DOCSLIB.ORG

Tio2 Photocatalysis: a Historical Overview and Future Prospects Tio2 Photocatalysis: a Historical Overview and Future Prospects

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Tio2 Photocatalysis: a Historical Overview and Future Prospects Tio2 Photocatalysis: a Historical Overview and Future Prospects Printed with permission of The Institute of Pure and Applied Physics (IPAP) JAPANESE JOURNAL OF APPLIED PHYSICS Vol.44, No.12 (2005) pp.8269-8285[Part1] Invited Review Paper TiO2 Photocatalysis: A Historical Overview and Future Prospects Kazuhito Hashimoto1,2, Hiroshi Irie2 and Akira Fujishima3 Photocatalysis has recently become a 1. Historical Background be- compared the photocatalytic activities of common word and various products using fore Honda–Fujishima Effect various TiO2 powders using twelve types of photocatalytic functions have been commer- commercial anatase and three types of rutile, cialized. Among many candidates for photo- TiO2 powders have been commonly used and concluded that the anatase activity of catalysts, TiO2 is almost the only material as white pigments from ancient times. They the autooxidation is much higher than that of suitable for industrial use at present and also are inexpensive, chemically stable and harm- rutile, suggesting a fairly high degree of prog- 4) probably in the future. This is because TiO2 has less, and have no absorption in the visible ress of the research. In those days, however, the most efficient photoactivity, the highest region. Therefore, they have a white color. the photocatalytic power of TiO2 might have stability and the lowest cost. More signifi- However, the chemical stability of TiO2 holds attracted only partially limited scientists’ atten- cantly, it has been used as a white pigment only in the dark. Instead, it is active under UV tion in the field of either catalysis or photo- from ancient times, and thus, its safety to light irradiation, inducing some chemical reac- chemistry, and the study of TiO2 photocatalysis humans and the environment is guaranteed tions. Such activity under sunlight was known had not developed widely in either academic by history. There are two types of photo- from the flaking of paints and the degrada- or industrial society. 1) chemical reaction proceeding on a TiO2 tion of fabrics incorporating TiO2. Scientific surface when irradiated with ultraviolet light. studies on such photoactivity of TiO2 have 2. Water Photolysis with TiO2 One includes the photo-induced redox reac- been reported since the early part of the 20th Electrode in 1970s tions of adsorbed substances, and the other is century. For example, there was a report on the photo-induced hydrophilic conversion of the photobleaching of dyes by TiO2 both in In the late 1960s, one of the present 2) TiO2 itself. The former type has been known vacuo and in oxygen in 1938. It was reported authors (AF) began to investigate the photo- since the early part of the 20th century, but that UV absorption produces active oxygen electrolysis of water, using a single crystal the latter was found only at the end of the species on the TiO2 surface, causing the n-type TiO2 (rutile) semiconductor electrode, century. The combination of these two func- photobleaching of dyes. It was also known because it has a sufficiently positive valence tions has opened up various novel applications that TiO2 itself does not change through the band edge to oxidize water to oxygen. It is of TiO2, particularly in the field of building photoreaction, although the ``photocatalyst’’ also an extremely stable material even in the materials. Here, we review the progress of the terminology was not used for TiO2 in the presence of aqueous electrolyte solutions, scientific research on TiO2 photocatalysis as report, but called a photosensitizer. much more so than other types of semicon- well as its industrial applications, and describe ductor that have been tried. The possibility of future prospects of this field mainly based on It is equivocal when and who started solar photoelectrolysis was demonstrated for the present authors’ work. utilizing first such a photochemical power the first time in 1969 with the system shown of TiO2 to induce chemical reactions actively, in Fig. 1, which was exposed to near-UV KEYWORDS: titanium dioxide, Honda– but at least in Japan, there were a series of light, and was connected to a platinum black Fujishima effect, photoelectrol- reports by Mashio et al., from 1956, entitled counter electrode through an electrical load.5) 3) ysis, redox reaction, hydrophilic ``Autooxidation by TiO2 as a photocatalyst’’. Then, this electrochemical photolysis of water conversion, environmental They dispersed TiO2 powders into various was reported in Nature by analogy with a application organic solvents such as alcohols and hydro- natural photosynthesis in 1972.6) In those carbons followed by the UV irradiation with days, crude oil prices ballooned suddenly, an Hg lamp. They observed the autooxida- and the future lack of crude oil was a serious tion of solvents and the simultaneous forma- concern. Thus, this became known as the time tion of H2O2 under ambient conditions. It of ``oil crisis’’. Therefore, this report attracted is interesting to note that they had already the attention not only of electrochemists but 1 Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan 2 Department of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan 3 Kanagawa Academy of Science and Technology, 3-2-1 Sakado, Takatsu-ku, Kawasaki, Kanagawa 213-0012, Japan (Received August 11, 2005; accepted September 26, 2005; published December 8, 2005) ©2005 The Japan Society of Applied Physics 4 JSAP International No.14 (July 2006) JSAP International No.14 (July 2006) 5 also of many scientists in a broad area, and 1–103nm, depending on the carrier density It is desirable that the band gap of the numerous related studies were reported in the and dielectric constant of the semiconductor. semiconductor is near that for the optimum 1970s. If this electrode receives photons with ener- utilization of solar energy, which would be gies greater than that of the material band about 1.35eV. When semiconductor electrodes When the surface of the rutile TiO2 elec- gap, EG, electron–hole pairs are generated are used as either photoanodes or photo- trode was irradiated with light consisting of and separated in the space-charge layer. In cathodes for water electrolysis, the bandgap wavelengths shorter than its band gap, about the case of an n-type semiconductor, the should be at least 1.23eV (i.e., the equilibrium 415nm (3.0eV), photocurrent flowed from the electric field existing across the space-charge cell potential for water electrolysis at 25°C and platinum counter electrode to the TiO2 elec- layer drives photogenerated holes toward the 1atm), particularly considering the existence of trode through the external circuit. The direc- interfacial region (i.e., solid–liquid) and elec- polarization losses due to, for example, oxygen tion of the current revealed that the oxidation trons toward the interior of the electrode and evolution. Although various semiconductors reaction (oxygen evolution) occurs at the TiO2 from there to the electrical connection to the with smaller band gaps were investigated, electrode and the reduction reaction (hydrogen external circuit. The reverse process occurs none succeeded for the water photoelectrol- evolution) at the Pt electrode. This observa- at a p-type semiconductor electrode. These ysis with visible light. This is because they were tion shows that water can be decomposed, fundamental processes of semiconductor in most cases corroded in an aqueous electro- using UV light, into oxygen and hydrogen, photoelectrochemistry have been discussed in lyte under irradiation, i.e., the photogenerated without the application of an external voltage, many recent reviews.7–11) holes oxidized the semiconductor itself. according to the following scheme. – + If the conduction band energy ECB is One of the other approaches to utilize TiO2 +hν → e +h (1) higher (i.e., closer to the vacuum level, or longer wavelength light could involve the dye (at the TiO2 electrode) + + more negative on the electrochemical scale) sensitization of TiO2. This approach, although 2H2O+4h → O2 +4H (2) than the hydrogen evolution potential, photo- it is theoretically possible to use it for water (at the Pt electrode) + – generated electrons can flow to the counter photoelectrolysis, has practical problems, prin- 2H +2e → H2 (3) electrode and reduce protons, resulting in cipally that most photosensitizer dyes would The overall reaction is hydrogen gas evolution without an applied be far too unstable under these conditions. potential, although, as shown in Fig. 2, ECB Therefore, the so-called regenerative photo- 2H2O+4hν → O2 +2H2 (4) should be at least as negative as –0.4V versus electrochemical cells, in which a single redox When a semiconductor electrode is in contact the standard hydrogen electrode (SHE) in couple exists, the reduced form is oxidized at with an electrolyte solution, thermodynamic acid solution or –1.2V (SHE) in alkaline solu- the TiO2 photoanode and the oxidized form is equilibration occurs at the interface. This may tion. Among the oxide semiconductors, TiO2 reduced at the counter electrode, were studied result in the formation of a space-charge layer (acid), SrTiO3, CaTiO3, KTaO3, Ta2O5, and ZrO2 intensively. Chlorophyll and various organic within a thin surface region of the semicon- satisfy this requirement. On the other hand, dyes, such as xanthene dyes, were used as ductor, in which the electronic energy bands the employment of an external bias or of a sensitizers, but neither the solar conversion are generally bent upwards and downwards difference in pH between the anolyte and the efficiency nor the stability of the dyes was in the cases of the n- and p-type semicon- catholyte is required in the case of other mate- very high in those days. It is, however, to be ductors, respectively. The thickness of the rials in order to achieve hydrogen evolution. emphasized that this approach was intensively space-charge layer is usually of the order of researched later by Gratzel et al.
Load more

Recommended publications
  • Application of the Photocatalytic Chemistry of Titanium Dioxide to Disinfection and the Killing of Cancer Cells
    Separation and Purification Methods Volume 28(1) 1999, pp. 1-50 APPLICATION OF THE PHOTOCATALYTIC CHEMISTRY OF TITANIUM DIOXIDE TO DISINFECTION AND THE KILLING OF CANCER CELLS Daniel M. Blake, Pin-Ching Maness, Zheng Huang, Edward J. Wolfrum, and Jie Huang The National Renewable Laboratory 1617 Cole Boulevard Golden, Colorado 80401-3393 William A. Jacoby Department of Chemical Engineering W2016 Engineering Building East University of Missouri Columbia, MO 65211 Table of Contents Abstract........................................................................................................................... 2 Introduction .................................................................................................................... 2 Background..................................................................................................................... 3 Mode of Action of TiO2................................................................................................... 6 Photocatalytic Reactor Configurations .......................................................................... 9 Structure of Target Organisms....................................................................................... 10 Bacteria...................................................................................................................... 10 Viruses ....................................................................................................................... 13 Fungi.........................................................................................................................
    [Show full text]
  • Application of Titanium Dioxide Photocatalysis to Create Self-Cleaning Building Materials
    Application of Titanium Dioxide Photocatalysis to Create Self-Cleaning Building Materials Roland Benedix1 Frank Dehn2 Jana Quaas, Marko Orgass3 SUMMARY To realize self-cleaning material surfaces there are two principal ways: the de- velopment of super-hydrophobic or super-hydrophilic materials. By transferring the microstructure of selected plant surfaces to practical materials like tiles and facade paints, super-hydrophobic surfaces were obtained (Lotus effect). Super- hydrophilic materials were developed by coating glass, ceramic tiles or plastics with the semiconducting photocatalyst titanium dioxide (TiO2). If TiO2 is illumi- nated by light, grease, dirt and organic contaminants are decomposed and can easily be swept away by water (rain). Subject of our further research is a detailed study of the interaction between TiO2 and traditional building materials like con- crete, mortar and plaster. 1 INTRODUCTION In practice, surface cleaning of building materials like tiles, facades and glass panes causes considerable trouble, high consumption of energy and chemical detergents and, consequently, high costs. To realize self-cleaning material sur- faces there are two principal ways: the development of so-called super- hydrophobic or super-hydrophilic surfaces. 1 Prof. Dr. rer. nat. habil., FB IMN/Chemie, HTWK Leipzig 2 Dipl.-Ing., Institut für Massivbau und Baustofftechnologie, Universität Leipzig 3 cand.-Ing., Institut für Massivbau und Baustofftechnologie, Universität Leipzig 157 LACER No. 5, 2000 The wetting of a solid with water, where air is the surrounding medium, is de- pendent on the relation between the interfacial tensions (water/air, water/solid and solid/air). The ratio between these tensions determines the contact angle θ be- tween a water droplet on a given surface.
    [Show full text]
  • The Highly Efficient Photocatalytic and Light Harvesting Property of Ag-Tio2
    www.nature.com/scientificreports OPEN The highly efcient photocatalytic and light harvesting property of Ag-TiO2 with negative nano-holes Received: 3 October 2017 Accepted: 24 November 2017 structure inspired from cicada wings Published: xx xx xxxx Imran Zada1, Wang Zhang1, Wangshu Zheng1, Yuying Zhu1, Zhijian Zhang2, Jianzhong Zhang2, Muhammad Imtiaz1, Waseem Abbas1 & Di Zhang1 The negative replica of biomorphic TiO2 with nano-holes structure has been efectively fabricated directly from nano-nipple arrays structure of cicada wings by using a simple, low-cost and highly efective sol-gel ultrasonic method. The nano-holes array structure was well maintained after calcination in air at 500 °C. The Ag nanoparticles (10 nm–25 nm) were homogeneously decorated on the surface and to the side wall of nano-holes structure. It was observed that the biomorphic Ag-TiO2 showed remarkable photocatalytic activity by degradation of methyl blue (MB) under UV-vis light irradiation. The biomorphic Ag-TiO2 with nano-holes structure showed superior photocatalytic activity compared to the biomorphic TiO2 and commercial Degussa P25. This high-performance photocatalytic activity of the biomorphic Ag-TiO2 may be attributed to the nano-holes structure, localized surface plasmon resonance (LSPR) property of the Ag nanoparticles, and enhanced electron-hole separation. Moreover, the biomorphic Ag-TiO2 showed more absorption capability in the visible wavelength range. This work provides a new insight to design such a structure which may lead to a range of novel applications. Photolysis of organic containments has paid a great attention in environmental cleaning and water purifcation1–5. TiO2 has been extensively used as a photocatalytic material due to its signifcant photostability, environmentally friendliness, high chemical stability, non-toxicity and low-cost6.
    [Show full text]
  • Hydrogen Production from Water on Heterogeneous Photocatalysts
    May 26, 2011; Renaissance Washington DC The Science for Our Nation’s Energy Future: EFRC Summit & Forum Basic solar energy research in Japan Kazunari Domen Chemical System Engineering The University of Tokyo Chemical System Engineering The University of Tokyo Government Energy Technology R&D Budgets 2395 Million US$ 846 340 12000 1272 1228 4202 0 1457 10000 145 165 2762 8000 154 157 Total Other Technologies or Research 10 354 68 457 Other Power and Storage Technologies 246 Hydrogen and Fuel Cells 6000 200 545 Nuclear Fission and Fusion 45 4000 Renewable Energy Sources Fossil Fuels Energy Efficiency 2000 0 Germany Japan US IEA (International Energy Agency) Energy Technology R&D Statistics 2009 Ratios of Energy R&D Budgets 100% 90% 80% Total Other Technologies or Research 70% Other Power and Storage Technologies 60% Hydrogen and Fuel Cells Nuclear Fission and Fusion 50% Renewable Energy Sources 40% Fossil Fuels 30% Energy Efficiency 20% 10% 0% Germany Japan US IEA (International Energy Agency) Energy Technology R&D Statistics 2009 2011 Great East Japan Earthquake and Tsunami Attack on Fukushima Daiichi Nuclear Power Plant 11 March 11 March 11 March 11 March Copyright: The Yomiuri Shinbun, The Asahi Shinbun Co. Nuclear Meltdown at Fukushima Daiichi Nuclear Power Plant 12 March, at 15:30 12 March, before 15:30 15 March 15 March Copyright: The Yomiuri Shinbun, The Asahi Shinbun Co. 24 March Production of PVs in Japan Single-Si Poly-Si Japan Photovoltaic Energy Association 104-kW a-Si Others http://www.jpea.gr.jp/04doc01.html Governmental Financial
    [Show full text]
  • Photodehydrogenation of Ethanol Over Cu2o/Tio2 Heterostructures
    nanomaterials Article Photodehydrogenation of Ethanol over Cu2O/TiO2 Heterostructures Congcong Xing 1,2, Yu Zhang 1, Yongpeng Liu 3 , Xiang Wang 1, Junshan Li 1, Paulina R. Martínez-Alanis 4 , Maria Chiara Spadaro 5 , Pablo Guardia 1, Jordi Arbiol 5,6 , Jordi Llorca 2,* and Andreu Cabot 1,6,* 1 Catalonia Institute for Energy Research (IREC), Sant Adrià de Besòs, 08930 Barcelona, Spain; [email protected] (C.X.); [email protected] (Y.Z.); [email protected] (X.W.); [email protected] (J.L.); [email protected] (P.G.) 2 Institute of Energy Technologies, Department of Chemical Engineering and Barcelona Research Center in Multiscale Science and Engineering, Universitat Politècnica de Catalunya, EEBE, 08019 Barcelona, Spain 3 Laboratory for Molecular Engineering of Optoelectronic Nanomaterials (LIMNO), École Polytechnique Fédérale de Lausanne (EPFL), Station 6, CH-1015 Lausanne, Switzerland; yongpeng.liu@epfl.ch 4 ENFOCAT-IN2UB, Universitat de Barcelona (UB), C/Martí i Franquès 1, 08028 Barcelona, Spain; [email protected] 5 Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193 Barcelona, Spain; [email protected] (M.C.S.); [email protected] (J.A.) 6 ICREA, Pg. Lluis Companys 23, 08010 Barcelona, Spain * Correspondence: [email protected] (J.L.); [email protected] (A.C.) Abstract: The photodehydrogenation of ethanol is a sustainable and potentially cost-effective strategy to produce hydrogen and acetaldehyde from renewable resources. The optimization of this process requires the use of highly active, stable and selective photocatalytic materials based on abundant elements and the proper adjustment of the reaction conditions, including temperature.
    [Show full text]
  • 201126 Entering Into an Advisory Agreement with Akira Fujishima
    November 26, 2020 < Press Release > Entering into an advisory agreement with Akira Fujishima, Professor Emeritus, Tokyo University of Science, a World-renowned Chemist and the Discoverer of Photocatalytic Reactions. - Photocatalytic research launched in pursuit of environmental protection and hygiene management, which are issues facing modern society - Aderans Co., Ltd. (headquartered in Shinjuku-ku, Tokyo; Group CEO, Representative Director and President Yoshihiro Tsumura) promoting the wellness industry of hair, beauty and health, has concluded an advisory contract with Akira Fujishima, a world-renowned chemist, professor emeritus at Tokyo University of Science and discoverer of photocatalytic reactions, in conjunction with the launch of its hygiene business using photocatalytic technology. In response to the recent increase in awareness of hygiene management, Aderans will launch a hygiene business using photocatalysts as a part of SDGs activities, based on the philosophy of contributing to the hygienic environment of society. In addition, we will establish a new research facility for photocatalyst in our “Aderans Niiza Artificial Hair Research Institute” (Niiza City, Saitama Prefecture) to promote full-scale research and development. Accordingly, we have invited Professor Emeritus Fujishima, the father of photocatalyst and a leading researcher, to become our advisor and ask for his technical cooperation in our photocatalytic business. In 1967, while a graduate student at the University of Tokyo, Professor Emeritus Fujishima first discovered that a photocatalytic reaction occurred on the surface of titanium dioxide when a titanium dioxide electrode in aqueous solution was exposed to strong light. This phenomenon was later termed the “Honda-Fujishima Effect” in combination with the name of his co-researcher, Kenichi Honda.
    [Show full text]
  • Metal-Organic Frameworks with Photocatalytic Bactericidal Activity for Integrated Air Cleaning
    ARTICLE https://doi.org/10.1038/s41467-019-10218-9 OPEN Metal-organic frameworks with photocatalytic bactericidal activity for integrated air cleaning Ping Li1, Jiazhen Li1, Xiao Feng1, Jie Li1, Yuchen Hao1, Jinwei Zhang1, Hang Wang1, Anxiang Yin1, Junwen Zhou1, Xiaojie Ma1 & Bo Wang 1 Air filtration has become an essential need for passive pollution control. However, most of the commercial air purifiers rely on dense fibrous filters, which have good particulate matter 1234567890():,; (PM) removal capability but poor biocidal effect. Here we present the photocatalytic bac- tericidal properties of a series of metal-organic frameworks (MOFs) and their potentials in air pollution control and personal protection. Specifically, a zinc-imidazolate MOF (ZIF-8) exhibits almost complete inactivation of Escherichia coli (E. coli) (>99.9999% inactivation efficiency) in saline within 2 h of simulated solar irradiation. Mechanistic studies indicate that photoelectrons trapped at Zn+ centers within ZIF-8 via ligand to metal charge transfer (LMCT) are responsible for oxygen-reduction related reactive oxygen species (ROS) pro- duction, which is the dominant disinfection mechanism. Air filters fabricated from ZIF-8 show remarkable performance for integrated pollution control, with >99.99% photocatalytic killing efficiency against airborne bacteria in 30 min and 97% PM removal. This work may shed light on designing new porous solids with photocatalytic antibiotic capability for public health protection. 1 Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, Key Laboratory of Cluster Science, Ministry of Education, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, 100081 Beijing, China. Correspondence and requests for materials should be addressed to X.M.
    [Show full text]
  • Daniel M. Blake
    Air Daniel M. Blake National Renewable Energy Laboratory 1617 Cole Boulevard Golden, Colorado 80401-3393 I A national laboratory of the U.S. Department of Energy Operated by Midwest Research Institute I for the U.S. Department of Energy Under Contract No. DE-AC36-83CH10093 NRELr'Tp-430-22197 UC Category 1600 DE97000084 Daniel M. Blake National Renewable Energy Laboratory 1617 Cole Boulevard Golden, Colorado 80401-3393 A national laboratory of the U.S. Department of Energy Operated by Midwest Research Institute for the U. S . Department of Energy Under Contract No. DE-AC36-83CH10093 Prepared under TaskNo. SI513010 January 1997 NOTICE This report was prepared as an account of work sponsored by an agency of the United States government. Neither the .United States government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States government or any agency thereof. Available to DOE and DOE contractors from: Office of Scientific and Technical Information (OSTI) P.O. Box 62 Oak Ridge, TN 37831 Prices available by calling (423)576-8401 Available to the public from: National Technical Information Service (NTIS) U.S.
    [Show full text]
  • Research Progress on Catalytic Water Splitting Based on Polyoxometalate/Semiconductor Composites
    catalysts Review Research Progress on Catalytic Water Splitting Based on Polyoxometalate/Semiconductor Composites Yue Wu * and Lihua Bi * College of Chemistry, Jilin University, Changchun 130012, China * Correspondence: [email protected] (Y.W.); [email protected] (L.B.) Abstract: In recent years, due to the impact of global warming, environmental pollution, and the energy crisis, international attention and demand for clean energy are increasing. Hydrogen energy is recognized as one of the clean energy sources. Water is considered as the largest potential supplier of hydrogen energy. However, artificial catalytic water splitting for hydrogen and oxygen evolution has not been widely used due to its high energy consumption and high cost during catalytic cracking. Therefore, the exploitation of photocatalysts, electrocatalysts, and photo-electrocatalysts for rapid, cost effective, and reliable water splitting is essentially needed. Polyoxometalates (POMs) are regarded as the potential candidates for water splitting catalysis. In addition to their excellent catalytic properties and reversibly redox activities, POMs can also modify semiconductors to overcome their shortcomings, and improve photoelectric conversion efficiency and photocatalytic activity, which has attracted more and more attention in the field of photoelectric water splitting catalysis. In this review, we summarize the latest applications of POMs and semiconductor composites in the field of photo-electrocatalysis (PEC) for hydrogen and oxygen evolution by catalytic water splitting in recent years and take the latest applications of POMs and semiconductor composites in photocatalysis for water splitting. In the conclusion section, the challenges and strategies of photocatalytic and PEC water-splitting by POMs and semiconductor composites are discussed. Citation: Wu, Y.; Bi, L.
    [Show full text]
  • Enhanced Photocatalytic Activity of the Carbon Quantum Dot-Modified Bioi Microsphere
    CORE Metadata, citation and similar papers at core.ac.uk Provided by Springer - Publisher Connector Chen et al. Nanoscale Research Letters (2016) 11:60 DOI 10.1186/s11671-016-1262-7 NANO EXPRESS Open Access Enhanced Photocatalytic Activity of the Carbon Quantum Dot-Modified BiOI Microsphere Yuan Chen1,2, Qiuju Lu1, Xuelian Yan1,2, Qionghua Mo1,3, Yun Chen1, Bitao Liu1*, Liumei Teng1, Wei Xiao1, Liangsheng Ge1 and Qinyi Wang4 Abstract Novel carbon quantum dot (CQD)-modified BiOI photocatalysts were prepared via a facile hydrothermal process. The CQD-modified BiOI materials were characterized by multiple techniques. The CQD with an average size around several nanometers was distributed on the surface of BiOI microsphere. Its photocatalytic activity was investigated sufficiently by the photodegradation of methylene orange (MO). The results showed that the CQD/BiOI 1.5 wt.% sample exhibited the optimum photocatalytic activity, which was 2.5 times that of the pure BiOI. This improvement was attributed to the crucial role of CQDs, which could be acted as a photocenter for absorbing solar light, charge separation center for suppressing charge recombination. Keywords: BiOI, CQDs, Photocatalytic, Visible light Background CQD-based composites [7, 8]. Previous studies have shown The exploration and construction of new photocatalysts that the electron-accepting and transport properties of car- with high catalytic efficiency in sunlight is a core issue in bon nanomaterials provide a convenient way to separate photocatalysis all the time and is also significant in solv- photogenerated electrons; thus, enhanced photocatalytic ing current environment and energy problems [1–3]. performance can be achieved through the construction Recently, bismuth oxyhalides (BiOX, X = Cl, Br, and I) as of semiconductor/carbon composites [9, 10].
    [Show full text]
  • Metal Organic Frameworks As Emerging Photocatalysts
    Chapter 11 Metal Organic Frameworks as Emerging Photocatalysts Ahmad Alshammari, Zheng Jiang and Kyle E. Cordova Additional information is available at the end of the chapter http://dx.doi.org/10.5772/63489 Abstract Increasing number of metal-organic frameworks (MOFs) have recently been recog‐ nised as a new generation of emerging porous photocatalysts in photocatalysis and photoelectrocatalysis, since their intrinsic coordination structure between the metal cluster and organic ligands offers MOFs great flexibility to tune their semiconducting property for enhanced light harvesting. In order to improve their performance substan‐ tially and achieve widespread application of MOF photocatalysts, it is necessary to develop effective synthesis strategies and understand their semiconducting crystal structure, photocatalytic mechanism in depth. This chapter firstly provides a brief introduction of the MOF materials; this chapter addresses the crystallinity, porosity and electronic semiconducting structures that are essential in solar energy conversion. Established and innovative syntheses strategies of MOFs are then categorised and illustrated, followed by various characterisations techniques applied to investigate their structural and semiconducting properties (band structure and charge transfer), including X-ray Diffraction XRD, small angle X-ray Diffraction SAXRD, adsorption/desorption, UV- Vis, nuclear magnetic resonance (NMR), extended fine Auger structures (EXFAS), inelastic neutron scattering (INS) spectroscopy, high-resolution transmission
    [Show full text]
  • Investigation of the Photocatalytic Degradation of Ethanol and Acetone
    ESL-IC-06-11-14 ICEBO2006, Shenzhen, China Maximize Comfort: Temperature, Humidity, and IAQ Vol. I-3-4 Investigation of the Photocatalytic Degradation of Ethanol and Acetone Yanhua Liu Bo Ding Shuping Dong Professor Master Student Master Student Department of Building Service Engineering, Xi’an Jiaotong University，Xi’an 710049 , China [email protected] Abstract: In-situ transmission Fourier-transform decomposition are limited. In this paper, the infrared spectroscopy has been used to study the photocatalytic oxidation of acetone, ethanol and the photocatalytic oxidation of acetone, ethanol and the interaction between them during photocatalysis interaction between acetone and ethanol. Compared process have been investigated using a with the degradation of acetone alone, it cannot be Fourier-transform infrared spectroscopy. Ethanol and described by Langmuir-Hinshelwood equation in acetone are chosen as target pollutants because presence of ethanol. The presence of ethanol reduces ethanol is a well-known organic compound and the initial degradation rate of acetone and the acetone is a popular indoor air pollutant. inhibition increases with increasing of ethanol in the system. Acetone also inhibits the degradation of 2. EXPERIMENTAL ethanol but it still can be described by the L-H equation. Acetaldehyde in the system comes from the 2.1 Reactor and gas generator degradation of ethanol, the behavior of production Fig.1 shows the schematic diagram of the and consumption of which is affected by the amount experimental set-up for the study. It consists of a of ethanol and acetone in the mixture. Temperature reactor and an air stream circulation system. The significantly affects the degradation of organic reactor includes a 20-W UV lamp with a 254nm compounds in the mixture.
    [Show full text]