A novel ZnIn 2 S 4 catalyst synthesized by hydrothermal method shows high and stable photocatalytic activity for water reduction under visible light illumination.In recent years photocatalytic water splitting using solar energy has received a great deal of attention because of the global energy and environmental problems. During the past decades many mixed oxide photocatalysts such as SrTiO 3 , 1 KNb 6 O 17 2 and NaTaO 3 3 have been reported to show high activity for overall water splitting. These photocatalysts, however, are effective only in the ultraviolet region due to their wide band gap. In order to improve the efficiency of utilizing the solar energy, the development of visible-light-driven photocatalysts for water splitting is indispensable. Unfortunately, the number of photocatalysts working under visible light irradiation is still limited. [4][5][6] In contrast to the metal oxide photocatalysts, many metal sulfides have the narrower band gaps that correspond to the visible light absorption. 7 The ternary sulfides with strong absorption in the visible region may be good candidates for photocatalytic water splitting to produce hydrogen. But, it is commonly believed that metal sulfides are unstable during the photocatalytic reaction. Improving the stability of metal sulfide catalyst such as CdS for water splitting is challenging. A few efforts have been made, for example, by incorporating the nanoparticles of metal sulfide into the interlayer 8 or mesoporous silica 9 to stabilize the metal sulfides. The preparation procedure is complicated and the photocatalytic efficiency is still very low. It has recently been reported that multicomponent metal sulfide 7 and oxysulfide 4 show stable photocatalytic activity for water reduction and oxidation. These results imply that the multicomponent metal sulfide could be a new class of stable photocatalyst for water reduction.Zinc indium sulfide, ZnIn 2 S 4 , is a ternary chalcogenide which belongs to the family of ternary compound AB 2 X 4 . ZnIn 2 S 4 is a potential photoconducting material 10 and has been extensively applied to the electrochemical recording and photovariable capacitor. But, there is no report on the photocatalytic water reduction over the ternary compound of AB 2 X 4 . These compounds are conventionally prepared by the chemical transport method. 11 This method usually requires high temperature and high vacuum, as well as a transporting agent such as iodine. In this communication, we report a chemically stable ZnIn 2 S 4 photocatalyst prepared by a direct hydrothermal synthesis method. UV-visible diffuse reflectance spectra shows that the absorption edge of ZnIn 2 S 4 is in the visible region, corresponding to the band gap of 2.3 eV. It is found that the ZnIn 2 S 4 shows high activity for photocatalytic water reduction under visible light (l > 420 nm) irradiation. More interestingly, the H 2 evolution rate gradually increases with prolonged photocatalytic reaction time. No deactivation is observed even after photocatalytic reaction for 150 h.The ZnS...

A series of all-inorganic, abundant-metal-based, high-nuclearity cobalt-phosphate (Co-Pi) molecular catalysts [{Co4(OH)3(PO4)}4(SiW9O34)4](32-) (1), [{Co4(OH)3(PO4)}4(GeW9O34)4](32-) (2), [{Co4(OH)3(PO4)}4(PW9O34)4](28-) (3), and [{Co4(OH)3(PO4)}4(AsW9O34)4](28-) (4) were synthesized and shown to be highly effective at photocatalytic water oxidation. The {Co16(PO4)4} cluster contains a Co4O4 cubane which is structurally analogous to the [Mn3CaO4] core of the oxygen-evolving complex (OEC) in photosystem II (PSII). Compounds 1-4 were shown to be the first POM-based Co-Pi-cluster molecular catalysts for visible light-driven water oxidation, thus serving as a functional model of the OEC in PSII. The systematic synthesis of four isostructural analogues allowed for investigating the influence of different heteroatoms in the POM ligands on the photocatalytic activities of these Co-Pi cluster WOCs. Further, the POM-based photocatalysts readily recrystallized from the photocatalytic reaction systems with the polyoxoanion structures unchanged, which together with the laser flash photolysis, dynamic light-scattering, (31)P NMR, UV-vis absorption, POM extraction, and ICP-MS analysis results collectively confirmed that compounds 1-4 maintain their structural integrity under the photocatalytic conditions. This study provides not only a valuable molecular model of the "Co-Pi" catalysts with a well-defined structure but also an unprecedented opportunity to fine-tune high-nuclearity POM clusters for visible light-driven water splitting.

The surface properties, porosities, and adsorption capacities of activated carbons (AC) are modified by the oxidation treatment using concentrated H2SO4 at temperatures 150−270 °C. The modified AC was characterized by N2 adsorption, base titration, FTIR, and the adsorption of iodine, chlorophenol, methylene blue, and dibenzothiophene. The treatment of AC with concentrated H2SO4 at 250 °C greatly increases the mesoporous volume from 0.243 mL/g to 0.452 mL/g, specific surface areas from 393 m2/g to 745 m2/g, and acidic surface oxygen complexes from 0.071 meq/g to 1.986 meq/g as compared with the unmodified AC. The base titration results indicate that the amount of acidic surface oxygen groups on the modified AC increases with increasing the treatment temperatures and carboxyls and phenols are the most abundant carbon−oxygen functional groups. The carboxyl groups, COO- species, and hydroxyl groups are detected mainly for the sample treated at 250 °C. The mesoporous properties of the AC modified by concentrated H2SO4 were further tested by the adsorption of methylene blue and dibenzothiophene. The AC modified by concentrated H2SO4 at 250 °C has much higher adsorption capacities for large molecules (e.g., methylene blue and dibenzothiophene) than the unmodified AC but less adsorption capacities for small molecules (e.g., iodine). The adsorption results from aqueous solutions have been interpreted using Freundlich adsorption models.