Energy transfer in plasmonic photocatalytic composites

Among the many novel photocatalytic systems developed in very recent years, plasmonic photocatalytic composites possess great potential for use in applications and are one of the most intensively investigated photocatalytic systems owing to their high solar energy utilization efficiency. In these composites, the plasmonic nanoparticles (PNPs) efficiently absorb solar light through localized surface plasmon resonance and convert it into energetic electrons and holes in the nearby semiconductor. This energy transfer from PNPs to semiconductors plays a decisive role in the overall photocatalytic performance. Thus, the underlying physical mechanism is of great scientific and technological importance and is one of the hottest topics in the area of plasmonic photocatalysts. In this review, we examine the very recent advances in understanding the energy transfer process in plasmonic photocatalytic composites, describing both the theoretical basis of this process and experimental demonstrations. The factors that affect the energy transfer efficiencies and how to improve the efficiencies to yield better photocatalytic performance are also discussed. Furthermore, comparisons are made between the various energy transfer processes, emphasizing their limitations/benefits for efficient operation of plasmonic photocatalysts. Recent developments in plasmonic enhancement of photocatalysis are reviewed with a focus on the energy transfer mechanisms involved. The use of plasmonic nanoparticles to enhance photocatalysis—the process whereby light is used to split water into its constituent parts of hydrogen and oxygen—is a topic of great interest. Xiangchao Ma and co-workers from Shandong University in China describe the theoretical basis and experimental demonstrations of localized surface plasmon resonances in plasmonic metal nanoparticles. They then compare the various energy transfer processes that can occur between such nanoparticles and a nearby semiconductor photocatalyst, namely plasmon-induced hot electron injection, plasmon-induced radiative energy transfer, plasmon-induced resonance, and plasmon-induced direct electron injection. Finally, the scientists give guidance for optimizing plasmonic photocatalytic activity and provide an outlook for the future of the field.