Ti Foil Substrate Research Articles

Deeper Insights into the Morphology Effect of Na2Ti3O7 Nanoarrays on Sodium-Ion Storage.

Na2Ti3O7-based anodes show great promise for Na+ storage in sodium-ion batteries (SIBs), though the effect of Na2Ti3O7 morphology on battery performance remains poorly understood. Herein, hydrothermal syntheses is used to prepare free-standing Na2Ti3O7 nanosheets or Na2Ti3O7 nanotubes on Ti foil substrates, with the structural and electrochemical properties of the resulting electrodes explored in detail. Results show that the Na2Ti3O7 nanosheet electrode (NTO NSs) delivered superior performance in terms of reversible capacity, rate capability, and especially long-term durability in SIBs compared to its nanotube counterpart (NTO NTs). Electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) investigations, combined with density functional theory calculations, demonstrated that the flexible 2D Na2Ti3O7 nanosheets are mechanically more robust than the rigid Na2Ti3O7 nanotube arrays during prolonged battery cycling, explaining the superior durability of the NTO NSs electrode. This work prompts the use of anodes based on Na2Ti3O7 nanosheets in the future development of high-performance SIBs.

Glucose detection via photoelectrochemical sensitivity of 3D CuO-TiO2 heterojunction nanotubes/Ti combined with chemometric tools

High sensitivity and low detection limit are important targets for biosensors. Using 3D hydrogen titanate nanotubes/Ti as precursor, CuO-TiO2 heterojunction nanotubes/Ti (CuO-TiO2NTs/Ti) photoelectrode was prepared to fabricate photoelectrochemical (PEC) glucose sensor. The prominent Ti foil substrate, 3D mesoporous structure, and CuO-TiO2 heterojunction of this PEC sensor can effectively improve the separation efficiency of charge carriers, facilitate electron transfer, and generate strong photoelectronic signals. Under visible light irradiation, the CuO-TiO2NTs/Ti electrode exhibited high sensitivity, low LOD, and good selectivity. Through density functional theory simulation, the enhanced electron-hole separation and improved PEC properties were illuminated in the CuO-TiO2 heterojunction. Associated with chemometric tools, the accuracy of the sensitivity was significantly improved, which could enhance the practical application capability of PEC biosensors.

Hydrous RuO2 film synthesized in an alkali-assisted steam thermal reactor: Low temperature synthesis and pseudocapacitance

The method of preparing RuO2 thin film by decomposing RuCl3 precursor in steam has shown a potential of having lower temperature and higher capacitance in our previous research work. We have further improved the method of thermal decomposition in steam in our previous work and proposed the alkali-assisted steam thermal reactor (AASTR) method, which has achieved the synthesis of RuO2 thin film with a capacitance of 514 F·g−1 at a low temperature of 150 °C. In the AASTR method, a concentrated sodium hydroxide solution is chosen and placed at the bottom of the reactor. The Ti foil substrates are placed in the vapor phase and do not contact the sodium hydroxide solution. The sodium hydroxide solution is employed to absorb hydrogen chloride generated in the hydrolysis process of RuCl3 and thus promotes the hydrolysis process. As a result, thermal decomposition at a lower temperature (around 150 °C, the critical crystallization temperature) becomes possible due to the modified hydrolysis process. The film exhibits an almost ideal surface controlled pseudocapacitive performance due to its low charge transfer resistance in the charge/discharge process. Therefore, the AASTR method has promising applications in low-temperature synthesis of other hydrous metallic oxides.

The Impact of Side-Selective Laser Tailoring of Titania Nanotubes on Changes in Photoelectrocatalytic Activity

Over the last few decades, titanium(IV) oxide-based materials have gained particular attention due to their stability, corrosion resistance, photocatalytic activity under UV light, and possibilities for modification. Among various structures, TiO2 nanotubes (NTs) grown on Ti foil or glass substrates and obtained through a simple anodization process are widely used as photocatalysts or photoanodes. During the anodization process, the geometry of the nanotubes (length, distribution, diameter, wall thickness, etc.) is easily controlled, though the obtained samples are amorphous. Heat treatment is required to transform the amorphous material into crystalline material. However, instead of time- and cost-consuming furnace treatment, fast and precise laser annealing is applied as a promising alternative. Nonetheless, laser treatment can result in geometry changes of TiO2 NTs, consequently altering, their electrochemical activity. Moreover, modification of the TiO2 NTs surfaces with transition metals and further laser treatment can result in materials with unique photoelectrochemical properties. In this regard, we gathered the latest achievements in the field of laser-treated titania for this review paper. We mainly focused on single structural and morphological changes resulting from pulsed laser annealing and their influence on the electrochemical properties of titania. Finally, the theoretical basis for and combination of laser- and metal-modifications and their impact on the resulting possibilities for electrochemical water splitting are also discussed.

Facile Electrodeposition and Aging to Generate 3-Dimensional α-MnO2 Battery Cathodes

Conventional tape casting forms 2-dimensional (2D) electrodes containing active material, conductive additive, and binder with restricted ion access as electrodes increase in thickness. To improve the transport properties, 3D architectures were developed using electrodeposition to ensure contact between the active material with the substrate, and provide enhanced electrolyte access. This paper investigates electrodeposition of cryptomelane (α-MnO2) as a model cathode material to efficiently accommodate (de)lithation and increase areal capacity vs conventional 2D coatings. Electodeposited samples on titantium (Ti) foil substrates were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) and show a linear increase of the average oxidation of Mn (3.5–3.8) and active mass loading (1.27–9.9 mg) with deposition and aging times (0–120 min). The initial deposition is amorphous and forms the crystalline material during the elevated temperature aging step. The active material, α-MnO2, was also deposited on C-cloth and these cathodes at deposition times of 3, 6, and 9 min deliver 9, 36, and 69% higher areal capacities, respectively, at 0.2 mA cm−2 compared to conventional 2D electrodes with a mass loading equal to the 3 min sample. These results demonstrate the benefit of α-MnO2 within a porous architecture providing enhanced transport properties.

A novel two-step strategy to fabricate phase-pure SnS photoelectrodes with tunable conductivity: formation mechanism and photoelectrochemical properties

Tin monosulfide (SnS) is a narrow band gap semiconductor for visible-light harvesting, however the easy formation of secondary phases such as Sn2S3 and SnS2 severely restricts its photoelectrochemical (PEC) properties. Herein, we propose a novel two-step strategy to fabricate phase-pure SnS photoelectrodes with tunable conductivity on Ti foil substrate and carefully investigated the formation mechanism and PEC properties. The tunable conductivity is determined by Na2SO4 pretreatment before annealing, which is supported by energy-dispersive x-ray spectroscopy, x-ray photoelectron spectroscopy, and electron paramagnetic resonance characterizations. Na+ adsorbed to the edge of the precursor SnS2 nanosheets forming a dangling bond adsorption will protect S2− against reaction with the trace oxygen in the chemical vapor deposition system within a certain temperature range (<525 °C), thereby reducing the generation of S vacancies to adjust the S/Sn ratio and further regulate the conductivity type. Moreover, the anodic photocurrent density of SnS thin films was about 0.32 mA cm−2 at 1.23 V vs reversible hydrogen electrode (RHE) with the separation and injection efficiency of 1.22% and 72.78% and a maximum cathodic photocurrent density reaching approximately −0.36 mA cm−2 at 0 V vs RHE with the separation and injection efficiency 1.15% and 5.44% respectively. The method shown in this work provides an effective approach to control the electrical conductivity of SnS thin films with considerable photocurrent response for phase-pure SnS.

Growth of dimensionally favoured TiO2 morphologies by AACVD and their recognized performance as LIB anode

The current effort aims at the morphological displays of TiO2 materials grown on Ti foil substrates using aerosol assisted chemical vapour deposition. Optimization of temperature, surfactant concentrations and substrate orientation has been found to play a vital role in the smart designing of micro/nanostructures, ranging from microspheres, nanopetals, nanospikes to the nanorods. Interestingly, when tested as LIB anode these various morphologies showed a much distinct performance and stability during charge/discharge cycles. The nanorod structures with smooth carbon covering have shown excellent reversibility followed by the nano-petals that showed an impressively stable capacity.

Implementation of Na diffusion layer at Cu2ZnSnSe4/Mo interface for flexible thin film solar cell fabricated on Ti foil by solid state selenization

A Cu2ZnSnSe4 (CZTSe) photovoltaic absorber thin films were prepared using a 2-step selenization process on a Ti substrate including a Na precursor layer and a Na-free Ti substrate, and the effect of Na on the solar cell performance was compared. A CZTSe flexible solar cell fabricated on a Ti foil substrate exhibited an efficiency of 3.06%, which was less than half that of a solar cell fabricated on a soda lime glass substrate. This was attributed to the absence of Na and severe Zn crowding near the back contact. By depositing a 100‐nm-thick sodalime glass thin film on a Ti substrate to supply Na, the efficiency increased up to 5.59%. In the Na-doped CZTSe absorber layer grown on the Ti substrate, the back crowding of Zn was eliminated and the upper part of the absorption layer was converted to a Zn-rich environment, which prevented the formation of CuZn antisite defects.

Enhancing hydrogen evolution by photoelectrocatalysis of water splitting over a CdS flowers-loaded TiO2 nanotube array film on the Ti foil substrate

This study is devoted to the scalable fabrication of a high-performance composite photocatalyst by incorporation of the visible-light-active CdS flowers (with sharp edges exposed) onto a TiO2 nanotube array (TNA) film on the Ti foil substrate. To evaluate the visible-light-harvesting performance of the prepared hierarchical architecture consisting of the CdS flowers, TNAs, and Ti foil, we subsequently assembled a photoelectrochemical (PEC) cell with membrane electrode assemblies fabricated innovatively by thermocompression. The CdS flowers can efficiently harvest the visible light energy, while TiO2 collects photoelectrons, effectively separating of the photoexcited electron-hole pairs and hence enhancing the photocatalysis efficiency in the photoelectrochemical conversion and yield of hydrogen production from water splitting. An impressive hydrogen production rate of 22.44 μmol▪h−1▪cm−2 was obtained in the PEC cell with the CdS flowers-sensitized TNA film under simulated solar light with an active irradiation area of around 42 cm2, thus showing great potential for practical applications.

Highly textured boron/nitrogen co-doped TiO2 with honeycomb structure showing enhanced visible-light photoelectrocatalytic activity

In this work, we report a novel photocatalyst based on boron and nitrogen co-doped TiO2 rutile (1 1 0) honeycomb structures. The photocatalyst has been prepared by simultaneously oxidizing and doping a Ti-foil substrate at 750 °C. The unit cell volume and the crystallite size of grown TiO2 films were measured by Rietveld refinement analysis. The co-doping by boron and nitrogen was achieved simultaneously with the oxidation of the titanium, resulting in a rutile (1 1 0) textured TiO2 film. X-ray photoelectron spectroscopy analysis revealed the presence of Ti-O-N and Ti-O-B-N bonds, and the presence of crystal defects in the lattice was detected and displayed by Raman spectroscopy. The water photo-oxidation properties have been measured as well, and the photocurrent of the B/N co-doped rutile sample prepared reached 270 µA/cm2 at 1 V under visible light and was stable in time. The efficient visible light absorption properties of the fabricated nanomaterial were attributed to the presence of oxygen vacancies and the introduction of impurity levels, as well as to synergistic effects between the introduced boron and nitrogen elements. The results presented demonstrate a new route for the preparation of TiO2 based catalysts, and open prospects for the photocatalysis community.

Ultrathin PEDOT:PSS/rGO Aerogel Providing Tape‐Like Self‐Healable Electrode for Sensing Space Electric Field with Electrochemical Mechanism

AbstractA versatile composite aerogel is developed by introducing of PEDOT:PSS in reduced graphene oxide, resulting in an ultrathin aerogel film around 100 µm thick. Like a tape, the aerogel can tightly attach to smooth or rough substrate, and there forms a self‐healable and anti‐vibration energy storage electrode. With a Ti foil substrate, the electrode offers an electrochemical capacity of 190 mF cm−2 at 0.1 mA cm−2 working current density. It also exhibits 98.7% capacitance retention after 10 000 charge/discharge cycles, with almost negligible capacitance decline even after eight damaging/healing cycles or 4000 vibrating cycles. With symmetrical aerogel‐based electrodes, a smart electrochemical device is explored as a sensor for sensitively detecting space electric field strength, ranging from 1100 to 19 000 V m−1. Simulation results verify that the response current in the sensor comes from the internal recombination current in the electrochemical device, which originates from ion recombination near the electrode substrate in space electric field. Further, a validation sensor experiment is designed and realized with affiliated modules, successfully monitoring space electric field.

Facile one-pot preparation of Ti3+, N co-doping TiO2 nanotube arrays and enhanced photodegradation activities by tuning tube lengths and diameters

Abstract Well aligned Ti3+, N co-doping TiO2 nanotube array (NTA) film on Ti foil substrate has been successfully prepared by anodic oxidation method using fluoride-based electrolyte in ethylene glycol solution with 3 vol.% H2O, followed by calcination at 400 °C for 2 h. The TiO2 NTA exhibits high UV and visible light absorption capability with a narrow band gap of 2.74 eV, which is attributed to Ti3+ self-doping, probably induced by N doping. The Ti3+ site was found to be 0.46 eV below the conduction band and the N 2p surface state is 1.04 eV above the valence band. Effects of the preparation parameters on tube lengths and diameters of the TiO2 NTAs were investigated based on series of control experiments. The photocatalytic activities of two series of Ti3+, N co-doping TiO2 NTAs with different tube lengths (similar diameter) and different diameters (similar tube length) were assessed by means of photodegradations of rhodamine B (RhB) solutions under simulated sunlight irradiation. The results show that the photocatalytic activity of the Ti3+, N co-doping TiO2 NTA can be enhanced by simply tuning the tube length and diameter in an appropriate range. The photocatalytic reaction mechanism was proposed, based on series of radical-trapping experiments. The results show that ⋅OH is the major active species for photodegradation of RhB.

TiO2 Self-Assembled, Thin-Walled Nanotube Arrays for Photonic Applications.

Two-dimensional arrays of hollow nanotubes made of TiO are a promising platform for sensing, spectroscopy and light harvesting applications. Their straightforward fabrication via electrochemical anodization, growing nanotube pillars of finite length from a Ti foil, allows precise tailoring of geometry and, thus, material properties. We theoretically investigate these photonic crystal structures with respect to reduction of front surface reflection, achievable field enhancement, and photonic bands. Employing the Rigorous Coupled Wave Analysis (RCWA), we study the optical response of photonic crystals made of thin-walled nanotubes relative to their bare Ti foil substrate, including under additional charge carrier doping which might occur during the growth process.

MOFs-derived hybrid nanosheet arrays of nitrogen-rich CoS2 and nitrogen-doped carbon for efficient hydrogen evolution in both alkaline and acidic media

Rational design of highly active, economical and stable electrocatalysts for hydrogen evolution reaction (HER) is still a great challenge for future applications. Herein, we use a 2D metal-organic framework array as the reactive template and precursor, to fabricate a hybrid nanosheet array of nitrogen-rich CoS2@nitrogen-doped carbon on Ti foil substrate (N–CoS2@NC/Ti) through a simple thermal treatment in the presence of thiourea. Owing to the prominent synergistic effect of the coupling between CoS2 and NC, a high content of Co-Nx species as well as unique nanoarray architectures, the as-synthesized N–CoS2@NC/Ti electrode exhibits remarkable activity and robust durability for HER under both acidic and alkaline conditions, which is obviously superior to the CoS2@NC/Ti.

Effects of the Structure of TiO2 Nanotube Arrays on Its Catalytic Activity for Microbial Fuel Cell.

To enhance the microbial fuel cell (MFC) for wastewater treatment and chemical oxygen demand degradation, TiO2 nanotubes arrays (TNA) are successfully synthesized on Ti foil substrate by the anodization process in HF and NH4F solution, respectively (hereafter, denoted as TNA‐HF and TNA‐NF). The differences between the two kinds of TNA are revealed based on their morphologies and spectroscopic characterizations. It should be highlighted that 3D TNA‐NF with an appropriate dimension can make a positive contribution to the high photocatalytic activity. In comparison with the TNA‐HF, the 3D TNA‐NF sample exhibits a significant enhancement in current generation as the MFC anode. In particular, the TNA‐NF performs nearly 1.23 times higher than the TNA‐HF, and near twofold higher than the carbon felt. It is found that the two kinds of TiO2‐based anodes have different conductivities and corrosion potentials, which are responsible for the difference in their current generation performances. Based on the experimental results, excellent stability, reliability, and low cost, TNA‐NF can be considered a promising and scalable MFC bioanode material.

In-situ synthesis of TiO2 nanostructures on Ti foil for enhanced and stable photocatalytic performance

TiO2 nanostructures with strong interfacial adhesion and diverse morphologies have been in-situ grown on Ti foil substrate through a multiple-step method based on conventional plasma electrolytic oxidation (PEO) technology, hydrothermal reaction and ion exchange process. The PEO process is critical to the formation of TiO2 seeding layer for the nucleation of Na2Ti3O7 and H2Ti3O7 mediates that are strongly attached to the Ti foil. An ion exchange reaction can finally lead to the formation of H2Ti3O7 nanostructures with diverse morphologies and the calcination process can turn the H2Ti3O7 nanostructures into TiO2 nanostructures with enhanced crystallinity. The morphology of the TiO2 nanostructures including nanoparticles (NP), nanowhiskers (NWK), nanowires (NW) and nanosheets (NS) can be easily tailored by controlling the NaOH concentration and reaction time during hydrothermal process. The morphology, composition and optical properties of TiO2 photocatalysts were analyzed using scanning electron microscope (SEM), X-ray diffraction (XRD), photoluminescence (PL) spectroscopy and UV–vis absorption spectrum. Photocatalytic tests indicate that the TiO2 nanosheets calcined at 500 °C show good crystallization and the best capability of decomposing organic pollutants. The decoration of Ag cocatalyst can further improve the photocatalytic performance of the TiO2 nanosheets as a result of the enhanced charger separation efficiency. Cyclic photocatalytic test using TiO2 nanostructures grown on Ti foil substrate demonstrates the superior stability in the photodegradation of organic pollutant, suggesting the promising potential of in-situ growth technology for industrial application.

Characteristics and anticorrosion performance of WSe2/TiO2 nanocomposite materials for 304 stainless steel

As a widely used corrosion-resistant material, stainless steel is still prone to pitting corrosion in marine environments where many Cl− and microorganisms are present. These potential hazards directly affect the service life of metal structures. Thus, it is necessary to take measures to protect stainless steel in the marine environment. In this paper, WSe2/TiO2 nanocomposite films were fabricated on Ti foil substrates via anodic oxidation and electrochemical deposition. The morphology, crystalline phase and optical characteristics of the WSe2/TiO2 nanocomposites were examined by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and UV–vis diffuse reflectance spectroscopy. The photocathodic protection performance of the nanocomposite photoanodes for 304 stainless steel (304SS) under visible-light illumination was investigated through electrochemical measurements. Under visible-light illumination, the WSe2/TiO2 nanocomposite films showed stronger photoresponse properties and better photocathodic protection performances for 304SS than pure TiO2 nanotube films.

Formation mechanism of the rutile-phase of TiO2 nanorods on Ti foil substrate by gel-calcination method

A formation mechanism that leads to the synthesis of rutile-phase TiO2 nanorods at high temperatures on Ti foil by NaOH-based gel-calcination is discussed based on a series of experimental investigations. TiO2 nanostructures are prepared on Ti foil following two steps, namely gelation and calcination. It is shown that the use of an alkali-based solution during gelation, such as NaOH and KOH, leads to the formation of faceted TiO2 nanorods upon calcination at high temperature (~800 °C). When an acidic solution that does not contain an alkali element, such as H2O2, is used during gelation, the shape of the nanostructures upon calcination at high temperature does not display the faceted nanorod shape. The following formation mechanism is suggested: the high temperature calcination of the Na based amorphous network of dendritic structures (formed on the Ti surface during a 24-h soak in NaOH solution) converts it into Na-titanate in the shape of nanorods. This in turn converts into nanorods of rutile-phase TiO2 when Na evaporates in the form of an oxide.

Influence of sulfurization temperature on Cu2ZnSnS4 absorber layer on flexible titanium substrates for thin film solar cells

In this study, the effect of sulfurization temperature on the morphology, composition and structure of Cu2ZnSnS4 (CZTS) thin films grown on titanium (Ti) substrates has been investigated. Since Ti foils are flexible, they were preferred as a substrate. As a result of their flexibility, they allow large area manufacturing and roll-to-roll processes. To understand the effects of sulfurization temperature on the CZTS formation on Ti foils, CZTS films fabricated with various sulfurization temperatures were investigated with several analyses including x-ray diffraction (XRD), scanning electron microscopy (SEM), x-ray photoelectron spectroscopy and Raman scattering. XRD measurements showed a sharp and intense peak coming from the (112) planes of the kesterite type lattice structure (KS), which is strong evidence for good crystallinity. The surface morphologies of our thin films were investigated using SEM. Electron dispersive spectroscopy was also used for the compositional analysis of the thin films. According to these analysis, it is observed that Ti foils were suitable as substrates for the growth of CZTS thin films with desired properties and the sulfurization temperature plays a crucial role for producing good quality CZTS thin films on Ti foil substrates.

Controllable preparation of TiO2 nanotube arrays on Ti foil substrates

ABSTRACTTiO2 nanotubes were prepared by anodic oxidation method using HF electrolyte solution and NH4F electrolyte solution on the titanium foil substrate. The morphology and crystal structures of the nanotube arrays were characterized. The structures of TiO2 nanotube arrays prepared by HF acid aqueous solution are not clear and regular. However, TiO2 nanotube arrays prepared by NH4F / organic ethylene glycol electrolyte are more orderly and clear. By controlling the composition of the electrolyte, anodic oxidation voltage and anodization time parameters, TiO2 nanotube arrays with a highly ordered and controllable process were obtained on the Ti foil substrate.