TiO(2) is one of the most studied compounds in materials science. Owing to some outstanding properties it is used for instance in photocatalysis, dye-sensitized solar cells, and biomedical devices. In 1999, first reports showed the feasibility to grow highly ordered arrays of TiO(2) nanotubes by a simple but optimized electrochemical anodization of a titanium metal sheet. This finding stimulated intense research activities that focused on growth, modification, properties, and applications of these one-dimensional nanostructures. This review attempts to cover all these aspects, including underlying principles and key functional features of TiO(2), in a comprehensive way and also indicates potential future directions of the field.

TiO2 nanotubes: synthesis and applications.

TiO 2 photocatalysis is widely used in a variety of applications and products in the environmental and energy fields, including self-cleaning surfaces, air and water purification systems, sterilization, hydrogen evolution, and photoelectrochemical conversion. The development of new materials, however, is strongly required to provide enhanced performances with respect to the photocatalytic properties and to find new uses for TiO 2 photocatalysis. In this review, recent developments in the area of TiO 2 photocatalysis research, in terms of new materials from a structural design perspective, have been summarized. The dimensionality associated with the structure of a TiO 2 material can affect its properties and functions, including its photocatalytic performance, and also more specifically its surface area, adsorption, reflectance, adhesion, and carrier transportation properties. We provide a brief introduction to the current situation in TiO 2 photocatalysis, and describe structurally controlled TiO 2 photocatalysts which can be classified into zero-, one-, two-, and three-dimensional structures. Furthermore, novel applications of TiO 2 surfaces for the fabrication of wettability patterns and for printing are discussed.

TiO2 photocatalysis: Design and applications

Solar driven catalysis on semiconductors to produce clean chemical fuels, such as hydrogen, is widely considered as a promising route to mitigate environmental issues caused by the combustion of fossil fuels and to meet increasing worldwide demands for energy. The major limiting factors affecting the efficiency of solar fuel synthesis include; (i) light absorption, (ii) charge separation and transport and (iii) surface chemical reaction; therefore substantial efforts have been put into solving these problems. In particular, the loading of co-catalysts or secondary semiconductors that can act as either electron or hole acceptors for improved charge separation is a promising strategy, leading to the adaptation of a junction architecture. Research related to semiconductor junction photocatalysts has developed very rapidly and there are a few comprehensive reviews in which the strategy is discussed (A. Kudo and Y. Miseki, Chemical Society Reviews, 2009, 38, 253–278, K. Li, D. Martin, and J. Tang, Chinese Journal of Catalysis, 2011, 32, 879–890, R. Marschall, Advanced Functional Materials, 2014, 24, 2421–2440). This critical review seeks to give an overview of the concept of heterojunction construction and more importantly, the current state-of-the art for the efficient, visible-light driven junction water splitting photo(electro)catalysts reported over the past ten years. For water splitting, these include BiVO4, Fe2O3, Cu2O and C3N4, which have attracted increasing attention. Experimental observations of the proposed charge transfer mechanism across the semiconductor/semiconductor/metal junctions and the resultant activity enhancement are discussed. In parallel, recent successes in the theoretical modelling of semiconductor electronic structures at interfaces and how these explain the functionality of the junction structures is highlighted.

/pdf/visible-light-driven-heterojunction-photocatalysts-for-water-33q4busijg.pdf

Visible-light driven heterojunction photocatalysts for water splitting – a critical review

Development of efficient and affordable oxygen evolution catalysts is essential for large-scale electrolytic water splitting. Here, the authors report mesoporous nickel–iron composite nanosheets loaded on macroporous nickel foam substrates, and evaluate their electrocatalytic oxygen evolution in basic media.

/pdf/electrodeposition-of-hierarchically-structured-three-54tud3jo7o.pdf

Electrodeposition of hierarchically structured three-dimensional nickel-iron electrodes for efficient oxygen evolution at high current densities.

The present paper gives an overview and review on self-organized TiO2 nanotube layers and other transition metal oxide tubular structures grown by controlled anodic oxidation of a metal substrate We describe mechanistic aspects of the tube growth and discuss the electrochemical conditions that need to be fulfilled in order to synthesize these layers Key properties of these highly ordered, high aspect ratio tubular layers are discussed In the past few years, a wide range of functional applications of the layers have been explored ranging from photocatalysis, solar energy conversion, electrochromic effects over using the material as a template or catalyst support to applications in the biomedical field A comprehensive view on state of the art is provided

TiO2 nanotubes: Self-organized electrochemical formation, properties and applications

ZnO/ZnGaNO heterostructure with enhanced photocatalytic properties prepared from a LDH precursor using a coprecipitation method

Hydrogen fuel generation using solar light via photoelectrochemical (PEC) methods can help meet growing global energy demands and decrease environmental pollution. The key to efficient PEC hydrogen production is the synthesis of solar light driven photoelectrodes with efficient charge carrier separation. Here, we designed and prepared a ternary Bi2MoO6/Pd/TiO2 photoelectrode composed of Bi2MoO6 nanosheets, Pd nanoparticles (NPs), and TiO2 nanotube arrays (NTAs) on a Ti substrate using electrochemical methods. This novel photoelectrode had good visible light absorbance and significantly improved PEC hydrogen production rates (∼5- and >15-times higher under UV–vis and visible light irradiation, respectively, compared with TiO2NTAs). The interfacial charge transfer mechanism of Bi2MoO6/Pd/TiO2 NTAs was comprehensively studied by comparing its PEC and photoelectrocatalytic performance with that of other TiO2 NTAs (i.e., Pd/TiO2 NTAs, Bi2MoO6/TiO2 NTAs, and Pd/Bi2MoO6/TiO2 NTAs). For Bi2MoO6/Pd/TiO2 NTAs, Pd N...

3D Heterostructured Ti-Based Bi2MoO6/Pd/TiO2 Photocatalysts for High-Efficiency Solar Light Driven Photoelectrocatalytic Hydrogen Generation

Single-crystal PbS nanorods were successfully synthesized through a simple hydrothermal route using PEO-PPO-PEO triblock copolymer (P123) as a structure-directing agent. The XRD pattern indicates that the crystal structure of the nanorods is face-centre-cubic rocksalt. A SEM image shows that the nanorods have a diameter of 40-70 nm and a length of 200-600 nm, and both tips exhibit taper-like structures. HRTEM and SAED images reveal the single-crystalline nature of the nanorods with the growth along the (111) direction. The experimental results indicated that the P123 concentration and reaction temperature played important roles in controlling the morphology of the PbS nanostructures. The optical property of PbS nanorods was investigated by UV-Vis absorption spectroscopy and the band structure was calculated by the B3LYP hybrid density functional theory.

Synthesis of single-crystal PbS nanorods via a simple hydrothermal process using PEO–PPO–PEO triblock copolymer as a structure-directing agent

National Natural Science Foundation of China [50571085]; Natural Science Foundation of Fujian Province [U0750015]; RD Xiamen [3502Z20073004]

Controllable incorporation of CdS nanoparticles into TiO2 nanotubes for highly enhancing the photocatalytic response to visible light

Correction for ‘Inorganic-modified semiconductor TiO2 nanotube arrays for photocatalysis’ by Mengye Wang et al., Energy Environ. Sci., 2014, 7, 2182–2202.

/pdf/correction-inorganic-modified-semiconductor-tio2-nanotube-3dro5wkumw.pdf

Lan Sun

Papers

ZnO/ZnGaNO heterostructure with enhanced photocatalytic properties prepared from a LDH precursor using a coprecipitation method

3D Heterostructured Ti-Based Bi2MoO6/Pd/TiO2 Photocatalysts for High-Efficiency Solar Light Driven Photoelectrocatalytic Hydrogen Generation

Synthesis of single-crystal PbS nanorods via a simple hydrothermal process using PEO–PPO–PEO triblock copolymer as a structure-directing agent

Controllable incorporation of CdS nanoparticles into TiO2 nanotubes for highly enhancing the photocatalytic response to visible light

Correction: Inorganic-modified semiconductor TiO2 nanotube arrays for photocatalysis