Mixed-phase TiO2 Research Articles

Highly efficient wurtzite/zinc blende CdS visible light photocatalyst with high charge separation efficiency and stability.

Mixed phase TiO2 (Degussa P25) exhibits superior photocatalytic performance and stability due to the formation of the hetero-phase junction between anatase and rutile. However, the large bandgap limits its visible light activity. CdS is a photocatalyst with a broad light absorption band up to 550 nm. Constructing a hetero-phase junction will greatly promote the photocatalytic activity of CdS. In this work, the one-step solvothermal method was used to synthesize CdS hetero-phase junction with both hexagonal wurtzite (WZ) and cubic zinc blende (ZB) phases. The ratio of WZ and ZB phases can be tuned by adjusting the solvent ratio and reaction time to construct type I junction and effectively separate the photogenerated electron-hole pair. Under visible-light illumination, the optimal photocatalytic activity of the prepared material reaches 7.96 mmol h-1 g-1, and the quantum efficiency is 36.7% at 420 nm, which is three times higher than that of any single-phase sample (cubic or hexagonal phase) and maintains high photocatalytic stability as well. It is expected that this work will provide a feasible prospect for the practical application of high-efficiency homogeneous junction photocatalysts.

Phase evolution, morphological, optical and electrical properties of femtosecond pulsed laser deposited TiO2 thin films

In this paper, we report anatase and rutile titanium oxide (TiO2) nanoparticulate thin films fabricated on silica and Indium Tin Oxide (ITO) substrates using femtosecond pulsed laser deposition (fs-PLD). Depositions were carried-out at substrate temperatures of 25 °C, 400 °C and 600 °C from anatase and rutile phase target materials. Effect of substrate temperature on the surface morphology, microstructural, optical, and electrical properties of these films were systematically investigated by using various range of measurements such as scanning electron microscopy, (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, Ultraviolet–visible-near infrared (UV–Vis–NIR) spectroscopy, and Hall Effect measurements. It is observed that the TiO2 thin films surface are predominated with nanoparticulates of diameter less 35 nm, which constitute about ~ 70%; while the optical bandgaps and electrical resistivity decrease with increasing substrate temperature. A mixed-phase (anatase/rutile) TiO2 thin film was produced at a substrate temperature of 400 °C when samples are fabricated with anatase and rutile target materials. The results of this study indicate that the structural and crystallinity, optical, and electrical properties can be controlled by varying fs-PLD process parameters to prepare TiO2 thin films, which are suitable for applications in photovoltaics, solar cells, and photo-catalysis.

Fabrication of hydroxyl group-enriched mixed-phase TiO2 nanoflowers consisting of nanoflakes for efficient photocatalytic activity

We present hydrothermal fabrication of hydroxyl group-rich mixed-phase TiO2 nanoflowers (surface area ~ 252 m2/g) (MTNF) and their tremendous sunlight-induced photodegradation nature for methylene blue (MB), methyl orange (MO), rhodamine 6G (R6G), and oxytetracycline hydrochloride (OTC-HCl) molecules. The morphology of MTNF has been confirmed through the transmission electron microscope and scanning electron microscope studies. Microscopy studies reveal that each flower-like nanostructures formed by the assembly of nanoflakes. X-ray diffraction and Raman studies confirm the presence of mixed (anatase/rutile) phase of TiO2. The optical behavior of MTNF is explored by the UV-visible diffuse reflectance spectroscopy (UV-DRS) and photoluminescence spectroscopy (PL). Urbach energy calculation indicates the appearance of oxygen-related defects which are further assured by the PL studies. Existence of the hydroxyl group over the surface of MTNF is confirmed through Fourier transform infrared spectroscopy studies. Adsorption study results show the higher tendency of MTNF to adsorb the MB dye molecules as compared to R6G and MO dye molecules due to the presence of hydroxyl group and effective high surface area. Sunlight-driven photodegradation activity of MTNF was demonstrated by the decoloration of MB, MO, R6G, and OTC-HCl solution. Hydroxyl group functionalized MTNF with effective surface area decomposes the 16 µM MB, 10 µM MO, 10 µM R6G, and 0.5 mg/mL OTC-HCl molecules in just 12 min, 40 min, 30 min, and 60 min, respectively. Sunlight-induced photodegradation activity of MTNF can be attributed to the combined feature of hydroxyl radicals and synergistic effects in the TiO2 nanoflower-like structures.

Solvent exfoliated graphene incorporated mixed phase TiO2 transparent photoelectrode for the efficient and color transparent dye-sensitized solar cell

Dye-Sensitized Solar Cells have emerged as solar technology for practical application as building-integrated photovoltaic (BIPV) due to low-cost processing, working ability in the ambient environment, and colour transparency. The colour transparency is inherited from the nanostructured mesoporous TiO2 and colourful dye. However, mesoporous TiO2 possesses poor electron transport properties due to multiple grain boundaries, resulting in undesirable recombination reactions that lead to the loss of photoconversion efficiency (PCE). Reduced graphene oxide (rGO) is incorporated in the TiO2 matrix to improve its electron transport properties. Nevertheless, rGO cannot give full benefit of graphene due to its defective structure, which promotes recombination. Therefore, here a solvent exfoliated high-quality graphene in mesoporous TiO2 photoelectrode having mixed phase composition anatase, rutile, and brookite phase is introduced. Graphene/TiO2 hybrid structures are produced with different graphene loading, and their structural, optical, and electron transport properties are thoroughly investigated. Electrochemical impedance spectroscopy (EIS) indicates that electron lifetime increases by 159%, electron diffusion length increases by 25%, while recombination rate reduces by 62.77% than the pure TiO2 at optimum graphene loading (0.0025 wt%). Consequently, an increase of 18.45% and 30.89% PCE is obtained relative to pure TiO2 and commercial paste, respectively.

Low temperature ionothermal synthesis of TiO 2 nanomaterials for efficient photocatalytic H 2 production, dye degradation and photoluminescence studies

The photocatalytic hydrogen generation is a novel, eco-friendly and favourable method for production of green and clean energy using light energy. In this direction, we report low-temperature ionothermal method for the preparation of TiO2 nanoparticles (NPs) using methoxy ethyl methyl imidazolium tris (pentafluoroethyl) trifluoro phosphate (MOEMINtf2) as an ionic liquid (IL) at 120°C for 1 day. The synthesized nanomaterials were examined using different spectrochemical methods like UV-DRS, XRD, FT-IR, TEM, BET and TGA-DTA techniques. The mixed phase TiO2 is obtained with 81.7% of anatase and 18.3% of rutile phase by the XRD studies, and average crystallite size is found to be ∼7 nm. The stretching of Ti-O bond (∼555 cm−1) and few other bands related to ionic liquid were confirmed by FTIR spectrum. The band gap energy was observed to be ∼3.38 eV by UV-DRS analysis. TEM images reveal spherical shape with an average particles size of about 10 nm. Photocatalytic H2 generation was carried out using TiO2 NPs and observed the generation of 553 μmol h−1 g−1 via water splitting reaction. Furthermore, the prepared TiO2 NPs employed for the photocatalytic degradation of methylene blue dye (84.54%), and photoluminescence studies confirms the obtained material can be used in optoelectronic applications with green emission.

Photocatalytic Oxidative Degradation of Carbamazepine by TiO2 Irradiated by UV Light Emitting Diode

Here, ultraviolet light-emitting diodes (UV-LED) combined with TiO2 was used to investigate the feasibility of carbamazepine (CBZ) degradation. The effects of various factors, like crystal form of the catalyst (anatase, rutile, and mixed phase), mass concentration of TiO2, wavelength and irradiation intensity of the UV-LED light source, pH of the reaction system, and coexisting anions and cations, on the photocatalytic degradation of CBZ were studied. The mixed-phase (2.8 g/L) showed the best degradation efficiency at 365 nm among three kinds of TiO2, wherein CBZ (21.1 µM) was completely oxidized within 1 h. The results of batch experiments showed that: (i) CBZ degradation efficiency under UV-LED light at 365 nm was higher than 275 nm, due to stronger penetrability of 365 nm light in solution. (ii) The degradation efficiency increased with increase in irradiation intensity and pH, whereas it decreased with increase in initial CBZ concentration. (iii) The optimal amount of mixed-phase TiO2 catalyst was 2.8 g/L and excessive catalyst decreased the rate. (iv) The co-existence of CO32−, HCO3−, and Fe3+ ions in water significantly accelerated the degradation rate of photocatalytic CBZ, whereas Cu2+ ions strongly inhibited the degradation process of CBZ. ·OH was found to be the main active species in the UV-LED photocatalytic degradation of CBZ. UV-LED is more environmentally friendly, energy efficient, and safer, whereas commercial TiO2 is economical and readily available. Therefore, this study provides a practically viable reference method for the degradation of pharmaceuticals and personal care products (PPCPs).

Synthesis of Mixed Phase nanoTiO2 particles & Their Application in Photocatalytic Water Decontamination

A green, sustainable hydrolytic precipitation process is used to synthesize different blends of intrinsically heterostructured (mixed phase) titanium dioxide (TiO2) nanoparticles (NPs). NPs are evaluated for the decontamination of organic and inorganic pollutants. The NPs are characterized for their morphological, semiconductor and photocatalytic properties. As organic compound, methyl orange was used to evaluate the mixed phase TiO2 NPs through adsorption and photo-oxidation, while selenium (IV and VI) species were the inorganic pollutants of interest, removed by adsorption and photo-reduction. A comparative assessment of photocatalytic effectiveness of different nanoTiO2 varieties is presented revealing contrasting behavior between organic and inorganic removal, while exemplifying the importance of tuning phase composition, as per intended application.

MOF-Templated Metal Oxides Sensitized with Quantum Dots Heterojunction for Efficient Solar Fuels Generation

The separation and transport of photogenerated charges carriers are two of the most crucial factors that determine the overall efficiency of photoelectrochemical (PEC) systems. Various strategies have been exploited for achieving efficient charge separation and transfer. Among them, the design of semiconductor heterojunction has been shown to be one of the most effective approaches. Metal oxides, such as TiO2, are the among the most common materials for water splitting. However, the control of phase alignment and the interface structure remains a challenge. A promising solution is to use a template approach by employing metal-organic frameworks (MOF) which are of broad interest as a new class of organic-inorganic hybrid materials and have been intensely exploited in various fields due to their unique physical and chemical properties. Furthermore, common metal oxides, such TiO2 or NiO have limited absorption of sunlight due to their large intrinsic band gap (i.e. TiO2 anatase: 3.2 eV) which hinders effective use in solar water splitting. To extend the absorption range of the MOF-templated metal oxides in the visible and near-infrared range, we employed metal chalcogenide QDs as sensitizers.In this presentation, for example, we explore a simple metal organic framework (MOF)-derived synthesis to obtain a controlled mixed-phase (anatase and rutile) of TiO2 nanoparticles, which retain the MOF crystal morphology. After sensitization with core@shell CdSe@CdS QDs, the mixed-phase TiO2 film exhibited a remarkable photocurrent of 10.72 mA/cm2 and long-term stability, with a retained value of more than 78.1% after two hours. Compared with commercial TiO2 films, the MOF-derived TiO2 film sensitized by core-shell CdSe@CdS QDs, showed an enhanced PEC device stability of +42.1% and PEC performance of +47.6%. The enhanced performance is due to the presence of mixed rutile/anatase phases, that creates a favorable band energy alignment for the separation of the photogenerated charges. The proposed photoanode based on MOF-derived metal oxide is an efficient strategy to improve the efficiency of the heterojunction-based PEC system for hydrogen generation. Furthermore, the combined use of QDs can extend the absorption range exploiting a larger part of the sun spectrum. Figure 1

Engineering the Morphology and Crystal Phase of 3 D Hierarchical TiO2 with Excellent Photochemical and Photoelectrochemical Solar Water Splitting

Owing to the unique advantages, hierarchical TiO 2 nanostructures have several advantages in solar fuel production. In this work, a single step approach has been demonstrated to control both crystal phase and morphology of TiO 2 with 3D urchin-like structure via a surfactant-free solvothermal route. The growth principle of 3D hierarchical structure with phase-engineered band-alignment, role of mixed solvent ratio H 2 O:HCl and reaction parameters are finely tuned and investigated systematically. An optimum percentage of anatase (41%) to rutile (59%) in the mixed phase TiO 2 (AR-2) shows an excellent photocatalytic H 2 generation activity of 5753 μmol g -1 after 5 h of irradiation with an apparent quantum yield of 20.9% at 366 nm and 4.5% at 420 nm. The superior performance of AR-2, attributed to efficient separation of charge carriers through phase-junction as apparent from the transient photocurrent ( i-t ) response and photoluminescence (PL) study. The 3D urchin-like pure rutile TiO 2 (R-1) composed of nanorods shows enhanced photocatalytic activity than pure anatase (A-1) and pure rutile TiO 2 nanoparticles, underlying the role of morphology. The best performing mixed phase 3D TiO 2 shows excellent durability up to 25 h and is further demonstrated to produce 3522 μmol g -1 of H 2 under natural sunlight highlighting its potential for long-term viable application.

Tunable Composition Aqueous-Synthesized Mixed-Phase TiO2 Nanocrystals for Photo-Assisted Water Decontamination: Comparison of Anatase, Brookite and Rutile Photocatalysts

Mixed-phase nanoTiO2 materials attract a lot of attention as advanced photocatalysts for water decontamination due to their intrinsic structure that allows better photo-excited e−cb-h+vb charge separation, hence improved photocatalytic efficiency. Currently, the best-known mixed-phase TiO2 photocatalyst is P25 with approximate composition 80% Anatase/20% Rutile (A/r). Apart from Anatase (A) and Rutile (R) phases, there is Brookite (B) which has been evaluated less as photocatalyst in mixed-phase nanoTiO2 systems. In this work we present a sustainable solution process to synthesize tunable composition mixed-phase nanotitania photocatalysts in a continuously stirred tank reactor (CSTR) by modulating conditions like pH, CTiCl4 and time. In particular three mixed-phase TiO2 nanomaterials were produced, namely one predominantly anatase with brookite as minor component (A/b), one predominantly brookite with minor component rutile (B/r), and one predominantly rutile with minor component brookite (R/b) and evaluated as photocatalysts in the degradation of methyl orange. The three semiconducting nanomaterials were characterized by XRD and Raman spectroscopy to quantify the phase ratios and subjected to nano-morphological characterization by FE-SEM and TEM/HR-TEM. The new mixed-phase nanoTiO2 materials are shown to be endowed with large specific surface area, ranging from 90–125 m2 g−1, double of that of P25, to be mesoporous and be surface-rich in Ti–OH molecular groups varying from 12%–20% versus 4% for P25. These properties though impact the adsorptive capacity with R/b and B/r removing > 50% of MO but not photocatalytic activity. The latter depends on nanograined mixed-phase structure and not mere assembly of different phase nanoparticles. First-order rate constants reveal essentially equivalent photocatalytic activity for anatase nanocrystals with either rutile (P25) or brookite (this work) domains.

Charge Transfer in Mixed-Phase TiO2 Photoelectrodes for Perovskite Solar Cells

In mesoscopic perovskite solar cells (PSCs) the recombination processes within the TiO2 photoelectrode and at the TiO2/perovskite interface limit power conversion efficiency. To overcome this challenge, we investigated the effect of TiO2 phase composition on the electronic structure of TiO2 photoelectrodes, as well as on PSCs performance. For this, a set of PSCs based on TiO2 thin films with different content of anatase and rutile particles was fabricated under ambient conditions. X-ray diffraction, optical spectroscopy and scanning electron microscopy were used to study the structural, morphological and optical characteristics of TiO2 powders and TiO2-based thin films. X-ray photoelectron spectroscopy (XPS) analysis of anatase revealed a cliff conduction band alignment of 0.2 eV with respect to the rutile. Energy band alignment at the anatase/rutile/perovskite interfaces deduced from the XPS data provides the possibility for interparticle electron transport from the rutile to anatase phase and the efficient blocking of electron recombination at the TiO2/perovskite interface, leading to efficient electron-hole separation in PSCs based on mixed-phase TiO2 photoelectrodes. PSCs based on TiO2 layers with 60/40 anatase/rutile ratio were characterized by optimized charge extraction and low level of recombination at the perovskite/TiO2 interface and showed the best energy conversion efficiency of 13.4% among the studied PSCs. Obtained results provide a simple and effective approach towards the development of the next generation high efficiency PSCs.

Defect-enhanced photocatalytic removal of dimethylarsinic acid over mixed-phase mesoporous TiO2

Much attention has been paid to the pollutant dimethylarsenic acid (DMA), because of its high toxicity even at very low doses. Although TiO2 photocatalytic oxidation (PCO) is one of the few effective methods for treating DMA-containing water, the efficient decomposition of DMA and simultaneous removal of toxic arsenic species remains a significant but challenging task. Here, defective mesoporous TiO2 with mixed-phase structure was synthesized and used as both photocatalyst and adsorbent for DMA removal. Due to the reduced band-gap and enhanced separation of photogenerated charge carriers, the oxygen-deficient TiO2 nanostructures exhibited 4.2 times higher PCO efficiency than commercial TiO2 (P25). More importantly, the high surface area of the mesoporous TiO2 provided sufficient active sites for in-situ adsorption and reaction, resulting in the efficient removal of as-formed As(V). Combining the experimental and characterization results, the different roles of reactive species during PCO reactions were clarified. In the presence of hole (h+) as the dominant oxidation species, DMA was demethylated and transformed into MMA. Thereafter, MMA was subsequently reduced to As(III) by photo-generated electrons. Superoxide radicals (O2•–) played a significant role in oxidizing As(III) into As(V), which was finally adsorptively removed by the mesoporous TiO2.

Core–shell α-Fe2O3-mixed phase TiO2 nanocubes as a highway for electron transport with efficient energy harvesting

Morphology (shape + phase) driven nanoassemblies are emerging materials for faster charge transport and have immense potential for the development of photoelectric devices.

Antibacterial and photocatalytic activities of controllable (anatase/rutile) mixed phase TiO2 nanophotocatalysts synthesized via a microwave-assisted sol–gel method

TiO2 with different ratios of anatase/rutile phases were synthesized via a microwave assisted sol–gel method and by applying a single source precursor (SSP) with a constant concentration of nitric acid that was used as the structure directing agent.

Enhanced photocatalytic activity in TiO2 mixed phase nanostructures

Titanium dioxide (TiO2) is one of the most effective n-type semiconductors for photocatalytic applications. Compared with the bulk TiO2 nanostructures, the one-dimensional (1D) TiO2 nanostructures have elicited great interest due to its various advantageous properties such as high surface-volume ratio, high chemical stability, strong oxidizing power, nontoxicity and low cost. TiO2exists mainly in two crystalline phases namely anatase and rutile. When different phases of TiO2are combined, they have better charge transport and light absorption properties than pristine nanotubes and nanorods. In reference to that, mixed phases play an important role in the modification of the photocatalytic properties.In the present work, three different nanostructures (TiO2 nanotubes, nanorods and mixed phase nanohybrids) are fabricated by electrochemical anodization and hydrothermal processes, respectively. TiO2 nanotubes are synthesized by electrochemical anodization of highly pure titanium foil in a solution containing ethylene glycol, ammonium fluoride and distilled water, TiO2 nanorods are grown on fluorine-doped tin oxide (FTO) using a hydrothermal method and hybrid TiO2 nanostructures consisting of rutile TiO2 nanorods synthesized by hydrothermal method on anodized TiO2 nanotubes in a high temperature and high-pressure condition with titanium-n-butoxide as the reaction precursor. The three different morphologies of nanotubes, nanorods and nanohybrids are investigated using scanning electron microscopy (SEM). The crystallinity of the TiO2 nanotubes, nanorods and nanohybrids are studied using Raman spectroscopy and X-ray diffraction (XRD) techniques. TiO2 nanotubes, nanorods and nanohybrids are crystalized in anatase, rutile and mixed phase (anatase and rutile), respectively. The structural transformation of the formed TiO2 nanohybrid is compared with TiO2 nanorods and nanotubes that further be explored for photocatalysis by degradation of methylene blue (10 μM) under xenon lamp in the presence of catalysts. It is observed that overall photocatalytic activity of mixed phase TiO2 nanohybrids is better than TiO2 nanotubes and nanorods owing to better electron hole separation and transportation.

Construction of K-doped mixed-phase TiO2 nanowires@MoS2 nanosheets core-shell structure for researching on supercapacitors

To enhance the specific capacitance of titanium-based supercapacitor, a novel binder-free titanium supported electrode material is first assembled with K-doped mixed-phase (anatase and rutile) TiO2 nanowires coated by MoS2 nanosheets (K-TNW@MNs). The K-TNW@MNs core-shell structure is prepared by chitosan-assisted hydrothermal reaction. The soft template of chitosan is chosen to grow MNs uniformly on K-TNW and reduce the agglomeration of MNs. K-TNW backbone structure provides a large surface area for attaching and anchoring the MoS2 nanosheets. As a result, The K-TNW@MNs exhibits a high specific capacitance of 123.53 mF cm−2 at 0.4 mA cm−2, desirable rate capability, and outstanding cycling stability of 84.49% capacitance retention over 6000 cycles. A novel all-solid-state symmetrical supercapacitor assembled with two pieces of K-TNW@MNs electrodes and KCl/polyvinyl alcohol gel electrolyte exhibits a good capacitance retention rate of 78.44% after 6000 cycles. The researches offer a novel strategy to reduce the agglomeration of MoS2 nanosheets on TiO2 nanowires by chitosan-assisted.

Photocatalytic Degradation of Atenolol by TiO2 Irradiated with an Ultraviolet Light Emitting Diode: Performance, Kinetics, and Mechanism Insights

Batch experiments were performed to investigate the effect of several environmental factors on atenolol (ATL) degradation efficiency, including catalyst crystal phase (anatase TiO2, rutile TiO2, and mixed phase), catalyst dosage, UV-LED wavelength and intensity, co-existing anions, cations, and pH. The mixed phase (2 g/L) exhibited the best photocatalytic activity at 365 nm, with ATL (18.77 µM) completely oxidized within 1 h. These results suggest that: (i) The mixed phase exhibits the highest activity due to its large specific surface area and excellent charge separation efficiency. (ii) ATL can be effectively degraded using mixed phase TiO2 combined with UV-LED technology and the ATL degradation efficiency could reach 100% for 60 min; (iii) ATL photodegradation was more effective under 365 nm UV-LED than 254 nm, which was caused by the effect of light-induced charge separation; (iv) the ATL Degradation efficiency(De) decreased with an increase in initial ATL concentrations; and (v) co-existing anions and cations had different effects on the ATL De, mainly by changing the concentration of hydroxyl radicals. Considering that UV-LED is more energy-saving and environmentally friendly, and commercial TiO2 is cheap and easy to obtain, our research provides feasibility for practical application.

Thermal annealing induced cave in and formation of nanoscale pits in Ag–TiO2 plasmonic nanocomposite thin film

Ag–TiO2 nanocomposite thin films on silica glass were prepared through thermal evaporation in combination with RF magnetron sputtering. Thermal annealing induced changes in the optical, morphological and structural properties of Ag–TiO2 nanocomposites were examined using optical absorption, photoluminescence spectroscopy, Raman spectroscopy, FESEM, AFM and XRD. FESEM and AFM studies revealed cave in of the Ag–TiO2 thin film at various places leading to the formation nanoscale pits upon thermal annealing at 600 °C. The computed average size of pits was found to be 54 nm. Raman studies indicated 600 °C annealing induced transformation of anatase phase of TiO2 into anatase/rutile mixed phase TiO2. Optical absorption spectra showed systematic changes due to the effects of mixed phase formation and variation in the plasmonic behavior upon annealing. PL results of the as deposited Ag–TiO2 thin film showed peaks at 377, 402, 432 and 486 nm. PL studies of Ag–TiO2 nanocomposites treated at different annealing temperatures revealed changes in defect concentration in TiO2. The tentative mechanism for the creation of nanoscale pits in Ag–TiO2 thin film through thermal annealing was proposed.

Analysis of Structural and Photocatalytical Properties of Anatase, Rutile and Mixed Phase TiO2 Films Deposited by Pulsed-Direct Current and Radio Frequency Magnetron Co-Sputtering

Analysis of Structural and Photocatalytical Properties of Anatase, Rutile and Mixed Phase TiO2 Films Deposited by Pulsed-Direct Current and Radio Frequency Magnetron Co-Sputtering

Facile Formation of Anatase/Rutile TiO2 Nanocomposites with Enhanced Photocatalytic Activity.

Anatase/rutile mixed-phase TiO2 nanoparticles were synthesized through a simple sol-gel route with further calcination using inexpensive titanium tetrachloride as a titanium source, which effectively reduces the production cost. The structural and optical properties of the prepared materials were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV-vis adsorption. The specific surface area was also analyzed by Brunauer–Emmett–Teller (BET) method. The anatase/rutile mixed-phase TiO2 nanocomposites containing of rod-like, cuboid, and some irregularly shaped anatase nanoparticles (exposed {101} facets) with sizes ranging from tens to more than 100 nanometers, and rod-like rutile nanoparticles (exposed {110} facets) with sizes ranging from tens to more than 100 nanometers. The photocatalytic activities of the obtained anatase/rutile mixed-phase TiO2 nanoparticles were investigated and compared by evaluating the degradation of hazardous dye methylene blue (MB) under ultraviolet light illumination. Compared to the commercial Degussa P25-TiO2, the mixed-phase TiO2 nanocomposites show better photocatalytic activity, which can be attributed to the optimal anatase to rutile ratio and the specific exposed crystal surface on the surface. The anatase/rutile TiO2 nanocomposites obtained at pH 1.0 (pH1.0-TiO2) show the best photocatalytic activity, which can be attributed to the optimal heterojunction structure, the smaller average particle size, and the presence of a specific exposed crystal surface. The enhanced photocatalytic activity makes the prepared anatase/rutile TiO2 photocatalysts a potential candidate in the removal of the organic dyes from colored wastewater.