Graphene Oxide-Mediated Synthesis of Ultrathin Co-MOL for CO2 Photoreduction.

Metal-organic framework (MOF) materials have broad application prospects in catalysis because of their ordered structure and molecular adjustability. However, the large volume of bulky MOF usually leads to insufficient exposure of the active sites and the obstruction of charge/mass transfer, which greatly limits their catalytic performance. Herein, we developed a simple graphene oxide (GO) template method to fabricate ultrathin Co-metal-organic layer (2.0 nm) on reduced GO (Co-MOL@r-GO). The as-synthesized hybrid material Co-MOL@r-GO-2 exhibits highly efficient photocatalytic performance for CO2 reduction, and the CO yield can reach as high as 25,442 µmol/gCo-MOL, which is over 20 times higher than that of the bulky Co-MOF. Systematic investigations demonstrate that GO can act as a template for the synthesis of the ultrathin Co-MOL with more active sites and can be used as the electron transport medium between the photosensitizer and the Co-MOL to enhance the catalytic activity for CO2 photoreduction.

Three Keggin-Type Transition Metal-Substituted Polyoxometalates as Pure Inorganic Photosensitizers for p-Type Dye-Sensitized Solar Cells.

In light of the serious challenge of severe global energy shortages, p-type dye-sensitized solar cells (p-DSSCs) have attracted increasing levels of interest. The potential of three Keggin-type transition metal-substituted polyoxometalates, TBA8 Na2 [SiW9 O37 {Co(H2 O)3 }]⋅ 11 H2 O (SiW9 Co3 ), TBA4 [(SiO4 )W10 MnIII2 O36 H6 ]⋅1.5 CH3 CN⋅ 2 H2 O (SiW10 MnIII2 ), and TBA3.5 H5.5 [(SiO4 )W10 MnIII/IV2 O36 ]⋅ 10 H2 O⋅0.5 CH3 CN (SiW10 MnIII/IV2 ) has been explored as pure inorganic dye photosensitizers for p-DSSCs (TBA=(n-C4 H9 )4 N+ ). The three dyes show overall conversion efficiencies of 0.038, 0.029, and 0.027 %, respectively, all of which are higher than that of coumarin 343 (0.017 %). These polyoxometalates are the first three pure inorganic dyes reported for use with p-DSSCs and therefore demonstrate a new strategy for designing efficient dyes, especially pure inorganic dyes. Moreover, they broaden the range of applications for polyoxometalates.