Plasmon-Driven Catalysis on Molecules and Nanomaterials

Abstract

As a new class of photocatalysts, plasmonic noble metal nanoparticles with the unique ability to harvest solar energy across the entire visible spectrum and produce effective energy conversion have been explored as a promising pathway for the energy crisis. The resonant excitation of surface plasmon resonance allows the nanoparticles to collect the energy of photons to form a highly enhanced electromagnetic field, and the energy stored in the plasmonic field can induce hot carriers in the metal. The hot electron-hole pairs ultimately dissipate by coupling to phonon modes of the metal nanoparticles, resulting in a higher lattice temperature. The plasmonic electromagnetic field, hot electrons, and heat can catalyze chemical reactions of reactants near the surface of the plasmonic metal nanoparticles. This Account summarizes recent theoretical and experimental advances on the excitation mechanisms and energy transfer pathways in the plasmonic catalysis on molecules. Especially, current advances on plasmon-driven crystal growth and transformation of nanomaterials are introduced. The efficiency of the chemical reaction can be dramatically increased by the plasmonic electromagnetic field because of its higher density of photons. Similar to traditional photocatalysis, energy overlap between the plasmonic field and the HOMO-LUMO gap of the reactant is needed to realize resonant energy transfer. For hot-carrier-driven catalysis, hot electrons generated by plasmon decay can be transferred to the reactant through the indirect electron transfer or direct electron excitation process. For this mechanism, the energy of hot electrons needs to overlap with the unoccupied orbitals of the reactant, and the particular chemical channel can be selectively enhanced by controlling the energy distribution of hot electrons. In addition, the local thermal effect following plasmon decay offers an opportunity to facilitate chemical reactions at room temperature. Importantly, surface plasmons can not only catalyze chemical reactions of molecules but also induce crystal growth and transformation of nanomaterials. As a new development in plasmonic catalysis, plasmon-driven crystal transformation reveals a more powerful aspect of the catalysis effect, which opens the new field of plasmonic catalysis. We believe that this Account will promote clear understanding of plasmonic catalysis on both molecules and materials and contribute to the design of highly tunable catalytic systems to realize crystal transformations that are essential to achieve efficient solar-to-chemical energy conversion.