Synthesis of edge-site selectively deposited Au nanocrystals on TiO₂ nanosheets: An efficient heterogeneous catalyst with enhanced visible-light photoactivity

As a result of their particular electronic structure [nd¹⁰(n+1)s¹] and size sensitive tunable photoresponse properties, nanocrystals of Au on a transition metal oxide support are potential candidates for use in heterogeneous photocatalysis to improve their photocatalytic activities in visible light. In the present work, by taking advantage of well-defined anatase TiO₂ nanosheets with highly active (001) facets exposure as a support, we have successfully prepared randomly-deposited Au/TiO₂ nanosheets nanostructures. Furthermore, with the help of a precise position-controlled synthesis strategy, we have transformed these randomly-deposited Au/TiO₂ nanosheets into novel edge-site deposited Au/TiO₂ nanosheets with enhanced crystalline interface contact. A noticeable dependence on Au positioning on the surface of TiO₂ nanosheets for photocatalytic Rhodamine B degradation activity was identified. This remarkably enhanced photocatalytic activity of edge-site deposited Au/TiO₂ nanosheets can be attributed to the synergistic effect between the Au nanocrystals and its intimate interfacial contact with TiO₂ nanosheets having (001) facet exposure, which greatly improved the separation rate of the photogenerated carriers. Interestingly, from the photocurrent response measurements, it was found that the edge-site deposited Au/TiO₂ nanosheets showed significantly enhanced visible photocurrent response activity compared to the randomly-deposited Au/TiO₂ nanosheets. We believe that the proposed strategy, based on engineering the position of Au nanocrystals on TiO₂ nanosheets, will encourage further interest in the development of high-performance wide bandgap semiconductor photocatalysts under visible light.