Elucidating the Origin of Plasmon-Generated Hot Holes in Water Oxidation

Abstract

Plasmon-generated hot electrons in metal/oxide heterostructures have been used extensively for driving photochemistry. However, little is known about the origin of plasmon-generated hot holes in promoting photochemical reactions. Herein, we discover that, during the nonradiative plasmon decay, the interband excitation rather than the intraband excitation generates energetic hot holes that enable to drive the water oxidation at the Au/TiO 2 interface. Distinct from lukewarm holes via the intraband excitation that only remain on Au, hot holes from the interband excitation are found to be transferred from Au into TiO 2 and stabilized by surface oxygen atoms on TiO 2 , making them available to oxidize adsorbed water molecules. Taken together, our studies provide spectroscopic evidence to clarify the photophysical process for exciting plasmon-generated hot holes, unravel their atomic-level accumulation sites to maintain the strong oxidizing power in metal/oxide heterostructures, and affirm their crucial functions in governing photocatalytic oxidation reactions.

Ultrafast Dynamics of Nonthermal Carriers Following Plasmonic and Interband Photoexcitation of 2D Arrays of Gold Nanoparticles

“…The delayed A-M decay of interband excitation is quite insensitive to the specific morphology of the nanostructure under study and will be observed on a wide range of gold plasmonic systems. Therefore, the above discussion is relevant to the possible use of photogenerated hot d -holes in many gold plasmonic nanostructures for photocatalysis which has been proposed by a number of recent works: − it is clear that the efficient use of d -holes requires an extremely rapid extraction of those carriers to the photocatalytic site as the extraction must compete with the ultrafast A-M process (as opposed to the possibly slower dynamics of electron thermalization). Furthermore, our results may be of importance for the understanding of whether or not and why interband excitation is more efficient than plasmonic excitation for photocatalytic purposes ,,, or indeed heating, , as suggested by recent publications.…”

“…Direct interband excitation indeed generates large densities of highly energetic vacancies in the d -band, ,, whereupon the hot-electron generation by hot-hole Auger–Meitner decay heavily affects the lifetime of the photoexcited carriers and the possibility to exploit them for applications requiring high-energy photons. This is a critical aspect when exploiting hot-hole systems for catalytic purposes, − as their extraction from metallic NPs has to compete with the ultrashort lifetimes of the Auger–Meitner process.…”

Boosting photoelectrochemical water oxidation by sandwiching gold nanoparticles between BiVO4 and NiFeOOH

“…Therefore, the holes generated by the interband transition are more favorable to driving the H 2 O oxidation. 28,45–48…”

Probing local charge transfer processes of Pt–Au heterodimers in plasmon-enhanced electrochemistry by CO stripping techniques

“…Furthermore, directly probing the local charge transfer processes of heterostructures at the nanoscale is of vital importance for the elucidation of their catalytic mechanisms. Previously, several analytical methods using transient absorption (TA), 16 in situ electron paramagnetic resonance (EPR), 17 photoluminescence (PL), 18 surface-enhanced Raman spectroscopy (SERS), 19 and Kelvin probe force microscopy (KPFM) 20 techniques have been utilized to characterize the plasmonic processes. However, most of these analytical methods still face challenges in probing the plasmon-enhanced electrocatalytic reactions in situ or at the nanoscale, and their implementation is complicated and time-consuming.…”