Ruthenium Dioxide Electrodes as Suitable Anodes for Water Photolysis

Neumann‐Spallart, M.; Kalyanasundaram, K.; Grätzel, Carole; Grätzel, Michaël

doi:10.1002/hlca.19800630502

Cited by 50 publications

(19 citation statements)

References 15 publications

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“…In addition, chloride and sulfate ions are produced as inorganic products. The ruthenium(III) complex is a powerful oxidant (Eº 1·26 V [178,179]), and can oxidize either water [175] or 4-chlorophenol (Eº 0·94 V for the ClϕOH .+ /ClϕOH couple at pH 7 [53]) to regenerate Ru(bpy) 3…”

Section: ·3mentioning

confidence: 99%

Kinetics and Mechanism of Photodegradation of Chlorophenols

Burrows¹,

Ernestova²,

Kemp³

et al. 1998

prog. rct. kin. mech.

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3. HOMOGENEOUS SENSITIZED SYSTEMS170 3·1 General background 170 3·1·1 Singlet oxygen as oxidant 171 3·2 Sensitized oxidation of chlorophenols by singlet oxygen 172 3·3 Homogeneous reactions of chlorophenols with metal complexes 176 4. PHOTOINDUCED DEGRADATION OF CHLOROPHENOLS 180 4·1 Free radical oxidation of chlorophenols 180 4·2 Free radical processes in semiconductor-photocatalysed degradation of chlorophenols 182 4·2·1 TiO 2 -mediated degradation of chlorophenols 183 4·3 Sensitization of chlorophenol degradation by supported catalysts 188 4·4 Radiation induced degradation of 2,4,6-trichlorophenol 191 5. REACTIONS OF CHLOROPHENOLS WITH TRANSIENT INTERMEDIATES 193 6. CONCLUSIONS 197 7. ACKNOWLEDGEMENTS 198 8. REFERENCES 198 ABSTRACTThe photodegradation of mono-, di-, tri-and pentachlorophenols in aqueous solution is surveyed from several viewpoints, namely kinetic and mechanistic, the nature of the reactive intermediates and final products, and the potential of photochemical means of treating water contaminated by chlorophenols. In direct photolysis, the roles of heterolytic and homolytic processes are considered, and the appearance of carbene, in addition to ionic and radical, intermediates noted. Sensitized photolysis deals with the roles of singlet oxygen and of a variety of metal complexes. The induced degradation of chlorophenols refers to the oxidation of chlorophenols by free radicals generated from photo-and radiolytic systems, particularly illuminated semiconductors such as titanium dioxide. The article finishes with an overview of the reactions of various types of reactive intermediates with chlorophenols. 1. dIonization potentials of 2-chlorophenol (8·66 eV) and 4-chlorophenol (8·94 eV) in organic solvents have been determined from charge transfer spectra with TCNE [51] e Values obtained for 4-chlorophenol for OH bond dissociation energies by this method, photoacoustic calorimetry [52], pulse radiolysis [53] and theoretical calculations [54] vary over the range 84·4-90·3 kcal mol -1 f Calculated in [50] g From [55] h n-butanol solution [56]

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Section: ·3mentioning

confidence: 99%

Kinetics and Mechanism of Photodegradation of Chlorophenols

Burrows¹,

Ernestova²,

Kemp³

et al. 1998

prog. rct. kin. mech.

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“…a rate constant of k2 = 5 x 10' M-1 s-' was estimated. It is known that this second bleaching step is accompmied by an increase of the transient absorbance at 650 nm due to the formation of Ru(bpy)g+ (k, > 1 x 10: M-' s-I) (Neumann-Spallart et al, 1980). (k4), the latter measured by pulse radiolysis.…”

Section: Time-rerolved Photobleaching Measurements In the Presence Omentioning

confidence: 99%

“…In the present work we have chosen as a photosensitizer the well-known heavy metal complex, tris(2,2'bipyridyl)ruthenium(II), Ru(bpy)f'. Its photochemistry has been extensively studied (Neumann-Spallart et a(., 1980;Bolletta et a/. , 1980;Humphry-Baker et al.…”

Section: Introductionmentioning

confidence: 99%

Photoreactions of Tris(2,2′‐bipyridyl)‐ruthenium(ii) With Peroxydisulfate in Deoxygenated Aqueous Solution in the Presence of Nucleic Acid Components, Polynucleotides, and Dna*

Görner

Stradowski

Schulte‐Frohlinde

1988

Photochem & Photobiology

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Abstract— The photobleaching of excited tris(2,2′‐bipyridyl)‐ruthenium(II), *Ru(bpy)32+, by peroxydis‐ulfate in the presence of DNA and a series of polynucleotides, mononucleosides (uridine, cytidine, adenosine, guanosine), and purine or pyrimidine bases was studied in deoxygenated aqueous solution at room temperature. A reaction scheme is proposed which is confirmed by data obtained from mixing experiments with Ru(III) and bleaching measurements of Ru(II) using either continuous visible light or a nanosecond laser pulse (353 nm). The primary photobleaching step is the formation of Ru(bpy)32+ and the SO4‐ radical anion. In the presence of nucleic acids the two oxidizing species are formed in close proximity to the strand, since we used conditions where the Ru(bpy) 32+ ion is bound to the strand. Concerning the secondary reactions two clear cases (and several more complex cases) can be distinguished. On addition of uracil to the Ru(bpy)32+/S2O82‐ system the quantum yield for photobleaching is not significantly changed (φrel⋍ 0.95), whereas it drops to virtually zero for guanosine‐containing substrates, including DNA. The former result is explained by a reaction of SO4‐ with uracil leading to theN–1 radical which oxidizes Ru(II) to Ru(IIl). In contrast, the guanine moiety reacts with Ru(III) converting it into Ru(II). Therefore, in the presence of S2O82‐ and a substrate carrying a guanine moiety, Ru(bpy32+ acts as a photocatalyst.

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“…Considering these observations the following reaction pathways may be proposed. (9) Ru(bipy):+ a Ru(bipy)32'* (20) Ru(bipy):+* + H3P20,-3 Ru(bipy);+ + HzPO4' + H,P04- HP0,'-PO,"-Even though the reduction potential of peroxodiphosphate (2.07 V) is [3] higher than those of PMS (1.84 V) [l] and PDS (2.01 V) [2], no detectable thermal oxidation between PDP and Ru(bipy);+ is observed.…”

Section: Peroxod Iphosphatementioning

confidence: 99%

“…Although Irvine had reported [181 the thermal oxidation of Ru(bipy):' by PDS, no detailed kinetics was presented. Boletta [19] and Gratzel [20] have individually reported the photochemical reactions of PDS with Ru(bipy);+. The photobleaching of the excited state Ru(bipy);+ by PDS in the presence of DNA and a series of mononucleotides, polynucleotides, and purineipyrimidine bases were studied by Gorner et a1 [21].…”

Section: Introductionmentioning

confidence: 99%

Kinetics and mechanism of oxidation of excited state Tris‐(2,2′‐bipyridyl)‐ruthenium (II) complex by peroxomonosulfate, peroxodisulfate, and peroxodiphosphate

Venkatasubramanian

Dharmalingam

Maruthamuthu

1990

Int J of Chemical Kinetics

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Excitation of Ru(bipy);'ion by visible radiation of wavelength A = 436 nm in aqueous medium in presence of inorganic peroxides, peroxomonosulfate (PMS), peroxodisulfate (PDS), and peroxodiphosphate (PDP) was found to generate Ru(bipy),3'. The kinetics of this photochemical oxidation of Ru(bipy);' by each peroxide was followed spectrophotometrically and found to obey a total second-order, first-order each in [Ru(bipy):+] and [peroxide]. In the absence of light, thermal reaction of PMS and PDS with Ru(bipy);+ occurred but only when a t 1.0 M [H'] and M [peroxide]. The reaction of PMS with the complex is found to be cyclic, ie., Ru(bipy);+ formed oxidizes PMS itself and such a reaction was not observed in the case of PDS and PDP. The effects of pH, [peroxide], and [Ru(bipy);'] on the visible light induced oxidation of Ru(bipy);' by these peroxides are investigated. The results are discussed with suitable reaction mechanisms.

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Ruthenium Dioxide Electrodes as Suitable Anodes for Water Photolysis

Cited by 50 publications

References 15 publications

Kinetics and Mechanism of Photodegradation of Chlorophenols

Kinetics and Mechanism of Photodegradation of Chlorophenols

Photoreactions of Tris(2,2′‐bipyridyl)‐ruthenium(ii) With Peroxydisulfate in Deoxygenated Aqueous Solution in the Presence of Nucleic Acid Components, Polynucleotides, and Dna*

Kinetics and mechanism of oxidation of excited state Tris‐(2,2′‐bipyridyl)‐ruthenium (II) complex by peroxomonosulfate, peroxodisulfate, and peroxodiphosphate

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