Abstract
We create ordered arrays of shape-selective gold-titania composite nanomaterials at the mesoscale (100 µm to 5 mm) by a combination of both bottom-up and top-down approaches for exquisite control of the size, shape, and arrangement of nanomaterials. Lithographic techniques along with wet chemical synthetic methods were combined to create these composite nanomaterials. The photocatalytic activity of these TiO2, TiO2-Au and SiO2-TiO2-Au nano-composite mesoscale materials was monitored by the photodegradation of a model analyte, methyl orange, under UV and visible (Vis) illumination. Bare TiO2- and SiO2-TiO2-coated pillar arrays showed significant activity toward methyl orange in UV light with degradation rates on the order of 10−4–10−3 min−1. The photocatalytic activity of these arrays was also found to depend on the nanoparticle shape, in which particles with more edges and corners were found to be more reactive than spherical particles (i.e., the photocatalytic activity decreased as follows: diamonds > squares > triangles > spheres). SiO2-TiO2-Au nano-composite pillar arrays were tested in both UV and Vis light and showed increased activity in Vis light but decreased activity in UV light as compared to the bare semiconductor arrays. Additionally, the Au nanorod-functionalized nanoarrays exhibit a strong shape-dependence in their photocatalytic activity toward methyl orange degradation in Vis light.
Highlights
A large number of studies have been dedicated to the development of sophisticated, bottom-up and top-down approaches to produce unique nanomaterials and nanoarchitectures with tailored properties and functionalities [1,2]
We investigate their photocatalytic activity toward degradation of the model analyte, methyl orange, under UV and visible illumination
Counterparts, likely due to the presence of more edges and corners in the triangle array, which tends to Electrons and holes are generated when an UV-active material is illuminated by photons with energy be more reactive, as discussed in the Introduction
Summary
A large number of studies have been dedicated to the development of sophisticated, bottom-up and top-down approaches to produce unique nanomaterials and nanoarchitectures with tailored properties and functionalities [1,2]. This is due to their promising applications for molecular scale electronics [3]. Nanomaterials can spontaneously or deliberately assemble into larger structures and patterns through a myriad of molecular interactions, including ionic, covalent, hydrogen and coordination bonds or weaker interactions—van der Waals, π–π and hydrophobic, capillary, magnetic, electrical and optical forces. Upon UV illumination, the generated surface electrons react with the molecular oxygen (O2)
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