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Department of Chemistry College of Liberal Arts and Sciences


Electromagnetic Field Enhancement

Fabrication of Robust and Scalable SERS Substrates

Au/p-PANI/PDMS pyramid Surface enhanced Raman Scattering (SERS) substrate

The combination of soft lithography and wet chemical techniques has enabled the fabrication of chemically robust and mechanically flexible surface enhanced Raman scattering (SERS) substrates.

"SERS results obtained with 4-ABT as the Raman probe molecule. (a) comparison of SERS intensities obtained from the Au pyramid tips for the substrates fabricated via p-PANI reduction (blue) and e-beam evaporation (orange); (b) a large-area (55 × 55 μm2) Raman mapping result of the 1079 cm−1 band acquired from a single Au pyramid (white dash line) on the p-PANI/PDMS SERS substrate, demonstrating that the strongest Raman intensity originates from the pyramid tip. The scale bar is 10 μm; (c) SEM image of the Au/p-PANI/PDMS pyramid corresponding to Raman mapping area in (b)."
Wang, Y., et al. Nanoscale, 2014, 6, 7232-7236

The prepared flexible substrates exhibit significantly strong SERS signals to facilitate 4-aminobenzenethiol (4-ABT) detection, boasting large SERS enhancement factors of 10⁸ orders of magnitude. More importantly, the engineered “hot spots” are uniformly distributed in a large-scale area with consistent SERS enhancements. The top right images exhibit the typical SERS spectra and mapping results of 4-ABT molecules adsorbed on the designed substrate.

Plasmonic Photoelectrochemical Enhancement

Plasmonic photocathode comprised of Au@SiO2 (core@shell) nanoparticles embedded within a Cu2O nanowire network demonstrating that the near-field enhancement is the sole mechanism responsible for increased light absorption in the plasmonic photocathode.

The enhanced near-fields from plasmonic Au nanoparticles can be used to amplify the optical transition rate within a nearby semiconductor (Cu2O nanowire) and enhance the light-harvesting efficiency of photoelectrochemical cells.

Graph showing the incident photo conversion efficiency percentage (IPCE) vs. wavelength. The plasmonic material has a significantly higher value from 470 nm to 600 nm compared to the control.
Duchene, J., et al. Adv. Energy Mater. 2016, 6, 1501250

Incident photon-to-charge conversion efficiency (IPCE) of a control device (Cu2O-only, red) and plasmonic device (Cu2O/Au@SiO2, blue) showing enhanced photoelectrochemical performance from 500-600 nm in the plasmonic device as a result of the Au@SiO2 nanoparticles.