Plasmon-induced photoelectrochemistry at metal nanoparticles supported on nanoporous TiO2

Abstract

Nanoporous TiO(2) films loaded with gold and silver nanoparticles exhibit negative potential changes and anodic currents in response to visible light irradiation, so that the films would potentially be applicable to inexpensive photovoltaic cells, photocatalysts and simple plasmon sensors.

Molecular interfaces for plasmonic hot electron photovoltaics

“…In those approaches, metal nanostructures act as passive elements that introduce parasitic ohmic losses. However, it was shown recently that, a direct photoelectric energy conversion from light absorbed in the metal is within reach, by properly harnessing the hot-electron population derived from the Landau damping of these plasmonic resonances, [9][10][11][12][13][14][15][16][17][18][19][20] This opens the exciting possibility of a new sensing and light harvesting technology, whose spectral response can be tailored by properly modifying the topology of a metal nanostructure, and is beyond the band-to-band absorption paradigm in traditional semiconductors. 11 Theoretical predictions set maximum photovoltaic power conversion efficiencies that range from 10% to 22% depending on the applied model for hot electron population and emission.…”

Plasmonic Rectenna for Efficient Conversion of Light into Electricity

“…However, in these recent metal-TiO2 Schottky diode structures [37][38][39][40][41][42][43][44][45][46][47], it would appear that the barrier layer was actually quite a bit thicker than 10 nm (probably in excess of 1 um) and further details was unable to be found in these papers. Semi-classical models did not account for non-equilibrium energy distributions of carriers, or do so through a localize lattice temperature.…”

“…First, Tatsuma et al [37,38,45] and other workers [42,46] proposed that the photoexcited electrons in the metal nanoparticles transferred from the metal particle to the TiO2 conduction band since the photoresponse of these metal-TiO2 diode structures was consistent with the absorption spectra of Au or Ag nanoparticles. Second, Kamat et al [43,44] and Li et al [47] have suggested that the noble metal nanoparticles act as electron sinks or traps in the metal-TiO2 diode structures to accumulate the photogenerated electrons, which could minimize charge recombination in the semiconductor films.…”

“…The diode of choice for the optical frequency rectifier is a metal-insulator-metal (MIM) diode, it is previously considered that these diodes are the fastest available diodes for detection in the optical region. However, plasmon absorption in metal-TiO2 Schottky diode structures have recently been applied to photovoltaic devices [37,38] and photocatalysts [39,40] in the UV-visible and wavelength range, and an enhanced light harvesting property and a visible-light-induced charge separation are obtained for the benefit of the metal nanoparticles. Furthermore, different explanations have been presented about the role of metal nanoparticles in the observed improvement in light conversion efficiency.…”

“…Furthermore, different explanations have been presented about the role of metal nanoparticles in the observed improvement in light conversion efficiency. These include (i) metal nanoparticles increased absorption due to surface plasmons and light trapping effects [41], (ii) metal nanoparticles functioned as electron donor promoting electron transfer from metal to semiconductor [37,38,42] and (iii) metal nanoparticles served as electron trapping media that can minimize the surface charge recombination in semiconductor [43 , 44].…”