Limits...
Hot plasmonic electrons for generation of enhanced photocurrent in gold-TiO2 nanocomposites.

Brennan LJ, Purcell-Milton F, Salmeron AS, Zhang H, Govorov AO, Fedorov AV, Gun'ko YK - Nanoscale Res Lett (2015)

Bottom Line: The composite film demonstrates a significant increase in the short circuit current (I sc) compared to unmodified TiO2 when excited at or close to the plasmon resonance of the gold nanoparticles.Photo-electrochemical investigations revealed that the increase in photocurrent is attributed to the generation and separation of plasmonically generated hot electrons at the gold/TiO2 interface and also the inter-band generation of holes in gold nanoparticles by photons with λ < 520 nm.Theoretical modelling outputs perfectly match our results obtained from photo-physical studies of the processes leading to enhanced photocurrent.

View Article: PubMed Central - PubMed

Affiliation: School of Chemistry and CRANN Institute, Trinity College Dublin, Dublin 2, Ireland.

ABSTRACT
In this manuscript, for the first time, we report a combination of electrophoretic and sintering approaches for introducing gold nanoparticles into nanoporous TiO2 films to generate 'hot' electrons resulting in a strong enhancement of photocurrent. The Au-TiO2 nanocomposite material was prepared by the electrophoretic deposition of gold nanoparticles into a porous nanoparticulate titanium dioxide film, creating a photoactive electrode. The composite film demonstrates a significant increase in the short circuit current (I sc) compared to unmodified TiO2 when excited at or close to the plasmon resonance of the gold nanoparticles. Then, we employed a thermal ripening process as a method of increasing the I sc of these electrodes and also as a method of tuning the plasmon peak position, with a high degree of selectivity. Photo-electrochemical investigations revealed that the increase in photocurrent is attributed to the generation and separation of plasmonically generated hot electrons at the gold/TiO2 interface and also the inter-band generation of holes in gold nanoparticles by photons with λ < 520 nm. Theoretical modelling outputs perfectly match our results obtained from photo-physical studies of the processes leading to enhanced photocurrent.

No MeSH data available.


Related in: MedlinePlus

Band diagram of the Au-TiO2system and the optical and relaxation processes used in the photocurrent model. Blue and red dots represent photo-generated hot plasmonic electrons and holes, respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4385105&req=5

Fig8: Band diagram of the Au-TiO2system and the optical and relaxation processes used in the photocurrent model. Blue and red dots represent photo-generated hot plasmonic electrons and holes, respectively.

Mentions: A schematic band diagram of the Au-TiO2 system and the optical and relaxation processes involved in the photocurrent model are shown in Figure 8. The hot electron–hole pair can be excited in TiO2 (the left-hand side) or in Au nanoparticles (the right-hand side of the Figure 8). In the case of Au nanoparticles, the hole can be excited in the sp-bands or in the d-band. The excitation of hole in the d-band is especially prominent since such holes have a large density of states. Regarding the hot electrons generated in the sp-band of Au NP, these electrons are generated from both sp- and d-bands (two vertical blue arrows in Figure 8). When an electron is excited from the sp-band via the intra-band transition, its energy is high and this electron can be injected into TiO2. When an electron is excited from the deep d-band, its energy is small and this electron remains trapped in the Au NP and cannot be used for the injection. The vertical red arrows depict the optical excitation processes whereas the horizontal black arrows show the transport processes such as injection from a NP, trapping in a NP and electron transfer from the Co mediator.Figure 8


Hot plasmonic electrons for generation of enhanced photocurrent in gold-TiO2 nanocomposites.

Brennan LJ, Purcell-Milton F, Salmeron AS, Zhang H, Govorov AO, Fedorov AV, Gun'ko YK - Nanoscale Res Lett (2015)

Band diagram of the Au-TiO2system and the optical and relaxation processes used in the photocurrent model. Blue and red dots represent photo-generated hot plasmonic electrons and holes, respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4385105&req=5

Fig8: Band diagram of the Au-TiO2system and the optical and relaxation processes used in the photocurrent model. Blue and red dots represent photo-generated hot plasmonic electrons and holes, respectively.
Mentions: A schematic band diagram of the Au-TiO2 system and the optical and relaxation processes involved in the photocurrent model are shown in Figure 8. The hot electron–hole pair can be excited in TiO2 (the left-hand side) or in Au nanoparticles (the right-hand side of the Figure 8). In the case of Au nanoparticles, the hole can be excited in the sp-bands or in the d-band. The excitation of hole in the d-band is especially prominent since such holes have a large density of states. Regarding the hot electrons generated in the sp-band of Au NP, these electrons are generated from both sp- and d-bands (two vertical blue arrows in Figure 8). When an electron is excited from the sp-band via the intra-band transition, its energy is high and this electron can be injected into TiO2. When an electron is excited from the deep d-band, its energy is small and this electron remains trapped in the Au NP and cannot be used for the injection. The vertical red arrows depict the optical excitation processes whereas the horizontal black arrows show the transport processes such as injection from a NP, trapping in a NP and electron transfer from the Co mediator.Figure 8

Bottom Line: The composite film demonstrates a significant increase in the short circuit current (I sc) compared to unmodified TiO2 when excited at or close to the plasmon resonance of the gold nanoparticles.Photo-electrochemical investigations revealed that the increase in photocurrent is attributed to the generation and separation of plasmonically generated hot electrons at the gold/TiO2 interface and also the inter-band generation of holes in gold nanoparticles by photons with λ < 520 nm.Theoretical modelling outputs perfectly match our results obtained from photo-physical studies of the processes leading to enhanced photocurrent.

View Article: PubMed Central - PubMed

Affiliation: School of Chemistry and CRANN Institute, Trinity College Dublin, Dublin 2, Ireland.

ABSTRACT
In this manuscript, for the first time, we report a combination of electrophoretic and sintering approaches for introducing gold nanoparticles into nanoporous TiO2 films to generate 'hot' electrons resulting in a strong enhancement of photocurrent. The Au-TiO2 nanocomposite material was prepared by the electrophoretic deposition of gold nanoparticles into a porous nanoparticulate titanium dioxide film, creating a photoactive electrode. The composite film demonstrates a significant increase in the short circuit current (I sc) compared to unmodified TiO2 when excited at or close to the plasmon resonance of the gold nanoparticles. Then, we employed a thermal ripening process as a method of increasing the I sc of these electrodes and also as a method of tuning the plasmon peak position, with a high degree of selectivity. Photo-electrochemical investigations revealed that the increase in photocurrent is attributed to the generation and separation of plasmonically generated hot electrons at the gold/TiO2 interface and also the inter-band generation of holes in gold nanoparticles by photons with λ < 520 nm. Theoretical modelling outputs perfectly match our results obtained from photo-physical studies of the processes leading to enhanced photocurrent.

No MeSH data available.


Related in: MedlinePlus