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

Photoinduced reactivity of titanium dioxide

Recent years have seen a renewed interest in the harvesting and conversion of solar energy. Among various technologies, the direct conversion of solar to chemical energy using photocatalysts has received significant attention. Although heterogeneous photocatalysts are almost exclusively semiconductors, it has been demonstrated recently that plasmonic nanostructures of noble metals (mainly silver and gold) also show significant promise. Here we review recent progress in using plasmonic metallic nanostructures in the field of photocatalysis. We focus on plasmon-enhanced water splitting on composite photocatalysts containing semiconductor and plasmonic-metal building blocks, and recently reported plasmon-mediated photocatalytic reactions on plasmonic nanostructures of noble metals. We also discuss the areas where major advancements are needed to move the field of plasmon-mediated photocatalysis forward.

Plasmonic-metal nanostructures for efficient conversion of solar to chemical energy

Nano-sized TiO 2 photocatalytic water-splitting technology has great potential for low-cost, environmentally friendly solar-hydrogen production to support the future hydrogen economy. Presently, the solar-to-hydrogen energy conversion efficiency is too low for the technology to be economically sound. The main barriers are the rapid recombination of photo-generated electron/hole pairs as well as backward reaction and the poor activation of TiO 2 by visible light. In response to these deficiencies, many investigators have been conducting research with an emphasis on effective remediation methods. Some investigators studied the effects of addition of sacrificial reagents and carbonate salts to prohibit rapid recombination of electron/hole pairs and backward reactions. Other research focused on the enhancement of photocatalysis by modification of TiO 2 by means of metal loading, metal ion doping, dye sensitization, composite semiconductor, anion doping and metal ion-implantation. This paper aims to review the up-to-date development of the above-mentioned technologies applied to TiO 2 photocatalytic hydrogen production. Based on the studies reported in the literature, metal ion-implantation and dye sensitization are very effective methods to extend the activating spectrum to the visible range. Therefore, they play an important role in the development of efficient photocatalytic hydrogen production.

A review and recent developments in photocatalytic water-splitting using TiO2 for hydrogen production

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

A novel reaction mode using H2 produced from solid-liquid reaction to promote CO2 reduction through solid-gas reaction

Enhancement of biodiesel production via sequential esterification/transesterification over solid superacidic and superbasic catalysts

An optical fiber photocatalytic reactor is provided. The reactor comprises a reaction zone and multiple fibers located in the reaction zone. The fiber comprises a photocatalyst that is coated onto its surface via a thermal hydrolysis method. The adhesion between the fiber and the photocatalyst thereon is strong, and thus, the delamination of the photocatalyst film on the fiber can be prevented. Moreover, the optical fiber photocatalytic reactor is useful for the decomposition of nitrogen oxide which is one of air's most harmful contaminants. The present invention exhibits a high conversion of nitrogen oxide.

Optical Fiber Photocatalytic Reactor And Process For The Decomposition Of Nitrogen Oxide Using Said Reactor

Influence of co-feeds additive on the photo-epoxidation of propylene over V–Ti/MCM-41 photocatalyst

An optical-fiber photo reactor (OFPR) was designed and assembled to provide uniform light distribution inside the reactor, which spread light energy more efficiently than a traditional fixed-bed reactor. TiO2 films were coated on optical fibers using the dip-coating method. Titania solutions were prepared through the thermal hydrolysis of titanium butoxide, commercial Hombikat XXS100 solution, and Degussa P25 suspension for comparison. The thicknesses of the films ranged from 60 to 600 nm after calcination at 500℃, and the sizes of the nanocrystals in the TiO2 films were 15-25 nm, as estimated from SEM micrographs. Anatase phase was found from the XRD patterns in all the TiO2 films. The profilemeter and ASTM D3359 adhesion test results showed that uniform TiO2 films were formed with strong adhesion using the thermal hydrolysis and Hombikat XXS100 solutions, while those coated with P25-suspension exhibited poor adhesion on a glass surface. The contact angle of the water decreased to almost zero within 30 minutes under UV-light irradiation and then recovered to the initial contact angle in darkness, implying super hydrophilicity and perfection of the TiO2 films. Ammonia was photocatalytically decomposed in the OFPR under artificial light irradiation, indicating good photocatalytic reactivity of the TiO2-coated fibers.

http://ntur.lib.ntu.edu.tw/bitstream/246246/93154/1/23.pdf

Jeffrey C.S. Wu

Papers

A novel reaction mode using H2 produced from solid-liquid reaction to promote CO2 reduction through solid-gas reaction

Enhancement of biodiesel production via sequential esterification/transesterification over solid superacidic and superbasic catalysts

Optical Fiber Photocatalytic Reactor And Process For The Decomposition Of Nitrogen Oxide Using Said Reactor

Influence of co-feeds additive on the photo-epoxidation of propylene over V–Ti/MCM-41 photocatalyst

Preparation and Characterization of TiO2-Coated Optical-Fiber in a Photo Reactor