Surface Modification of Small Particle TiO2 Colloids with Cysteine for Enhanced Photochemical Reduction: An EPR Study

Insights into the Unanticipated Chemical Reactivity of Functionalized Nanosheets Derived from TiB2

Titanium diboride (TiB2) is a member of the AlB2-type layered metal boride family; the materials of this family are receiving renewed research interest owing to their amenability to nanoscaling. Earlier, we showed that TiB2 can be nanoscaled to yield quasi 2D nanostructures following a dissolution-recrystallization approach. This approach yielded nanosheets that were chemically functionalized with oxy-functional groups. Also, these nanosheets could inherently form a gel-like substance. In this work, we show that these functionalized nanosheets can interact with ascorbic acid in a way that first imparts a characteristic orange hue to the original yellowish nanosheet dispersion. Second, this interaction results in the loss of gel-like behavior of the nanosheet dispersion. We utilize several spectroscopic techniques such as UV-visible, FT-IR, NMR, EPR, XPS, and XANES to unravel this unexplored chemical interaction. The findings show that both titania as well as oxy-boron species react with ascorbic acid, leading to a profound modification of the nanosheets. This modification results in an augmented electrochemical response, implying that the modified nanosheets can be used in novel applications. This study is therefore a step toward gaining an even deeper understanding of the chemical opportunities that these nanoscaled borides can provide.

Triggering cell death in cancers using self-illuminating nanocomposites

Bioinspired photocatalysis has resulted in efficient solutions for many areas of science and technology spanning from solar cells to medicine. Here we show a new bioinspired semiconductor nanocomposite (nanoTiO₂-DOPA-luciferase, TiDoL) capable of converting light energy within cancerous tissues into chemical species that are highly disruptive to cell metabolism and lead to cell death. This localized activity of semiconductor nanocomposites is triggered by cancer-generated activators. Adenosine triphosphate (ATP) is produced in excess in cancer tissues only and activates nearby immobilized TiDoL composites, thereby eliminating its off-target toxicity. The interaction of TiDoL with cancerous cells was probed in situ and in real-time to establish a detailed mechanism of nanoparticle activation, triggering of the apoptotic signaling cascade, and finally, cancer cell death. Activation of TiDoL with non-cancerous cells did not result in cell toxicity. Exploring the activation of antibody-targeted semiconductor conjugates using ATP is a step toward a universal approach to single-cell-targeted medical therapies with more precision, efficacy, and potentially fewer side effects.

Ligand-Assisted Charge-Transfer Mechanism: The Case of CdSe/Cysteine/MoS2 Heterostructures

Molecular linkers, such as cysteine, are used to stabilize colloidal quantum dots (QDs) and anchor them. Despite the typically large molecular HOMO/LUMO gap of linkers, they can increase the quantum yield and provide an effective charge-transfer channel. Through first-principles calculations, we investigate the ligand binding and the implications for charge transfer using a prototypical CdSe-Cysteine-MoS₂ three-way heterostructure. We find that the deprotonated ligand interacts with both sides of the heterostructure, which allows for successful self-passivation of the cysteine ligand molecule and the formation of dative bonds with a greatly reduced molecular gap compared with the gas phase. This leads to the formation of a charge-transfer state that is delocalized across the ligand and can directly assist electron transfer from the conduction band of colloidal CdSe QDs to the underlying MoS₂ substrate, which is a mechanism that could extend far beyond 0D-2D hybrid systems.

Green Approach Towards Morphology-Controlled Synthesis of Zein-Functionalized TiO2 Nanoparticles for Cosmeceutical Application

Biomolecular approaches for synthesis of inorganic nanoparticle are very popular among researchers and exhibit significant shape-directing morphologies in classified condition. The proteins are the most abundant macromolecules and employed for the hybrid synthesis as well as shape-directing agent. The present study is designed to investigate the potential role of a plant protein 'zein' to synthesize hybrid TiO₂ nanoparticles. This versatile amphiphilic protein paves a unique path towards shape directing synthesis and act as template in the biomineralization process. The structural changes occurred in protein structure is thoroughly characterized using the circular dichroism (CD) and FTIR spectroscopy. UV, XPS and HRTEM analysis confirms the presence of zein on the nanoparticle surface. The proposed approach provides finely engineered nano-cuboidal (22.75±5.07 nm) geometry with homogenous dispersion, curved edged cuboids (403.51±0.05 nm) and spherical (97.85±0.62 nm) shaped from different modification, as evidenced by TEM. We also discussed in-vitro method for the detection of antimicrobial activity of nanocuboids against acne causing microorganisms such as Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Streptococcus agalactiae. Our results demonstrate that hybrid nanocuboids could be an efficient green material and provide cognitive antimicrobial evidence that could be deployed for cosmeceutical application.

Rich oxygen vacancies, mesoporous TiO2 derived from MIL-125 for highly efficient photocatalytic hydrogen evolution

Here we report a mesoporous TiO₂ with a large specific surface area and rich oxygen vacancies using a Ti-based MOF (MIL-125) as a precursor through high-temperature annealing. Such integration of a unique mesoporous structure and oxygen vacancies provides effective carrier transport channels, increases surface active sites, and enhances photocatalytic activity for the hydrogen evolution reaction.

Trap-Assisted Charge Storage in Titania Nanocrystals toward Optoelectronic Nonvolatile Memory

Transistor-based memories are of particular significance in the pursuit of next-generation nonvolatile memories. The charge storage medium in a transistor-based memory is pivotal to the device performance. In this report, nitrogen doping titania nanocrystals (N-TiO₂ NCs) synthesized through a low-temperature nonhydrolytic method are used as the charge storage medium in a graphene transistor-based memory. The decoration of the N-TiO₂ NCs enables the device to perform as an ultraviolet (UV) light-programmable nonvolatile optoelectronic memory. Multilevel nonvolatile information recording can be realized through accurate control of the incident light dose, which is ascribed to the vast and firm hole trapping abilities of the N-TiO₂ NCs induced by the N dopant. Accordingly, a positive gate voltage can be used to erase the programmed state by promoting the recombination of stored holes in N-TiO₂ NCs. This study manifests the importance of trap engineering for information storage and provides an alternative path toward nonvolatile optoelectronic memory.

On interaction of arginine, cysteine and guanine with a nano-TiO2 cluster

Nanoscopic properties of TiO₂ augmented with its physicochemical properties and biocompatibility make it a material interest in the biomedical field. Efficient methods to design of such materials require a thorough understanding of associated nano-bio interfaces. In the present study, density functional theory calculations were performed to study the interactions of arginine, cysteine and guanine with a nano-TiO₂ cluster. Different configurations were sampled for the adsorption of arginine, cysteine and guanine to probe the nano-bio interface via the interaction of various functional groups present on biomolecules. Adsorption energies for arginine, cysteine and guanine were in a range of -25.0 to -57.6, -12.1 to -29.6 and -45.6 to -58.7 kcal/mol, respectively. From the change in adsorption energies and free energies, interaction of amino acids with carboxylic (COOH), thiol (SH) and amine (NH₂) groups while the interaction of the nucleobase via O bonded to C and N of purine ring was found to be essential for thermodynamically stable and energetically favorable states. Density of states analysis also disclosed the prominent interactions of the biomolecules with the nano-TiO₂ cluster. Decrease in band gaps on adsorption of the biomolecules was a pertinent phenomenon indicating the strong chemical interactions of the biomolecules with the nanoscopic TiO₂ chosen for analysis in this study.

Synthesis and Photocatalytic Sterilization Performance of SA/TiO2

The photocatalyst sorbic acid (SA)/titanium dioxide (TiO₂) was successfully synthesized by sol–gel method and characterized. The composite exhibited regularly spherical particles with the size of 50 nm and the specific surface area of 90.3 m² g⁻¹, furthermore, it showed mesoporous structure and significantly improved dispersion. SA was grafted on TiO₂ surface by –COOTi and TiO₂ existed as pure anatase phase in the composite. The addition of SA made the band gap of TiO₂ increased from 3.03 to 3.35 eV, which indicting that the composite exhibited a strong response to the ultraviolet light. The optimum preparation parameters of the catalyst were as follows: n(Ti):n(SA) = 1:0.05, ethanol 60 mL, glacial acetic acid 40 mL, hydrothermal temperature 180 °C, hydrothermal time 12 h. The composite could reach the 4.31 log reduction of E. coli, with the optimum catalyst dosage of 0.7 g L⁻¹, irradiated by UV light for 60 min. SA/TiO₂ was an environmentally friendly, non-toxic and safe sterilized nanocomposite material appropriate for future bactericidal applications, providing a new way to effectively increase the dispersion of TiO₂ particles to achieve superior photocatalytic sterilization efficiency.

Amperometric Flow-Injection Analysis of Phenols Induced by Reactive Oxygen Species Generated under Daylight Irradiation of Titania Impregnated with Horseradish Peroxidase

Titanium dioxide (TiO₂) is a unique material for biosensing applications due to its capability of hosting enzymes. For the first time, we show that TiO₂ can accumulate reactive oxygen species (ROS) under daylight irradiation and can support the catalytic cycle of horseradish peroxidase (HRP) without the need of H₂O₂ to be present in the solution. Phenolic compounds, such as hydroquinone (HQ) and 4-aminophenol (4-AP), were detected amperometrically in flow-injection analysis (FIA) mode via the use of an electrode modified with TiO₂ impregnated with HRP. In contrast to the conventional detection scheme, no H₂O₂ was added to the analyte solution. Basically, the inherited ability of TiO₂ to generate reactive oxygen species is used as a strategy to avoid adding H₂O₂ in the solution during the detection of phenolic compounds. Electron paramagnetic resonance (EPR) spectroscopy indicates the presence of ROS on titania which, in interaction with HRP, initiate the electrocatalysis toward phenolic compounds. The amperometric response to 4-AP was linear in the concentration range between 0.05 and 2 μM. The sensitivity was 0.51 A M^-1 cm^-2, and the limit of detection (LOD) 26 nM. The proposed sensor design opens new opportunities for the detection of phenolic traces by HRP-based electrochemical biosensors, yet in a more straightforward and sensitive way following green chemistry principles of avoiding the use of reactive and harmful chemical, such as H₂O₂.

Electron magnetic resonance in heterogeneous photocatalysis research

The contribution of electron magnetic resonance techniques, and in particular of CW-EPR, to the experimental research on photocatalytic phenomena is illustrated in this paper with selected examples. In the first part of the paper the role of EPR in unravelling the nature and the features of extrinsic point defects in semiconducting oxides is epitomized using the important example of the photoactive nitrogen center in various semiconducting oxides. In the second part we describe how EPR can monitor the processes that follow the initial photoinduced charge separation in photocatalysis, namely the stabilisation, migration and surface reactivity of electrons and holes. Finally, we will discuss how the role of EPR in photocatalysis is not limited to monitor phenomena occurring in the solid or at its surface but it can be extended to the investigation of the liquid phase by employing the spin trapping techniques to monitor the nature and the concentration of the reactive free radicals formed along the photocatalytic process.

Immobilization of Fructofuranosidase from Aureobasidium sp. Onto TiO2 and Its Encapsulation on Gellan Gum for FOS Production

Fructofuranosidase (EC 3.2.1.26) from Aureobasidium sp. ATCC 20524, recovered from 5 L fermented medium, purified by two simple steps with a yield of 65 % and a purification factor of 16, was immobilized by adsorption onto titanium dioxide (FTIO). The enzyme was also covalently immobilized onto TiO2 coated with polyethyleneimine (FTIOP) and encapsulated in gellan gum (FTIOPG). FTIO and FTIOP recorded an activity of 903 U g−1 and 9212 U g−1, respectively. The immobilized enzyme showed high activity and stability at pH levels ranging from 4.0 to 8.0 and there were no changes in the temperature profile for either methodology when compared with free fructofuranosidase. The immobilized biocatalysts were reused 7 times for FOS production without significant activity loss, except FTIO at pH 5.0. Gellan gum was used for FTIOP encapsulation. FOS production was performed in a batch and a continuous reactor using FTIOPG as a biocatalyst. Batch conversion (gFOS/ginitial sucrose) was around 60 % for initial sucrose concentrations of 100, 300 and 600 g L−1, at a time of maximum conversion. Fixed-bed reactor operational stability was remarkable, providing a constant FOS production in the outlet of the column during 720 h.

Adjusting the ratio of bulk single-electron-trapped oxygen vacancies/surface oxygen vacancies in TiO2 for efficient photocatalytic hydrogen evolution

Co-existence of bulk single-electron-trapped and surface oxygen vacancies favor the improvement of photocatalytic hydrogen evolution.

Mesoporous TiO2 Embedded with a Uniform Distribution of CuO Exhibit Enhanced Charge Separation and Photocatalytic Efficiency

Mixed metal oxide nanoparticles have interesting physical and chemical properties, but synthesizing them with colloidal methods is still challenging and often results in very heterogeneous structures. Here, we describe a simple method to synthesize mesoporous titania nanoparticles implanted with a uniform distribution of copper oxide nanocrystals (CuO@MTs). By calcining a titanium-based metal-organic framework (MIL-125) in the presence of Cu ions, we can trap the Cu in the TiO₂ matrix. Removal of the organic ligand creates mesoporosity and limits phase separation so that tiny CuO nanocrystals form in the interstices of the TiO₂. The CuO@MTs exhibits superior performance for photocatalytic hydrogen evolution (4760 μmol h^-1) that is >90 times larger than pristine titania.

Remarkable Charge Separation and Photocatalytic Efficiency Enhancement through Interconnection of TiO2 Nanoparticles by Hydrothermal Treatment

Although tremendous effort has been directed to synthesizing advanced TiO2 , it remains difficult to obtain TiO2 exhibiting a photocatalytic efficiency higher than that of P25, a benchmark photocatalyst. P25 is composed of anatase, rutile, and amorphous TiO2 particles, and photoexcited electron transfer and subsequent charge separation at the anatase-rutile particle interfaces explain its high photocatalytic efficiency. Herein, we report on a facile and rational hydrothermal treatment of P25 to selectively convert the amorphous component into crystalline TiO2 , which is deposited between the original anatase and rutile particles to increase the particle interfaces and thus enhance charge separation. This process produces a new TiO2 exhibiting a considerably enhanced photocatalytic efficiency. This method of synthesizing this TiO2 , inspired by a recently burgeoning zeolite design, promises to make TiO2 applications more feasible and effective.

Enhanced photoredox chemistry in surface-modified Mg2TiO4 nano-powders with bidentate benzene derivatives

The absorption of Mg₂TiO₄ nano-powder was extended to visible spectral region upon surface modification with salicylate-and catecholate-type of ligands. Degradation of crystal violet over synthesized powders indicated their photocatalytic ability.

Sonophotocatalytic degradation of dye C.I. Acid Orange 7 by TiO2 and Ag nanoparticles immobilized on corona pretreated polypropylene non-woven fabric

This study discusses the possibility of using corona pre-treated polypropylene (PP) non-woven fabric as a support for immobilization of colloidal TiO2 and Ag nanoparticles in order to remove dye C.I. Acid Orange 7 from aqueous solution. Dye removal efficiency by sonocatalysis, photocatalysis and sonophotocatalysis was evaluated on corona pre-treated fabric loaded with TiO2 nanoparticles, corona pre-treated fabric double loaded with TiO2 nanoparticles and corona pre-treated fabrics loaded with TiO2 nanoparticles before and after deposition of Ag nanoparticles. In addition, the stability of PP non-woven fabric during these processes was investigated. The substrates were characterized by SEM, EDX and AAS analyses. The change of the dye concentration was evaluated by UV-VIS spectrophotometry. Unlike sonocatalysis and photocatalysis, complete dye removal from both solution and non-woven fabric was obtained already after 240-270 min of sonophotocatalysis. Corona pre-treated PP non-woven fabric loaded with Ag nanoparticles prior to deposition of TiO2 nanoparticles provided excellent degradation efficiency and superior reusability. Sonophotocatalytic degradation of dye in the presence of all investigated samples was the most prominent in acidic conditions. Although this nanocomposite system ensured fast discoloration of dye solution, TOC values of water measured after sonophotocatalysis were not satisfactory because of PP degradation. Therefore, it is suggested to include TOC evaluation in each case study where different supports for TiO2 nanoparticles are used since these nanoparticles may guarantee the dye removal from solution but the stability of support could be problematic causing even more serious environmental impact.

Surface Enhanced Raman Spectroscopy of Organic Molecules on Magnetite (Fe3O4) Nanoparticles

Surface-enhanced Raman spectroscopy (SERS) of species bound to environmentally relevant oxide nanoparticles is largely limited to organic molecules structurally related to catechol that facilitate a chemical enhancement of the Raman signal. Here, we report that magnetite (Fe3O4) nanoparticles provide a SERS signal from oxalic acid and cysteine via an electric field enhancement. Magnetite thus likely provides an oxide substrate for SERS study of any adsorbed organic molecule. This substrate combines benefits from both metal-based and chemical SERS by providing an oxide surface for studies of environmentally and catalytically relevant detailed chemical bonding information with fewer restrictions of molecular structure or binding mechanisms. Therefore, the magnetite-based SERS demonstrated here provides a new approach to establishing the surface interactions of environmentally relevant organic ligands and mineral surfaces.

Fe doped TiO2-graphene nanostructures: synthesis, DFT modeling and photocatalysis

In this work, Fe-doped TiO(2) nanoparticles ranging from a 0.2 to 1 weight % were grown from the surface of graphene sheet templates containing -COOH functionalities using sol-gel chemistry in a green solvent, a mixture of water/ethanol. The assemblies were characterized by a variety of analytical techniques, with the coordination mechanism examined theoretically using the density functional theory (DFT). Scanning electron microscopy and transmission electron microscopy images showed excellent decoration of the Fe-doped TiO(2) nanoparticles on the surface of the graphene sheets >5 nm in diameter. The surface area and optical properties of the Fe-doped photocatalysts were measured by BET, UV and PL spectrometry and compared to non-graphene and pure TiO(2) analogs, showing a plateau at 0.6% Fe. Interactions between graphene and Fe-doped anatase TiO(2) were also studied theoretically using the Vienna ab initio Simulation Package based on DFT. Our first-principles theoretical investigations validated the experimental findings, showing the strength in the physical and chemical adsorption between the graphene and Fe-doped TiO(2). The resulting assemblies were tested for photodegradation under visible light using 17β-estradiol (E2) as a model compound, with all investigated catalysts showing significant enhancements in photocatalytic activity in the degradation of E2.

Surface modification of anatase nanoparticles with fused ring salicylate-type ligands (3-hydroxy-2-naphthoic acids): a combined DFT and experimental study of optical properties

The surface modification of nanocrystalline TiO2 particles (45 Å) with salicylate-type ligands consisting of an extended aromatic ring system, specifically 3-hydroxy-2-naphthoic acid, 3,5-dihydroxy-2-naphthoic acid and 3,7-dihydroxy-2-naphthoic acid, was found to alter the optical properties of nanoparticles in a similar way to salicylic acid. The formation of the inner-sphere charge-transfer (CT) complexes results in a red shift of the semiconductor absorption compared to unmodified nanocrystallites and a reduction in the band gap upon the increase in the electron delocalization when including an additional ring. The investigated ligands have the optimal geometry for binding to surface Ti atoms, resulting in ring coordination complexes of a salicylate-type (binuclear bidentate binding-bridging) thus restoring the six-coordinated octahedral geometry of surface Ti atoms. From both absorption measurements in methanol/water = 90/10 solutions and steady-state quenching measurements of modifier fluorescence upon binding to TiO2 in aqueous solutions, stability constants in the order of 10(3) M(-1) have been determined at pH 2 and pH 3. Fluorescence lifetime measurements, in the presence and absence of colloidal TiO2 nanoparticles, indicated that the fluorescence quenching process is primarily static quenching, thus proving the formation of a nonfluorescent CT complex. The binding structures were investigated by using FTIR spectroscopy. Quantum chemical calculations on model systems using density functional theory (DFT) were performed to obtain the vibrational frequencies of charge transfer complexes, and the calculated values were then compared with the experimental data.

CO2 Preactivation in Photoinduced Reduction via Surface Functionalization of TiO2 Nanoparticles

Salicylate and salicylic acid derivatives act as electron donors via charge-transfer complexes when adsorbed on semiconducting surfaces. When photoexcited, charge is injected into the conduction band directly from their highest occupied molecular orbital (HOMO) without needing mediation by the lowest unoccupied molecular orbital (LUMO). In this study, we successfully induce the chemical participation of carbon dioxide in a charge transfer state using 3-aminosalicylic acid (3ASA). We determine the geometry of CO2 using a combination of ultraviolet-visible spectroscopy (UV-vis), surface enhanced Raman scattering (SERS), (13)C NMR, and electron paramagnetic resonance (EPR). We find CO2 binds on Ti sites in a carbonate form and discern via EPR a surface Ti-centered radical in the vicinity of CO2, suggesting successful charge transfer from the sensitizer to the neighboring site of CO2. This study opens the possibility of analyzing the structural and electronic properties of the anchoring sites for CO2 on semiconducting surfaces and proposes a set of tools and experiments to do so.

Recent Development on Titania Based Mixed Oxide Photocatalysts for Environmental Application under Visible Light

In the recent years most of the studies are confined to the mixing of ZrO2, SiO2, WO4 or ceria with titania in different composition so as to stabilize anatase phase, maintain high surface area and increase visible light absorption for better photocatalytic activity. Method of synthesis also helps in effective doping and enhancing surface area of the resultant materials. Nonmetal doping of oxide semiconductor materials facilitates the visible light application of photocatalysis. Based on the recent literature this review elaborately discuss on the development of titania based mixed oxide catalyst with or without different doping for visible light application. In addition this review deals with critical analysis of these materials towards photocatalytic oxidation of organics and reduction of pollutants like toxic metal ions and nitrates.

Colloidal TiO2 nanoparticles as substrates for M(S)ALDI mass spectrometry of transition metal complexes

RATIONALE

Nanoparticles as substrates for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) have advantages over organic matrices, since they enable acquisition of spectra in the low-mass range. It has been previously shown that TiO(2) nanoparticles can be used as substrate for MALDI-TOF MS analysis of phospholipids and for other types of molecules, but none of them was applied to the analysis of transition metal complexes.

METHODS

The MALDI-TOF mass spectra of potential anti-tumor drugs [AuCl(2)(bipy)]Cl, [PtCl(4)(bipy)], and [RuCl(2)(bipy)(2) ]Cl acquired with organic matrices have been compared with spectra acquired with colloidal titanium dioxide nanoparticles. Colloidal TiO(2) nanoparticles (NPs) with average diameter of 5 nm were synthesized and characterized by microscopy. For some experiments, the TiO(2) NPs were treated at 60 °C. Suspensions of matrix and the analyte were premixed, applied to the MALDI target and left at room temperature. Mass spectra were acquired with a 50-Hz pulsed nitrogen laser emitting at a wavelength of 337 nm.

RESULTS

The MALDI spectra of transition metal complexes acquired with TiO(2) NPs exhibited somewhat lower sensitivity than those with organic matrices; on the other hand, they are characterized by significantly lower number of signals arising from the tested complexes than the organic matrices. Whereas adducts between organic matrices and the analytes were detectable in the spectra, this was not the case for the TiO(2)-assisted mass spectra.

CONCLUSIONS

We have shown that colloidal TiO(2) NPs can be used as substrates for MALDI-TOF MS of transition metal complexes. Although the sensitivity of this approach in comparison with the use of organic matrices might still be a problem, the potential of the applications of NPs for the mass spectrometric characterization of transition metal complexes is clearly demonstrated.

Interface engineering: Boosting the energy conversion efficiencies for nanostructured solar cells

Nanostructured solar cells have attracted increasing attention in recent years because their low cost and ease of preparation offer unique advantages and opportunities unavailable with conventional single-crystalline solar cells. The efficiencies of this kind of solar cell largely depend on the interfacial structure owing to the large specific interface areas and the inherent high density of interface states. In this review article, strategies of interface engineering will be introduced in detail. The up-to-date progress and understanding of interface engineering and its role in influencing the efficiency of nanostructured solar cells will be discussed. Some of the representative examples of the interface engineering method will be presented wherever necessary. Continued boosting of the energy conversion efficiency for nanostructured solar cells is anticipated in the coming years and will bring this kind of solar cell to the status of commercialization.

Nonaqueous synthesis of TiO2 nanocrystals using TiF4 to engineer morphology, oxygen vacancy concentration, and photocatalytic activity

Control over faceting in nanocrystals (NCs) is pivotal for many applications, but most notably when investigating catalytic reactions which occur on the surfaces of nanostructures. Anatase titanium dioxide (TiO(2)) is one of the most studied photocatalysts, but the shape dependence of its activity has not yet been satisfactorily investigated and many questions still remain unanswered. We report the nonaqueous surfactant-assisted synthesis of highly uniform anatase TiO(2) NCs with tailorable morphology in the 10-100 nm size regime, prepared through a seeded growth technique. Introduction of titanium(IV) fluoride (TiF(4)) preferentially exposes the {001} facet of anatase through in situ release of hydrofluoric acid (HF), allowing for the formation of uniform anatase NCs based on the truncated tetragonal bipyramidal geometry. A method is described to engineer the percentage of {001} and {101} facets through the choice of cosurfactant and titanium precursor. X-ray diffraction studies are performed in conjunction with simulation to determine an average NC dimension which correlates with results obtained using electron microscopy. In addition to altering the particle shape, the introduction of TiF(4) into the synthesis results in TiO(2) NCs that are blue in color and display a broad visible/NIR absorbance which peaks in the infrared (λ(max) ≈ 3400 nm). The blue color results from oxygen vacancies formed in the presence of fluorine, as indicated by electron paramagnetic resonance (EPR) and X-ray photoelectron spectroscopy (XPS) studies. The surfactants on the surface of the NCs are removed through a simple ligand exchange procedure, allowing the shape dependence of photocatalytic hydrogen evolution to be studied using monodisperse TiO(2) NCs. Preliminary experiments on the photoreforming of methanol, employed as a model sacrificial agent, on platinized samples resulted in high volumes of evolved hydrogen (up to 2.1 mmol h(-1) g(-1)) under simulated solar illumination. Remarkably, the data suggest that, under our experimental conditions, the {101} facets of anatase are more active than the {001}.