F. Liebig, R. M. Sarhan, M. Sander, W. Koopman, R. Schuetz, M. Bargheer, J. Koetz
Deposition of Gold Nanotriangles in Large Scale Close-Packed Monolayers for X-ray-Based Temperature Calibration and SERS Monitoring of Plasmon-Driven Catalytic Reactions
ACS Appl. Mater. Interfaces 2017, 9, 20247-20253
DOI: 10.1021/acsami.7b07231
Anisotropic plasmonic particles such as gold nanotriangles have extraordinary structural, optical, and physicochemical properties. For many applications in different fields, it is essential to prepare them in a chemically and physically stable, structurally well-defined manner, e.g., as large and uniform coverage on a substrate. We present a direct method for the large scale close-packed monolayer formation of edge-to-edge ordered, ultrathin crystalline gold nanotriangles on Si wafers or quartz glass via the transfer of these asymmetric particles to the air-liquid interface after adding ethanol - toluene mixtures without any subsequent surface functionalization. X-ray diffraction monitoring of the close-packed, large area monolayer with a mosaicity of less than 0.1° allows for calibrating the temperature of the particles during continuous laser heating. This is important for characterizing the microscopic temperature of the metal particles in the plasmon-driven dimerization process of 4- nitrothiophenol (4-NTP) into 4,4´-dimercaptoazobenzene (DMAB), monitored in real time by surface-enhanced Raman scattering (SERS). The gold nanotriangles can act as a source of hot electrons and initiate the dimerization process.
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