Application Of Polyoxometalates In Semiconductor Photocatalytic H₂ Evolution

Polyoxometalates ?POMs?, a class of molecular metal-oxo cluster compounds exhibit remarkably rich redox and photochemical properties. However, the polyoxoanions do not absorb significantly in the visible spectrum. To induce visible-light sensitization, strategies have normally involved the incorporation of dye cations, increase the catalytic activity.CdS is a promising semiconductor that applied to photocatalyst H2 evolution. But its catalytic activity is limited because of the recombination of photo-generated carriers on its surface and the phenomenon of corrosion. So we use co-catalysts that accelerated transfer electrons, suppress recombination of electrons and holds.In this work, we report the synthesis of hybrid POM-aminoaobenzene dye compounds, (C₁₂H₁₂N₃)₃PW₁₂O40 · 2CH₃CN ?1?, (C₁₂H₁₂N₃)₃PMo₁₂O₄₀·4CH₃CN ?2? under conventional aqueous. Compounds show strong hydrogen bonds between the cations and the polyoxoanions. The absorption edge of compounds are largely red-shifted compared to the pure polyoxoanions, due to the introduction of the dye cations. Photocatalytic studies indicated that compound 1 exhibits effective photocatalytic H2 evolution activity under visible-light.The MoS₂/grapheme-CdS ?M/G-CdS? composite photocatalyst was synthesized using a facile one-step hydrothermal process, the composite photocatalyst were evaluated under visible light irradiation ??>400 nm? with (SiW₁₁)₂Ce as homogeneous co-catalyst, lactic acid as a sacrificial reagent, research the H₂ evolution rate. The H2 evolution rate achieved the highest amount of 1.02mmol/h that the amount of (SiW₁₁)₂Ce is 1% and lactic acid is 30%.The SiW₁₂@UiO-67/M/G-CdS composite photocatalyst was synthesized using a facile two-step hydrothermal process, the as-prepared SiW₁₂@UiO-67 was used as a supporting matrix to support the CdS nanoparticles,and M/G cocatalyst. The composite photocatalyst were evaluated under visible light irradiation ??>400 nm?, research the H2 evolution rate. The H2 evolution rate achieved the highest amount of 1.02mmol/h that the amount of SiW₁₂@UiO-67 is 30%, lactic acid is 30% and M/G is 5%.Incorporation of dye cations in Polyoxometalates and induce Polyoxometalates to CdS that can greatly increase the photocatalytic activity.It is proved that POMs will have excellent prospects of development in improving semiconductor photocatalytic H₂ production systems.