Improving the rates of Pd-catalyzed reactions by exciting the surface plasmons of AuPd bimetallic nanotriangles

Abstract

Gold nanoparticles exhibit unique optical properties due to surface plasmon oscillations when they interact with light. By utilizing their optical properties, the rates of many chemical reactions have been improved in the presence of visible light. The properties of plasmonic nanoparticles are highly tunable based on the size and shape of the nanoparticle. Here, we have used anisotropic AuPd bimetallic nanotriangles to improve the rates of Pd-catalyzed reactions in the presence of visible light. We synthesized AuPd core-shell bimetallic nanotriangles and performed Suzuki cross-coupling and hydrogenation reactions in light and dark conditions. Upon illuminating AuPd nanotriangles with an array of green LEDs (power $ 500 mW), enhanced catalytic activity of palladium was observed. In order to understand the relative contributions of individual plasmonic effects, such as plasmonic hot electron transfer and plasmonic heating effects, the reaction temperatures were monitored, and careful control experiments were run at different temperatures. Our results indicated that the enhancement in the rate of these Pd-catalyzed reactions is primarily due to the plasmonic heating effect.

“Hot” in Plasmonics: Temperature‐Related Concepts and Applications of Metal Nanostructures

“…[138] Similar core-shell nanostructures have been used extensively over the last five years to catalyze a wide variety of chemical reactions. [118,[139][140][141][142][143] However, the exact mechanism that underpins the catalytic reaction (thermal or nonthermal) has proven to be specific to each system. For example, when AuPd bimetallic nanostructures were used to catalyze the reaction rate of hydrogenation [141] and the yield of a set of Suzuki reactions, [142] it was identified that the role of the electronic mechanism was overshadowed by that of photothermal heating, occurring after the hot electron population has thermalized with the lattice.…”

“…A recent example of purely electron driven nonthermal catalysis with such core–shell structures was demonstrated by Ortiz et al, who used Pt end‐capped Au nanorods for the efficient production of hydrogen using white light . Similar core–shell nanostructures have been used extensively over the last five years to catalyze a wide variety of chemical reactions . However, the exact mechanism that underpins the catalytic reaction (thermal or nonthermal) has proven to be specific to each system.…”

“…However, the exact mechanism that underpins the catalytic reaction (thermal or nonthermal) has proven to be specific to each system. For example, when AuPd bimetallic nanostructures were used to catalyze the reaction rate of hydrogenation and the yield of a set of Suzuki reactions, it was identified that the role of the electronic mechanism was overshadowed by that of photothermal heating, occurring after the hot electron population has thermalized with the lattice. By introducing a 25 nm thick layer of TiO x in between the Au core and the Pd caps, the authors were able to prevent the electrons from spreading from the Au core into the Pd caps.…”

Controlled Assembly of Hierarchical Metal Catalysts with Enhanced Performances

“…acid as the reducing agent ( Figure 6A). 29 During Suzuki coupling reactions, the plasmonic Au nanotriangles were used to harvest light to improve the catalytic activity of Pd ( Figure 6B). Upon exciting the surface plasmons in AuPd nanotriangles using green LEDs with wavelengths near the maximum of the plasmon band, a significant improvement in the reaction rate of Suzuki was observed ( Figure 6C).…”

Recent Progress in Plasmonic Hybrid Photocatalysis for CO2 Photoreduction and C–C Coupling Reactions

“…For C-C cross-coupling reactions, Au-Pd nanocomposites can be utilized, where the Au part absorbs visible light and transfers hot electrons into Pd, and the Pd part acts as electron acceptors and active sites. Some studies using Au-Pd alloys without nonplasmonic materials, such as AuPd nano-wheels [98] and AuPd nanotriangles [99] for photocatalytic C-C cross-coupling, have been reported (Figure 7). Huang et al prepared AuPd nano-wheels, in which Pd encircles an Au core, with a controllable edge length and tunable SPR using a facile wet-chemical reduction method.…”