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This work spotlights the recently discovered photoelectrocatalytic properties of iron-based metal-organic frameworks (MOFs) for water oxidation reaction (WOR) under visible light irradiation. The low efficiency of WOR is one of the biggest difficulties faced by photoelectrochemical solar energy conversion; the development of new photoanodes for WOR is greatly desired. In view of the fact that a higher efficiency for WOR was forecast thanks to the peculiar properties of MOFs, such as a highly ordered framework and homogenous porous structure, the photoelectrodes based on MIL-101(Fe) containing photo-active iron(III) clusters have been fabricated by using a drop-casting method and applied to photoelectrochemical water oxidation as photoanodes. XRD measurements revealed the successful formation of MIL-101(Fe) electrodes while retaining their framework structures. From the results of photoelectrochemical measurements, the optimal thickness of the MIL-101(Fe) electrodes was determined to be ca. 60 μm, and the optimized MIL-101(Fe) electrode was found to promote photoelectrochemical WOR under visible light irradiation more efficiently than conventional α-Fe2O3 electrodes. Moreover, electrochemical impedance spectroscopy measurements demonstrated a lower resistance of charge transfer at the interface between the MOF surface and the electrolyte, resulting in better photoelectrochemical performance of the MIL-101(Fe) electrode. [ABSTRACT FROM AUTHOR]

An iron-based metal–organic framework, MIL-101(Fe), promotes photocatalytic water oxidation to produce oxygen from aqueous silver nitrate solution under visible-light irradiation. The finely dispersed iron-oxo clusters embedded as nodes of the porous framework would contribute importantly to the efficient promotion of the reaction as compared to bulk hematite (α-Fe2O3). [ABSTRACT FROM AUTHOR]

A hybrid photocatalyst was prepared from visible light-responsive Pt/WO and siliceous mordenite (MOR) zeolite by simple impregnation with an aqueous solution of (NH)WO·5HO. Unmodified Pt/WO had low photocatalytic activity in gas phase oxidation of acetaldehyde because of its low surface area (3-5 m/g). In contrast, the Pt/WO-MOR had higher photocatalytic activity under focused sunlight and Xe lamp irradiation. Pt/WO-MOR with low WO content (<20 wt%) adsorbed sufficient acetaldehyde, but absorption of light in the visible region was low. The optimum zeolite content enhancing the photocatalytic activity of Pt/WO was estimated to be 30-50 % ( w/ w). Adsorption of the gaseous reactants and the efficiency of absorption of incident light are both important aspects of high photocatalytic activity. [ABSTRACT FROM AUTHOR]

The photocatalytic oxidation of benzyl alcohol into benzaldehyde proceeded with high conversion and selectivity on a TiO2 photocatalyst by O2 under visible light irradiation. Surface complex formed by the interaction of benzyl alcohol with the Ti sites and/or surface OH groups of TiO2 play an important role in the absorption of visible light and unique selective photocatalytic reaction. [ABSTRACT FROM AUTHOR]

TiO2 thin film photocatalysts which could induce photoreactions under visible light irradiation were successfully developed in a single process by applying an ion engineering technique, i.e., the radio frequency (RF) magnetron sputtering deposition method. The TiO2 thin films prepared at temperatures greater than 773 K showed the efficient absorption of visible light; on the other hand, the TiO2 thin films prepared at around 573 K were highly transparent. This clearly means that the optical properties of TiO2 thin films, which absorb not only UV but also visible light, can be controlled by the preparation temperatures of the RF magnetron sputtering deposition method. These visible light responsive TiO2 thin films were found to exhibit effective photocatalytic reactivity under visible light irradiation ( λ > 450 nm) at 275 K for the reductive decomposition of NO into N2 and N2O. From various characterizations, the orderly aligned columnar TiO2 crystals could be observed only for the visible light responsive TiO2 thin films. This unique structural factor is expected to modify the electronic properties of a TiO2 semiconductor, enabling the efficient absorption of visible light. [ABSTRACT FROM AUTHOR]

The photocatalytic preferential oxidation of CO with O2 in the presence of H2 (photo-PROX) was found to proceed efficiently on the NiO-loaded TiO2 (NiO/TiO2) catalyst under UV light irradiation at 293 K. NiO/TiO2 exhibited higher CO conversion as well as CO2 selectivity for a photo-PROX reaction than the original unloaded TiO2 (P-25). Various spectroscopic investigations have revealed that the small NiO clusters formed on TiO2 play an important role in the enhancement of CO oxidation activity in this reaction. [ABSTRACT FROM AUTHOR]

Visible light-responsive TiO2 (Vis-TiO2) thin films were prepared by a radio frequency magnetron sputtering deposition method. The photoelectrochemical performance was improved by adding various kinds and concentrations of alcohol, i.e., model compounds of biomass, to water. The separate evolution of pure H2 was observed to proceed efficiently on these Vis-TiO2 thin films under visible light irradiation by using an aqueous solution of methanol. [ABSTRACT FROM AUTHOR]

N-doped TiO2 adsorbed platinum chloride (PtCl x /N-TiO2, x being an unidentified number) was found to show much higher photocatalytic activity than either N-TiO2 or PtCl x /TiO2 for the decomposition of acetic acid into CO2 and H2O under Visible-light irradiation, while neither PtCl x /SiO2, PtCl x /Al2O3 nor an aqueous solution of H2PtCl6 was active. An enhancement of the photo-activity on PtCl x /N-TiO2 has been proposed as a Z-scheme mechanism. [ABSTRACT FROM AUTHOR]

A highly dispersed Cr6+-oxide species on silica (Cr/SiO2) was found to act as an efficient photocatalyst for the selective oxidation of CO into CO2 with O2 in the presence of H2 under visible (λ > 420 nm) or solar light irradiation at 293 K. UV-Vis, photoluminescence and FT-IR investigations revealed that the selective reactivity of the photoexcited tetrahedral Cr6+-oxide species ([Cr5+–O–]*) with CO, as well as the high reactivity of the photoreduced Cr6+-oxide species (Cr4+-oxide species) with O2 both play significant roles in this reaction. [ABSTRACT FROM AUTHOR]

Abstract: Recent advances in photocatalytic water splitting reactions, especially under visible light irradiation, are reviewed here. In line with such work, the development of various unique photocatalysts including cation or anion-doped metal oxides or metal oxynitride has been introduced. Special attention is focused on the preparation of visible light-responsive TiO2 thin films by a RF-magnetron sputtering method and their applications for the separate evolution of H2 and O2 from water under visible or solar light irradiation. [Copyright &y& Elsevier]

Vanadium ion-containing mesoporous molecular sieves V-MCM-41 were successfully prepared using a photo-assisted synthesis method with UV irradiation of the starting solutions at room temperature. Important advantages such as a shortened synthesis reaction time could be seen, leading to highly ordered regularly oriented pore structures for the V-MCM-41, when compared with synthesis using conventional method. [ABSTRACT FROM AUTHOR]