Photocatalysis

From Wikipedia, the free encyclopedia
Jump to navigation Jump to search
In the experiment above, photons from a light source (out of frame on the right hand side) are absorbed by the surface of the titanium dioxide (TiO
2
) disc, exciting electrons within the material. These then react with the water molecules, splitting it into its constituents of hydrogen and oxygen. In this experiment, chemicals dissolved in the water prevent the formation of oxygen, which would otherwise recombine with the hydrogen.

In chemistry, photocatalysis is the acceleration of a photoreaction in the presence of a catalyst.[1] In catalyzed photolysis, light is absorbed by an adsorbed substrate. In photogenerated catalysis, the photocatalytic activity depends on the ability of the catalyst to create electron–hole pairs, which generate free radicals (e.g. hydroxyl radicals: •OH) able to undergo secondary reactions. Its practical application was made possible by the discovery of water electrolysis by means of titanium dioxide (TiO
2
).

History[edit]

Early mentions (1911–1938)[edit]

The earliest mention came in 1911, when German chemist Dr. Alexander Eibner integrated the concept in his research of the illumination of zinc oxide (ZnO) on the bleaching of the dark blue pigment, Prussian blue.[2][3] Around this time, Bruner and Kozak published an article discussing the deterioration of oxalic acid in the presence of uranyl salts under illumination,[3][4] while in 1913, Landau published an article explaining the phenomenon of photocatalysis. Their contributions led to the development of actinometric measurements, measurements that provide the basis of determining photon flux in photochemical reactions.[3][5] After a hiatus, in 1921, Baly et al. used ferric hydroxides and colloidal uranium salts as catalysts for the creation of formaldehyde under visible light.[3][6]

In 1938 Doodeve and Kitchener discovered that TiO
2
, a highly-stable and non-toxic oxide, in the presence of oxygen could act as a photosensitizer for bleaching dyes, as ultraviolet light absorbed by TiO
2
led to the production of active oxygen species on its surface, resulting in the blotching of organic chemicals via photooxidation. This was the first observation of the fundamental characteristics of heterogeneous photocatalysis.[3][7]

1964–1981[edit]

Research in photocatalysis again paused until1964, when V.N. Filimonov investigated isopropanol photooxidation from ZnO and TiO
2
 ;[3][8] while in 1965 Kato and Mashio, Doerffler and Hauffe, and Ikekawa et al. (1965) explored oxidation/photooxidation of CO
2
and organic solvents from ZnO radiance.[3][9][10][11] In 1970, Formenti et al. and Tanaka and Blyholde observed the oxidation of various alkenes and the photocatalytic decay of N2O, respectively.[3][12][13]

A breakthrough occurred in 1972, when Akira Fujishima and Kenichi Honda discovered that electrochemical photolysis of water occurred when a TiO
2
electrode irradiated with ultraviolet light was electrically connected to a platinum electrode. As the ultraviolet light was absorbed by the TiO
2
electrode, electrons flowed from the anode to the platinum cathode where hydrogen gas was produced. This was one of the first instances of hydrogen production from a clean and cost-effective source, as the majority of hydrogen production comes from natural gas reforming and gasification.[3][14] Fujishima's and Honda's findings led to other advances. In 1977, Nozik discovered that the incorporation of a noble metal in the electrochemical photolysis process, such as platinum and gold, among others, could increase photoactivity, and that an external potential was not required.[3][15] Wagner and Somorjai (1980) and Sakata and Kawai (1981) delineated hydrogen production on the surface of strontium titanate (SrTiO3) via photogeneration, and the generation of hydrogen and methane from the illumination of TiO
2
and PtO2 in ethanol, respectively.[3][16][17]

Photocatalysis has not been developed for commercial purposes. Chu et al. (2017) assessed the future of electrochemical photolysis of water, discussing its major challenge of developing a cost-effective, energy-efficient photoelectrochemical (PEC) tandem cell, which would, “mimic natural photosynthesis".[3][18]

Types of photocatalysis[edit]

Homogeneous photocatalysis[edit]

In homogeneous photocatalysis, the reactants and the photocatalysts exist in the same phase. The most commonly used homogeneous photocatalysts include ozone and photo-Fenton systems (Fe+ and Fe+/H2O2). The reactive species is the •OH radical, which is used for various purposes. The mechanism of hydroxyl radical production by ozone can follow two paths:[19]

O3 + hν → O2 + O(1D)
O(1D) + H2O → •OH + •OH
O(1D) + H2O → H2O2
H2O2 + hν → •OH + •OH

Similarly, the Fenton system produces hydroxyl radicals by the following mechanism:[20]

Fe2+ + H2O2→ HO• + Fe3+ + OH
Fe3+ + H2O2→ Fe2+ + HO•2 + H+
Fe2+ + HO• → Fe3+ + OH

In photo-Fenton type processes, additional sources of OH radicals should be considered, such as photolysis of H2O2 and reduction of Fe3+ ions under UV light:

H2O2 + hν → HO• + HO•
Fe3+ + H2O + hν → Fe2+ + HO• + H+

The efficiency of Fenton type processes is influenced by several operating parameters like the concentration of hydrogen peroxide, pH and intensity of UV. The main advantage of this process is the ability of using sunlight with light sensitivity up to 450 nm, thus avoiding the high costs of UV lamps and electrical energy. These reactions have been proven more efficient than other examples of photocatalysis but the disadvantages of the process are the low pH values, which are required since iron precipitates at higher pH values and the fact that iron has to be removed after treatment.

Homogeneous photocatalysis can also be conducted by Cu(II)/Cu(I) complexes.The photoredox behavior of Cu(II) complexes, similar to Fe(III) complexes, is derived mostly from the reactive decay of their LMCT states. Excitation to LMCT states can be achieved by direct sunlight when the ionization energy of the ligands coordinated to Cu(II) is not very high. In consequence of the reactive decay of the LMCT excited state by inner-sphere electron transfer, the Cu(II) central atom is reduced to Cu(I), whereas the ligand is oxidized to its radical and leaves the coordination sphere:[21]

The photoredox behaviour is demonstrated by the simple Cu(II) complexes with halogens. After excitation of [CuClx] 2−x the metal centre is reduced and Cl• and Cl2 radicals are formed:[22]

[23]

[23]

The Cl2 radicals are strong oxidation and chlorination agents. For instance they are able to oxidize phenol and its derivatives to para-benzochinone and CO2.

Heterogeneous photocatalysis[edit]

In heterogeneous catalysis the catalyst is in a different phase from the reactants. Heterogeneous photocatalysis is a discipline which includes a large variety of reactions: mild or total oxidations, dehydrogenation, hydrogen transfer, 18O216O2 and deuterium-alkane isotopic exchange, metal deposition, water detoxification, and gaseous pollutant removal.

Most heterogeneous photocatalysts are transition metal oxides and semiconductors. Unlike metals, which have a continuum of electronic states, semiconductors possess a void energy region where no energy levels are available to promote recombination of an electron and hole produced by photoactivation in the solid. The void region of energy, which extends from the top of the filled valence band to the bottom of the vacant conduction band, is called the band gap.[24] When a photon with energy equal to or greater than the material's band gap is absorbed by the semiconductor, an electron is excited from the valence band to the conduction band, generating a hole in the valence band. Such a photogenerated electron-hole pair is termed an exciton. The excited electron and hole can recombine and release the energy gained from the excitation of the electron as heat. Such exciton recombination is undesirable and higher levels cost efficieny. Efforts to develop functional photocatalysts often emphasize extending exciton lifetime, improving electron-hole separation using diverse approaches that may rely on structural features such as phase hetero-junctions (e.g. anatase-rutile interfaces), noble-metal nanoparticles, silicon nanowires and substitutional cation doping.[25] The ultimate goal of photocatalyst design is to facilitate reactions of the excited electrons with oxidants to produce reduced products, and/or reactions of the generated holes with reductants to produce oxidized products. Due to the generation of positive holes and excited electrons, oxidation-reduction reactions take place at the surface of semiconductors irradiated with light.

In one mechanism of the oxidative reaction, holes react with the moisture present on the surface and produce a hydroxyl radical. The reaction starts by photo-induced exciton generation in the metal oxide (MO) surface:

MO + hν → MO (h+ + e)

Oxidative reactions due to photocatalytic effect:

h+ + H2O → H+ + •OH
2 h+ + 2 H2O → 2 H+ + H2O2
H2O2→ 2 •OH

Reductive reactions due to photocatalytic effect:

e + O2 → •O2
•O2 + H2O + H+ → H2O2 + O2
H2O2 → 2 •OH

Ultimately, hydroxyl radicals are generated in both reactions. These radicals are oxidative in nature and nonselective with a redox potential of E0 = +3.06 V.[26]

TiO
2
is a common choice for heterogeneous catalysis. Inertness to chemical environment and long-term photostability has made TiO
2
an important material in many practical applications. TiO
2
is a wide band-gap semiconductor. It is commonly investigated in the rutile (bandgap 3.0 eV) and anatase (bandgap 3.2 eV) phases. Photocatalytic reactions are initiated by the absorption of illumination with energy equal to or greater than the band gap of the semiconductor. This produces electron-hole (e /h+) pairs:[27]

where the electron is in the conduction band and the hole is in the valence band. The irradiated TiO
2
particle can behave as an electron donor or acceptor for molecules in contact with the semiconductor. It can participate in redox reactions with adsorbed species, as the valence band hole is strongly oxidizing while the conduction band electron is strongly reducing.[27]

Plasmonic antenna-reactor photocatalysis[edit]

A plasmonic antenna-reactor photocatalyst is a photocatalyst that combines a catalyst with attached antenna that increases the catalyst's ability to absorb light, thereby increasing its efficiency.

A SiO
2
catalyst combined with an Au light absorber accelerated hydrogen sulfide-to-hydrogen reactions. The process is an alternative to the conventional Claus process that operates at 800–1,000 °C (1,470–1,830 °F).[28]

A Fe catalyst combined with a Cu light absorber can produce hydrogen from ammonia (NH
3
) at ambient temperature using visible light. Conventional Cu-Ru production operates at 650–1,000 °C (1,202–1,832 °F).[29]

Applications[edit]

SEM image of wood pulp (dark fibers) and tetrapodal zinc oxide micro particles (white and spiky) in paper.[30]

Photoactive catalysts have been introduced over the last decade, such as TiO
2
and ZnO nano rodes. Most suffer from the fact that they can only perform under UV irradiation due to their band structure. Other photocatalysts, including a graphene-ZnO nanocompound counter this problem.[31]

Bioethanol[edit]

Photocatalytic bioethanol production, research by Professor Linda Lawton, Robert Gordon University and her collaborators under CyanoSol was funded by BBSRC.[32]

Paper[edit]

Micro-sized ZnO tetrapodal particles added to pilot paper production.[30] The most common are one-dimensional nanostructures, such as nanorods, nanotubes, nanofibers, nanowires, but also nanoplates, nanosheets, nanospheres, tetrapods. ZnO is strongly oxidative, chemically stabile, with enhanced photocatalytic activity, and has a large free-exciton binding energy. It is non-toxic, abundant, biocompatible, biodegradable, environmentally friendly, low cost, and compatible with simple chemical synthesis. ZnO faces limits to its widespread use in photocatalysis under solar radiation. Several approaches have been suggested to overcome this limitation, including doping for reducing the band gap and improving charge carrier separation.[33]

Water splitting[edit]

Photocatalytic water splitting separates water into hydrogen and oxygen.[34] The most prevalently investigated material, TiO
2
, has limited production efficiency, was mixed with nickel oxide (NiO). NiO allows a significant explоitation of the visible spectrum.[35] One efficient photocatalyst in the UV range is based on sodium tantalite (NaTaO3) doped with lanthanum and loaded with a nickel oxide cocatalyst. The surface is grooved with nanosteps from doping with lanthanum (3–15 nm range, see nanotechnology). The NiO particles are present on the edges, with the oxygen evolving from the grooves.

Self-cleaning glass[edit]

Titanium dioxide takes part in self-cleaning glass. Free radicals[36][37] generated from TiO
2
oxidize organic matter.[38][39] The rough wedge-like TiO
2
surface can be modified with a hydrophobic monolayer of octadecylphosphonic acid (ODP). TiO
2
surfaces that were plasma etched for 10 seconds and subsequent surface modifications with ODP showed a water contact angle greater than 150◦. The surface was converted into a superhydrophilic surface (water contact angle = 0◦) upon UV illumination, due to rapid decomposition of octadecylphosphonic acid coating resulting from TiO
2
photocatalysis. Due to TiO
2
's wide band gap, light absorption by the semiconductor material and resulting superhydrophilic conversion of undoped TiO
2
requires ultraviolet radiation (wavelength <390 nm) and thereby restricts self-cleaning to outdoor applications.[40]

Disinfection and cleaning[edit]

  • Water disinfection/decontamination,[41] a form of solar water disinfection (SODIS).[42][43] Adsorbents attract organics such as tetrachloroethylene. Adsorbents are placed in packed beds for 18 hours. Spent adsorbents are placed in regeneration fluid, essentially removing organics still attached by passing hot water opposite to the flow of water during adsorption. The regeneration fluid passes through fixed beds of silica gel photocatalysts to remove and decompose remaining organics.
  • TiO
    2
    self-sterilizing coatings (for application to food contact surfaces and in other environments where microbial pathogens spread by indirect contact).[44]
  • Magnetic TiO
    2
    nanoparticle oxidation of organic contaminants agitated using a magnetic field.[45]
  • Sterilization of surgical instruments and removal of fingerprints from electrical and optical components.[46]

Hydrocarbon production from CO
2
[edit]

TiO
2
conversion of CO
2
into gaseous hydrocarbons.[47] The proposed reaction mechanisms involve the creation of a highly reactive carbon radical from carbon monoxide and carbon dioxide which then reacts with photogenerated protons to ultimately form methane. Efficiencies of TiO
2
-based photocatalysts are low, although nanostructures such as carbon nanotubes[48] and metallic nanoparticles[49] help.

Paints[edit]

ePaint is a less-toxic alternative to conventional antifouling marine paints that generates hydrogen peroxide.

Photocatalysis of organic reactions by polypyridyl complexes,[50] porphyrins,[51] or other dyes[52] can produce materials inaccessible by classical approaches. Most photocatalytic dye degradation studies have employed TiO
2
. The anatase form of TiO
2
has higher photon absorption characteristics.[53]

Filtration membranes[edit]

Antifouling coatings for filtration membranes,[54] can act as a separation layer[55] for contaminant degradation.[56] or Cr(VI) removal.[57]

Crude oil[edit]

TiO
2
nanoparticle decomposition of crude oil can turn hydrocarbons into H2O and CO2. The particles can be placed on floating substrates, which are easier to recover and catalyze the reaction. This is relevant since oil slicks float on the ocean suface and photons from the sun reach the surface. Covering floating substrates with epoxy adhesives prevents waterlogging and TiO
2
particles can stick to them.

Decomposition of polyaromatic hydrocarbons (PAHs). Triethylamine (TEA) solvates and extracts PAHs in crude oil. TEA attracts the PAHs to itself. TiO
2
slurries can degrade the PAHs. Recoveries of 93–99% of these contaminants have been demonstrated at ambient pressure and temperature, and at lower cost.[citation needed]

Construction[edit]

Light2CAT was a project funded by the European Commission from 2012 to 2015. It aimed to develop a modified TiO
2
that can absorb visible light and include this modified TiO
2
into construction concrete. The TiO
2
degrades harmful pollutants such as NOx into NO3. The modified TiO
2
was utilized in Copenhagen and Holbæk, Denmark, and Valencia, Spain. This “self-cleaning” concrete led to a 5-20% reduction in NOx over the course of a year.[58][59]

Quantification[edit]

ISO 22197-1:2007 specifies a test method for the measurement of NO
2
removal for materials that contain a photocatalyst or have superficial photocatalytic films.[60]

Specific FTIR systems are used to characterize photocatalytic activity or passivity, especially with respect to volatile organic compounds, and representative binder matrices.[61]

Mass spectrometry allows measurement of photocatalytic activity by tracking the decomposition of gaseous pollutants such as nitrogen NOx or CO
2
[62]

See also[edit]

References[edit]

  1. ^ Shafiq, Iqrash; Shafique, Sumeer; Akhter, Parveen; Abbas, Ghulam; Qurashi, Ahsanulhaq; Hussain, Murid (2021-01-04). "Efficient catalyst development for deep aerobic photocatalytic oxidative desulfurization: recent advances, confines, and outlooks". Catalysis Reviews: 1–46. doi:10.1080/01614940.2020.1864859. ISSN 0161-4940. S2CID 234186125.
  2. ^ Eibner, Alexander (1911). "Action of Light on Pigments I". Chem-ZTG. 35: 753–755.
  3. ^ a b c d e f g h i j k l Coronado, Juan M.; Fresno, Fernando; Hernández-Alonso, María D.; Portela, Racquel (2013). Design of Advanced Photocatalytic Materials for Energy and Environmental Applications. London: Springer. pp. 1–5. doi:10.1007/978-1-4471-5061-9. hdl:10261/162776. ISBN 978-1-4471-5061-9.
  4. ^ Bruner, L.; Kozak, J. (1911). "Information on the Photocatalysis I The Light Reaction in Uranium Salt Plus Oxalic Acid Mixtures". Elktrochem Agnew P. 17: 354–360.
  5. ^ Landau, M. (1913). "Le Phénomène de la Photocatalyse". Compt. Rend. 156: 1894–1896.
  6. ^ Baly, E.C.C.; Helilbron, I.M.; Barker, W.F. (1921). "Photocatalysis. Part I. The Synthesis of Formaldehyde and Carbohydrates from Carbon Dioxide and Water". J Chem Soc. 119: 1025–1035. doi:10.1039/CT9211901025.
  7. ^ Goodeve, C.F.; Kitchener, J.A. (1938). "The Mechanism of Photosensitization by Solids". Transactions of the Faraday Society. 34: 902–912. doi:10.1039/tf9383400902.
  8. ^ Filimonov, V.N. (1964). "Photocatalytic Oxidation of Gaseous Isopropanol on ZnO + TiO
    2
    ". Dokl. Akad. Nauk SSSR. 154 (4): 922–925.
  9. ^ Ikekawa, A.; Kamiya, M.; Fujita, Y.; Kwan, T. (1965). "On the Competition of Homogeneous and Heterogeneous Chain Terminations in Heterogeneous Photooxidation Catalysis by Zinc Oxide". Bulletin of the Chemical Society of Japan. 38: 32–36. doi:10.1246/bcsj.38.32.
  10. ^ Doerffler, W.; Hauffe, K. (1964). "Heterogeneous Photocatalysis I. Influence of Oxidizing and Reducing Gases on the Electrical Conductivity of Dark and Illuminated Zinc Oxide Surfaces". J Catal. 3 (2): 156–170. doi:10.1016/0021-9517(64)90123-X.
  11. ^ Kato, S.; Mashio, F. (1964). "Titanium Dioxide-Photocatalyzed Liquid Phase Oxidation of Tetralin". The Journal of the Society of Chemical Industry, Japan. 67 (8): 1136–1140. doi:10.1246/nikkashi1898.67.8_1136.
  12. ^ Formenti, M.; Julliet F., F.; Teichner SJ, S.J. (1970). "Controlled Photooxidation of Paraffins and Olefins over Anatase at Room Temperature". Comptes Rendus de l'Académie des Sciences, Série C. 270C: 138–141.
  13. ^ Tanaka, K.I.; Blyholde, G. (1970). "Photocatalytic and Thermal Catalytic Decomposition of Nitrous Oxide on Zinc Oxide". J. Chem. Soc. D. 18 (18): 1130. doi:10.1039/c29700001130.
  14. ^ Fujishima, A.; Honda, K. (1972). "Electrochemical Photolysis of Water at a Semiconductor Electrode". Nature. 238 (5358): 37–38. Bibcode:1972Natur.238...37F. doi:10.1038/238037a0. PMID 12635268. S2CID 4251015.
  15. ^ Nozik, A.J. (1977). "Photochemical Diodes". Appl Phys Lett. 30 (11): 567–570. Bibcode:1977ApPhL..30..567N. doi:10.1063/1.89262.
  16. ^ Wagner, F.T.; Somorjai, G.A. (1980). "Photocatalytic and Photoelectrochemical Hydrogen Production on Strontium Titanate Single Crystals". J Am Chem Soc. 102 (17): 5494–5502. doi:10.1021/ja00537a013.
  17. ^ Sakata, T.; Kawai, T. (1981). "Heterogeneous Photocatalytic Production of Hydrogen and Methane from Ethanol and Water". Chem Phys Lett. 80 (2): 341–344. Bibcode:1981CPL....80..341S. doi:10.1016/0009-2614(81)80121-2.
  18. ^ Chu, S.; Li, W.; Yan, Y.; Hamann, T.; Shih, I.; Wang, D.; Mi, Z. (2017). "Roadmap on Solar Water Splitting: Current Status and Future Prospects". Nano Futures. IOP Publishing Ltd. 1 (2): 022001. Bibcode:2017NanoF...1b2001C. doi:10.1088/2399-1984/aa88a1.
  19. ^ Wu, CH; Chang, CL (2006). "Decolorization of Reactive Red 2 by advanced oxidation processes: Comparative studies of homogeneous and heterogeneous systems". Journal of Hazardous Materials. 128 (2–3): 265–72. doi:10.1016/j.jhazmat.2005.08.013. PMID 16182444.
  20. ^ Peternel, IT; Koprivanac, N; Bozić, AM; Kusić, HM (2007). "Comparative study of UV/TiO
    2
    , UV/ZnO and photo-Fenton processes for the organic reactive dye degradation in aqueous solution". Journal of Hazardous Materials. 148 (1–2): 477–84. doi:10.1016/j.jhazmat.2007.02.072. PMID 17400374.
  21. ^ P. Cie´sla (August 2004). "Homogeneous photocatalysis by transition metal complexes in the environment". Journal of Molecular Catalysis A: Chemical 224 (2004) 17–33: 23.
  22. ^ Cervone, E.; Diomedi Camassei, F.; Giannini, I.; Sykora, J. (January 1979). "Photoredox behaviour of chlorocopper(II) complexes in acetonitrile: mechanism and quantum yields". Journal of Photochemistry. 11 (5): 321–332. doi:10.1016/0047-2670(79)85021-2. ISSN 0047-2670.
  23. ^ a b Cieśla, Paweł; Kocot, Przemysław; Mytych, Piotr; Stasicka, Zofia (2004-12-15). "Homogeneous photocatalysis by transition metal complexes in the environment". Journal of Molecular Catalysis A: Chemical. Special Issue Dedicated to Professor Jozef J. Ziolkowski on the Occasion of His 70th Birthday. 224 (1): 17–33. doi:10.1016/j.molcata.2004.08.043. ISSN 1381-1169.
  24. ^ Linsebigler, Amy L.; Lu, Guangquan.; Yates, John T. (1995). "Photocatalysis on TiO
    2
    Surfaces: Principles, Mechanisms, and Selected Results". Chemical Reviews. 95 (3): 735–758. doi:10.1021/cr00035a013.
  25. ^ Karvinena, Saila; Hirvab, Pipsa; Pakkanen, Tapani A (2003). "Ab initio quantum chemical studies of cluster models for doped anatase and rutile TiO
    2
    ". Journal of Molecular Structure: Theochem. 626 (1–3): 271–277. doi:10.1016/S0166-1280(03)00108-8.
  26. ^ Daneshvar, N; Salari, D; Khataee, A.R (2004). "Photocatalytic degradation of azo dye acid red 14 in water on ZnO as an alternative catalyst to TiO
    2
    ". Journal of Photochemistry and Photobiology A: Chemistry. 162 (2–3): 317–322. doi:10.1016/S1010-6030(03)00378-2.
  27. ^ a b Ibhadon, Alex; Fitzpatrick, Paul (2013-03-01). "Heterogeneous Photocatalysis: Recent Advances and Applications". Catalysts. 3 (1): 189–218. doi:10.3390/catal3010189. ISSN 2073-4344. CC BY icon.svg Text was copied from this source, which is available under a Creative Commons Attribution 3.0 (CC BY 3.0) license.
  28. ^ Blain, Loz (2022-11-02). "Light-powered catalyst makes profitable hydrogen from stinky waste gas". New Atlas. Retrieved 2022-11-30.
  29. ^ Blain, Loz (2022-11-29). "Revolutionary photocatalyst is huge news for green hydrogen and ammonia". New Atlas. Retrieved 2022-11-30.
  30. ^ a b Sandberg, Mats; Håkansson, Karl; Granberg, Hjalmar (2020-10-01). "Paper machine manufactured photocatalysts - Lateral variations". Journal of Environmental Chemical Engineering. 8 (5): 104075. doi:10.1016/j.jece.2020.104075. ISSN 2213-3437.
  31. ^ Rouzafzay, F.; Shidpour, R. (2020). "Graphene@ZnO nanocompound for short-time water treatment under sun-simulated irradiation: Effect of shear exfoliation of graphene using kitchen blender on photocatalytic degradation". Alloys and Compounds. 829: 154614. doi:10.1016/J.JALLCOM.2020.154614. S2CID 216233251.
  32. ^ "Major funding granted to CyanoSol, Robert Gordon University". Algal Solutions For Local Energy Economy (ASLEE). 2017-03-31. Retrieved 2021-06-25.
  33. ^ Nunes, Daniela; Pimentel, Ana; Branquinho, Rita; Fortunato, Elvira; Martins, Rodrigo (2021-04-16). "Metal Oxide-Based Photocatalytic Paper: A Green Alternative for Environmental Remediation". Catalysts. 11 (4): 504. doi:10.3390/catal11040504. ISSN 2073-4344.
  34. ^ Kudo, Akihiko; Kato, Hideki; Tsuji, Issei (2004). "Strategies for the Development of Visible-light-driven Photocatalysts for Water Splitting". Chemistry Letters. 33 (12): 1534. doi:10.1002/chin.200513248.
  35. ^ Banić, Nemanja; Krstić, Jugoslav; Stojadinović, Stevan; Brnović, Anđela; Djordjevic, Aleksandar; Abramović, Biljana (September 2020). "Commercial TiO 2 loaded with NiO for improving photocatalytic hydrоgen prоduction in the presence оf simulated solar radiation". International Journal of Energy Research. 44 (11): 8951–8963. doi:10.1002/er.5604. ISSN 0363-907X. S2CID 225707644.
  36. ^ "Snapcat Photo Catalytic Oxidation with TIO
    2
    (2005)"
    . CaluTech UV Air. Retrieved 2006-12-05.
  37. ^ Kondrakov AO, Ignatev AN, Lunin VV, Frimmel FH, Braese S, Horn H (2016). "Roles of water and dissolved oxygen in photocatalytic generation of free OH radicals in aqueous TiO
    2
    suspensions: An isotope labeling study". Applied Catalysis B: Environmental. 182: 424–430. doi:10.1016/j.apcatb.2015.09.038.
  38. ^ "Photocatalysis Applications of TiO
    2
    "
    . Titanium Information. titaniumart.com.
  39. ^ Kondrakov AO, Ignatev AN, Frimmel FH, Braese S, Horn H, Revelsky AI (2014). "Formation of genotoxic quinones during bisphenol A degradation by TiO
    2
    photocatalysis and UV photolysis: A comparative study". Applied Catalysis B: Environmental. 160: 106–114. doi:10.1016/j.apcatb.2014.05.007.
  40. ^ Banerjee, Swagata; Dionysiou, Dionysios D.; Pillai, Suresh C. (October 2015). "Self-cleaning applications of TiO
    2
    by photo-induced hydrophilicity and photocatalysis"
    . Applied Catalysis B: Environmental. 176–177: 396–428. doi:10.1016/j.apcatb.2015.03.058. ISSN 0926-3373.
  41. ^ Shafiq, Iqrash; Hussain, Murid; Shehzad, Nasir; Maafa, Ibrahim M.; Akhter, Parveen; Amjad, Um-e-salma; Shafique, Sumeer; Razzaq, Abdul; Yang, Wenshu; Tahir, Muhammad; Russo, Nunzio (2019-08-01). "The effect of crystal facets and induced porosity on the performance of monoclinic BiVO4 for the enhanced visible-light driven photocatalytic abatement of methylene blue". Journal of Environmental Chemical Engineering. 7 (4): 103265. doi:10.1016/j.jece.2019.103265. ISSN 2213-3437. S2CID 198742844.
  42. ^ McCullagh C, Robertson JM, Bahnemann DW, Robertson PK (2007). "The application of TiO
    2
    photocatalysis for disinfection of water contaminated with pathogenic micro-organisms: a review". Research on Chemical Intermediates. 33 (3–5): 359–375. doi:10.1163/156856707779238775. S2CID 94649652.
  43. ^ Hanaor, Dorian A. H.; Sorrell, Charles C. (2014). "Sand Supported Mixed-Phase TiO
    2
    Photocatalysts for Water Decontamination Applications". Advanced Engineering Materials. 16 (2): 248–254. arXiv:1404.2652. Bibcode:2014arXiv1404.2652H. doi:10.1002/adem.201300259. S2CID 118571942.
  44. ^ Cushnie TP, Robertson PK, Officer S, Pollard PM, Prabhu R, McCullagh C, Robertson JM (2010). "Photobactericidal effects of TiO
    2
    thin films at low temperature"
    . Journal of Photochemistry and Photobiology A: Chemistry. 216 (2–3): 290–294. doi:10.1016/j.jphotochem.2010.06.027.
  45. ^ Kostedt IV, William L.; Jack Drwiega; David W. Mazyck; Seung-Woo Lee; Wolfgang Sigmund; Chang-Yu Wu; Paul Chadik (2005). "Magnetically agitated photocatalytic reactor for photocatalytic oxidation of aqueous phase organic pollutants". Environmental Science & Technology. American Chemical Society. 39 (20): 8052–8056. Bibcode:2005EnST...39.8052K. doi:10.1021/es0508121. PMID 16295874.
  46. ^ "New visible light photocatalyst kills bacteria, even after light turned off". ScienceDaily.
  47. ^ Tan, S. S.; L. Zou; E. Hu (2006). "Photocatalytic reduction of carbon dioxide into gaseous hydrocarbon using TiO
    2
    pellets". Catalysis Today. 115 (1–4): 269–273. doi:10.1016/j.cattod.2006.02.057.
  48. ^ Yao, Y. Yao; G. Li; S. Ciston; R. M. Lueptow; K. Gray (2008). "Photoreactive TiO
    2
    /Carbon Nanotube Composites: Synthesis and Reactivity". Environmental Science & Technology. American Chemical Society. 42 (13): 4952–4957. Bibcode:2008EnST...42.4952Y. doi:10.1021/es800191n. PMID 18678032.
  49. ^ Linsebigler, A. L.; G. Lu; J.T. Yates (1995). "Photocatalysis on TiO
    2
    Surfaces: Principles, Mechanisms, and Selected Results". Chemical Reviews. 95 (3): 735–758. doi:10.1021/cr00035a013.
  50. ^ Stephenson, Corey; Yoon, Tehshik; MacMillan, David W. C. (2018-04-02). Visible Light Photocatalysis in Organic Chemistry. doi:10.1002/9783527674145. ISBN 9783527674145.
  51. ^ Barona-Castaño, Juan C.; Carmona-Vargas, Christian C.; Brocksom, Timothy J.; De Oliveira, Kleber T. (March 2016). "Porphyrins as Catalysts in Scalable Organic Reactions". Molecules. 21 (3): 310. doi:10.3390/molecules21030310. PMC 6273917. PMID 27005601.
  52. ^ Sirbu, Dumitru; Woodford, Owen J.; Benniston, Andrew C.; Harriman, Anthony (2018-06-13). "Photocatalysis and self-catalyzed photobleaching with covalently-linked chromophore-quencher conjugates built around BOPHY". Photochemical & Photobiological Sciences. 17 (6): 750–762. doi:10.1039/C8PP00162F. ISSN 1474-9092. PMID 29717745.
  53. ^ Viswanathan, Balasubramanian (December 2017). "Photocatalytic Degradation of Dyes: An Overview". Current Catalysis, 2018, 7, 000-000: 3.
  54. ^ Bortot Coelho, Fabrício Eduardo; Deemter, Dennis; Candelario, Victor M.; Boffa, Vittorio; Malato, Sixto; Magnacca, Giuliana (December 2021). "Development of a photocatalytic zirconia-titania ultrafiltration membrane with anti-fouling and self-cleaning properties". Journal of Environmental Chemical Engineering. 9 (6): 106671. doi:10.1016/j.jece.2021.106671. S2CID 240244656.
  55. ^ Lu, Yawei; Chen, Ting; Chen, Xianfu; Qiu, Minghui; Fan, Yiqun (September 2016). "Fabrication of TiO
    2
    -doped ZrO2 nanofiltration membranes by using a modified colloidal sol-gel process and its application in simulative radioactive effluent". Journal of Membrane Science. 514: 476–486. doi:10.1016/j.memsci.2016.04.074.
  56. ^ Bortot Coelho, Fabrício; Gionco, Chiara; Paganini, Maria; Calza, Paola; Magnacca, Giuliana (3 April 2019). "Control of Membrane Fouling in Organics Filtration Using Ce-Doped Zirconia and Visible Light". Nanomaterials. 9 (4): 534. doi:10.3390/nano9040534. PMC 6523972. PMID 30987140.
  57. ^ Bortot Coelho, Fabrício Eduardo; Candelario, Victor M.; Araújo, Estêvão Magno Rodrigues; Miranda, Tânia Lúcia Santos; Magnacca, Giuliana (18 April 2020). "Photocatalytic Reduction of Cr(VI) in the Presence of Humic Acid Using Immobilized Ce–ZrO2 under Visible Light". Nanomaterials. 10 (4): 779. doi:10.3390/nano10040779. PMC 7221772. PMID 32325680.
  58. ^ Mathiesen, D. (2012). "Final Report Summary - LIGHT2CAT (Visible LIGHT Active PhotoCATalytic Concretes for Air pollution Treatment)". European Commission.
  59. ^ Light2CAT (2015). "Light2CAT Visible Light Active PhotoCATalytic Concretes for Air Pollution Treatment [YouTube Video]". YouTube. Archived from the original on 2021-12-13.
  60. ^ "ISO 22197-1:2007". ISO.
  61. ^ "Unique Gas Analyser Helps to Characterize Photoactive Pigments | CoatingsPro Magazine". www.coatingspromag.com.
  62. ^ Nuño, Manuel (2014). "Study of solid/gas phase photocatalytic reactions by electron ionization mass spectrometry" (PDF). Journal of Mass Spectrometry. 49 (8): 716–726. Bibcode:2014JMSp...49..716N. doi:10.1002/jms.3396. PMID 25044899.