From plasmon-enhanced molecular spectroscopy to plasmon-mediated chemical reactions

The excitation of surface plasmons (SPs) — collective oscillation of conduction-band electrons in nanostructures — can afford photon, electron and heat energy redistribution over time and space. Making use of this ability, plasmon-enhanced molecular spectroscopy (PEMS) techniques with ultra-high sensitivity and surface selectivity have attracted much attention and have undergone considerable development over the past four decades. Recently, the development of plasmon-mediated chemical reactions (PMCRs) has shown the potential to have a large impact on the practice of chemistry. PMCRs exhibit some obvious differences from and potential advantages over traditional thermochemistry, photochemistry and photocatalysis. However, our physicochemical understanding of PMCRs is still far from complete. In this Review, we analyse the similarities and distinctive features of PEMS and PMCRs and compare PMCRs with traditional photochemical and thermochemical reactions. We then discuss how PMCRs can be improved by rationally designing and fabricating plasmonic nanostructures, selecting suitable surface and interface mediators and teaming them synergistically. Surface plasmons can redistribute photoenergy over different time, space and energy scales and have been exploited in new spectroscopic techniques. This Review reports on how surface plasmons can also drive chemical reactions by localizing photon, electronic and/or thermal energies.