Two‐Dimensional Arrays of Au Halfshells with Different Sizes for Plasmon‐Induced Charge Separation

Abstract

Plasmon‐induced charge separation (PICS) at plasmonic metal‐semiconductor interfaces has been used for photovoltaics, photocatalysis, and many other photofunctional materials and devices. In most of those cases, dispersed and disordered metal nanoparticle ensembles have been used. We prepared two‐dimensionally ordered and interconnected Au halfshell arrays on SiO2@TiO2 core‐shell nanosphere colloidal crystals and exploited them for PICS. The present system exhibits broad light absorption over the visible to near‐infrared (NIR) range, leading to wide photoelectrochemical responses. Here we report that this system is characterized not only by localized and propagating surface plasmons but also by light propagation through the colloidal crystals, which enhances plasmonic light harvesting. Effects of the SiO2 core size were examined, and the middle‐sized cores were found to be optimum for efficient PICS processes because of strong electric field at the photoelectrode.

Understanding Hot-Electron Generation and Plasmon Relaxation in Metal Nanocrystals: Quantum and Classical Mechanisms

“…One convenient way to see the structure of the many-body state of a plasmon is to compute the energy distribution of electrons. 28,29 Experimentally, this topic mainly concerns two types of applications: nanomaterials for enhanced photochemistry 1,2,[5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]30 and photodetectors. 3,4,[21][22][23][24][25][26][27] Current literature has a large number of theoretical publications on hot plasmonic electrons.…”

“…The generation of energetic (hot) electrons in plasmonic nanostructures is currently attracting a lot of attention. − The motivations for this research topic are both fundamental and applied. It is interesting to learn more about the complexity of the plasmon’s wave function in a nanocrystal (NC).…”

“…Such wave functions involve many interacting electrons. One convenient way to see the structure of the many-body state of a plasmon is to compute the energy distribution of electrons. , Experimentally, this topic mainly concerns two types of applications: nanomaterials for enhanced photochemistry ,,− , and photodetectors. ,,− …”

Hot Electrons in TiO2–Noble Metal Nano-Heterojunctions: Fundamental Science and Applications in Photocatalysis

“…Apart from the electronic structure of the metal nanoparticle, numerous other properties, including the loading amount and size [ 151 ], architecture of the noble metal nanoparticle [ 58 , 60 , 181 , 238 ], the amplitude of UV irradiation [ 151 ], the structural distribution of the noble metal nanoparticle forming the semiconductor heterojunction (composite plasmonic nanostructure systems where the plasmonic noble metal is embedded within the semiconductor nanostructure as opposed to decorating the nanostructure have resulted in greater performance efficiencies), all influence the mechanism of hot electron injection in noble metal nanoparticle–semiconductor heterojunctions [ 195 , 249 , 289 ].…”

“…Plasmonic noble metal nanostructures have electron densities that can couple with wavelengths of electromagnetic radiation (in the visible spectral range) that are far larger than the nanostructure itself due to the dielectric-metal interface between the particles and the surrounding medium; contrastingly, in pure metals, there is a maximum limit on the magnitude of wavelengths (work-function dependent) that can effectively couple with the material sizes involved [ 56 ]. Plasmonic noble metal nanospheres have commonly been utilized as hot electron photocatalysts although recently diverse nanostructures, such as nanocubes, nanorods, nanoshells, gap plasmon structures, etc., have also been investigated [ 57 , 58 , 59 , 60 ].…”