There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

2.3. Evaluation of Photocatalytic Water Splitting 6507 2.3.1. Photocatalytic Activity 6507 2.3.2. Photocatalytic Stability 6507 3. UV-Active Photocatalysts for Water Splitting 6507 3.1. d0 Metal Oxide Photocatalyts 6507 3.1.1. Ti-, Zr-Based Oxides 6507 3.1.2. Nb-, Ta-Based Oxides 6514 3.1.3. W-, Mo-Based Oxides 6517 3.1.4. Other d0 Metal Oxides 6518 3.2. d10 Metal Oxide Photocatalyts 6518 3.3. f0 Metal Oxide Photocatalysts 6518 3.4. Nonoxide Photocatalysts 6518 4. Approaches to Modifying the Electronic Band Structure for Visible-Light Harvesting 6519

Semiconductor-based Photocatalytic Hydrogen Generation

Fujishima and Honda (1972) demonstrated the potential of titanium dioxide (TiO2) semiconductor materials to split water into hydrogen and oxygen in a photo-electrochemical cell. Their work triggered the development of semiconductor photocatalysis for a wide range of environmental and energy applications. One of the most significant scientific and commercial advances to date has been the development of visible light active (VLA) TiO2 photocatalytic materials. In this review, a background on TiO2 structure, properties and electronic properties in photocatalysis is presented. The development of different strategies to modify TiO2 for the utilization of visible light, including non metal and/or metal doping, dye sensitization and coupling semiconductors are discussed. Emphasis is given to the origin of visible light absorption and the reactive oxygen species generated, deduced by physicochemical and photoelectrochemical methods. Various applications of VLA TiO2, in terms of environmental remediation and in particular water treatment, disinfection and air purification, are illustrated. Comprehensive studies on the photocatalytic degradation of contaminants of emerging concern, including endocrine disrupting compounds, pharmaceuticals, pesticides, cyanotoxins and volatile organic compounds, with VLA TiO2 are discussed and compared to conventional UV-activated TiO2 nanomaterials. Recent advances in bacterial disinfection using VLA TiO2 are also reviewed. Issues concerning test protocols for real visible light activity and photocatalytic efficiencies with different light sources have been highlighted.

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A review on the visible light active titanium dioxide photocatalysts for environmental applications

UV-Visible ار راد ن .د TiO2 ( تیفرظ راون مان هب نورتکلا یاراد یژرنا زارت لماش VB و ) رگید زارت ی یژرنا اب ( ییاناسر راون مان هب نورتکلا زا یلاخ و رتلااب VB یم ) .دشاب ت ود نیا نیب یژرنا توافت یژرنا فاکش زار ، پگ دناب هدیمان یم .دوش هک ینامز زا نورتکلا لاقتنا VB هب VB یم ماجنا دریگ ، TiO2 اب ودح یژرنا بذج د ev 2 / 3 ، نورتکلا تفج کی دیلوت یم هرفح .دیامن و نورتکلا هرفح ی نا اب هدش دیلوت یم کرتشم حطس هب لاقت ثعاب دناوت شنکاو ماجنا اه یی ددرگ . TiO2 دربراک ،دراد یدایز یاه هلمج زا یم ناوت اوه یگدولآ هیفصت یارب (CO2) و بآ و ... نآ زا هدافتسا درک .

Advanced Nanoarchitectures for Solar Photocatalytic Applications

A surface science perspective on TiO2 photocatalysis

The polyaniline (PANI)/TiO2 nanocomposites have been successfully synthesized via a hydrothermal method and followed by a low-temperature calcination treatment process. We find that such a PANI/TiO2 nanocomposite exhibits higher photocatalytic activity and stability than bare TiO2 and TiO2-xNx toward the liquid-phase degradation of methyl orange (MO) under both UV and visible light (420 nm < λ < 800 nm) irradiation. More noteworthy, the PANI/TiO2 photocatalyst still perform good activity toward MO and 4-chlorophenol (4-CP) under the longer wavelength of light (550 nm < λ < 800 nm). The total organic carbon (TOC) tests show that the mineralization rate of MO and 4-CP over PANI/TiO2 are apparently higher than bare TiO2 under the irradiation of both UV and visible light. The presence of synergic effect between PANI and TiO2 is believed to play an essential role in affecting the photoreactivity. At last, the roles of active species in the photocatalytic process are compared by using different types of active ...

Highly Efficient Photocatalytic Degradation of Organic Pollutants by PANI-Modified TiO2 Composite

Active species such as holes, electrons, hydroxyl radicals (•OH), and superoxide radicals (O2•–) involved in the photodegradation process of methyl orange (MO) over TiO2 photocatalyst were detected by several techniques. Using different types of active species scavengers, the results showed that the MO oxidation was driven mainly by the participation of O2•–, holes and •OH radicals. Characterized by the liquid chromatography/mass spectrometry, the transversion of the degradation products with the light irradiation time was first analyzed. Combined with the measurement of oxidation reduction potential, dissolved oxygen, conductivity, and pH values, the degradation process of MO on TiO2 under the effect of the active species was revealed. This was the first time that electrodes were introduced to track the degradation process in situ, and these parameters would be helpful to explain the degradation processes of other organic pollutants.

Evidence for the Active Species Involved in the Photodegradation Process of Methyl Orange on TiO2

A low-cost, time-saving coupling method was developed to prepare a novel BiVO4/TiO2 heterostructure photocatalyst. Benzene was selected as a target pollutant to evaluate the enhanced heterogenous photocatalytic oxidation process of this photocatalyst. The results clearly indicated that the addition of BiVO4 accelerated the degradation of benzene, and the optimum composition was recognized as BiVO4: TiO2 with ratio of 1:200 (mass ratio). Compared with TiO2−xNx (nitrogen-doped TiO2), its efficiency of removing gaseous benzene and producing CO2 under visible light irradiation (λ > 450 nm) was demonstrated more than 3 and 4 times, respectively. Such high conversion and mineralization ratio could be maintained for more than 50 h. Applications were also given for the photocatalytic elimination of gaseous benzene under simulated solar light and UV light irradiation. The benzene conversion reached 92% and 11%, corresponding to extremely high mineralization ratios of about 80% and 84%, respectively. Hence, this improved wide spectrum responsive photocatalyst would be needed, which were of importance to the potential application in the photocatalytic field.

BiVO4/TiO2 nanocrystalline heterostructure: A wide spectrum responsive photocatalyst towards the highly efficient decomposition of gaseous benzene

A nanocrystal heterojunction LaVO4TiO2 visible light photocatalyst has been successfully prepared by a simple coupled method. The catalyst was characterized by powder X-ray diffraction, nitrogen adsorption-desorption, transmission electron microscopy, UV-vis diffuse reflectance spectroscopy, X-ray photoelectron spectra, photoluminescence, and electrochemistry technology.The results showed that the prepared nanocomposite catalysts exhibited strong photocatalytic activity for decomposition of benzene under visible light irradiation with high photochemical stability. The enhanced photocatalytic performance of LaVO4/TiO2 may be attributed to not only the matched band potentials but also interconnected heterojunction of LaVO4 and TiO2 nanoparticles.

Efficient degradation of benzene over LaVO4/TiO2 nanocrystalline heterojunction photocatalyst under visible light irradiation.

A facile approach is developed to synthesis the highly efficient photocatalyst of Bi2O2CO3/BiOCl. The composite of Bi2O2CO3/BiOCl exhibits excellent photocatalytic activity toward Rhodamine B (RhB) under visible light, which is even better than that of P25 (commercial TiO2) under UV light. The role of the active species in the process of the degradation is evaluated by using different types of active species scavengers and measurement of electron spin resonance (ESR). The relative band structures of the Bi2O2CO3 and BiOCl are determined combined with the flat potential (Vfb) and bandgap energy (Eg) evaluated by UV–vis diffuse reflectance spectra. The results show that the composite of the two semiconductors facilitates the photosensitized degradation of RhB under visible light (420 nm

Danzhen Li

Papers

Highly Efficient Photocatalytic Degradation of Organic Pollutants by PANI-Modified TiO2 Composite

Evidence for the Active Species Involved in the Photodegradation Process of Methyl Orange on TiO2

BiVO4/TiO2 nanocrystalline heterostructure: A wide spectrum responsive photocatalyst towards the highly efficient decomposition of gaseous benzene

Efficient degradation of benzene over LaVO4/TiO2 nanocrystalline heterojunction photocatalyst under visible light irradiation.

Highly efficient Bi2O2CO3/BiOCl photocatalyst based on heterojunction with enhanced dye-sensitization under visible light