Photocatalytic Hydrogen Evolution from Hexaniobate Nanoscrolls and Calcium Niobate Nanosheets Sensitized by Ruthenium(II) Bipyridyl Complexes

Maeda, Kazuhiko; Eguchi, Miharu; Lee, Seung Hyun Anna; Youngblood, W. Justin; Hata, Hideo

doi:10.1021/jp900842e

Cited by 152 publications

(130 citation statements)

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“…units [28], and cobalt(II)tetraphenylporphyrin/methylviologen/Pt-loaded poly (L-glutamate) [ [31], [RuL(bpy) 2 ](PF 6 ) 2 /Pt/TiO 2 (L = 2-hydroxyl-5-(imidazo-[4,5-f]-1,10-phenanthrolin) benzoic acid [32], Ru(bpy) 2 (4,4 0 -(PO 3 H 2 ) 2 bpy) 2? /Pt/hexaniobate nanoscrolls or acid-restacked calcium niobate nanosheets [33], and metal-free organic dyes containing benzo[b] phenothiazine/Pt/TiO 2 [34] were in the range 100-840 h -1 for hydrogen evolution from aqueous TEOA and EDTA solutions under visible light irradiation (k = [400 and C420 nm); however, the rates rapidly decreased after a few hours. Therefore, the Cs-Pt-1/EY/K-Al-1/TiO 2 photocatalytic system achieved high TOFs and steady hydrogen production over a long-term of light irradiation.…”

Section: Resultsmentioning

confidence: 99%

A Novel Photocatalytic System Constructed Using Eosin Y, Titanium Dioxide, and Keggin-Type Platinum(II)- and Aluminum(III)-Coordinated Polyoxotungstates for Hydrogen Production from Water Under Visible Light Irradiation

2015

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A novel photocatalytic system constructed using Eosin Y, a-Keggin-type diplatinum(II)-coordinated tungstophosphate Cs 3 [a-PW 11 O 39 {cis-Pt(NH 3 ) 2 } 2 ]Á8H 2 O (Cs-Pt-1), a-Keggin-type mono-aluminum(III)-coordinated tungstosilicate K 5 [a-SiW 11 {Al(OH 2 )}O 39 ]Á7H 2 O (KAl-1), and titanium dioxide achieved a steady rate of hydrogen evolution with highly effective utilization of platinum sites from aqueous triethanolamine solution during a long-term visible light irradiation. Graphical Abstract Eosin Y TiO 2 Visible light Aqueous TEOA solution H 2 Cs-Pt 1 K-Al-1

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Section: Resultsmentioning

confidence: 99%

A Novel Photocatalytic System Constructed Using Eosin Y, Titanium Dioxide, and Keggin-Type Platinum(II)- and Aluminum(III)-Coordinated Polyoxotungstates for Hydrogen Production from Water Under Visible Light Irradiation

2015

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“…Such excess loading can cause an inner-filter effect, contributing to a decrease in activity. [23][24][25][26] Another possibility is that electron-hole recombination on the surface of the Rh catalyst, which was indicated by our recent spectroscopic study, [27] increases at higher loading, contributing to a decrease in H 2 evolution activity.…”

Section: Wwwchemeurjorgmentioning

confidence: 90%

Preparation of Core–Shell‐Structured Nanoparticles (with a Noble‐Metal or Metal Oxide Core and a Chromia Shell) and Their Application in Water Splitting by Means of Visible Light

Maeda

Sakamoto

Ikeda

et al. 2010

Chemistry A European J

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Core-shell-structured nanoparticles, consisting of a noble metal or metal oxide core and a chromia (Cr(2)O(3)) shell, were studied as promoters for photocatalytic water splitting under visible light. Core nanoparticles were loaded by impregnation, adsorption or photodeposition onto a solid solution of gallium nitride and zinc oxide (abbreviated GaN:ZnO), which is a particulate semiconductor photocatalyst with a band gap of approximately 2.7 eV, and a Cr(2)O(3) shell was formed by photodeposition using a K(2)CrO(4) precursor. Photodeposition of Cr(2)O(3) on GaN:ZnO modified with a noble metal (Rh, Pd and Pt) or metal oxide (NiO(x), RuO(2) and Rh(2)O(3)) co-catalyst resulted in enhanced photocatalytic activity for overall water splitting under visible light (lambda>400 nm). This enhancement in activity was primarily due to the suppression of undesirable reverse reactions (H(2)-O(2) recombination and/or O(2) photoreduction) and/or protection of the core component from chemical corrosion, depending on the core type. Among the core materials examined, Rh species exhibited relatively high performance for this application. The activity for visible-light water splitting on GaN:ZnO modified with an Rh/Cr(2)O(3) core-shell configuration was dependent on both the dispersion of Rh nanoparticles and the valence state. In addition, the morphology of the Cr(2)O(3) photodeposits was significantly affected by the valence state of Rh and the pH at which the photoreduction of K(2)CrO(4) was conducted. When a sufficient amount of K(2)CrO(4) was used as the precursor and the solution pH ranged from 3 to 7.5, Cr(2)O(3) was successfully formed with a constant shell thickness (approximately 2 nm) on metallic Rh nanoparticles, which resulted in an effective promoter for overall water splitting.

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“…We recently observed external quantum yields of 20-25% for hydrogen evolution from EDTA 2-solutions with niobate nanoscrolls and nanosheets catalyzed by Pt and sensitized by a phosphonated [Ru(bpy) 3 ] 2+ derivative (Figure 4). 31 Taking into account light scattering, the low extinction coefficient of the dye, and the charge injection efficiency, this system has >50% internal quantum yield for hydrogen evolution from photoinjected electrons. This high internal quantum yield shows that the single crystal oxide nanoscrolls and sheets are good mediators of electron transfer between the dye molecules and Pt particles.…”

Section: Visible Light Water Splittingmentioning

confidence: 99%

Visible Light Water Splitting Using Dye-Sensitized Oxide Semiconductors

et al. 2009

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R esearchers are intensively investigating photochemical water splitting as a means of converting solar to chemical energy in the form of fuels. Hydrogen is a key solar fuel because it can be used directly in combustion engines or fuel cells, or combined catalytically with CO 2 to make carbon containing fuels. Different approaches to solar water splitting include semiconductor particles as photocatalysts and photoelectrodes, molecular donor-acceptor systems linked to catalysts for hydrogen and oxygen evolution, and photovoltaic cells coupled directly or indirectly to electrocatalysts.Despite several decades of research, solar hydrogen generation is efficient only in systems that use expensive photovoltaic cells to power water electrolysis. Direct photocatalytic water splitting is a challenging problem because the reaction is thermodynamically uphill. Light absorption results in the formation of energetic charge-separated states in both molecular donor-acceptor systems and semiconductor particles. Unfortunately, energetically favorable charge recombination reactions tend to be much faster than the slow multielectron processes of water oxidation and reduction. Consequently, visible light water splitting has only recently been achieved in semiconductor-based photocatalytic systems and remains an inefficient process.This Account describes our approach to two problems in solar water splitting: the organization of molecules into assemblies that promote long-lived charge separation, and catalysis of the electrolysis reactions, in particular the four-electron oxidation of water. The building blocks of our artificial photosynthetic systems are wide band gap semiconductor particles, photosensitizer and electron relay molecules, and nanoparticle catalysts. We intercalate layered metal oxide semiconductors with metal nanoparticles. These intercalation compounds, when sensitized with [Ru(bpy) 3 ] 2+ derivatives, catalyze the photoproduction of hydrogen from sacrificial electron donors (EDTA 2-) or non-sacrificial donors (I -). Through exfoliation of layered metal oxide semiconductors, we construct multilayer electron donor-acceptor thin films or sensitized colloids in which individual nanosheets mediate light-driven electron transfer reactions. When sensitizer molecules are "wired" to IrO 2 · nH 2 O nanoparticles, a dye-sensitized TiO 2 electrode becomes the photoanode of a water-splitting photoelectrochemical cell.Although this system is an interesting proof-of-concept, the performance of these cells is still poor (∼1% quantum yield) and the dye photodegrades rapidly. We can understand the quantum efficiency and degradation in terms of competing kinetic pathways for water oxidation, back electron transfer, and decomposition of the oxidized dye molecules. Laser flash photolysis experiments allow us to measure these competing rates and, in principle, to improve the performance of the cell by changing the architecture of the electron transfer chain.

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Photocatalytic Hydrogen Evolution from Hexaniobate Nanoscrolls and Calcium Niobate Nanosheets Sensitized by Ruthenium(II) Bipyridyl Complexes

Cited by 152 publications

References 61 publications

A Novel Photocatalytic System Constructed Using Eosin Y, Titanium Dioxide, and Keggin-Type Platinum(II)- and Aluminum(III)-Coordinated Polyoxotungstates for Hydrogen Production from Water Under Visible Light Irradiation

A Novel Photocatalytic System Constructed Using Eosin Y, Titanium Dioxide, and Keggin-Type Platinum(II)- and Aluminum(III)-Coordinated Polyoxotungstates for Hydrogen Production from Water Under Visible Light Irradiation

Preparation of Core–Shell‐Structured Nanoparticles (with a Noble‐Metal or Metal Oxide Core and a Chromia Shell) and Their Application in Water Splitting by Means of Visible Light

Visible Light Water Splitting Using Dye-Sensitized Oxide Semiconductors

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