Bioinorganic Photochemistry:  Frontiers and Mechanisms

Szaciłowski, Konrad; Macyk, Wojciech; Drzewiecka-Matuszek, Agnieszka; Brindell, Małgorzata; Stochel, Grażyna

doi:10.1021/cr030707e

Cited by 683 publications

(542 citation statements)

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“…Electron transfer from one of these levels to the conduction band requires lower photon energy than in the situation of an unmodified semiconductor. TiO 2 has been doped with many different transition metals [72][73][74][75][76][77][78][79][80][81][82][83][84][85][86]. Grätzel et al [73] studied the effect of doping TiO 2 with transition metals such as Fe, V, and Mo by electron paramagnetic resonance.…”

Section: Doping With Transition Metal Cationsmentioning

confidence: 99%

A review of TiO2 nanoparticles

2011

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Climate change and the consumption of non-renewable resources are considered as the greatest problems facing humankind. Because of this, photocatalysis research has been rapidly expanding. TiO 2 nanoparticles have been extensively investigated for photocatalytic applications including the decomposition of organic compounds and production of H 2 as a fuel using solar energy. This article reviews the structure and electronic properties of TiO 2 , compares TiO 2 with other common semiconductors used for photocatalytic applications and clarifies the advantages of using TiO 2 nanoparticles. TiO 2 is considered close to an ideal semiconductor for photocatalysis but possesses certain limitations such as poor absorption of visible radiation and rapid recombination of photogenerated electron/hole pairs. In this review article, various methods used to enhance the photocatalytic characteristics of TiO 2 including dye sensitization, doping, coupling and capping are discussed. Environmental and energy applications of TiO 2 , including photocatalytic treatment of wastewater, pesticide degradation and water splitting to produce hydrogen have been summarized. Historical backgroundThe growth of industry worldwide has tremendously increased the generation and accumulation of waste byproducts. In general, the production of useful products has been focused on and the generation of waste byproducts has been largely ignored. This has caused severe environmental problems that have become a major concern. Researchers all over the world have been working on various approaches to address this issue. Photoinduced processes have been studied and various applications have been developed. One important technique for removing industrial waste is the use of light energy (electromagnetic radiation) and particles sensitive to this energy to mineralize waste which aids in its removal from solution. Titanium dioxide (TiO 2 ) is considered very close to an ideal semiconductor for photocatalysis because of its high stability, low cost and safety toward both humans and the environment.*Corresponding author (email: shipra.mital@gmail.com)In 1964, Kato et al.[1] published their work on the photocatalytic oxidation of tetralin (1,2,3,4-tetrahydronaphthalene) by a TiO 2 suspension, which was followed by McLintock et al. [2] investigating the photocatalytic oxidation of ethylene and propylene in the presence of oxygen adsorbed on TiO 2 . However, the most important discovery that extensively promoted the field of photocatalysis was the "Honda-Fujishima Effect" first described by Fujishima and Honda in 1972 [3]. This well-known chemical phenomenon involves electrolysis of water, which is related to photocatalysis. Photoirradiation of a TiO 2 (rutile) single crystal electrode immersed in an aqueous electrolyte solution induced the evolution of oxygen from the TiO 2 electrode and the evolution of hydrogen from a platinum counterelectrode when an anodic bias was applied to the TiO 2 working electrode. In 1977, Frank and Bard [4] examined the reduction of ...

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Section: Doping With Transition Metal Cationsmentioning

confidence: 99%

A review of TiO2 nanoparticles

2011

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“…8, 9 The myriad of applications are founded on the well defined chemistry of these compounds and take advantage of the versatile photophysical, 10 photochemical 11 and electrochemical 12 properties that are associ-10 ated with the metal-to-ligand charge-transfer (MLCT) excitation in these metal complexes. 13 Amongst the many multinuclear polypyridyl complexes reported, 14 an interesting subclass is represented by those binuclear systems that display additional spectroelectrochemical features 15 due to the electronic interaction between the two metal centres in the mixed valence redox state(s).…”

Section: Introductionmentioning

confidence: 99%

Spectroelectrochemical properties of homo- and heteroleptic ruthenium and osmium binuclear complexes: intercomponent communication as a function of energy differences between HOMO levels of bridge and metal centres

et al. 2009

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A series of binuclear ruthenium and osmium complexes [(bipy) (5) and [(bipy) 2 Os(bpbt)Os(bipy) 2 ] 2+ (6) {bipy = 2,2¢-bipyridyl; qpy = 2,2¢:5¢,5¢¢:2¢¢,2¢¢¢-quaterpyridyl; pytr-bipy = 3-(2,2¢-bipyrid-6-yl)-5-(pyrid-2-yl)-1,2,4-triazolato, and bpbt = 5,5¢-bis-(pyrid-2¢¢-yl)-3,3¢-bis-1,2,4-triazolato} are reported. Analysis of the electrochemical data focuses on structural factors and on determining the extent of electronic communication between the metal centres in the mixed valence oxidation state. Intervalence charge transfer (IT) bands could be identified in the spectra of the complexes 4 and 6 only. Analysis of their spectroelectrochemical data leads to the conclusion that the IT is superexchange mediated through the HOMO of the bridging ligand. IntroductionMetal complexes based on polypyridyl ligands constitute versatile components for the construction of multifunctional supramolecular systems in molecular photonics and molecular electronics, 1 sensors, 2 photocatalysis, 3 solar energy 5 conversion, 4 artificial photosynthesis, 5 non-linear optics, 6 and electrochemoluminescence 7 amongst others. 8, 9 The myriad of applications are founded on the well defined chemistry of these compounds and take advantage of the versatile photophysical, 10 photochemical 11 and electrochemical 12 properties that are associ-10 ated with the metal-to-ligand charge-transfer (MLCT) excitation in these metal complexes. 13 Amongst the many multinuclear polypyridyl complexes reported, 14 an interesting subclass is represented by those binuclear systems that display additional spectroelectrochemical features 15 due to the electronic interaction between the two metal centres in the mixed valence redox state(s). 15,16 "Communication" between metal centres where direct overlap of atomic orbitals is not possible is achieved when the bridging ligand (BL) has a system of polarisable electrons that are capable of mediating 20 the redistribution of the electronic charge between the two metal centres. Sciences, Dublin City University, Dublin 9, Analysis of these absorption bands 25 can provide detailed information as to the nature and extent of the interaction between the metals centres. 30 Recently, we reported the synthesis and characterisation of a series of homo-and hetero-binuclear ruthenium(II) and osmium(II) complexes of the general formula [M 1 (bipy) 2 -BL-M 2 (bipy) 2 ], where M = Ru or Os, bipy is 2,2¢-bipyridyl (bipy), and BL the bridging ligands 2,2¢:5¢,5¢¢:2¢¢,2¢¢¢-quaterpyridyl (qpy), 3-(2,2¢-35 bipyrid-6-yl)-5-(pyrid-2-yl)-1,2,4-triazolato (pytr-bipy), and 5,5¢-bis-(pyrid-2¢¢-yl)-3,3¢-bis-1,2,4-triazolato (bpbt). 26 In the present contribution, we describe in detail the electrochemical and spectroelectrochemical properties of these compounds. The goal of the present study is to evaluate the extent 40 of electronic communication between the two metal centres as a function of the electronic properties of the bridging ligand and the positioning of the two metal centres. In particular, attention is directed towards the hom...

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“…The employed semi-A C H T U N G T R E N N U N G conductor photochemistry principle has already been applied to many fields. [7][8][9][10] Specifically, under the UV-laser irradiation, electrons are excited from the valence band to the conduction band of TiO 2 nanoparticles, [11][12][13] leaving oxidative holes to drive in-source oxidation reactions and reductive electrons to induce in-source reduction reactions. As an Abstract: In-source photocatalytic redox reactions based on a photosensitive target plate have been developed to realize peptide fragmentation during laser desorption ionization.…”

Section: Introductionmentioning

confidence: 99%