Plasmon-Enhanced Photocatalytic Activity of Iron Oxide on Gold Nanopillars

Abstract

Photocatalytic water splitting represents a promising way to produce renewable hydrogen fuel from solar energy. Ultrathin semiconductor electrodes for water splitting are of particular interest because the optical absorption occurs in the region where photogenerated charge carriers can effectively contribute to the chemical reactions on the surface. It is therefore important to manipulate and concentrate the incident light so that more photons can be absorbed within the thin film. Here we show an enhanced photocurrent in a thin-film iron oxide photoanode coated on arrays of Au nanopillars. The enhancement can be attributed primarily to the increased optical absorption originating from both surface plasmon resonances and photonic-mode light trapping in the nanostructured topography. The resonances can be tuned to a desirable wavelength by varying the thickness of the iron oxide layer. A net enhancement as high as 50% was observed over the solar spectrum.

Research Update: Strategies for efficient photoelectrochemical water splitting using metal oxide photoanodes

“…109 of Au nanopillars. 108 The photoanodes exhibited a net photocurrent enhancement as high as 50% over the solar spectrum at 1.5 V (vs. RHE) attributed primarily to the optical absorption increase originating from both SPR and photonic-mode light trapping in the nanostructured topography.…”

“…Therefore, the charge carriers generated in only a very thin layer (a few nanometers without bias and tens of nanometers with bias) near the interface with the electrolyte can contribute effectively to the water oxidation reactions on the surface of the α-Fe 2 O 3 electrode. 108 The photocurrent enhancement spectra of Au/α-Fe 2 O 3 were demonstrated by concentrating light near the α-Fe 2 O 3 /electrolyte interface to generate more photogenerated carriers (i.e., PRET and scattering effects) that can reach the interface and participate in water oxidation reactions (Figure 4(a)). 109 of Au nanopillars.…”

Enhanced Water Splitting on Thin-film Hematite Photoanodes Functionalized with Lithographically Fabricated Au Nanoparticles

“…[14][15][16] In previous work, an enhancement in photocurrent in hematite functionalized with Au nanostructures was found in the wavelength region where such nanostructures support (localized) surface plasmon resonances, or (L)SPR. The enhanced electric fields around the nanostructures and the increased light absorption in Fe 2 O 3 due to scattering by the Au were accounted for the observed changes in photocurrent.…”

Methods of photoelectrode characterization with high spatial and temporal resolution

“…144 Plasmonic nanostructures have been used in a number of studies to enhance the optical absorption close to the electrochemical interface and thus improve PEC efficiency, particularly at longer wavelengths that typically have low inherent absorption of the semiconductor photoelectrode. [145][146][147] Characterizing such hybrid photoelectrodes with Raman spectroscopy is an excellent opportunity to elucidate structure-property relationships in these PEC systems.…”