Photon-Induced Hot Electron Effect on the Catalytic Activity of Ceria-Supported Gold Nanoparticles

Abstract

The role of charge transfer at the metal−oxide interface is a long-standing issue in surface chemistry and heterogeneous catalysis. Previous studies have shown that the flow of hot electrons crossing metal−oxide interfaces correlates with catalytic activity. In this study, we employed ceria-supported gold nanoparticles to identify a correlation between the catalytic activity of CO oxidation and hot electrons generated via light irradiation. We tuned the size of the Au nanoparticles by changing the discharge voltages used in the arc plasma deposition process, thus allowing us to investigate the influence of Au nanoparticle size on changes in catalytic activity. CO oxidation over the Au/CeO X catalysts was carried out, and we found that the activity of the Au nanoparticles increased as the size of the nanoparticles decreased, which is associated with the cationic character of the Au nanoparticles, as demonstrated by X-ray photoelectron spectroscopy analysis. We also show that the activity of the Au nanoparticles decreases under light irradiation and that smaller nanoparticles show a higher change of turnover frequency compared with larger ones, presumably due to the mean free path of the hot electrons. From these results, we conclude that the cationic property of the gold species, induced by interaction with the CeO 2 support, and the flow of hot electrons generated on the interface during light irradiation are mainly responsible for the change in catalytic activity on the Au nanoparticles.

Highly efficient plasmon-mediated electron injection into cerium oxide from embedded silver nanoparticles

“…[8][9][10] In the class of semiconductor catalysts, cerium oxide CeO2 (the material studied here) is attracting a growing interest due to its efficiency in catalyzing redox reactions. [11][12][13][14] In CeO2 the presence of localized Ce 4f states between the O 2p valence band and the Ce 5d conduction band makes the material a very sensitive probe to identify charge transfer to/from neighboring metal atoms. 15 The occupation of 4f levels is in turn expected to modify the material properties, inducing a decrease of oxygen vacancy formation energy, and a change of the optical response.…”

Optical and electronic properties of silver nanoparticles embedded in cerium oxide

“…6 Methods to sensitize cerium oxide based materials to visible light include nanostructuration, [7][8][9] defect engineering, 10 doping 11,12 and the coupling with metallic nanoparticles (NPs), like for example Au or Ag. 9,11,[13][14][15] In the latter case visible light excites the socalled localized surface plasmon resonances (LSPR) within the NPs. The energy of such resonant excitations can be transferred to the neighboring oxide modifying its properties and its catalytic activity.…”

Wolkenstein’s Model of Size Effects in CO Oxidation by Gold Nanoparticles

“…conditions than traditional catalysts [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. CO oxidation is one of the important oxidation reactions catalyzed by gold NPs, where non-monotonic size effects were experimentally observed in the range of 1-5 nm [3][4][5][6][7][8][9][10][11][12].…”