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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.


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PEC analysis. A. Photoelectrochemical performance of heat-treated (600°C) Au-TiO2 film (green) and non-treated Au-TiO2 film (red) under visible light illumination (≥425 nm, 0.45 V vs. SCE) with a chopping frequency of 14 Hz. B. Highlighted region of PEC analysis. C. Photoaction response obtained for Au-TiO2 electrode when illuminated at 525 nm.
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Fig3: PEC analysis. A. Photoelectrochemical performance of heat-treated (600°C) Au-TiO2 film (green) and non-treated Au-TiO2 film (red) under visible light illumination (≥425 nm, 0.45 V vs. SCE) with a chopping frequency of 14 Hz. B. Highlighted region of PEC analysis. C. Photoaction response obtained for Au-TiO2 electrode when illuminated at 525 nm.

Mentions: The PEC tests revealed an extremely stable and reproducible on/off switching response to the chopped light. We have observed this stable switching response at chopping frequencies greater than 100 Hz, which is indicative of a stable and fast injection response from gold to TiO2. PEC tests observed below (Figue 3A) were carried out at 14 Hz for clarity. The photocurrent response for the electrodes can be calculated from the difference in photocurrent observed between the on and off states (Figue 3B), whereby the on/off response is regulated by the optical chopper. The PEC analysis (Figure 3A) clearly shows an increase in the photocurrent observed for the heat-treated electrode; it can also be seen from the PEC data that the heat-treated films produce a more regular and sharper on/off switching response which would indicate the formation of a higher quality junction between the gold and TiO2.Figure 3


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)

PEC analysis. A. Photoelectrochemical performance of heat-treated (600°C) Au-TiO2 film (green) and non-treated Au-TiO2 film (red) under visible light illumination (≥425 nm, 0.45 V vs. SCE) with a chopping frequency of 14 Hz. B. Highlighted region of PEC analysis. C. Photoaction response obtained for Au-TiO2 electrode when illuminated at 525 nm.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Fig3: PEC analysis. A. Photoelectrochemical performance of heat-treated (600°C) Au-TiO2 film (green) and non-treated Au-TiO2 film (red) under visible light illumination (≥425 nm, 0.45 V vs. SCE) with a chopping frequency of 14 Hz. B. Highlighted region of PEC analysis. C. Photoaction response obtained for Au-TiO2 electrode when illuminated at 525 nm.
Mentions: The PEC tests revealed an extremely stable and reproducible on/off switching response to the chopped light. We have observed this stable switching response at chopping frequencies greater than 100 Hz, which is indicative of a stable and fast injection response from gold to TiO2. PEC tests observed below (Figue 3A) were carried out at 14 Hz for clarity. The photocurrent response for the electrodes can be calculated from the difference in photocurrent observed between the on and off states (Figue 3B), whereby the on/off response is regulated by the optical chopper. The PEC analysis (Figure 3A) clearly shows an increase in the photocurrent observed for the heat-treated electrode; it can also be seen from the PEC data that the heat-treated films produce a more regular and sharper on/off switching response which would indicate the formation of a higher quality junction between the gold and TiO2.Figure 3

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