Hot Carrier Generation and Extraction of Plasmonic Alloy Nanoparticles

Hot Carrier Generation and Extraction of Plasmonic Alloy Nanoparticles

Valenti, M. (TU Delft ChemE/Materials for Energy Conversion and Storage)
Venugopal, A. (TU Delft ChemE/Materials for Energy Conversion and Storage)
Tordera, Daniel (Linköping University)
Jonsson, P.M. (Linköping University)
Biskos, G. (TU Delft Atmospheric Remote Sensing; The Cyprus Institute)
Schmidt-Ott, A. (TU Delft ChemE/Materials for Energy Conversion and Storage)
Smith, W.A. (TU Delft ChemE/Materials for Energy Conversion and Storage)

2017-05-17

The conversion of light to electrical and chemical energy has the potential to provide meaningful advances to many aspects of daily life, including the production of energy, water purification, and optical sensing. Recently, plasmonic nanoparticles (PNPs) have been increasingly used in artificial photosynthesis (e.g., water splitting) devices in order to extend the visible light utilization of semiconductors to light energies below their band gap. These nanoparticles absorb light and produce hot electrons and holes that can drive artificial photosynthesis reactions. For n-type semiconductor photoanodes decorated with PNPs, hot charge carriers are separated by a process called hot electron injection (HEI), where hot electrons with sufficient energy are transferred to the conduction band of the semiconductor. An important parameter that affects the HEI efficiency is the nanoparticle composition, since the hot electron energy is sensitive to the electronic band structure of the metal. Alloy PNPs are of particular importance for semiconductor/PNPs composites, because by changing the alloy composition their absorption spectra can be tuned to accurately extend the light absorption of the semiconductor. This work experimentally compares the HEI efficiency from Ag, Au, and Ag/Au alloy nanoparticles to TiO₂ photoanodes for the photoproduction of hydrogen. Alloy PNPs not only exhibit tunable absorption but can also improve the stability and electronic and catalytic properties of the pure metal PNPs. In this work, we find that the Ag/Au alloy PNPs extend the stability of Ag in water to larger applied potentials while, at the same time, increasing the interband threshold energy of Au. This increasing of the interband energy of Au suppresses the visible-light-induced interband excitations, favoring intraband excitations that result in higher hot electron energies and HEI efficiencies.

alloy nanoparticles
artificial photosynthesis
gold nanoparticles
hot electron injection
hydrogen photoproduction
plasmonic nanoparticles
silver nanoparticles

http://resolver.tudelft.nl/uuid:01b10488-e1c6-4453-b5c2-b0ef88d533fb

https://doi.org/10.1021/acsphotonics.6b01048

2330-4022

ACS Photonics, 4 (5), 1146-1152

Institutional Repository

journal article

© 2017 M. Valenti, A. Venugopal, Daniel Tordera, P.M. Jonsson, G. Biskos, A. Schmidt-Ott, W.A. Smith