Noble metal nanocrystals, possessing localized surface plasmon resonance, can interact strongly with light, efficiently converting light into heat and generating hot electrons and hot holes. Both plasmonic photothermal conversion and generation of hot charge carriers can accelerate chemical reactions. While the acceleration of chemical reactions by photothermal conversion is straightforward, the driving and acceleration of chemical reactions by plasmonic hot charge carriers represents a new research field. Plasmonic hot charge carriers can not only enhance the reaction yield and selectivity, but also introduce new reaction pathways. A full understanding of the latter process requires the knowledge of localized plasmon, electron/hole dynamics, charge transfer, and electron/hole-induced reactions. The study of plasmonic driving of chemical reactions will be rewarding in both fundamental and technological aspects.

The lifetime of plasmonic hot charge carriers is on the femtosecond scale. Without utilization, they will rapidly relax, converting their energy into heat. Two approaches have mainly been developed to facilitate the utilization of plasmonic hot charge carriers. The first is the integration of Au or Ag nanocrystals with Pd or Pt nanoparticles. Au and Ag nanocrystals possess strong localized plasmon resonance, while Pd and Pt nanoparticles are excellent catalysts for a variety of chemical reactions. A combination of the two types of metal nanocrystals can lead to efficient light absorption and generation of plasmonic hot charge carriers, which can subsequently inject into molecules that are adsorbed on the Pd or Pt component. The second is the integration of plasmonic metals with semiconductors. A barrier is formed at the interface. The generated hot electrons and holes can quickly inject into the conduction or valence band and therefore get separated. The injected charge carriers can then drive chemical reactions. We have synthesized bimetallic nanocrystals as well as metal/semiconductor hybrid nanostructures to demonstrate plasmonic driving of chemical reactions by both approaches.