We are using visible light illumination to excite non-thermal electron distributions in noble metal nanoparticles to achieve reaction selectivity that is not possible using purely thermal reaction chemistry in both materials synthesis and catalytic transformations.
Noble metal nanoparticles, particularly those of silver and gold, have unique optical properties that arise from a phenomenon known as localized surface plasmon resonance, which is the collective oscillation of conduction band electrons in a metal nanoparticle upon excitation with incident light. The excited “hot” electrons and resulting “hot” holes can be used as reducing and oxidizing equivalents, respectively, in chemical transformations. Direct transfer of plasmonically excited electrons to adsorbed molecules can also drive desorption or bond dissociation, thereby enabling selectivity that is unachievable using thermal catalysis. We are employing this non-thermal plasmon-driven chemistry to selectively accelerate kinetically slow metal ion reduction processes and overcome key challenges in the synthesis of bimetallic nanoparticles.
Our group recently reported the first use of plasmon excitation to drive the reduction of ions of a poorly plasmonic metal by a weak reducing agent, yielding a core-satellite nanoparticle architecture that was not accessible via existing methods. In addition to challenges in nanoparticle synthesis, the mechanisms of plasmon-driven catalysis on metal nanoparticles are just beginning to be understood. We are exploring the mechanistic complexities of plasmon-mediated chemical reactions at crystalline defects and bimetallic interfaces—including core-shell, core-satellite, and dilute bimetallic surface architectures—using precision nanoscale materials synthesized via both thermal and plasmonic approaches. Reactions relevant to air quality remediation, such as the oxidation of volatile organic compounds, are ideal targets for this work. These reactions are required to proceed at or near room temperature and thus would benefit from light-mediated rate enhancement rather than standard thermal approaches. Finally, are using plasmonic excitation as a tool for actively modulating the binding strength of weakly adsorbed reaction intermediates on nanoscale metal surfaces. This approach will enable us to shift the competitive binding of reaction intermediates away from thermal equilibrium, thereby tailoring reaction selectivity.
Personick, M. L., Plasmon-Mediated Syntheses of Polyhedral Noble Metal Nanoparticles. In World Scientific Reference on Plasmonic Nanomaterials, World Scientific: Singapore, 2022; Vol. Volume 22, pp 47-88. [Book Chapter]
Habib, A.†; King, M. E.†; Etemad, L. L.; Distler, M. E.; Morrissey, K. H.; Personick, M. L. “Plasmon-Mediated Synthesis of Hybrid Silver-Platinum Nanostructures.” J. Phys. Chem. C 2020, 124, 6853-6860. †Authors contributed equally.
Argento, G. M.; Judd, D. R.; Etemad, L. L.; Bechard, M. M.; Personick, M. L. “Plasmon-Mediated Reconfiguration of Twin Defect Structures in Silver Nanoparticles.” J. Phys. Chem. C. 2023, 127, 3890-3897.