Sensitized layered metal oxide semiconductor particles for photochemical hydrogen evolution from nonsacrificial electron donors

Kim, Yeong Il; Atherton, Stephen J.; Brigham, Elaine S.; Mallouk, Thomas E.

doi:10.1021/j100147a038

Cited by 434 publications

(267 citation statements)

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“…The band-gap energy values (Table 1), estimated by reporting the modified Kubelka-Munk function, [F(R∞ ′ )hν] 1/2 against the exciting light energy [57], showed that the TiO2-10%CeO2 sample had a lower Eg (2.93 eV) compared to the bare TiO2 (2.98 eV). This can be related to the replacement of Ti 4+ cations by Ce 4+ or Ce 3+ cations in the TiO2 network [51,54,58].…”

Section: Discussionmentioning

confidence: 99%

Au/TiO2-CeO2 Catalysts for Photocatalytic Water Splitting and VOCs Oxidation Reactions

et al. 2016

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Photocatalytic water splitting for H 2 production and photocatalytic oxidation of 2-propanol, an example of volatile organic compounds, were investigated over TiO 2 catalysts loaded with gold and/or ceria. In the water splitting reaction the presence of gold only slightly affected the performance of TiO 2 whereas the presence of CeO 2 had a more remarkable positive effect. In the 2-propanol oxidation Au/TiO 2 was the most active sample in terms of alcohol conversion whereas Au/TiO 2 -CeO 2 exhibited the highest CO 2 yield. On the basis of characterization experiments (X-Ray Diffraction (XRD), Energy Dispersive X-ray Analysis EDX, surface area measurements, Diffuse Reflectance Spectroscopy (DRS) and Raman spectroscopy), it was suggested that the interaction of Au with TiO 2 causes an increase in the charge separation between the photo-excited electron/hole pairs, leading to an enhanced photocatalytic activity (to acetone over Au/TiO 2 and to CO 2 over Au/TiO 2 -CeO 2 ), whereas the presence of ceria, acting as a hole trap, positively mainly affects the formation of hydrogen by water splitting.

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Section: Discussionmentioning

confidence: 99%

Au/TiO2-CeO2 Catalysts for Photocatalytic Water Splitting and VOCs Oxidation Reactions

et al. 2016

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“…, versus the energy of the exciting light [15] considering brookite as an indirect semiconductor [16][17][18][19][20][21][22][23][24]. Direct band gap values have been also obtained [3,5,16,17,25].…”

Section: Electronic Propertiesmentioning

confidence: 94%

Brookite, the Least Known TiO2 Photocatalyst

2013

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Abstract:Brookite is the least studied TiO 2 photocatalyst due to the difficulties usually encountered in order to obtain it as a pure phase. In this review, a comprehensive survey of the different methods available for preparing brookite powders and films is reported. Attention has been paid both to the most traditional methods, such as hydrothermal processes at high temperatures and pressures, and to environmentally benign syntheses using water soluble compounds and water as the solvent. Papers reporting the photocatalytic activity of pure and brookite-based samples have been reviewed.

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“…A stringent test of the compartmentalization of the catalyst for the hydrogen half reaction was the inability of these materials to catalyze the thermodynamically downhill reaction of H 2 and I 3 -in the dark. 27 The rate of hydrogen evolution decreases, approaching zero, as the concentration of triiodide builds up. Since no dark reaction was observed between hydrogen and triiodide, the cause of the rate decay was identified as charge recombination between oxidized electron donor species and the LMOS.…”

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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Sensitized layered metal oxide semiconductor particles for photochemical hydrogen evolution from nonsacrificial electron donors

Cited by 434 publications

References 0 publications

Au/TiO2-CeO2 Catalysts for Photocatalytic Water Splitting and VOCs Oxidation Reactions

Au/TiO2-CeO2 Catalysts for Photocatalytic Water Splitting and VOCs Oxidation Reactions

Brookite, the Least Known TiO2 Photocatalyst

Visible Light Water Splitting Using Dye-Sensitized Oxide Semiconductors

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