Positioning the Water Oxidation Reaction Sites in Plasmonic Photocatalysts

Abstract

Plasmonic photocatalysis, stemming from the effective light absorbance and confinement of surface plasmons, provides a pathway to enhance solar energy conversion. Although the plasmonic hot electrons in water reduction have been extensively studied, exactly how the plasmonic hot holes participate in the water splitting reaction has not yet been well understood. In particular, where the plasmonic hot holes participate in water oxidation is still illusive. Herein, taking Au/TiO as a plasmonic photocatalyst prototype, we investigated the plasmonic hot holes involved in water oxidation. The reaction sites are positioned by photodeposition together with element mapping by electron microscopy, while the distribution of holes is probed by surface photovoltage imaging with Kelvin probe force microscopy. We demonstrated that the plasmonic holes are mainly concentrated near the gold-semiconductor interface, which is further identified as the reaction site for plasmonic water oxidation. Density functional theory also corroborates these findings by revealing the promotion role of interfacial structure (Ti-O-Au) for oxygen evolution. Furthermore, the interfacial effect on plasmonic water oxidation is validated by other Au-semiconductor photocatalytic systems (Au/SrTiO, Au/BaTiO, etc.).

Ultrathin, Porous and Oxygen Vacancies‐Enriched Ag/WO3−x Heterostructures for Electrocatalytic Hydrogen Evolution

“…The existed vacancies can further cause the transformation of crystal to amorphous, and simultaneously spiral lattices as a new type of crystallography is formed owing to the reassembly of W‐O molecular clusters as well as the principle of energy minimization . Furthermore, the occurrence of more than one nucleation centres will lead to the separation of the whole nanosheets, suggesting more active edge sites are exposed. The dynamic light scattering (DLS) patterns shown in Figure c,d illustrate that the size of the as‐prepared WO 3− x nanosheets is smaller than that of the exfoliated WS 2 nanosheets.…”

“…It should be noted that the WO 3− x nanosheets are originated from the fully exfoliated WS 2 nanosheets, which are very unstable and easily oxidized . The existed vacancies can further cause the transformation of crystal to amorphous, and simultaneously spiral lattices as a new type of crystallography is formed owing to the reassembly of W‐O molecular clusters as well as the principle of energy minimization . Furthermore, the occurrence of more than one nucleation centres will lead to the separation of the whole nanosheets, suggesting more active edge sites are exposed.…”

Plasmonic Heterostructure TiO2‐MCs/WO3−x‐NWs with Continuous Photoelectron Injection Boosting Hot Electron for Methane Generation

“…Plasmonic photocatalyst coupling noble metal nanoparticle (NPs) and semiconductors have been applied in various fields including water splitting, environmental treatment, and artificial photosynthesis . Surface plasmon resonance (SPR) is unique optical property which occurs on rare noble metals (Au, Ag, and Cu) under light irradiation; however, the low‐reserve and high‐cost noble metals restrict their practical utilization in plasmonic photocatalysis.…”

Visible‐Light‐Driven Plasmonic Photocatalysis Enhanced by Charge Accumulation

“…PICS has been applied to many different visible‐light‐driven photocatalytic reactions including oxidation of organic species such as alcohols, oxygen and hydrogen evolution from water, and even water splitting . Most of the PICS systems are based on plasmonic metal nanoparticles coupled with n‐type semiconductor (n‐M system) .…”

“…Recently, plasmoninduced charge separation (PICS), [2] which involves uphill charge transfer from a resonant plasmonic nanoparticle to a semiconductor in direct contact through external photoelectric effect or direct interfacial charge transfer, has drawn considerable attention because it allows plasmonics to be used for many different applications. [3] PICS has been applied to many different visible-light-driven photocatalytic reactions including oxidation of organic species such as alcohols, [2,[4][5][6] oxygen and hydrogen evolution from water, [7][8][9][10][11][12][13] and even water splitting. [14,15] Most of the PICS systems are based on plasmonic metal nanoparticles coupled with n-type semiconductor (n-M system).…”