Sunlight-Operated TiO2-Based Photocatalysts (original) (raw)
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Titanium-Dioxide-Based Visible-Light-Sensitive Photocatalysis: Mechanistic Insight and Applications
Catalysts
Titanium dioxide (TiO2) is one of the most practical and prevalent photo-functional materials. Many researchers have endeavored to design several types of visible-light-responsive photocatalysts. In particular, TiO2-based photocatalysts operating under visible light should be urgently designed and developed, in order to take advantage of the unlimited solar light available. Herein, we review recent advances of TiO2-based visible-light-sensitive photocatalysts, classified by the origins of charge separation photo-induced in (1) bulk impurity (N-doping), (2) hetero-junction of metal (Au NPs), and (3) interfacial surface complexes (ISC) and their related photocatalysts. These photocatalysts have demonstrated useful applications, such as photocatalytic mineralization of toxic agents in the polluted atmosphere and water, photocatalytic organic synthesis, and artificial photosynthesis. We wish to provide comprehension and enlightenment of modification strategies and mechanistic insight, a...
Development of alternative photocatalysts to TiO2: Challenges and opportunities
Energy & Environmental Science, 2009
Since the early development of this technology in the 1970s, TiO 2 constitutes the archetypical photocatalyst due to its relatively high efficiency, low cost and availability. However, during the last decade a considerable number of new photocatalytic materials, either semiconductor or not, have been proposed as potential substitutes of TiO 2 , particularly in the case of solar applications, for which this standard photocatalyst is not very suitable because of its wide band gap. Semiconductors based on cations with d 0 configuration such Ta 5+ or Nb 5+ , as well as oxides or nitrides of d 10 elements such as Bi 3+ , In 3+ or Ga 3+ are among the most successful novel photocatalysts, but non-semiconductor solids like cation-interchanged zeolites also produce interesting results. In addition, some classical semiconductors like ZnO or CdS, initially discarded as a consequence of their poor stability under irradiation, have been reconsidered as feasible photocatalysts for particular applications. This growing body of data requires new analysis of the challenges and opportunities facing photocatalysis in order to assess which of the photoactive materials are best for each particular application. In this review, we summarize, with an historical perspective, the main achievements obtained with photocatalyst alternatives to TiO 2 in the three main niches for this technology: water splitting for hydrogen production, decontamination and disinfection processes, and organic synthesis.
Insights into the TiO2-Based Photocatalytic Systems and Their Mechanisms
2019
Photocatalysis is a multifunctional phenomenon that can be employed for energy applications such as H2 production, CO2 reduction into fuels, and environmental applications such as pollutant degradations, antibacterial disinfection, etc. In this direction, it is not an exaggerated fact that TiO2 is blooming in the field of photocatalysis, which is largely explored for various photocatalytic applications. The deeper understanding of TiO2 photocatalysis has led to the design of new photocatalytic materials with multiple functionalities. Accordingly, this paper exclusively reviews the recent developments in the modification of TiO2 photocatalyst towards the understanding of its photocatalytic mechanisms. These modifications generally involve the physical and chemical changes in TiO2 such as anisotropic structuring and integration with other metal oxides, plasmonic materials, carbon-based materials, etc. Such modifications essentially lead to the changes in the energy structure of TiO2 t...
Modified Titanium Dioxide for Photocatalytic Applications
Photocatalysts - Applications and Attributes [Working Title]
Titanium dioxide (TiO 2 ) has been widely used as a photocatalyst in many environmental and energy applications due to its efficient photoactivity, high stability, low cost, and safety to the environment and humans. However, its large band gap energy, ca. 3.2 eV limits its absorption of solar radiation to the UV light range which accounts for only about 5% of the solar spectrum. Furthermore, the photocatalytic activity of TiO 2 is also limited by the rapid recombination of the photogenerated electron-hole pairs. When used in water treatment applications, TiO 2 has a poor affinity toward organic pollutants, especially hydrophobic organic pollutants. Several strategies have been employed to reduce its band gap energy, its electron-hole recombination rates as well as enhance its absorption of organic pollutants. In this chapter, we review some of the most recent works that have employed the doping, decoration, and structural modification of TiO 2 particles for applications in photocatalysis. Additionally, we discuss the effectiveness of these dopants and/or modifiers in enhancing TiO 2 photoactivity as well as some perspective on the future of TiO 2 photocatalysis.
Enhancement of the activity of TiO 2-based photocatalysts : a review
2015
Titania is one of the most widely used standard reference photocatalysts in the field of environmental applications. However, the wide anatase band gap and high degree of recombination between photogenerated charge carriers is limiting titania overall photocatalytic efficiency in water and air purification. This paper reviews recent studies on semiconductor photocatalysis, carried out at the Institute of Catalysis of the Bulgarian Academy of Sciences, aimed at enhancing the efficiency of TiO2-based photocatalysts and obtaining novel photocatalytic systems for sunlight utilization and application of methods improving the overall performance of the photocatalytic processes.
Visible-light activation of TiO2 photocatalysts: Advances in theory and
Though there are many advantages for the TiO2 compared to other semiconductor photocatalysts, its band gap of 3.2 eV restrains application to the UV-region of the electromagnetic spectrum ( ≤ 387.5 nm). As a result, development of visible-light active titanium dioxide is one of the key challenges in the field of semiconductor photocatalysis. In this review, advances in the strategies for the visible light activation, origin of visible-light activity, and electronic structure of various visible-light active TiO2 photocatalysts are discussed in detail. It has also been shown that if appropriate models are used, the theoretical insights can successfully be employed to develop novel catalysts to enhance the photocatalytic performance in the visible region. Recent developments in theory and experiments in visible-light induced water splitting, degradation of environmental pollutants, water and air purification and antibacterial applications are also reviewed. Various strategies to identify appropriate dopants for improved visible-light absorption and electron–hole separation to enhance the photocatalytic activity are discussed in detail, and a number of recommendations are also presented.
J Mod Green Energy , 2024
The term "photocatalysis" has recently gained high popularity, and various products using photocatalytic functions have been commercialized. Of all the materials that may be used as photocatalysts, titanium dioxide (TiO 2) is virtually the only one that is now and most likely will remain appropriate for industrial application. Water and air purification systems, sterilization, hydrogen evolution, self-cleaning surfaces, and photoelectrochemical conversion are just a few of the products and applications in the environmental and energy domains that make extensive use of TiO 2 photocatalysis. This is due to the fact that TiO 2 has the lowest cost, most stability, and most effective photoactivity. Furthermore, history attests to its safety for both people and the environment because it has been used as a white pigment since antiquity. This review discusses some important aspects and issues concerning different synthesis methods and their influence on the structure and properties of TiO 2 , as well as the concept of photocatalysis based on it as a promising biocompatible functional material that has been widely used in recent years. The advantages of TiO 2 applications in various fields of science and technology are discussed, including environmental protection, photocatalysis including self-cleaning surfaces, water and air purification systems, hydrogen liberation, photovoltaic energy, cancer diagnosis and therapy, coatings and dental products, etc. Information on the structure and properties of TiO 2 phases is presented, as well as modern methods of synthesizing functional materials based on it. A detailed review of the basic principles of TiO 2 photocatalysis is then given, with a brief introduction to the modern concept of TiO 2 photocatalysis. Recent advances in the fundamental understanding of TiO 2 photocatalysis at the atomic-molecular level are highlighted, and advances in TiO 2 photocatalysis from the perspective of design and engineering of new materials are discussed. The challenges and prospects of TiO 2 photocatalysis are briefly discussed.
Journal of Catalysis, 2003
This review deals with the preparation of highly reactive titanium oxide photocatalysts and the clarification of the active sites as well as the detection of the reaction intermediates at the molecular level. Furthermore, we discuss the advancement of photofunctional systems and processes that can utilize visible and/or solar light. The photocatalytic reactivity of semiconducting TiO 2 powder was found to be dramatically enhanced by the loading of small amounts of Pt, which work to enhance the charge separation of the electrons and holes generated by light irradiation. Highly dispersed titanium oxide species prepared within zeolite frameworks or silica matrices showed unique photocatalytic performance much higher than that of conventional semiconducting TiO 2 photocatalysts. The potential for the effective utilization and conversion of solar energy makes research into the modification of the electronic properties of TiO 2 photocatalysts by such methods as advanced metal ion implantation to produce photocatalysts which are able to absorb and operate efficiently even under visible light irradiation one of the most important fields in photocatalysis research. This modification process can be applied not only to semiconducting TiO 2 photocatalysts but also to TiO 2 thin film photocatalysts, as well as titanium oxide photocatalysts highly dispersed within zeolite frameworks. Significantly, a new alternative method for directly preparing such visible-light-responsive TiO 2 thin film photocatalysts has been successfully developed by applying a RF magnetron sputtering deposition method.