanium foil’s surface treatment on the final morphology of the TiO2 nanotubes and their photocatalytic activity. In our experiments, we used two different titanium foils that were electropolished or untreated prior to the anodic oxidation. The morphologies of the starting titanium foils and the resulting TiO2 nanotube layers were investigated and the photocatalytic activities measured by the decomposition of caffeine under UV irradiation. Our results showed that electropolishing of the starting foils produced a more uniform and smoother TiO2 nanotubes surface. In contrast, the TiO2 nanotube surfaces from untreated titanium foils mimic the initial surface roughness of the titanium foil. A comparison of the photocatalytic properties of the TiO2 nanotube layers obtained from the untreated and electropolished titanium foils showed that electropolishing does not necessarily improve the photocatalytic properties of the resulting TiO2 nanotube layer. It was found that the determining factors influencing the photocatalytic activity are the chemical impurities (Ti-nitride) on the surface of the titanium foils and the surface roughness of the TiO2 nanotube layer. The highest photocatalytic activity was achieved with the anodized untreated foil with the minimal presence of Ti-nitride and a relatively high roughness of the TiO2 nanotubes.

Anodization of electrodeposited titanium films towards TiO2 nanotube layers

Ti films electrodeposited on Ni foils from molten salts were anodized towards TiO2 nanotube formation for the first time. The resulting TiO2 nanotube (TNT) layers were compared with TNT layers prepared under identical conditions on Ti foils by means of scanning electron microscopy (SEM), X-ray diffraction (XRD) measurements, X-ray photoelectron spectroscopy (XPS), and photocurrent measurements. No significant differences were found between the TNT layers prepared on the two different substrates. Electrodeposited Ti films prepared in this way could thus be a viable option for anodization purposes.

Hierarchical Anodic TiO2 Nanostructures Formed in Ethylene Glycol/o‐H3PO4 Electrolytes for Direct Photocatalysis

AbstractIn this work, we describe a simple anodization process of titanium in a hot phosphoric acid/ethylene glycol electrolyte that forms a hierarchically structured photocatalytically active TiO2 layer that consists directly of anatase nanocrystallites. Such anodic layers show, without any annealing, a high photocatalytic degradation activity for AO7 (an azo‐dye used as model pollutant) that is higher than the activity of comparable fully crystallized TiO2 nanotube layers. Furthermore, the hierarchically structured layers have a remarkable mechanical bending stability. These features make these novel anodic layers highly promising for applications in flexible substrate based photocatalytic devices.

Atomic Layer Deposition of SnO2-Coated Anodic One-Dimensional TiO2 Nanotube Layers for Low Concentration NO2 Sensing.

The continuous emission of nitrous oxides contributes to the overall air pollution and deterioration of air quality. In particular, an effective NO2 sensor capable of low concentration detection for continuous monitoring is demanded for safety, health, and wellbeing. The sensing performance of a metal oxide-based sensor is predominantly influenced by the availability of surface area for O2 adsorption and desorption, efficient charge transport, and size or thickness of the sensing layer. In this study, we utilized anodic one-dimensional (1D) TiO2 nanotube layers of 5 μm thick which offer large surface area and unidirectional electron transport pathway as a platform to accommodate thin SnO2 coatings as a sensing layer. Conformal and homogeneous SnO2 coatings across the entire inner and outer TiO2 nanotubes were achieved by atomic layer deposition with a controlled thickness of 4, 8, and 16 nm. The SnO2-coated TiO2 nanotube layers attained a higher sensing response than a reference Figaro SnO2 sensor. Specifically, the 8 nm SnO2-coated TiO2 nanotube layer has recorded up to ten-fold enhancement in response as compared to the blank nanotubes for the detection of 1 ppm NO2 at an operating temperature of 300 °C with 0.5 V applied bias. This is attributed to the SnO2/TiO2 heterojunction effect and controlled SnO2 thickness within the range of the Debye length. We demonstrated in this work, a tailored large surface area platform based on 1D nanotubes with thin active coatings as an efficient approach for sensing applications and beyond.

Intrinsic properties of high-aspect ratio single- and double-wall anodic TiO2 nanotube layers annealed at different temperatures

In this work, we present the influence of thermal annealing on morphological, structural, electrical, optical, and photoelectrochemical properties of double- (DW) and single-wall (SW) TiO2 nanotube (TNT) layers. High-aspect ratio TNT layers with a thickness of ∼5 μm and ∼20 μm with an average inner diameter of ∼250 nm and ∼130 nm, respectively, were prepared via electrochemical anodization of Ti foil in two different fluoride containing ethylene glycol-based electrolytes. The inner wall of the native DW TNT layers was quantitatively removed via a mild pre-annealing followed by a selective etching treatment in piranha solution, yielding SW TNT layers. The obtained SW TNT layers annealed at 300–500 °C possess enhanced conductivity by 1–2 orders compared to their DW counterparts. The photoelectrochemical properties of SW TNT layers are enhanced compared to their DW counterparts in the annealing temperature range 300–800 °C. In principle, the SW TNT layers could be potentially favored to the DW TNT layers in electrical and photoelectrochemical applications due to their more superior intrinsic properties.

TiO2 Nanotube Layers Decorated with Al2O3/MoS2/Al2O3 as Anode for Li-ion Microbatteries with Enhanced Cycling Stability.

TiO2 nanotube layers (TNTs) decorated with Al2O3/MoS2/Al2O3 are investigated as a negative electrode for 3D Li-ion microbatteries. Homogenous nanosheets decoration of MoS2, sandwiched between Al2O3 coatings within self-supporting TNTs was carried out using atomic layer deposition (ALD) process. The structure, morphology, and electrochemical performance of the Al2O3/MoS2/Al2O3-decorated TNTs were studied using scanning transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and chronopotentiometry. Al2O3/MoS2/Al2O3-decorated TNTs deliver an areal capacity almost three times higher than that obtained for MoS2-decorated TNTs and as-prepared TNTs after 100 cycles at 1C. Moreover, stable and high discharge capacity (414 µAh cm−2) has been obtained after 200 cycles even at very fast kinetics (3C).

(Invited) Anodic TiO2 Nanotube Layers: Efficient Photocatalyst

The self-organized TiO2 nanotube layers have attracted considerable scientific and technological interest over the past 13 years motivated by their possible range of applications including photocatalysis, solar cells, hydrogen generation and biomedical uses [1,2]. The synthesis of these 1D TiO2 nanotube layers is carried out by a conventional electrochemical anodization of valve Ti metal sheet.Among other TiO2 nanomaterials, these nanotube layers stand out due to their directionality, tunability of dimensions, ability to absorb significant amount of incident light and the possibility to utilize nanotube interiors and exteriors for decoration-coating of secondary materials.One of the most significant applications of TiO2 nanomaterials is photocatalysis, which is very effective to decompose various pollutants (e.g. dyes) and kill bacteria [3,4].The presentation will focus on the utilization of the nanotube layer for photocatalytic removal of various species in the liquid phase [5, 6] as well as gas phase [7]. We will also show that various secondary materials have a positive influence on photo-electrochemical properties of nanotube layers [8, 9]. Experimental details and some recent photocatalytic results will be presented and discussed.

Anodic TiO2 Nanotube Layers As Scaffolds for Deposition of Functional Materials

The self-organized 1D TiO2 nanotubular layers have attracted considerable scientific and technological interest over the past two decades, all motivated by a great performance in the range of applications including photo-catalysis, solar cells, hydrogen generation and biomedical uses [1,2]. The synthesis of these nanotubular layers has been carried out by a conventional electrochemical anodization of Ti sheet. Except the 1D character, these nanotubes possess unique features such as tunable dimensionality, structural flexibility, unidirectional electron transport through nanotube walls, chemical and mechanical stability and biocompatibility.One of the major application targets of TiO2 nanotubes has been their utilization as scaffolds or templates for deposition of secondary materials towards new applications [3]. In particular, for the photoelectrochemical applications (e.g. photovoltaics) ordered nanostructures, such as self-organized TiO2 nanotubes, offer the advantage of directed charge transport and controlled phase separation between the donor and acceptor materials, unlike within randomly ordered mesoporous TiO2 supports.Numerous techniques were utilized for this purpose, such as for example hydrothermal routes, electrodeposition or Atomic Layer Deposition (ALD) techniques. Electrodeposition is very powerful technique to deposit metals [4], oxides [5] or other rather complex materials (such as CuInSe2 [6]) within the nanotubes various by means of complete filling or decoration with. On the other hand, ALD can deposit the widest range of secondary materials within TiO2 nanotubes by means of homogenous coatings [7-10]. ALD is the only technique of choice to coat in particular high-aspect ratio nanotube layers. Overall, the deposited materials influence strongly photo-electrochemical properties of nanotube layers.The presentation will be focused in detail on TiO2 nanotube layers of various aspect ratios filled, decorated or coated by various chalcogenide-based materials using electrodeposition and ALD. Experimental details and some very recent photo-electrochemical and structural characterizations of a new type of heterostructured photo-chemical cell will be presented and discussed.References1] J.M. Macak et al., Curr. Opin. Solid State Mater. Sci., 2007 , 1-2, 3-17.2] K.Lee, A. Mazare, P. Schmuki, Chem. Rev., 2014, 114, 9385-9454.3] J.M. Macak, Chapter 3 in: D. Losic and A. Santos, Electrochemically Engineered Nanoporous Structures, Springer International Publishing, Switzerland, 2015 4] J. M. Macak, B.G. Gong, M. Hueppe, P. Schmuki, Adv. Mater., 2007, 19, 3027.5] L. Wu & G. Zangari, J. Phys. Chem. C, 2010, 114, 11556] S. Das & J. M. Macak et al., ChemElectroChem, 2017, 4, 4957] R. Zazpe et al, Langmuir, 2016, 32, 105518] S. Ng et al., Adv. Eng. Mater., DOI: 10.1002/adem.2017005899] R.Zazpe et al., Nanoscale, 2018, 10, 16601-16612.10] F. Dvorak et al., Appl. Mater. Today, 2019 , 14, 1-20.

All-Solid-State Lithium Ion Batteries Using Self-Organized TiO2 Nanotubes Grown from Ti-6Al-4V Alloy.

All-solid-state batteries were fabricated by assembling a layer of self-organized TiO2 nanotubes grown on as anode, a thin-film of polymer as an electrolyte and separator, and a layer of composite LiFePO4 as a cathode. The synthesis of self-organized TiO2 NTs from Ti-6Al-4V alloy was carried out via one-step electrochemical anodization in a fluoride ethylene glycol containing electrolytes. The electrodeposition of the polymer electrolyte onto anatase TiO2 NTs was performed by cyclic voltammetry. The anodized Ti-6Al-4V alloys were characterized by scanning electron microscopy and X-ray diffraction. The electrochemical properties of the anodized Ti-6Al-4V alloys were investigated by cyclic voltammetry and chronopotentiometry techniques. The full-cell shows a high first-cycle Coulombic efficiency of 96.8% with a capacity retention of 97.4% after 50 cycles and delivers a stable discharge capacity of 63 μAh cm−2 μm−1 (119 mAh g−1) at a kinetic rate of C/10.

Efficiency enhancement in Dye Sensitized Solar Cells by light scattering in photoanode with TiO2 nanotubes

The effect of incorporating a composite double layered structure of photoanode, based on hydrothermally synthesized TiO2 nanotubes (TNT) as the light scattering layer, on the efficiency enhancement of dye sensitized solar cells (DSSCs) is reported. Device performances comprising this novel photoanode is compared with the DSSCs fabricated with the conventional type of photoanodes without TNT. Further enhancement in the device performances is obtained with the post treatment of the photoanode with TiCl4. The DSSC with post treated two layered composite photoanode showed an overall efficiency of 8.31% with a short circuit photocurrent density (Jsc ) of 16.91 mA cm−2 and 783.4 mV of an open circuit voltage (V oc) under the irradiance of 1000 W m−2. In comparison, the reference DSSC with a post treated photoanode having the same thickness showed 7.62% efficiency while delivering a Jsc of 15.60 mA cm−2 with 773.5 mV. The remarkable enhancement in the device performance is achieved due the employment of this double-layered novel photoanode in the DSSCs. However, lower electron life time is observed in the DSSCs with TNT layer suggesting that, rate of electron recombination is higher in the DSSCs with this novel photoanode, although the overall efficiency of the present device and the net result due to the enhanced light harvesting and scattering effect may still be regarded as an favorable alternative for certain applications.

Photoelectrochemical properties of “increasingly dark” TiO2 nanotube arrays

“Black” TiO2 nanotube arrays (TNTAs) of different darkness are formed by thermal reduction of anodic TiO2 nanotube layers in H2 atmosphere at different temperatures (300–500 °C), and their (photo-)electrochemical properties are studied by IPCE spectroscopy, transient photocurrent measurements, IMPS, PEIS, CV, and Mott-Schottky analysis. Hydrogenation of the TNTAs leads to the enhancement of their IPCE (by up to 1.5 times), despite increased recombination losses at anodic potentials. Reduced TNTAs demonstrate a “metallic” behavior by a characteristic frequency response of their impedance and phase angle, reduced charge transfer resistance at anodic bias, increased double layer capacitance, and remarkably increased donor densities (up to 7.25 × 1023 cm−3). The observed alterations in the properties of TNTAs after hydrogenation are ascribed to the formation of defects and TiHx.

Improving the fretting biocorrosion of Ti6Al4V alloy bone screw by decorating structure optimised TiO2 nanotubes layer

TiO2 nanotubes (NT) has been demonstrated its potential in orthopaedic applications due to its enhanced surface wettability and bio-osteointegration. However, the fretting biocorrosion is the main concern that limited its successfully application in orthopaedic application. In this study, a structure optimised thin TiO2 nanotube (SONT) layer was successfully created on Ti6Al4V bone screw, and its fretting corrosion performance was investigated and compared to the pristine Ti6Al4V bone screws and NT decorated screw in a bone-screw fretting simulation rig. The results have shown that the debonding TiO2 nanotube from the bone screw reduced significantly, as a result of structure optimisation. The SONT layer also exhibited enhanced bio-corrosion resistance compared pristine bone screw and conventionally NT modified bone screw. It is postulated that interfacial layer between TiO2 nanotube and Ti6Al4V substrate, generated during structure optimisation process, enhanced bonding of TiO2 nanotube layer to the Ti6Al4V bone screws that leading to the improvement in fretting corrosion resistance. The results highlighted the potential SONT in orthopaedic application as bone fracture fixation devices.

Complex cytotoxicity mechanism of bundles formed from self-organised 1-D anodic TiO2 nanotubes layers

The present study reports on a comprehensive investigation of mechanisms of in vitro cytotoxicity of high aspect ratio (HAR) bundles formed from anodic TiO2 nanotube (TNT) layers. Comparative cytotoxicity studies were performed using two types of HAR TNTs (diameter of ∼110 nm), differing in initial thickness of the nanotubular layer (∼35 μm for TNTs-1 vs. ∼10 μm for TNTs-2). Using two types of epithelial cell lines (MDA-MB-231, HEK-293), it was found that nanotoxicity is highly cell-type dependent and plausibly associates with higher membrane fluidity and decreased rigidity of cancer cells enabling penetration of TNTs to the cell membrane towards disruption of membrane integrity and reorganization of cytoskeletal network. Upon penetration, TNTs dysregulated redox homeostasis followed by DNA fragmentation and apoptotic/necrotic cell death. Both TNTs exhibited haemolytic activity and rapidly activated polarization of RAW 264.7 macrophages. Throughout the whole study, TNTs-2 possessing a lower aspect ratio manifested significantly higher cytotoxic effects. Taken together, this is the first report comprehensively investigating the mechanisms underlying the nanotoxicity of bundles formed from self-organised 1-D anodic TNT layers. Except for description of nanotoxicity of industrially-interesting nanomaterials, the delineation of the nanotoxicity paradigm in cancer cells could serve as solid basis for future efforts in rational engineering of TNTs towards selective anticancer nanomedicine.

Laser-induced crystallization of anodic TiO2 nanotube layers.

In this study, crystallization of amorphous TiO2 nanotube (TNT) layers upon optimized laser annealing is shown. The resulting anatase TNT layers do not show any signs of deformation or melting. The crystallinity of the laser annealed TNT layers was investigated using X-ray diffraction, Raman spectroscopy, and high-resolution transmission electron microscopy (HRTEM). The study of the (photo-)electrochemical properties showed that the laser annealed TNT layers were more defective than conventional TNT layers annealed in a muffle oven at 400 °C, resulting in a higher charge recombination rate and lower photocurrent response. However, a lower overpotential for hydrogen evolution reaction was observed for the laser annealed TNT layer compared to the oven annealed TNT layer.

Ti3+ doped anodic single-wall TiO2 nanotubes as highly efficient photocatalyst

In this work, a two-step treatment of TiO2 nanotube (TNT) layers towards enhanced photocatalytic performance is presented. TNT layers with a thickness of ∼7 μm and an average inner diameter of ∼190 nm were prepared via electrochemical anodization of Ti foil in a fluoride containing ethylene glycol-based electrolyte. To improve the photocatalytic activity of the produced TNT layers a two-step post-treatment was conducted. First, the inner shell of the native double-wall TNT layers was removed via a mild pre-annealing followed by a selective etching treatment of the inner shell in piranha solution yielding single-wall TNT layers. Second, reduction via annealing in H2/Ar atmosphere was performed. The resulting Ti3+ doped single-wall TNT layers possess 100% enhancement of photocatalytic activity compared to their non-treated counterparts.

Self-organized TiO2 nanotube layer on Ti–Nb–Zr alloys: growth, characterization, and effect on corrosion behavior

Ti alloys are widely applied in implanted biomedical devices due to their unique mechanical and biological performances. A strategy employed to improve bone integration on orthopedic and dental implants is to grow a self-organized TiO2 nanotube layer on the surface of titanium alloy implants. This paper describes the formation of self-organized TiO2 nanotubes on Ti–35Nb–2Zr and Ti–35Nb–4Zr alloys by the anodization process, as well as the effects of Zr content on TiO2 phase stability. The morphological and chemical characteristics of the nanotubes were analyzed by scanning electron microscopy, X-ray diffraction, and X-ray photoelectron microscopy. In addition, a comparison was made of the electrochemical stabilities of TiO2 nanotube-coated surfaces and surfaces without nanotubes, which revealed higher corrosion resistance for the nanotube-modified surface. The electrochemical impedance spectroscopy results were fitted with two-time constant equivalent circuit representing the barrier layer (nanotube bottom) and the porous layer (nanotube wall). The addition of Zr suppressed ω-phase formation, preserving the alloy’s low elastic modulus (64 GPa). This Zr addition also delayed the anatase-to-rutile transformation and slightly increased the nanotubes’ length to 1.14 µm. These features make the Ti–35Nb–4Zr alloy a very good candidate for use in the biomedical field, especially for applications that require low elastic modulus with enhanced corrosion resistance.

Model for Formation of Self-Ordered Anodic Oxide Nanomaterials

Porous anodic films are self-organized porous oxides nanomaterials formed by electrochemical oxidation. Pores in porous alumina and nanotubes in TiO2nanotube layers initiate after an initial stage of barrier oxide growth. The porous film eventually evolves into a hexagonally-ordered array of parallel cylindrical pores or nanotubes of order 10-100 nm diameter with a characteristic spacing that scales directly with the cell voltage. We explore the roles of mechanical stress and oxide flow in self-ordering, through a modeling analysis of stress-driven viscous flow of oxide (1-3). The model is based on coupled viscous flow of oxide and stress- and electric field-driven migration of metal and oxygen ions (1). Stress at the film interfaces is generated by ion-transfer processes and relaxed by viscous flow, resulting in layers with elevated compressive or tensile stress within a few nm of the interfaces (2,3). Experimental evidence for these layers has been found from in situ stress measurements (2-4). We present linear stability analysis incorporating the surface stress boundary conditions in the coupled oxide flow-electrical migration model of Houser and Hebert (1). The calculations reveal self-organized pattern formation with steady-state pore spacing-voltage scaling ratios that compare favorably to those found experimentally, for both porous alumina and TiO2nanotube layers. The scaling ratios are independent of oxide viscosity or uncertainties in the values of any other model parameters. In the case of Al anodization, oxide flow resulting in pore patterns is driven by elevated stress near the oxide-solution interface, through a mechanism that has common features with the Marangoni instability in thin liquid films. Stress near the oxide surface is produced because strong electrolyte anion adsorption suppresses oxide growth on the surface. Such near-surface stress is not present in TiO2nanotube layers (5). Instead, compressive stress driving flow arises at the metal-oxide interface from the volume change upon conversion of metal to oxide. REFERENCES J. E. Houser and K. R. Hebert, Nature Mater., 8, 415 (2009).K. R. Hebert, P. Mishra, J. Electrochem. Soc., 165, E737 (2018).K. R. Hebert, P. Mishra, J. Electrochem. Soc., 165, E744 (2018).Ö. Ö. Çapraz, P. Shrotriya, P. Skeldon, G. E. Thompson, K. R. Hebert, Electrochim. Acta, 167, 404 (2015). Q. Dou, P. Shrotriya, W. F. Li, K. R. Hebert, Electrochim. Acta, 295, 418 (2019).