A Comparison of Photocatalytic Activities of Gold Nanoparticles Following Plasmonic and Interband Excitation and a Strategy for Harnessing Interband Hot Carriers for Solution Phase Photocatalysis

Abstract

Light driven excitation of gold nanoparticles (GNPs) has emerged as a potential strategy to generate hot carriers for photocatalysis through excitation of localized surface plasmon resonance (LSPR). In contrast, carrier generation through excitation of interband transitions remains a less explored and underestimated pathway for photocatalytic activity. Photoinduced oxidative etching of GNPs with FeCl3 was investigated as a model reaction in order to elucidate the effects of both types of transitions. The quantitative results show that interband transitions more efficiently generate hot carriers and that those carriers exhibit higher reactivity as compared to those generated solely by LSPR. Further, leveraging the strong π-acidic character of the resulting photogenerated Au+ hole, an interband transition induced cyclization reaction of alkynylphenols was developed. Notably, alkyne coordination to the Au+ hole intercepts the classic oxidation event and leads to the formation of the catalytically active gold clusters on subnanometer scale.

Quantifying hot carrier and thermal contributions in plasmonic photocatalysis

“…At shorter l, the absorption was still high, owing to Cu interband transitions (21), but the reduction in E a was smaller, because the energetic electrons produced by interband transitions in Cu have substantially lower energies than those produced by plasmon decay (2). This is in contrast to recent observations that more, but less energetic, carriers generated by interband transitions in Au NPs were more efficient than those generated by plasmon resonant excitation in solution phase catalysis (22). In each case, however, the specific energetics of the reaction itself are likely to be very important in ultimately determining photocatalytic efficiencies.…”

Transient localized surface plasmon induced by femtosecond interband excitation in gold nanoparticles

“…When the excitation photon energy is above this threshold, interband transition will be induced, e.g. by electronic transition from 5d -band to 6sp -band in gold 13 – 15 . Such excitation definitely enhances electron density on the conduction band and will inevitably modulate the optical performance of the metallic nanostructures.…”

Progress in the Utilization Efficiency Improvement of Hot Carriers in Plasmon-Mediated Heterostructure Photocatalysis

“…First, the exact physical model for the process relating to the generation, transportation and injections of HCs needs to be built up. There are arguments that the dominating contributions of electrons (interband transitions with a relatively low energy of electrons or intraband transitions induced by SPs) from photoexcited metals is the improvement of catalytic reactivity, and some works have given different opinions [134,135]. The distinguishing of non-thermal effects (HCs effects) and thermal effects, which allows us to quantify each contribution for the enhancement of the process of photocatalysis, is also of great importance for designing specific structures with different purposes [136][137][138].…”