Schottky-barrier-free plasmonic photocatalysts

Plasmonic photocatalysis has recently attracted much attention in enhancing the solar-to-chemical conversion efficiency (SCCE) owing to localized surface plasmon resonance (LSPR), whose energy can be synthetically varied from the ultraviolet through the visible to the near-infrared region. This wide variability is inaccessible by traditional semiconductor photocatalysts. However, for all-metal plasmonic photocatalysts, the photogenerated hot charge carriers have an ultrashort lifetime because of their rapid recombination. For most metal-semiconductor hybrid plasmonic photocatalysts, a large portion of plasmonic hot charge carriers is lost during transfer from the metal to the semiconductor because of the Schottky barrier formed at the metal-semiconductor interface. As a result, both types of plasmonic photocatalysts exhibit limited SCCEs. To overcome the aforementioned shortcomings, a new type of plasmonic photocatalyst, the Schottky-barrier-free plasmonic photocatalyst, has been proposed recently. This type of plasmonic photocatalyst not only possesses LSPR to generate abundant hot charge carriers, but is also Schottky-barrier-free so that the hot charge carriers can be utilized more sufficiently to drive redox reactions. In this perspective, we first discuss the different types of plasmonic photocatalysts using representative examples, then introduce Schottky-barrier-free plasmonic photocatalysts, and finally provide the major challenges and remaining questions of this new type of plasmonic photocatalyst. We believe this perspective will offer insight into the further development of plasmonic photocatalysis and the improvement of its SCCEs.