Isotope tracing study on oxidation of water on photoirradiated TiO2 particles

Bui, Tammy; Yagi, En; Harada, Takashi; Ikeda, Shigeru; Matsumura, Michio

doi:10.1016/j.apcatb.2012.07.014

Cited by 4 publications

(7 citation statements)

References 23 publications

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“…Similar attempts were tried in previous photocatalytic water oxidation studies, yet in our experiments a quantitative O 2 species population analysis in realistic reaction medium is provided. 56 , 57 The population of O 2 species presented in Figure 8 ( 32 O 2 = 61.8%, 16 O 18 O = 33.4%, and 36 O 2 = 4.7%) is fairly similar to the theoretical one assuming a mean field approximation and no kinetic isotope effect ( 32 O 2 = 60.2%, 16 O 18 O = 34.7%, and 36 O 2 = 5%). Although in terms of relative ratios of 16 O 18 O and 36 O 2 labeled species to 32 O 2 this difference corresponds to 20% and 30% error respectively, showing a slight overpopulation of regular 32 O 2 , this deviation can be corrected considering a kinetic isotope effect (KIE).…”

Section: Resultssupporting

confidence: 68%

Toward Standardized Photocatalytic Oxygen Evolution Rates Using RuO2@TiO2 as a Benchmark

Vignolo‐González

Laha

Jiménez‐Solano

et al. 2020

Matter

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Summary Quantitative comparison of photocatalytic performances across different photocatalysis setups is technically challenging. Here, we combine the concepts of relative and optimal photonic efficiencies to normalize activities with an internal benchmark material, RuO 2 photodeposited on a P25-TiO 2 photocatalyst, which was optimized for reproducibility of the oxygen evolution reaction (OER). Additionally, a general set of good practices was identified to ensure reliable quantification of photocatalytic OER, including photoreactor design, photocatalyst dispersion, and control of parasitic reactions caused by the sacrificial electron acceptor. Moreover, a method combining optical modeling and measurements was proposed to quantify the benchmark absorbed and scattered light (7.6% and 81.2%, respectively, of λ = 300–500 nm incident photons), rather than just incident light (≈AM 1.5G), to estimate its internal quantum efficiency (16%). We advocate the adoption of the instrumental and theoretical framework provided here to facilitate material standardization and comparison in the field of artificial photosynthesis.

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Section: Resultssupporting

confidence: 68%

Toward Standardized Photocatalytic Oxygen Evolution Rates Using RuO2@TiO2 as a Benchmark

Vignolo‐González

Laha

Jiménez‐Solano

et al. 2020

Matter

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“…Matsumura et al. conducted photocatalytic water oxidation using several TiO 2 particles in the presence of 18 O‐enriched water . Their experiments indicated that the source of the evolved O 2 was solely O atoms in the isotope‐containing water, even in the presence of unlabeled O 2 gas in the reaction system.…”

Section: Rutile Tio2 As An Efficient Water Oxidation Photocatalystmentioning

confidence: 96%

“…This result supports the idea that O 2 evolution by water oxidation is initiated by nucleophilic attack of H 2 Om olecules on photogenerated holes at surface lattice O sites, and not by oxidation of surfaceO Hg roups by holes, which was previouslyc onsidered to be the main pathway for water photooxidation on rutile TiO 2 .A ccording to DFT calculations for the (photo)oxidation of water on the rutile TiO 2 (110) surfacec onducted by ValdØse tal.,p eroxo species undergo spontaneous decomposition to yield O 2 gas, and the most difficult step in the splitting of water is the reaction of aH 2 Om olecule with av acancy at the surfacet of orm an adsorbed hydroxyl group. [57] Their experiments indicated that the source of the evolvedO 2 was solely Oa toms in the isotope-containing water,even in the presence of unlabeled O 2 gas in the reaction system.H igher water oxidation activities of rutile samples than those for anatasew ere also observed in the isotopel abeling experiments. [57] Their experiments indicated that the source of the evolvedO 2 was solely Oa toms in the isotope-containing water,even in the presence of unlabeled O 2 gas in the reaction system.H igher water oxidation activities of rutile samples than those for anatasew ere also observed in the isotopel abeling experiments.…”

mentioning

confidence: 99%

“…[56] Matsumura et al conducted photocatalytic water oxidation using severalT iO 2 particles in the presence of 18 O-enriched water. [57] Their experiments indicated that the source of the evolvedO 2 was solely Oa toms in the isotope-containing water,even in the presence of unlabeled O 2 gas in the reaction system.H igher water oxidation activities of rutile samples than those for anatasew ere also observed in the isotopel abeling experiments.…”

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confidence: 99%

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Water Splitting on Rutile TiO₂‐Based Photocatalysts

Miyoshi

Nishioka

Maeda

2018

Chemistry A European J

154

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Water splitting using a semiconductor photocatalyst with sunlight has long been viewed as a potential means of large-scale H production from renewable resources. Different from anatase TiO , rutile enables preferential water oxidation, which is useful for the construction of a Z-scheme water-splitting system. The combination of rutile TiO with a suitable H -evolution photocatalyst such as a Pt-loaded BaZrO -BaTaO N solid solution enables solar-driven water splitting into H and O . While rutile TiO is a wide-gap semiconductor with a bandgap of 3.0 eV, co-doping of rutile TiO with certain metal ions and/or nitrogen produces visible-light-driven photocatalysts, which are also useful as a component for water oxidation in visible-light-driven Z-scheme water splitting. The key to achieving highly efficient water oxidation is to maintain a charge balance of dopants in the rutile, because single doping typically produces trap states that capture photogenerated electrons and/or holes. Here we provide a concise summary of rutile TiO -based photocatalysts for water-splitting systems.

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“…Another advantage of oxygen isotopic labeling technique is its flexibility, i.e. , each component such as 18 O-labeled 18 O 2 [10,11,12,13,14], H 2 18 O [15,16,17], Ti 18 O 2 [18,19,20,21,22,23] and 18 O-labeled substrate [24,25,26] can be labeled.…”

Section: Introductionmentioning

confidence: 99%

Unraveling the Photocatalytic Mechanisms on TiO2 Surfaces Using the Oxygen-18 Isotopic Label Technique

Pang

Chen

et al. 2014

Molecules

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During the last several decades TiO2 photocatalytic oxidation using the molecular oxygen in air has emerged as a promising method for the degradation of recalcitrant organic pollutants and selective transformations of valuable organic chemicals. Despite extensive studies, the mechanisms of these photocatalytic reactions are still poorly understood due to their complexity. In this review, we will highlight how the oxygen-18 isotope labeling technique can be a powerful tool to elucidate complicated photocatalytic mechanisms taking place on the TiO2 surface. To this end, the application of the oxygen-18 isotopic-labeling method to three representative photocatalytic reactions is discussed: (1) the photocatalytic hydroxylation of aromatics; (2) oxidative cleavage of aryl rings on the TiO2 surface; and (3) photocatalytic decarboxylation of saturated carboxylic acids. The results show that the oxygen atoms of molecular oxygen can incorporate into the corresponding products in aqueous solution in all three of these reactions, but the detailed incorporation pathways are completely different in each case. For the hydroxylation process, the O atom in O2 is shown to be incorporated through activation of O2 by conduction band electrons. In the cleavage of aryl rings, O atoms are inserted into the aryl ring through the site-dependent coordination of reactants on the TiO2 surface. A new pathway for the decarboxylation of saturated carboxylic acids with pyruvic acid as an intermediate is identified, and the O2 is incorporated into the products through the further oxidation of pyruvic acid by active species from the activation of O2 by conduction band electrons.

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Isotope tracing study on oxidation of water on photoirradiated TiO2 particles

Cited by 4 publications

References 23 publications

Toward Standardized Photocatalytic Oxygen Evolution Rates Using RuO2@TiO2 as a Benchmark

Toward Standardized Photocatalytic Oxygen Evolution Rates Using RuO2@TiO2 as a Benchmark

Water Splitting on Rutile TiO₂‐Based Photocatalysts

Unraveling the Photocatalytic Mechanisms on TiO2 Surfaces Using the Oxygen-18 Isotopic Label Technique

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Isotope tracing study on oxidation of water on photoirradiated TiO2 particles

Cited by 4 publications

References 23 publications

Toward Standardized Photocatalytic Oxygen Evolution Rates Using RuO2@TiO2 as a Benchmark

Toward Standardized Photocatalytic Oxygen Evolution Rates Using RuO2@TiO2 as a Benchmark

Water Splitting on Rutile TiO2‐Based Photocatalysts

Unraveling the Photocatalytic Mechanisms on TiO2 Surfaces Using the Oxygen-18 Isotopic Label Technique

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Water Splitting on Rutile TiO₂‐Based Photocatalysts