Volume 214, 2019

Hot electron-driven photocatalysis and transient absorption spectroscopy in plasmon resonant grating structures

Abstract

Plasmon resonant grating structures provide an effective platform for distinguishing between the effects of plasmon resonant excitation and bulk metal absorption via interband transitions. By simply rotating the polarization of the incident light, we can switch between resonant excitation and non-resonant excitation, while keeping all other parameters of the measurement constant. With light polarized perpendicular to the lines in the grating (i.e., TE-polarization), the photocatalytic reaction rate (i.e., photocurrent) is measured as the angle of the incident laser light is tuned through the resonance with the grating. Here, hot holes photoexcited in the metal are used to drive the oxygen evolution reaction (OER), producing a measurable photocurrent. Using TE-polarized light, we observe sharp peaks in the photocurrent and sharp dips in the photoreflectance at approximately 9° from normal incidence, which corresponds to the conditions under which there is good wavevector matching between the incident light and the lines in the grating. With light polarized parallel to the grating (i.e., TM), we excite the grating structure non-resonantly and there is no angular dependence in the photocurrent or photoreflectance. In order to quantify the lifetime of these hot carriers, we performed transient absorption spectroscopy of these plasmon resonant grating structures. Here, we observe one feature in the spectra corresponding to interband transitions and another feature associated with the plasmon resonant mode in the grating. Both features decay over a time scale of 1–2 ps. The spectral responses of grating structures fabricated with Ag, Al, and Cu are also presented.

Graphical abstract: Hot electron-driven photocatalysis and transient absorption spectroscopy in plasmon resonant grating structures

Associated articles

Article information

Article type
Paper
Submitted
01 十月 2018
Accepted
12 十二月 2018
First published
12 十二月 2018

Faraday Discuss., 2019,214, 325-339

Author version available

Hot electron-driven photocatalysis and transient absorption spectroscopy in plasmon resonant grating structures

Y. Wang, L. Shen, Y. Wang, B. Hou, George N. Gibson, N. Poudel, J. Chen, H. Shi, E. Guignon, N. C. Cady, W. D. Page, A. Pilar, J. Dawlaty and S. B. Cronin, Faraday Discuss., 2019, 214, 325 DOI: 10.1039/C8FD00141C

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