Importance of Plasmonic Heating on Visible Light Driven Photocatalysis of Gold Nanoparticle Decorated Zinc Oxide Nanorods

Abstract

Herein we explore the role of localized plasmonic heat generated by resonantly excited gold (Au) NPs on visible light driven photocatalysis process. Au NPs are deposited on the surface of vertically aligned zinc oxide nanorods (ZnO NRs). The localized heat generated by Au NPs under 532 nm continuous laser excitation (SPR excitation) was experimentally probed using Raman spectroscopy by following the phonon modes of ZnO. Under the resonant excitation the temperature at the surface of the Au-ZnO NRs reaches up to about 300 °C, resulting in almost 6 times higher apparent quantum yield (AQY) for photocatalytic degradation of methylene blue (MB) compared to the bare ZnO NRs. Under solar light irradiation the Au-ZnO NRs demonstrated visible light photocatalytic activity twice that of what was achieved with bare ZnO NRs, while significantly reduced the activation energy required for the photocatalytic reactions allowing the reactions to occur at a faster rate.

Mechanistic Studies of Plasmon Chemistry on Metal Catalysts

“…Furthermore,arecent study suggested hot-hole transfer as areaction mechanism. [67] This temperature is sufficiently high to overcome the potential barrier, and thus,c hemical reactions are able to proceed. [66] It was reported that, under the excitation of the LSP of Au NPs deposited on zinc oxide nanorods (NRs), the temperature at the surface of the system reached up to approximately 300 8 8C.…”

Mechanistic Studies of Plasmon Chemistry on Metal Catalysts

“…Finally, the energy of the LSP is dissipated as heat by thermal conduction, and is used to induce thermal reactions of the molecules (Figure f) . It was reported that, under the excitation of the LSP of Au NPs deposited on zinc oxide nanorods (NRs), the temperature at the surface of the system reached up to approximately 300 °C . This temperature is sufficiently high to overcome the potential barrier, and thus, chemical reactions are able to proceed.…”

Light‐Activated Hydrogen Storage in Mg, LiH and NaAlH4

“…Theoretical calculations have predicted a maximum surface heat flux of 150 W m −2 for Au nanospheres ( d =110 nm) with an associated equilibrium temperature of 252 °C . Experimentally, the temperature was detected to increase up to 300 °C for ZnO nanorods with Au nanoparticles ( d =7–23 nm) deposited on the surface under laser excitation (532 nm, 250 W m −2 ) . The heat generated can then be transferred to the surrounding medium by elevation of the local temperature.…”