In Situ Formation of Disorder-Engineered TiO2(B)-Anatase Heterophase Junction for Enhanced Photocatalytic Hydrogen Evolution

Self-Modification of Defective TiO2 under Controlled H2/Ar Gas Environment and Dynamics of Photoinduced Surface Oxygen Vacancies

In recent years, defective TiO2 has caught considerable research attention because of its potential to overcome the limits of low visible light absorption and fast charge recombination present in pristine TiO2 photocatalysts. Among the different synthesis conditions for defective TiO2, ambient pressure hydrogenation with the addition of Ar as inert gas for safety purposes has been established as an easy method to realize the process. Whether the Ar gas might still influence the resulting photocatalytic properties and defective surface layer remains an open question. Here, we reveal that the gas flow ratio between H2 and Ar has a crucial impact on the defective structure as well as the photocatalyic activity of TiO2. In particular, transmission electron microscopy (TEM) in combination with electron energy loss spectroscopy (EELS) revealed a larger width of the defective surface layer when using a H2/Ar (50 %-50 %) gas mixture over pure H2. A possible reason could be the increase in dynamic viscosity of the gas mixture when Ar is added. Additionally, photoinduced enhanced Raman spectroscopy (PIERS) is implemented as a complementary approach to investigate the dynamics of the defective structures under ambient conditions which cannot be effortlessly realized by vacuum techniques like TEM.

Heterophase Polymorph of TiO2 (Anatase, Rutile, Brookite, TiO2 (B)) for Efficient Photocatalyst: Fabrication and Activity

TiO2 exists naturally in three crystalline forms: Anatase, rutile, brookite, and TiO2 (B). These polymorphs exhibit different properties and consequently different photocatalytic performances. This paper aims to clarify the differences between titanium dioxide polymorphs, and the differences in homophase, biphase, and triphase properties in various photocatalytic applications. However, homophase TiO2 has various disadvantages such as high recombination rates and low adsorption capacity. Meanwhile, TiO2 heterophase can effectively stimulate electron transfer from one phase to another causing superior photocatalytic performance. Various studies have reported the biphase of polymorph TiO2 such as anatase/rutile, anatase/brookite, rutile/brookite, and anatase/TiO2 (B). In addition, this paper also presents the triphase of the TiO2 polymorph. This review is mainly focused on information regarding the heterophase of the TiO2 polymorph, fabrication of heterophase synthesis, and its application as a photocatalyst.

Construction of TiO2(B)/Anatase Heterophase Junctions via a Water-Induced Phase Transformation Strategy for Enhanced Photocatalytic Hydrogen Production

The development of facile and green solution-phase routes toward the fabrication of TiO₂-based heterophase junctions with a delicate control of phase and structure is a challenging task. Herein, we report a simple and convenient method to controllably fabricate TiO₂(B)/anatase heterophase junctions, which was successfully realized by utilizing the ideal great solvent of water to treat the presynthesized TiO₂(B) nanosheet precursor at a low temperature of 80 °C. On the basis of phase structure transformation and morphology evolution data, the formation of these TiO₂(B)/anatase heterophase junctions was reasonably explained by a novel water-induced TiO₂(B) → anatase phase transformation mechanism. Benefiting from the desirable structural and photoelectronic advantages of more exposed active sites, enhanced light absorbance, and promoted separation of photogenerated electron-hole pairs, the thus-transformed TiO₂(B)/anatase heterophase junctions exhibit fascinating photocatalytic performance in water splitting. Specifically, with the help of Pt as a cocatalyst and methanol as a sacrificial agent, the H₂ production rate of optimized TiO₂(B)/anatase heterophase junction reaches 6.92 mmol·g^-1·h^-1, which is almost 7.1 and 2.1 times higher than those of the pristine TiO₂(B) nanosheets and the final anatase nanocrystals. More interestingly, the TiO₂(B)/anatase heterophase junction also delivers prominent activity toward pure water splitting to simultaneously produce H₂ and H₂O₂, with evolution rates of up to 1.10 and 0.55 mmol·g^-1·h^-1, respectively. Our work may advance the facile green solvent-mediated synthesis of metal oxide-based heterophase junctions for applications in energy- and environmental-related areas.

Electronic Structure, Optical and Magnetic Properties of Oxygen-Deficient Gray TiO2–δ(B)

The gray-colored oxygen-deficient TiO2–δ(B) nanobelts have been synthesized through a combination of the hydrothermal method followed by an ion exchange process and vacuum annealing. Electron paramagnetic resonance reveals an existence of F-centers in the form of electron-trapped oxygen vacancies within the anionic sublattice of the gray bronze TiO2 that induces its colouration. The diffuse reflectance spectroscopy showed that the formation of oxygen vacancies into TiO2(B) significantly increases its absorption intensity in both visible and near infrared ranges. The band gap of TiO2(B) with anionic defects is equal to 3.03 eV (against 3.24 eV for white TiO2(B) treated in air). Room temperature ferromagnetism associated with the defects was detected in gray TiO2–δ(B), thus indicating it belongs it to the class of dilute magnetic oxide semiconductors. It was found that in the low-temperature range (4 K), the magnetic properties of vacuum annealed TiO2(B) do not differ from those for TiO2(B) treated in air. We hope that the findings are defined here make a contribution to further progress in fabrication and manufacturing of defective TiO2-based nanomaterials for catalysis, magnetic applications, batteries, etc.

Tuning the shape and crystal phase of TiO2 nanoparticles for catalysis

Synthesis of TiO₂ nanoparticles with tunable shape and crystal phase has attracted considerable attention for the design of highly efficient heterogeneous catalysts. Tailoring the shape of TiO₂, in the crystal phases of anatase, rutile, brookite and TiO₂(B), allows tuning of the atomic configurations on the dominantly exposed facets for maximizing the active sites and regulating the reaction route towards a specific channel for achieving high selectivity. Moreover, the shape and crystal phase of TiO₂ nanoparticles alter their interactions with metal species, which are commonly termed as strong metal-support interactions involving interfacial strain and charge transfer. On the other hand, metal particles, clusters and single atoms interact differently with TiO₂, because of the variation of the electronic structure, while the surface of TiO₂ determines the interfacial bonding via a geometric effect. The dynamic behavior of the metal-titania interfaces, driven by the chemisorption of the reactive molecules at elevated temperatures, also plays a decisive role in elaborating the structure-reactivity relationship.

Preparation of carbon-coated brookite@anatase TiO2 heterophase junction nanocables with enhanced photocatalytic performance

One-dimensional TiO2@C nanocables with a heterophase junction have been successfully prepared by coating brookite@anatase TiO2 with a thin layer of hydrothermal carbon (HTC). Compared with anatase TiO2, the biphase brookite@anatase structure can reduce the recombination rate of the excited electron/hole pairs of TiO2. The HTC coating not only enhances the adsorption capability of the TiO2 catalyst for organic pollutants but also facilitates photogenerated electron transfer to further increase its photocatalytic activity. Therefore, compared with anatase TiO2, brookite@anatase TiO2, and TiO2@C, the brookite@anatase TiO2@C shows the highest photocatalytic activity for the photodegradation of tetracycline (TC) under the irradiation of UV-visible light. Moreover, ˙O2 has been proved to be the predominant active species for the photodegradation of TC, and the photocatalytic mechanism of brookite@anatase TiO2@C nanocables has also been proposed.

On the interface crystallography of heat induced self-welded TiO2 nanofibers grown by oriented attachment

The TiO₂ (B)–TiO₂ (B), TiO₂ (B)–anatase and anatase–anatase self-welded nanofibers have been investigated by TEM. The different exposed facets lead to the formation of different interface structures during the oriented attachment growth process.

Synthesis of Mesoporous TiO2-B Nanobelts with Highly Crystalized Walls toward Efficient H2 Evolution

Mesoporous TiO2 is attracting increasing interest due to properties suiting a broad range of photocatalytic applications. Here we report the facile synthesis of mesoporous crystalline TiO2-B nanobelts possessing a surface area as high as 80.9 m2 g-1 and uniformly-sized pores of 6-8 nm. Firstly, P25 powders are dissolved in NaOH solution under hydrothermal conditions, forming sodium titanate (Na2Ti3O7) intermediate precursor phase. Then, H2Ti3O7 is successfully obtained by ion exchange through acid washing from Na2Ti3O7 via an alkaline hydrothermal treatment. After calcination at 450 °C, the H2Ti3O7 is converted to a TiO2-B phase. At 600 °C, another anatase phase coexists with TiO2-B, which completely converts into anatase when annealed at 750 °C. Mesoporous TiO2-B nanobelts obtained after annealing at 450 °C are uniform with up to a few micrometers in length, 50-120 nm in width, and 5-15 nm in thickness. The resulting mesoporous TiO2-B nanobelts exhibit efficient H2 evolution capability, which is almost three times that of anatase TiO2 nanobelts.

Mini Review of TiO2 -Based Multifunctional Nanocomposites for Near-Infrared Light-Responsive Phototherapy

Phototherapy with the properties of specific spatial/temporal selectivity and minimal invasiveness has been acknowledged as one of the most promising cancer therapy types. Among all the photoactive substance for phototherapy, titanium dioxide (TiO₂ ) nanomaterials are paid more and more attention due to their outstanding photocatalytic properties, prominent biocompatibility, and excellent chemical stability. However, the wide bandgap (3.0-3.2 eV) of TiO₂ limits its absorption only to the ultraviolet (UV) light region. For a long time, UV light-stimulated TiO₂ was applied in the phototherapy researches of tumors located in the skin layer, while it is unsatisfactory for most deep-tissue tumors. Due to the maximum penetration into tissue existing in the near-infrared (NIR) region, how to use NIR light to trigger photochemical reaction of TiO₂ remains a big challenge. In this review, two strategies to develop and construct NIR-triggered TiO₂ -based nanocomposites (NCs) for phototherapy are summarized, and the relevant mechanism and background knowledge of TiO₂ -based phototherapy are also given in order to better understand the application value and current situation of TiO₂ in phototherapy. Finally, the challenges and research directions of TiO₂ in the future clinic phototherapy application are also discussed.

Revealing the Relationship between Photocatalytic Properties and Structure Characteristics of TiO2 Reduced by Hydrogen and Carbon Monoxide Treatment

Reduction is considered to be an effective method to improve the photocatalytic activity of TiO₂ ; however, the underlying relationship between structure and photocatalytic performance has not been adequately unveiled to date. To obtain insights into the effect of structure on photocatalytic activity, two types of reduced TiO₂ were prepared from CO (CO-TiO₂ ) and H₂ (H-TiO₂ ). For H-TiO₂ , Ti-H bonds and oxygen vacancies are formed on the surface of H-TiO₂ , which results in a more disordered surface lattice. However, for CO-TiO₂ , more Ti-OH bonds are formed on the surface and more bulk oxygen vacancies are introduced; the disorder layer of CO-TiO₂ is relatively thin, owing to most surface vacancies being filled by Ti-OH bonds. Under simulated solar irradiation, the photocatalytic H₂ evolution rate of CO-TiO₂ reaches 7.17 mmol g^-1  h^-1 , which is 4.14 and 1.50 times those of TiO₂ and H-TiO₂ , respectively. The photocatalytic degradation rate constant of methyl orange on CO-TiO₂ is 2.45 and 6.39 times those on H-TiO₂ and TiO₂ . The superior photocatalytic activity of CO-TiO₂ is attributed to the effective separation and transfer of photogenerated electron-hole pairs, due to the synergistic effects of oxygen vacancies and surface Ti-OH bonds. This study reveals the relationship between the photocatalytic properties and structure, and provides a new method to prepare highly active TiO₂ for H₂ production and environmental treatment.

Defect-engineered TiO2 Hollow Spiny Nanocubes for Phenol Degradation under Visible Light Irradiation

Herein, we mainly report a strategy for the facile synthesis of defect-engineered F-doped well-defined TiO2 hollow spiny nanocubes, constructed from NH4TiOF3 as precursor. The topological transformation of NH4TiOF3 mesocrystal is accompanied with fluorine anion releasing, which can be used as doping source to synthesize F-doped TiO2. Our result shows that the introduction of oxygen vacancies (Vo's) and F dopant can be further achieved by a moderate photoreduction process. The as prepared sample is beneficial to improve photocatalystic degradation and Photoelectrochemical (PEC) efficiency under visible light irradiation. And this improvement in photocatalytic and photoelectrocatalytic performance can be ascribed to the significant enhancement of visible light absorption and separation of excited charges resulted from the presence of oxygen vacancies, F- ions and hollow structure of TiO2.

Improved Stability of Atomic Layer Deposited Amorphous TiO2 Photoelectrode Coatings by Thermally Induced Oxygen Defects

Amorphous titanium dioxide (a-TiO₂) combined with an electrocatalyst has shown to be a promising coating for stabilizing traditional semiconductor materials used in artificial photosynthesis for efficient photoelectrochemical solar-to-fuel energy conversion. In this study we report a detailed analysis of two methods of modifying an undoped thin film of atomic layer deposited (ALD) a-TiO₂ without an electrocatalyst to affect its performance in water splitting reaction as a protective photoelectrode coating. The methods are high-temperature annealing in ultrahigh vacuum and atomic hydrogen exposure. A key feature in both methods is that they preserve the amorphous structure of the film. Special attention is paid to the changes in the molecular and electronic structure of a-TiO₂ induced by these treatments. On the basis of the photoelectrochemical results, the a-TiO₂ is susceptible to photocorrosion but significant improvement in stability is achieved after heat treatment in vacuum at temperatures above 500 °C. On the other hand, the hydrogen treatment does not increase the stability despite the ostensibly similar reduction of a-TiO₂. The surface analysis allows us to interpret the improved stability to the thermally induced formation of O^- species within a-TiO₂ that are essentially electronic defects in the anionic framework.

Hierarchical Nanotubular Anatase/Rutile/TiO2(B) Heterophase Junction with Oxygen Vacancies for Enhanced Photocatalytic H2 Production

Oxygen vacancies have been demonstrated to enhance the interfacial charge separation in TiO₂-based photocatalysts. In this report, we explored a facile route to synthesize hierarchical nanotubular anatase/rutile/TiO₂(B) nanostructures with high surface area and defective electronic structure. The formation of oxygen vacancies in the heterophase junction was analyzed by UV-vis absorption spectra, electron spin resonance, and X-ray photoelectron spectroscopy. The enhanced interfacial charge separation and transportation ensured the excellent photoactivity of oxygen-deficient junctions for the photocatalytic production of hydrogen. As a result, the defective anatase/rutile/TiO₂(B) junction showed a high hydrogen evolution rate of 2.79 mmol/h, which was 19 times higher than blank TiO₂ nanotubes. The results demonstrate that defect modulation is a powerful tool to enhance the catalytic performances of TiO₂-based photocatalysts.

Engineering surface defects and metal–support interactions on Pt/TiO2(B) nanobelts to boost the catalytic oxidation of CO

The thermally reduced Pt/TiO₂(B) catalysts show high catalytic activity and good water resistance for the catalytic oxidation of CO.

Highly Performance Core-Shell TiO2(B)/anatase Homojunction Nanobelts with Active Cobalt phosphide Cocatalyst for Hydrogen Production

In this paper, a highly efficient core-shell structure of TiO2(B)/anatase photocatalyst with CoP cocatalyst has been synthesized via hydrothermal processes and a mechanical milling method. The designed core-shell TiO2(B)/anatase photocatalysts exhibit excellent performance by compared with pure TiO2(B) and anatase phase. With the participation of CoP particles, there is drastically enhanced  photocatalytic activity of TiO2(B)/anatase, and the H2-production rate can be up to 7400 μmol·g-1, which is about 3.2 times higher than TiO2(B)/anatase photocatalyst. The improved activity is attributed to the contribution of the well-matched core-shell structure and cooperative effect of CoP cocatalyst. The photogenerated holes of anatase can migrate more promptly to the adjacent TiO2(B) core than the photogenerated electrons, which result in an accumulation of electrons in the anatase, and CoP nanoparticles can contribute significantly to transferring electrons from the surface of TiO2(A). It was found that the efficient separation of electron-hole pairs greatly improved the photocatalytic hydrogen evolution in water under UV light irradiation.

Ultrathin TiO2(B) Nanosheets as the Inductive Agent for Transfrering H2O2 into Superoxide Radicals

A reflux method to synthesize ultrathin polycrystalline TiO₂(B) nanosheets (NSs) which are assembled by single crystals, and further stacked into nanoflower structures, is described. On the basis of the theoretical calculations and experiments, H₂O₂ can easily substitute the ethylene glycol adsorbed on the surface of TiO₂(B) NSs, forming H₂O₂-NS due to the lower adsorption energy and the unique structural features of ultrathin TiO₂(B) nanosheets. TiO₂(B) NSs and the H₂O₂ system can be accelerated to generate superoxide radicals under heat or light and thus exhibit a great degradation property on dye molecules; the total organic carbon (TOC) removal rate was 6 times higher than that for H₂O₂ alone. Meanwhile, TiO₂(B) NSs and the H₂O₂ system have a good application on the selective oxidation due to the reactive species of superoxide radicals avoiding overoxidization of benzyl alcohol. The conversion of benzyl alcohol oxidized to benzaldehyde in water solution under low temperature and atmospheric pressure was 51.13%, while the selectivity was close to 100%. We believe that the present findings will provide valuable methods for highly efficient generation of superoxide radicals and broaden their applications in catalysis.

Synthesis, properties, and applications of black titanium dioxide nanomaterials

Photocatalysis has been regarded as one of best solutions to using the sunlight to produce hydrogen from water and to removing organic pollutants from the environment, and titanium dioxide (TiO₂) nanomaterials have been treated as the primary photocatalyst for these purposes. However, their large band gap has largely limited the activity to the UV region of the solar spectrum. The discovery of black TiO₂ in 2011 has triggered world-wide research interests with new hope to overcome this problem. This review briefly summarizes the recent progresses of black TiO₂ nanomaterials, including their synthesis, properties and applications, to provide a timely update and to inspire more ideas in the related research.

Black TiO2 nanobelts/g-C3N4 nanosheets Laminated Heterojunctions with Efficient Visible-Light-Driven Photocatalytic Performance

Black TiO₂ nanobelts/g-C₃N₄ nanosheets laminated heterojunctions (b-TiO₂/g-C₃N₄) as visible-light-driven photocatalysts are fabricated through a simple hydrothermal-calcination process and an in-situ solid-state chemical reduction approach, followed by the mild thermal treatment (350 °C) in argon atmosphere. The prepared samples are evidently investigated by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, N₂ adsorption, and UV-visible diffuse reflectance spectroscopy, respectively. The results show that special laminated heterojunctions are formed between black TiO₂ nanobelts and g-C₃N₄ nanosheets, which favor the separation of photogenerated electron-hole pairs. Furthermore, the presence of Ti³⁺ and g-C₃N₄ greatly enhance the absorption of visible light. The resultant b-TiO₂/g-C₃N₄ materials exhibit higher photocatalytic activity than that of g-C₃N₄, TiO₂, b-TiO₂ and TiO₂/g-C₃N₄ for degradation of methyl orange (95%) and hydrogen evolution (555.8 μmol h^-1g^-1) under visible light irradiation. The apparent reaction rate constant (k) of b-TiO₂/g-C₃N₄ is ~9 times higher than that of pristine TiO₂. Therefore, the high-efficient laminated heterojunction composites will have potential applications in fields of environment and energy.

In situ growing Bi2MoO6 on g-C3N4 nanosheets with enhanced photocatalytic hydrogen evolution and disinfection of bacteria under visible light irradiation

Bi₂MoO₆/g-C₃N₄ heterojunctions were fabricated by an in situ solvothermal method using g-C₃N₄ nanosheets. The photocatalytic activities of as-prepared samples were evaluated by hydrogen evolution from water splitting and disinfection of bacteria under visible light irradiation. The results indicate that exfoliating bulk g-C₃N₄ to g-C₃N₄ nanosheets greatly enlarges the specific surface area and shortens the diffusion distance for photogenerated charges, which could not only promote the photocatalytic performance but also benefit the sufficient interaction with Bi₂MoO₆. Furthermore, intimate contact of Bi₂MoO₆ (BM) and g-C₃N₄ nanosheets (CNNs) in the BM/CNNs composites facilitates the transfer and separation of photogenetrated electron-hole pairs. 20%-BM/CNNs heterojunction exhibits the optimal photocatalytic hydrogen evolution as well as photocatalytic disinfection of bacteria. Furthermore, h⁺ was demonstrated as the dominant reactive species which could make the bacteria cells inactivated in the photocatalytic disinfection process. This study extends new chance of g-C₃N₄-based photocatalysts to the growing demand of clean new energy and drinking water.

One-dimensional TiO2 Nanotube Photocatalysts for Solar Water Splitting

Hydrogen production from water splitting by photo/photoelectron-catalytic process is a promising route to solve both fossil fuel depletion and environmental pollution at the same time. Titanium dioxide (TiO2) nanotubes have attracted much interest due to their large specific surface area and highly ordered structure, which has led to promising potential applications in photocatalytic degradation, photoreduction of CO2, water splitting, supercapacitors, dye-sensitized solar cells, lithium-ion batteries and biomedical devices. Nanotubes can be fabricated via facile hydrothermal method, solvothermal method, template technique and electrochemical anodic oxidation. In this report, we provide a comprehensive review on recent progress of the synthesis and modification of TiO2 nanotubes to be used for photo/photoelectro-catalytic water splitting. The future development of TiO2 nanotubes is also discussed.

Ti3+ Self-Doped Blue TiO2(B) Single-Crystalline Nanorods for Efficient Solar-Driven Photocatalytic Performance

Ti³⁺ self-doped blue TiO₂(B) single-crystalline nanorods (b-TR) are fabricated via a simple sol-gelation method, cooperated with hydro-thermal treatment and subsequent in situ treatment method, and afterward annealed at 350 °C in Ar. The structures are characterized by X-ray diffraction (XRD), Raman, X-ray photoelectron spectroscopy (XPS), diffuse reflectance spectroscopy (UV-vis), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The prepared b-TR with narrow band gap possesses single-crystalline TiO₂(B) phase, Ti³⁺ self-doping, and one-dimensional (1D) rodlike nanostructure. In addition, the improved photocatalytic performance is studied by decomposition of Rhodamine B (RhB) and hydrogen evolution. The degradation rate of RhB by Ti³⁺ self-doped blue TiO₂(B) single-crystalline nanorods is ∼6.9- and 2.1-times higher compared with the rates of titanium dioxide nanoparticles and pristine TiO₂(B) nanorods under visible light illumination, respectively. The hydrogen evolution rate of b-TR is 26.6 times higher compared with that of titanium dioxide nanoparticles under AM 1.5 irradiation. The enhanced photocatalytic performances arise from the synergetic action of the special TiO₂(B) phase, Ti³⁺ self-doping, and the 1D rod-shaped single-crystalline nanostructure, favoring the visible light utilization and the separation and transportation of photogenerated charge carriers.

Hydrogenated Cagelike Titania Hollow Spherical Photocatalysts for Hydrogen Evolution under Simulated Solar Light Irradiation

We synthesized the hydrogenated cagelike TiO2 hollow spheres through a facile sacrificial template method. After the hydrogenation treatment, the disordered surface layer and cagelike pores were generated on the shell of the hollow spheres. The spheres exhibit a high hydrogen evolution rate of 212.7 ± 10.6 μmol h(-1) (20 mg) under the simulated solar light irradiation, which is ∼12 times higher than the hydrogenated TiO2 solid spheres and is ∼9 times higher than the original TiO2 hollow spheres. The high activity results from the unique architectures and hydrogenation. Both the multiple reflection that was improved by the cagelike hollow structures and the red shift of the absorption edge that was induced by hydrogenation can enhance the ultraviolet and visible light absorption. In addition, the high concentration of oxygen vacancies, as well as the hydrogenated disordered surface layer, can improve the efficiency for migration and separation of generated charge carriers.

Enhanced Photoelectrochemical Performance from Rationally Designed Anatase/Rutile TiO2 Heterostructures

In a photoelectrochemical (PEC) cell for water splitting, the critical issue is charge separation and transport, which is usually completed by designing semiconductor heterojunctions. TiO2 anatase-rutile mixed junctions could largely improve photocatalytic properties, but impairs PEC water splitting performance. We designed and prepared two types of TiO2 heterostructures with the anatase thin film and rutile nanowire phases organized in different sequences. The two types of heterostructures were used as PEC photoanodes for water splitting and demonstrated completely opposite results. Rutile nanowires on anatase film demonstrated enhanced photocurrent density and onset potential, whereas strong negative performance was obtained from anatase film on rutile nanowire structures. The mechanism was investigated by photoresponse, light absorption and reflectance, and electrochemical impedance spectra. This work revealed the significant role of phase sequence in performance gain of anatase-rutile TiO2 heterostructured PEC photoanodes.

Single crystal forms induced diverse interface structures in TiO2 (B)/anatase dual-phase nanocomposites

Two types of TiO₂ (B) single crystal forms (SCF) and the induced TiO₂ (B)/anatase interfaces with different orientation relationships are investigated by TEM. The dominated (001} SCF is confirmed to reveal larger nanotunnels at the interface which suggests an enhanced Li⁺ transport properties.