Hot Electron Plasmon-Resonant Grating Structures for Enhanced Photochemistry: A Theoretical Study

• Main Authors: Indu Aravind, Yu Wang, Zhi Cai, Lang Shen, Bofan Zhao, Sisi Yang, Yi Wang, Jahan M. Dawlaty, George N. Gibson, Ernest Guignon, Nathaniel C. Cady, William D. Page, Arturo Pilar, Stephen B. Cronin
• Format: Article
• Language: English
• Published: MDPI AG 2021-01-01
• Series: Crystals
• Subjects: hot electrons; plasmon-enhanced hot electrons; gratings; surface plasmon resonance; photocatalysis; FDTD
• Online Access: https://www.mdpi.com/2073-4352/11/2/118

Metallic grating structures have been shown to provide an effective platform for generating hot electrons and driving electrochemical reactions. Here, we present a systematic theoretical study of the surface plasmon resonance in different corrugated metallic grating structures using computational electromagnetic tools (i.e., the finite difference time domain (FDTD) method). We identify the corrugation parameters that produce maximum resonant field enhancement at commonly used wavelengths for photocatalytic applications (633 nm and 785 nm) in different material systems, including Ag, Au, Cu, Al, and Pt. The absorption spectra of each grating structure have been fitted with the analytical equation obtained from Coupled Mode Theory. We then extracted the absorptive and radiative loss rates. The field enhancement can be maximized by matching the absorption and radiation losses via tuning the geometric parameters. We could improve the average field enhancement of 633 nm and 785 nm modes by a factor of 1.8X and 3.8X for Ag, 1.4X and 3.6X for Au, and 1.2X and 2.6X for Cu. The optimum structures are found to be shallower for Ag, Au, and Cu; deeper for Pt; and to almost remain the same for Al. The gratings become flat for all the metals for increasing the average field enhancement. Overall, Ag and Au were found to be the best in terms of overall field enhancement while Pt had the worst performance.