Large-Scale Synthesis of Transition-Metal-Doped TiO<sub>2</sub> Nanowires with Controllable Overpotential

Liu, Bin; Chen, Hao Ming; Liu, Chong; Andrews, Sean C.; Hahn, Chris; Yang, Peidong

doi:10.1021/ja403761s

Cited by 332 publications

(205 citation statements)

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“…4d). This result is much lower than that reported for benchmark TiO 2 -based nanocatalysts in the literature (0.488 V vs. NHE) [40]. The fact that metal-doped TiO 2 hollow nanostructures were successfully prepared suggests the good compatibility of the supramolecular templates with various metal salts.…”

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confidence: 56%

Supramolecular nano-assemblies with tailorable surfaces: recyclable hard templates for engineering hollow nanocatalysts

Han

et al. 2014

Sci. China Mater.

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Supramolecular assemblies are introduced here as new-concept hard templates for the synthesis of hollow nanostructures (exemplified with TiO 2 hollow nanostructures in this work). Supramolecular templates with tunable morphology and rich surface functional groups facilitate the tight coating of other materials for the formation of hollow nanostructures. The weak interaction between the supramolecules or micromolecules benefits the facile removal of the templates for large-scale synthesis of hollow nanostructures and also affords excellent template reusability. This method allows for the incorporation of various metal dopants into the TiO 2 lattice, as a typical example of nanocatalyst, by introducing the corresponding metal salt as a dopant source. High-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and UV-vis absorption spectroscopy investigations suggested substitution of Ti 4+ sites by Co 2+, which increased the activity of the catalytic sites in the doped materials, reducing the overpotential of TiO 2 for the oxygen evolution reaction.The synthesis of hollow micro-and nanoscale structures has attracted great interest owing to their high surface areas, low density, and unique optical and electronic features [1,2]. All of these features make them suitable for a variety of applications including catalysis [3], solar cells [4,5], lithium-ion batteries [6], optical imaging [7], and drug delivery [8]. Especially for their applications in catalysis and photocatalysis, hollow micro-and nanoscale structures can provide a large active surface area, reduced diffusion resistance, excellent mass transfer efficiency, and high dispersity in reaction media with excellent reusability. The void space can also act as a catalyst container for embedded fine metal nanoparticles to extend their life-time [9,10]. Moreover, the thin shell of hollow micro-and nanoscale structures can facilitate charge transfer to surface active sites [11], which implies that they have great potential as highly efficient photocatalysts for water splitting and artificial photosynthesis [12].Although great efforts have been made towards the development of template-free routes for the preparation of hollow structures [13][14][15], template-directed synthetSchool of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China * Corresponding authors (email: xinhaoli@sjtu.edu.cn (Li XH); chemcj@sjtu.edu.cn (Chen JS)) ic methods have been established as one of the most effective and controllable methods for synthesizing hollow structures [16]. The most commonly used templates can broadly be divided into two categories: hard templates and soft templates. Monodisperse silica, polymers, carbon nanospheres, and nanoparticles of metals and metal oxides have been used as hard templates for preparation of hollow structures [17][18][19][20]. The synthesis of designed materials with hollow structures requires the templates to have additional surface functionalization. Because of droplet coalescence and Ostwa...

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confidence: 56%

Supramolecular nano-assemblies with tailorable surfaces: recyclable hard templates for engineering hollow nanocatalysts

Han

et al. 2014

Sci. China Mater.

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“…Following Ref. [20], we take pH ¼ 0 and U ¼ 1.93 V, which corresponds to an overpotential of 0.7 V, as found experimentally for rutile TiO 2 nanowires [32].…”

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confidence: 99%

TiO2 /Ferroelectric Heterostructures as Dynamic Polarization-Promoted Catalysts for Photochemical and Electrochemical Oxidation of Water

Lee

Selloni

2014

Phys. Rev. Lett.

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Using first-principles density functional theory calculations, we explore the chemical activity of epitaxial heterostructures of TiO 2 anatase on strained polar SrTiO 3 films focusing on the oxygen evolution reaction (OER), the bottleneck of water splitting. Our results show that the reactivity of the TiO 2 surface is tuned by electric dipoles dynamically induced by the adsorbed species during the intermediate steps of the reaction while the initial and final steps remain unaffected. Compared to the OER on unsupported TiO 2 , the combined effects of the dynamically induced dipoles and epitaxial strain strongly reduce rate-limiting thermodynamic barriers and significantly improve the efficiency of the reaction. DOI: 10.1103/PhysRevLett.112.196102 PACS numbers: 82.45.Jn, 82.45.Un, 82.50.−m, 77.55.fp Titanium dioxide (TiO 2 ) is widely used in photocatalysis and solar energy conversion due to its many favorable properties, like stability against photocorrosion and proper band alignment relative to the water redox potentials [1][2][3]. However, the efficiency of TiO 2 is notoriously low, and efforts at improving it through modifications such as doping [4] or synthesis of (nano)crystals exposing highly reactive facets [5] have encountered only limited success. Among the possible alternatives to TiO 2 , polar materials have recently attracted significant interest because their surface dipoles can react easily with charged species and supply built-in electric potentials to increase the carrier mobility [6,7]. However, control of the surface reactivity of these materials is difficult [8], e.g., because exposed surface dipoles often cause undesired atomic or electronic reconstructions and unexpected adsorption of charged species which can interfere with the reaction of interest [9][10][11]. Less well known than TiO 2 and polar semiconductors are heterostructures composed of stable TiO 2 thin films supported by a ferroelectric substrate [12,13]. Experimental studies have shown that the surface reactivity of TiO 2 is directly influenced and improved by the underlying ferroelectric domain structure, an effect that has been attributed to the combined efficient absorption and charge separation in the ferroelectric substrate and transport across the TiO 2 =substrate interface [12,13]. Despite some encouraging results [13,14], however, the interest in such TiO 2 =ferroeletric heterostructures has remained limited. In particular, their physical properties are largely unexplored and an atomic-scale understanding of their reactivity is missing.We present here a first-principles density functional theory (DFT) study of TiO 2 =ferroelectric heterostructures, which provides evidence that these composite materials can have a substantially enhanced reactivity relative to TiO 2 . We focus on model heterostructures composed of a TiO 2 (001) film of anatase (the TiO 2 polymorph most efficient for photocatalysis [15]) supported by a nearly ferroelectric SrTiO 3 (STO) substrate that can easily acquire a macroscopic polarization in the p...

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“…, which was about six orders of magnitude higher than the undoped sample [87]. In addition, the doped metal cations can also act as active sites for reactions, which is beneficial for catalysis.…”

Section: Dopingmentioning

confidence: 89%

Recent progress on advanced design for photoelectrochemical reduction of CO2 to fuels

et al. 2018

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The energy crisis and global warming become severe issues. Solar-driven CO 2 reduction provides a promising route to confront the predicaments, which has received much attention. The photoelectrochemical (PEC) process, which can integrate the merits of both photocatalysis and electrocatalysis, boosts splendid talent for CO 2 reduction with high efficiency and excellent selectivity. Recent several decades have witnessed the overwhelming development of PEC CO 2 reduction. In this review, we attempt to systematically summarize the recent advanced design for PEC CO 2 reduction. On account of basic principles and evaluation parameters, we firstly highlight the subtle construction for photocathodes to enhance the efficiency and selectivity of CO 2 reduction, which includes the strategies for improving light utilization, supplying catalytic active sites and steering reaction pathway. Furthermore, diversiform novel PEC setups are also outlined. These exploited setups endow a bright window to surmount the intrinsic disadvantages of photocathode, showing promising potentials for future applications. Finally, we underline the challenges and key factors for the further development of PEC CO 2 reduction that would enable more efficient designs for setups and deepen systematic understanding for mechanisms.

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Large-Scale Synthesis of Transition-Metal-Doped TiO₂ Nanowires with Controllable Overpotential

Cited by 332 publications

References 34 publications

Supramolecular nano-assemblies with tailorable surfaces: recyclable hard templates for engineering hollow nanocatalysts

Supramolecular nano-assemblies with tailorable surfaces: recyclable hard templates for engineering hollow nanocatalysts

TiO2 /Ferroelectric Heterostructures as Dynamic Polarization-Promoted Catalysts for Photochemical and Electrochemical Oxidation of Water

Recent progress on advanced design for photoelectrochemical reduction of CO2 to fuels

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Large-Scale Synthesis of Transition-Metal-Doped TiO2 Nanowires with Controllable Overpotential

Cited by 332 publications

References 34 publications

Supramolecular nano-assemblies with tailorable surfaces: recyclable hard templates for engineering hollow nanocatalysts

Supramolecular nano-assemblies with tailorable surfaces: recyclable hard templates for engineering hollow nanocatalysts

TiO2 /Ferroelectric Heterostructures as Dynamic Polarization-Promoted Catalysts for Photochemical and Electrochemical Oxidation of Water

Recent progress on advanced design for photoelectrochemical reduction of CO2 to fuels

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Large-Scale Synthesis of Transition-Metal-Doped TiO₂ Nanowires with Controllable Overpotential