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Abstract In this work, we grow oriented photonic TiO 2 nanotubes (TNTs) with a well-established anodization method and their intrinsic catalytic and electronic properties are studied by means of (photo)electrochemical methods. The oriented photonic TNTs are assessed by the R ct C dl (ΩF) product, which is a measure of the intrinsic photoelectrocatalytic activity (IPA) of the material. The R ct C dl product decouples any surface area effects and it can be applied at any potential and accompanied reaction without knowing the actual electrochemically active surface area (EASA). Moreover, electrochemical impedance spectroscopy (EIS) is used in order to investigate the frequency dispersion in the single frequency Mott-Schottky (MS) measurement. The choice of frequency and the frequency dispersion in MS measurements in nanostructured and of high surface area semiconductors are rarely addressed and can result in erroneous values of two important parameters, i.e. flat band position and donor or acceptor densities. This work provides further insights into important electrochemical aspects and catalytic properties of high surface area nanomaterials for photoelectrochemical applications. Graphical abstract fx1 [ABSTRACT FROM AUTHOR]

Abstract The TiO 2 -WO 3 heterostructures with superior interfacial interactions were synthesized by simple solvothermal method followed by calcination. The electrical property of the heterostructures was tuned by varying the amount of TiO 2 and WO 3 to achieve higher photoelectrochemical activity. The prepared samples were characterized by X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, scanning transmission electron microscopy and UV–vis diffuse reflectance spectroscopy. The strong interaction in the interface of TiO 2 -WO 3 heterostructures and the solar spectral response of TiO 2 and WO 3 reduce the electron-hole pair recombination rate and enhance the photoelectrochemical activity. The TiO 2 -WO 3 heterostructures show 17 times higher photon-to-hydrogen conversion efficiency than pure TiO 2 and WO 3 under solar light and almost complete removal of organic pollutant in 60 min under visible light. The TiO 2 -WO 3 heterostructures also show good adsorption capacity for organic pollutants. The present study demonstrates that the prepared TiO 2 -WO 3 heterostructures are promising materials for efficient water splitting as well as adsorption and photocatalytic removal of organic pollutants. Graphical abstract fx1 Highlights • TiO 2 -WO 3 heterostructures with superior interfacial interactions were synthesized. • Enhanced photocatalytic activity of TiO 2 -WO 3 heterostructures was demonstrated. • Electrical properties were tuned by varying the amount of TiO 2 and WO 3. [ABSTRACT FROM AUTHOR]

Sunlight-driven hydrogen production from water splitting, assisted with the commonly used Pt/TiO 2 catalyst, is a promising way to store clean and renewable energy. However, the photocatalytic activity of Pt/TiO 2 is limited owing to the agglomeration of Pt atoms. Herein, we successfully synthesized a Pt/TiO 2 catalyst, where Pt is atomically and selectively dispersed on the (1 0 1) facets of nanosized TiO 2 single crystals. A remarkably higher photocatalytic activity for H 2 evolution together with a considerable stability was observed as compared to commonly used Pt/TiO 2 . This study demonstrates a promising way to achieve atomically dispersed highly-active catalyst for water splitting. [ABSTRACT FROM AUTHOR]

La1−xCexCoO3 (x = 0, 0.2, 0.4) and La1−xCexMnO3 (x = 0, 0.2) perovskite-type oxides were prepared by sol-gel process. Characterization techniques EDS, FTIR, XRD, BET, and XPS experiments were performed to survey the composition, bulk structure, and the surface properties of perovskites. The reduction behavior, thermal stability, and catalytic activity were studied by H2-TPR and catalytic performance. All synthesized samples showed well crystalline perovskite structure, 8–22 nm crystallite sizes, and SSA with 2–27 m2 g−1. The XRD results showed that the Ce substitution promoted the structural transformation for LaCoO3 from rhombohedral into cubic and for LaMnO3 no change in lattice geometry. Substitution with cerium (x = 0.2) showed smaller crystallite size, higher SSA, and the highest reducibility and catalytic activity for LaCoO3. [ABSTRACT FROM AUTHOR]

TiO 2 modified with unique surface O–Zn–Cl species is prepared by a simple sol-gel method. The Zn modified TiO 2 samples exhibit improved photocatalytic activity on photo-reduction of CO 2 into CH 4 , compared with pure TiO 2 . The surface structure and photocatalytic properties are investigated by Raman, XRD, XPS, UV–vis absorption spectra, PL and time-resolved PL decay curves techniques. It is revealed that the existence of O–Zn–Cl species can extend the absorption into visible region, inhibit the recombination of charge carriers and prolong the lifetime of photogenerated electrons. Therefore the O–Zn–Cl modified TiO 2 samples represent an improved photocatalytic performance on photo-reduction of CO 2 into CH 4 . [ABSTRACT FROM AUTHOR]

A simple one-pot hydrothermal synthesis route has been employed to fabricate the bismuth-doped (Bi-doped) anatase TiO2 hollow thin sheets with {001} facets exposed. Controlling BiVO4 precursor concentration plays a key role in tuning the morphology and the Bi doping concentration of TiO2 hollow thin sheet catalysts. The photocatalytic activity of as-prepared catalysts was evaluated through the photodegradation of different organic dyes under visible light irradiation (>400 nm), including methylene blue (MB), methyl orange (MO), rhodamine-B (RhB), and p-nitroaniline (PNA). Results showed that the optimal dopant of 0.8 atom % Bi in TiO2 achieved the best photocatalytic activity, especially for possessing a much higher photodegradation of PNA, which could be ascribed to the results of photoinduced charge separation and transfer combined with low bulk recombination of charge carriers. This discussion demonstrates that the design of new TiO2 nanostructures for application in solar energy conversion could be easily achieved by coupling Bi cation-doping and active facets with hollow thin sheet morphology. [ABSTRACT FROM AUTHOR]

In this study, we reported on our attempt to synthesize few-layer MoS 2 -hybridized TiO 2 nanosheets with exposed {001} facets via a two-step hydrothermal method. The results demonstrated that MoS 2 has been successfully loaded on the surface of TiO 2 {001} nanosheets. The as-prepared MoS 2 /TiO 2 {001} hybrid composites showed better photocatalytic activity in the degradation of RhB under visible-light irradiation than pure MoS 2 and TiO 2 {001} nanosheets. Such a remarkable enhancement of photocatalytic activity was mainly attributed to the improved separation efficiency of photogenerated electron–hole pairs, which originated from the intimate interfacial contacts as well as the suitably matching conduction and valence band levels between MoS 2 and TiO 2 {001} nanosheets. [ABSTRACT FROM AUTHOR]

The effect of the hydrothermal temperature on the crystal structures and properties of {001} faceted anatase TiO 2 are systematically investigated. Results indicate that the reaction temperature has little effect on the particle size, but results in fusing the adjacent {001} facet and eliminating the cross-linked structure. Along with the decreased {001} facet percentage, the decreased crystal defects, increased crystallinity, and raised conduction band (CB) minimum dramatically increase the methylene blue (MB) decomposing efficiency. The present study indicates that it’s important to take into consideration of various factors in designing efficient photocatalysts, but not only to expose the high-reactive facets. [ABSTRACT FROM AUTHOR]

The photocatalytic activity of TiO 2 is correlated with its exposed crystal surface, phase composition, morphology, and crystallite size. In this study, TiO 2 microspheres with exposed crystal surface-controlled rutile TiO 2 nanorods were fabricated by employing a simple hydrothermal reaction in the presence of NaCl solution. The crystal phase, morphology, and size of the as-obtained materials were significantly dependent on the NaCl concentration. The exposed crystal surface of TiO 2 nanorods could be tailored by adjusting the NaCl concentration. With increasing NaCl concentration, the exposed area of the (1 1 1) crystal surface gradually decreased, whereas the area of the newly exposed (0 0 1) surface gradually increased. Characterization results indicated that the crystal phase of the TiO 2 microspheres was the only rutile structure in the system and no brookite phase was found. The diameter of the microspheres can be changed from 3.5 μm to 2 μm by tuning the NaCl concentration. Photocatalytic degradation of papermaking wastewater using the synthesized materials showed that the photocatalytic activities of the samples are affected by the exposed (0 0 1) crystal surface of TiO 2 , which can induce the separation of electrons and holes, thereby resulting in improved photocatalytic activity. [ABSTRACT FROM AUTHOR]

We describe a new strategy to control the number of cyclization steps in bioinspired radical (poly)- cyclizations involving epoxypolyenes containing keto units positioned along the polyene chain. This approach provides an unprecedentedly straightforward access to natural terpenoids with pendant unsaturated side chains. Additionally, in the case of bi- and tricyclizations, decalins with cis stereochemistry have been obtained as a consequence of the presence of the ketone. The preferential formation of cis-fused adducts was rationalized using DFT calculations. This result is completely unprecedented in biomimetic cyclizations and permits the access to natural terpenoids with this stereochemistry, as well as to non-natural analogues. [ABSTRACT FROM AUTHOR]

Highlights: [•] Nano-sized TiO2 terminals were linked to magnetic-cored dendrimers (MD). [•] Methyl orange degradation was enhanced with this new catalyst, compared to bare nano TiO2 and Fe/Ti mixture. [•] Enhanced photocatalytic activity is due to restrained recombination of electron–hole pairs by dendritic structure. [•] The suggested hybrid catalyst is conveniently recoverable with its magnetic core. [Copyright &y& Elsevier]

Highlights: [•] Mesoporous TiO2(001)/C microspheres are prepared via hydrothermal method. [•] HF promotes the growth of anatase crystal with {001} facet exposure. [•] Carbonacious species induce the assembly of TiO2 nanocrystals into microspheres. [•] The deposited carbon improves the surface area and mesoporous pore volume. [•] TiO2(001)/C facilitates the adsorption and degradation of MB under visible light. [Copyright &y& Elsevier]

Highlights: [•] Pt,N–TiO2 is the most active for both photocatalytic conversion and photocurrent generation. [•] The systematic comparison among the photocatalytic kinetics, TAS, and the DFT was conducted. [•] The synergistic effect is attributed to new mid-gap levels in which charge pairs are effectively separated. [Copyright &y& Elsevier]

Highlights: [•] Novel three-phase nanocomposites with two nanoclays and TiO2 were prepared under hydrothermal treatment at 180°C. [•] The nanocomposites showed significantly higher activity in decomposing NO x gas and toluene compared to P25. [•] The nanocomposites showed significantly higher activity in decomposing NO x gas and toluene compared to single-clay based nanocomposites. [•] The use of two nanoclays led to decreased agglomeration of the clay mineral particles compared to single-clay based nanocomposites. [ABSTRACT FROM AUTHOR]

Highlights: [•] The intermediates’ formation is dependent from the synthesis pathway. [•] Bulk-structural aspects influenced the intermediates: crystallinity grade, doping. [•] Surface-structural aspects governed the intermediates: W and Ti species. [•] The gold's deposition wavelength had a major impact on the WO3 structure. [•] The intermediates’ formation can be manipulated by the ratio of different species. [Copyright &y& Elsevier]

Highlights: [•] A high catalytic activity modified TiO2 was prepared by a simple annealing method. [•] Hydrogenated TiO2 decomposed formaldehyde without light illumination at room temperature. [•] The mechanism was attributed to the existence of oxygen vacancies and surface hydroxyl groups. [•] The concentration of oxygen vacancy played an important role in the degradation process. [Copyright &y& Elsevier]

TiO2-based nanostructures usually possess excellent photochemical properties. However, the relationship between their dimensionality and photocatalytic activity was rarely investigated. In this study, a series of TiO2-based nanostructures in various dimensionalities (such as nanosheets, nanotubes) were obtained by hydrothermal treatment of P25, and the process of structural evolution was also systematically investigated by TEM, BET, Raman, and XRD analysis. Much higher rate constant (3.7 × 10min) for the degradation of rhodamine B was found for nanosheets, comparing with those of three-dimensional P25 nanoparticles (0.59 × 10 min) and one-dimensional nanotubes (0.85 × 10 min). It is found that the hydrothermally prepared TiO2-based nanosheets possess small thickness (ca. 5 nm) and plentiful surface hydroxyl groups, and the reason why TiO2-based nanosheets possess superior photocatalytic activity is also discussed in detail from the microstructure and surface chemical states. In addition, TiO2-based nanosheets exhibit good reusability in the cyclic experiments, implying a potential application for photocatalytic degradation of organic pollutants. [ABSTRACT FROM AUTHOR]

In this reported work, TiO2 nanoparticles containing anatase-rutile and pure rutile phases were prepared by sol-gel and hydrolysis in acidic solution methods, respectively. Two general procedures, doping during synthesis (DDS) via a hydrolysis method and doping on the provided TiO2 nanoparticles (DOP) that is performed by the impregnation method have been studied by doping copper to these nanoparticles. The photocatalytic activity was evaluated by photodegradation of C.I. Acid Red 27 as a model contaminant. The prepared samples were characterised by X-ray diffraction, atomic absorption flame emission spectroscopy and scanning electron microscopy. It is found that the photosensitised degradation activity can be enhanced by doping an appropriate amount of Cu. Photocatalytic activity results indicated that samples that have been doped by the DDS procedure show higher photocatalytic efficiency than samples doped by the DOP procedure. [ABSTRACT FROM AUTHOR]

Doping catalytically inactive materials with dispersed atoms of an active species is a promising route toward realizing ultradilute binary catalyst systems. Beyond catalysis, strategically placed metal atoms can accelerate a wide range of solid-state reactions, particularly in hydrogen storage processes. Here we analyze the role of atomic Ti catalysts in the hydrogenation of Al-based hydrogen storage materials. We show that Ti atoms near the Al surface activate gas-phase H2 a key step toward hydrogenation. By controlling the placement of Ti, we have found that the overall reaction, comprising H2 dissociation and H spillover onto the Al surface, is governed by a pronounced trade-off between lowering of the H2 dissociation barrier and trapping of the products near the active site, with a sharp maximum in the overall activity for Ti in the subsurface layer. Our findings demonstrate the importance of controlling the placement of the active species in optimizing the activity of dilute binary systems. [ABSTRACT FROM AUTHOR]