In recent years a wide range of inorganic nanostructures have been used as photocatalysts for generating H2. To increase activity, “Z-scheme” photocatalytic systems in conjunction with redox active molecules have been implemented to overcome issues such as recombination events, photostability and aid in electron transfer to fully reduce water to hydrogen. To date, optimal catalysis has been obtained by interfacing different materials through aggregation or epitaxial nucleation of one material on top of another, all of which lowers the accessible active surface area. Mixing electron mediators with photocatalysts in solution also requires high concentrations of the Z-scheme components, which can lead to competing redox reactions. In this work, we demonstrate the utilization of DNA as a structure-directing agent to spatially organize well-defined TiO2 and Pt decorated CdS nanocrystals. By doing so, a significant increase in H2 production was observed upon photoillumination as compared to the CdS or TiO2 alone. The use of DNA also allowed positioning of single or series of electron mediators site-specifically in between the two catalysts. From this, we were able to see that the inclusion of a single mediator benzoquinone (BQ) equidistant between the TiO2 and Pt@CdS through DNA assembly led to a further increase in H2 production by 3.4 fold compared to the Pt decorated CdS alone. These BQ concentration were also ~104 fold less than typical concentrations in other Z-scheme studies. The use of a second quinone (2-dimethylamino-3-chlor-1,4-naphthoquinone) in conjunction with BQ however showed minimal increase, but this was also strongly dependent on the location of quinones. This talk will also demonstrate current research efforts toward extending the effort toward reducing carbon dioxide to relevant fuels such as methanol from water and solar energy.

Increased hydrogen production from DNA-assembled TiO2-CdS photocatalytic material

251st National Meeting (2016)

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