Enhanced Hydrogen Production from DNA-Assembled Z-Scheme TiO2-CdS Photocatalyst Systems

摘要

A wide range of inorganic nanostructures have been used as photocatalysts for generating H-2. To increase activity, Z-scheme photocatalytic systems have been implemented that use multiple types of photoactive materials and electron mediators. Optimal catalysis has previously been obtained by interfacing different materials through aggregation or epitaxial nucleation, all of which lowers the accessible active surface area. DNA has now been used as a structure-directing agent to organize TiO2 and CdS nanocrystals. A significant increase in H-2 production compared to CdS or TiO2 alone was thus observed directly in solution with no sacrificial donors or applied bias. The inclusion of benzoquinone (BQ) equidistant between the TiO2 and CdS through DNA assembly further increased H-2 production. While the use of a second quinone in conjunction with BQ showed no more improvement, its location within the Z-scheme was found to strongly influence catalysis.