Chemically assembled heterojunctions of SnO sub(2) nanorods with TiO sub(2) nanoparticles via"click" chemistry

• Published in: Journal of materials chemistry Vol. 22; no. 23; pp. 11561 - 11567
• Main Authors: Shah, Sohil, Benson, Michelle C, Bishop, Lee M, Huhn, Alex M, Ruther, Rose E, Yeager, Joseph C, Tan, Yizheng, Louis, Kacie M, Hamers, Robert J
• Format: Journal Article
• Language: English
• Published: 01.05.2012
• Subjects: Nanocomposites; Nanomaterials; Nanoparticles; Nanorods; Nanostructure; Tin dioxide; Tin oxides; Titanium dioxide
• ISSN: 0959-9428; 1364-5501
• DOI: 10.1039/c2jm31227a

SnO sub(2) is a promising material for photovoltaic and photocatalytic applications because it exhibits high electron mobility, its conduction band lies at a convenient energy to act as an electron acceptor, and it can be easily grown in a variety of different nanostructures including nanoparticles, nanorods, and nanosheets. However, strategies for surface functionalization of SnO sub(2) are much less well developed than alternative oxides. Here, we demonstrate the growth and subsequent chemical functionalization of SnO sub(2) nanorods to enable the chemically directed assembly of SnO sub(2) nanorod-TiO sub(2) nanoparticle heterojunctions, and we characterize the charge-transfer properties using time-resolved surface photovoltage measurements. Vertically aligned SnO sub(2) nanorods were grown viaa high-pressure chemical synthesis method. The SnO sub(2) nanorods were square in cross-section, exposing sidewalls consisting of {110}-type crystal planes. Functionalization viaphotochemical grafting with butenol yielded nanorods terminated with a high density of -OH groups that were converted to azide groups. The azide groups were linked with alkyne-modified TiO sub(2) nanoparticles viathe Cu(i)-catalyzed Azide-Alkyne Cycloaddition (CuAAC) reaction, a form of "click" chemistry, thereby covalently grafting the TiO sub(2) nanoparticles to the SnO sub(2) nanorods. Time-resolved surface photovoltage measurements of the resulting adducts showed that the covalent bonding of TiO sub(2) nanoparticles to the SnO sub(2) nanorods enhances the interfacial charge transfer compared to the unmodified SnO sub(2) nanorods, leading to an increased accumulation of holes at the surface.