Surface Plasmon-Induced Hot Carriers: Generation, Detection, and Applications

Abstract

Metrics & MoreArticle RecommendationsCONSPECTUS: During surface plasmon-mediated light−matter interactions, external energies on plasmonic metal nanostructures undergo energy dissipation via elastic e−e scattering, radiative luminescence, and nonradiative processes such as thermal relaxation (phonon) and electronic excitation (electron−hole pairs). In this process, surface plasmon decays dominantly through nonradiative recombination when the metal is smaller than 25 nm, forming hot carriers, including hot electrons and hot holes, with high kinetic energy of 1−3 eV. Although the ultrafast dynamics of hot carriers are on time scales ranging from femtoseconds to picoseconds, these fast-disappearing hot carriers can be collected as the steady-state photocurrent or chemicurrent by adopting the metal−semiconductor (M−S)based platform for detecting hot carrier flow. Plasmonic hot carriers, especially as they convert to an electrochemical signal, are a promising topic, and their energy conversion mechanisms are being actively studied in the fields of renewable energy, optoelectronics, and photocatalysis. Recent studies have demonstrated that these hot carriers can both improve the performance of solar energy conversion and control the catalytic activity or selectivity by directly participating in the photoelectrochemical (PEC) reaction.In this Account, we describe the inherent relationship between hot carriers and surface plasmon as well as what role hot carriers play throughout the catalytic reaction. The recent experimental work and the theoretical analysis of in situ hot carrier generation on Au nanostructures were conducted with photoconductive atomic force microscopy and finite-difference time-domain (FDTD) simulations, respectively. We highlight the recent nanoscale visualization of hot carrier flow occurring through light−matter interactions and that the localized surface plasmon field surrounding the Au nanostructure leads to boosted hot carrier generation. In addition, we highlight the recent demonstration that plasmonic hot carriers prolong the lifetime of photoexcited carriers in the MAPbI 3 /Au/TiO 2 hybrid nanodiode by the synergistic effect between plasmonic Au and perovskites. From this work, the solar-toelectron conversion performance of this nanodiode significantly increases due to the amplification of light absorption, which helps to design hybrid platforms for efficient hot carrier photovoltaics. We discuss the application of surface plasmon-driven hot electron generation, including hot electron-based photovoltaic devices and photocatalysts. We highlight the recent photoelectrochemical measurements on the Au/p-GaN heterostructures that are controlled by participating plasmonic hot carriers in the water splitting reaction. Furthermore, controlling the flow of both hot electrons and holes by developing hybrid platform configurations for hot carrier applications has promising opportunities for regulating the catalytic activities of hot carrier-based photocatalysis and improving the photoconversion efficie...

Which Nanoparticle Shape is the Most Effective in Generating Hot Charge Carriers from Plasmon Excitation?

“…The measured reaction yields are overall higher for excitation at 633 nm compared to that at 785 nm for all NPoM systems (represented by bars in Figure a). It is possibly due to the higher transfer efficiency at 633 nm, as its energy is more likely to surpass the interfacial energy barrier . Another contributing factor is the greater absorption at 633 nm than that at 785 nm, as indicated by the higher positions of the orange markers (σ abs, 633 nm ) compared with the cyan markers (σ abs, 785 nm ) in Figure a.…”

“…It is possibly due to the higher transfer efficiency at 633 nm, as its energy is more likely to surpass the interfacial energy barrier. 50 Another contributing factor is the greater absorption at 633 nm than that at 785 nm, as indicated by the higher positions of the orange markers (σ abs, 633 nm ) compared with the cyan markers (σ abs, 785 nm ) in Figure 6a. Dividing the reaction yields by the absorption cross sections leads to the hot carrier generation efficiency for 633 nm excitation (orange bars, Figure 6b).…”

Peeking into the Femtosecond Hot-Carrier Dynamics Reveals Unexpected Mechanisms in Plasmonic Photocatalysis

“…Such nonequilibrium state of excited electrons and holes rapidly thermalizes, resulting in a configuration where the carriers (electrons and holes) follow a Fermi–Dirac distribution at a higher temperature with respect to the lattice one, as if the electronic system was heated up. The electronic system remains “hot” until the electron–phonon scattering transfers all the extra electron energy to the lattice, getting further dissipated via thermalization to room temperature. − Mechanisms for hot-carrier production were studied both experimentally and theoretically over the past years, − but, despite the attention such a problem attracted recently, ,− the ways hot carriers mediate chemical reactions driving the photochemistry at the surface of metallic nanoparticles (NPs) are still largely unknown. Indeed, once generated, hot carriers may interact with other species in proximity of the metallic NP, like a solid semiconductor or a molecule, in the latter case directly triggering chemical reactions.…”

Probing Oxidation Mechanisms in Plasmonic Catalysis: Unraveling the Role of Reactive Oxygen Species

“…Plasmonic catalysis has emerged as an effective method to drive solar-to-chemical energy conversion, finding applications in diverse areas such as water splitting, , ammonia decomposition, , dry reforming of methane, etc. This process utilizes energetic hot carriers to facilitate the breaking or formation of chemical bonds, providing advantages for challenging reactions with high activation energy requirements. − In plasmonic catalysis, the hot carriers are generated during the nonradiative decay of surface plasmons. A prevailing interpretation suggests that the produced hot carriers are directly transferred to reactant molecules to initiate a redox reaction due to the reducibility of hot electrons and the oxidizability of hot holes. − While effective for plasmon-induced reduction, this theory encounters challenges when explaining the oxidation processes.…”