Interfacial Structure-Modulated Plasmon-Induced Water Oxidation on Strontium Titanate

Abstract

Plasmon-induced carrier transfer at metallic nanoparticle/semiconductor heterojunctions has received great attention because of its tremendous potential in applications, such as photocatalysis and photoelectric and energy conversion. The interfacial structure of the heterojunction is known to play an important role in charge transfer as well as the subsequent chemical reactions. Here, we studied the Au nanoparticle (Au-NP)-loaded (100)-, (110)-, and (111)-oriented single-crystalline strontium titanate (STO) as a model to investigate the effects of interfacial structure on the plasmon-induced charge separation between the metallic nanoparticles and semiconductors. Via photoelectrochemical characterizations, we found that the efficiency of the plasmon-induced water oxidation reaction on STO(100) is more than 1.4 times higher than that on the other two orientation facets. This enhancement was demonstrated to stem from the high oxidation ability of plasmon-induced holes captured in the surface states. Furthermore, the molecular processes of water oxidation were investigated by monitoring the surface oxidation status of Au-NP/STO as intermediates of plasmon-induced water oxidation using in situ electrochemical surface-enhanced Raman spectroscopy. The onset potential of Au–O vibrations on Au-NP/STO(100) was determined to be 0.4 V more negative than that of Au-NP/STO(110), further confirming the higher oxidation ability of the plasmon-induced holes. Our observation provides an opportunity to efficiently modulate plasmon-excited hot-carrier reaction processes for photochemical applications through interfacial engineering.

Investigation of Enhanced Water Oxidation under Plasmon–Nanocavity Strong Coupling Using In Situ Electrochemical Surface-Enhanced Raman Spectroscopy

“…The electrolyte used here was a 0.1 mol/L NaF solution, which had been bubbled with nitrogen gas for 1 h to remove the dissolved oxygen before tests. NaF did not participate in the chemical reactions; thus, the only electron donor during the photoelectrochemical reaction in this system was water. ,, EC-SERS measurements were performed under a series of electrochemical potentials in the range of −0.2 and 0.9 V vs Pt under an excitation laser of λ ex = 785 nm. Before performing the EC-SERS measurements, the Ag and its oxide layer on the surface of the Au–Ag alloy NPs were removed by an anodic oxidation reaction under an applied potential of 0.5 V vs Ag/AgCl and 620 nm light irradiation for 2 h to eliminate any effect by Ag oxidation reaction on the water oxidation, as the method reported in our previous study .…”

“…EC-SERS is an effective way to elucidate the reaction pathway because it allows for in situ observation of electrochemical reaction intermediates at the electrode surface. − Using this method, intermediates of plasmon-induced water oxidation occurring on Au ND/TiO 2 photoanodes, in which the Au NDs are supported on a TiO 2 single crystal, have been investigated . These authors found that the AuOOH intermediate, the most highly oxidized intermediate species in the oxygen evolution reaction, is the only water oxidation intermediate of plasmon-assisted water oxidation in the neutral electrolyte; the generation of this highly oxidized intermediate species promotes the water oxidation to occur at an overpotential lower than that of typical electrochemical oxidation of water. , In this study, using EC-SERS, we studied the intermediates of the water oxidation reaction on the Au–Ag alloy NPs/TiO 2 /Au film (AATA) photoanode to explore the water oxidation enhancement mechanism under strong coupling conditions.…”

Rational design for gold nanoparticle-based plasmonic catalysts and electrodes for water oxidation towards artificial photosynthesis

“…Misawa's group has recently reported the effect of the surface orientation of SrTiO 3 single crystals (Au/(klm)SrTiO 3 ) on the plasmonic activity of Au(d Au ≈ 11 nm)/SrTiO 3 for OER. 58 Three-electrode PEC cells were built with the structure of working electrode 0.1 M KClO 4 |SCE (reference electrode)|Pt (counter electrode) using Au/(klm)SrTiO 3 as the working electrode (Fig. 11a).…”

Plasmon-induced electron injection into the large negative potential conduction band of Ga2O3for coupling with water oxidation

“…Recently, we successfully demonstrated that plasmon-induced water oxidation is highly sensitive to the surface states of the crystal facets of SrTiO 3 , and Au nanoparticle-loaded SrTiO 3 that is terminated with a TiO 2 layer shows a high oxidation ability. 20 In addition, Murakoshi et al also reported that TiO 2 was beneficial for water oxidation by studying the intermediate species during plasmon-induced oxygen evolution. 21 Therefore, improving the hole-trapping ability at the interface by the surface states of TiO 2 is an efficient way to enhance the water oxidation efficiency.…”