Mechanistic Insights into Plasmonic Catalysis by Dynamic Calculations: O₂ and N₂ on Au and Ag Nanoparticles

Abstract

Plasmonic metal nanoparticles offer an interesting alternative to traditional heterogeneous catalytic processes due to their ability to harness energy from light. While plasmonic photocatalysis is a well-known phenomenon, the exact mechanism of these reactions is still debated. Understanding the precise workings of plasmon-driven reactions is crucial for the rational design of novel catalytic structures. Here, we utilize real-time, time-dependent density functional theory (RT-TD-DFT) to excite systems with oscillating electric fields and track the subsequent excited state dynamics in real time. We find that RT-TD-DFT with Ehrenfest dynamics gives results that are consistent with experimental tests of plasmonic excitations, in that the presence of nanoparticles facilitates light-induced molecular dissociation. Our results also demonstrate that the electric-field enhancement is the primary driving factor for the plasmon-driven dissociation of O2 on Au and Ag nanoparticles, while for N2 dissociation, both charge transfer and field enhancement appear to play important roles. Additionally, charge density and density of states calculations indicate that these excitations are π → π* on short time scales and a mixture of π, σ → π*, σ* over time.

Plasmonic Catalysis: New Opportunity for Selective Chemical Bond Evolution

“…Lee group also demonstrated that the highly intense local electric field provided by the well-organized Ag octahedra superlattice greatly boosts the adsorbed N 2 activation, reducing the energy barrier of N 2 reduction without extra cocatalyst . This local electric field-assisted O 2 /N 2 activation was also theoretically verified by Montemore and co-workers on Au and Ag NPs in different electric field configurations …”

Recent Advances in Real-Time Time-Dependent Density Functional Theory Simulations of Plasmonic Nanostructures and Plasmonic Photocatalysis

“…It was found that O 2 dissociation could proceed with very minimal charge transfer while charge transfer was an important factor for N 2 dissociation (Figure 5). 72 In the case of O 2 , the near-field enhancement effect was the main driver of plasmon-mediated dissociation. Additionally, the electric field polarization could affect dissociation outcomes, further supporting previously discussed findings that the field polarization is important.…”

“…(c) N 2 charge change and (d) bond length when subjected to electric fields polarized either along the molecular axis or normal to the Au 55 nanoparticle surface. For O 2 , dissociation occurs in both cases while for N 2 dissociation occurs only when the field is normal to the surface and large transient charge transfer is observed at roughly 25 to 30 fs . Reprinted with permission under a Creative Commons License from ref .…”

“…For O 2 , dissociation occurs in both cases while for N 2 dissociation occurs only when the field is normal to the surface and large transient charge transfer is observed at roughly 25 to 30 fs . Reprinted with permission under a Creative Commons License from ref . Copyright 2023 the Authors, published by American Chemical Society.…”

Connectivity between Static Field and Continuous Wave Field Effects on Excitation-Induced H2 Activation

“…To study the photo-dissociation of small molecules in the presence of an Au nanoparticle, the jellium model has previously been applied which treats the nanoparticle as a uniform charge density to reduce the computational cost . Other theoretical methods that explicitly consider the nuclei have also been considered. − Time-dependent density functional theory (TDDFT) has been employed to study plasmon-enhanced photocatalysis with small nanoparticles. − Computational methods with less expensive costs (i.e., TD-DFTB − and TDDFT + TB , ) have been developed to deal with larger-sized nanoparticles. In addition, mixed levels of computational methods have been used to study the plasmon-induced H 2 dissociation on a Au(111) slab, in order to reach a balance between computational accuracy and cost …”