Plasmon-induced Resonant Energy Transfer Research Articles

Surface plasmon resonance-mediated photocatalytic H2 generation.

The limited yield of H2 production has posed a significant challenge in contemporary research. To address this issue, researchers have turned to the application of surface plasmon resonance (SPR) materials in photocatalytic H2 generation SPR, arising from collective electron oscillations, enhances light absorption and facilitates efficient separation and transfer of electron-hole pairs in semiconductor systems, thereby boosting photocatalytic H2 production efficiency. However, existing reviews predominantly focus on SPR noble metals, neglecting non-noble metals and SPR semiconductors. In this review, we begin by elucidating five different SPR mechanisms, covering hot electron injection, electric field enhancement, light scattering, plasmon-induced resonant energy transfer, and photo-thermionic effect, by which SPR enhances photocatalytic activity. Subsequently, a comprehensive overview follows, detailing the application of SPR materials-metals, non-noble metals, and SPR semiconductors-in photocatalytic H2 production. Additionally, a personal perspective is offered on developing highly efficient SPR-based photocatalysis systems for solar-to-H2 conversion in the future. This review aims to guide the development of next-gen SPR-based materials for advancing solar-to-fuel conversion.

Active Manipulation of Luminescent Dynamics via Au NPs‐CsPbBr3 Interfacial Engineering

AbstractManipulating photocarrier dynamics for luminescent materials is fundamentally important for steering luminescent properties of optoelectronic devices. Here, interfacial engineering is realized by constructing Au NPs‐CsPbBr3 interfaces toward resonant coupling between localized surface plasmon and exciton. Through ultrafast laser spectroscopic measurements, it is demonstrated that photoluminance originating from CsPbBr3 excitonic recombination is significantly enhanced at the interface with prolonged lifetimes. Interfacial photocarrier dynamics are mediated by plasmon‐induced hot electron transfer (PHET) and plasmon‐induced resonant energy transfer (PIRET) processes. By simply varying excitation laser wavelengths, PHET path of photocarriers is actively switched on and off. The results are of great significance for actively manipulating photocarrier dynamics of perovskite luminescent devices.

Intermolecular Forces Dictate Vibrational Energy Transfer in Plasmonic-Molecule Systems.

Plasmonic materials are a promising category of photocatalysts for solar energy harvesting and conversion. However, there are some significant obstacles that need to be overcome to make plasmonic catalysts commercially available. One major challenge is to obtain a systematic understanding of how to design and optimize plasmonic systems from the perspective of both plasmonic materials and reagent molecules to achieve highly efficient and selective catalysis. It is well-known that the contributions of plasmon-molecule interactions such as plasmon-induced resonant energy transfer and charge transfer to the catalytic mechanism are rather complicated and possibly multifold. Observation of these phenomena is challenging due to the highly heterogeneous nature of plasmonic substrates as well as the large difference in sizes and optical cross sections between plasmonic materials and molecules. In this work, we use a molecular perspective to examine the crucial process of energy transfer between plasmons and molecules, with the goal of determining which experimental parameters can be used to control this energy flow. We employ ultrafast surface-enhanced anti-Stokes and Stokes Raman spectroscopy to investigate vibrational energy transfer in plasmonic-molecule systems. By comparing the energy transfer kinetics of five different aromatic thiols on the picosecond time scale, we find that intermolecular forces play an important role in energy distribution in molecules adsorbed to plasmonic materials, which changes the amount of energy deposited onto the molecule and the lifetime of the energy deposited. Our work implies that careful consideration of catalyst loading and molecule adsorption geometry is crucial for enhancing or suppressing the rate and efficiency of plasmon-driven energy transfer.

Materials characterization of TiO2 nanotubes decorated by Au nanoparticles for photoelectrochemical applications.

The structural and chemical modification of TiO2 nanotubes (NTs) by the deposition of a well-controlled Au deposit was investigated using a combination of X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), Scanning Transmission Electron Microscopy (STEM), Raman measurements, UV-Vis spectroscopy and photoelectrochemical investigations. The fabrication of the materials focused on two important factors: the deposition of Au nanoparticles (NPs) in UHV (ultra high vacuum) conditions (1–2 × 10−8 mbar) on TiO2 nanotubes (NTs) having a diameter of ∼110 nm, and modifying the electronic interaction between the TiO2 NTs and Au nanoparticles (NPs) with an average diameter of about 5 nm through the synergistic effects of SMSI (Strong Metal Support Interaction) and LSPR (Local Surface Plasmon Resonance). Due to the formation of unique places in the form of “hot spots”, the proposed nanostructures proved to be photoactive in the UV-Vis range, where a characteristic gold plasmonic peak was observed at a wavelength of 580 nm. The photocurrent density of Au deposited TiO2 NTs annealed at 650 °C was found to be much greater (14.7 μA cm−2) than the corresponding value (∼0.2 μA cm−2) for nanotubes in the as-received state. The IPCE (incident photon current efficiency) spectral evidence also indicates an enhancement of the photoconversion of TiO2 NTs due to Au NP deposition without any significant change in the band gap energy of the titanium dioxide (Eg ∼3.0 eV). This suggests that a plasmon-induced resonant energy transfer (PRET) was the dominant effect responsible for the photoactivity of the obtained materials.

(Invited) Plasmonic Nanostructures for Early Disease Detection and Precision Cancer Therapeutics

Cancers are one of the leading causes of death in the world taking nearly 9 million lives annually. Because cancers place a burden on society, there is considerable interest in developing biosensors for early diagnosis and new, more effective treatments. At early stages of the disease, early diagnosis is integral for treatment success; however, concentrations of cancer biomarkers are very low, and testing is very extensive. Point-of-care biosensors can overcome these challenges by offering fast, accurate results in healthcare fields compared to low-sensitivity, expensive, and time-consuming laboratory techniques. Because of their unique and highly tunable optical properties, plasmonic nanostructures have been applied for biosensor design and in-vivo therapeutics to improve performance. Plasmonic nanostructures have been integrated into paper-based biosensors for high sensitivity and accurate assessment of cancer biomarkers in whole blood with no sample preparation. Cancers are conventionally treated using chemotherapy and radiation treatment; however, advancements in precision medicine are working to overcome drug resistance and target cancer directly instead of through systemic treatment. A plasmon induced resonant energy transfer (PIRET) nanostructure has been designed for in-vivo dual-Raman imaging and photodynamic therapy of cancer. This design provides means for Raman-guided imaging and surgery and destruction of cancer while maintaining the integrity of healthy tissues.

Photocatalytic Degradation Mechanism of Tetracycline by Ag@ZnO/C Core–Shell Plasmonic Photocatalyst Under Visible Light

A series of hamburger-like Ag@ZnO/C core–shell plasmonic photocatalysts have been synthesized via a simple solvothermal method for degradation of tetracycline (TC) under visible light irradiation, possessing high photocatalytic activity and good stability. The presence of localized surface plasmon resonance (LSPR) in the Ag core has increased the photocatalytic activity over an extended wavelength range. The plasmon-induced resonant energy transfer (PIRET) and direct electron transfer (DET) have facilitated the excitation and separation of photogenerated [Formula: see text] pairs, which has been further confirmed by electrochemical investigations. The presences of hydroxyl radicals ([Formula: see text]), superoxide radicals ([Formula: see text] and singlet oxygen (1O[Formula: see text] in the photocatalytic reaction system of Ag@ZnO/C photocatalyst have been demonstrated by electron spin resonance (ESR) measurements. All of the experiment results indicate that the ternary structure of Ag@ZnO/C can effectively enhance the photocatalytic activity. Furthermore, the effects of introduced Ag contents and carbon source dosage were researched by comparative photocatalytic experiments, and the potential structures of photodegradation products were studied by HPLC-MS.

Reverse Ostwald ripening process induced dispersion of Cu2O nanoparticles in silver-matrix and their interfacial mechanism mediated sunlight driven photocatalytic properties

Plasmonic photocatalyst based on Cu2O nanoparticles dispersed Ag (Cu2O@Ag) matrix has been developed through reverse Ostwald ripening process. Compared to bare Cu2O nanoparticles, Cu2O@Ag matrix exhibits enhanced optical activity over a wide range of visible spectrum due to the manifestation of localized surface plasmon resonance (LSPR) of Ag matrix. The observed enhanced photocatalytic property of Cu2O@Ag matrix is attributed to their configuration, in which the three-dimensional contact between Cu2O and Ag facilitated the charge transfers via a simultaneous direct electron transfer (DET) and plasmon induced resonant energy transfer (PIRET) process. As a result, the photocatalytic activity of Cu2O@Ag system is varied with respect to their different configurations. This work has eventually demonstrated that the overall optical properties and photocatalytic efficiency of plamonic photocatalyst can be enhanced through configuring a three-dimensional contact between the semiconductor photocatalyst and plasmonic metal rather than the conventional point-contact configuration.

Enhancing Mo:BiVO4 Solar Water Splitting with Patterned Au Nanospheres by Plasmon‐Induced Energy Transfer

AbstractPlasmonic metal nanostructures have been extensively investigated to improve the performance of metal oxide photoanodes for photoelectrochemical (PEC) solar water splitting cells. Most of these studies have focused on the effects of those metal nanostructures on enhancing light absorption and enabling direct energy transfer via hot electrons. However, several recent studies have shown that plasmonic metal nanostructures can improve the PEC performance of metal oxide photoanodes via another mechanism known as plasmon‐induced resonant energy transfer (PIRET). However, this PIRET effect has not yet been tested for the molybdenum‐doped bismuth vanadium oxide (Mo:BiVO4), regarded as one of the best metal oxide photoanode candidates. Here, this study constructs a hybrid Au nanosphere/Mo:BiVO4 photoanode interwoven in a hexagonal pattern to investigate the PIRET effect on the PEC performance of Mo:BiVO4. This study finds that the Au nanosphere array not only increases light absorption of the photoanode as expected, but also improves both its charge transport and charge transfer efficiencies via PIRET, as confirmed by time‐correlated single photon counting and transient absorption studies. As a result, incorporating the Au nanosphere array increases the photocurrent density of Mo:BiVO4 at 1.23 V versus RHE by ≈2.2‐fold (2.83 mA cm−2).

Hollow Au–Cu2O Core–Shell Nanoparticles with Geometry-Dependent Optical Properties as Efficient Plasmonic Photocatalysts under Visible Light

Hollow Au-Cu2O core-shell nanoparticles were synthesized by using hollow gold nanoparticles (HGNs) as the plasmon-tailorable cores to direct epitaxial growth of Cu2O nanoshells. The effective geometry control of hollow Au-Cu2O core-shell nanoparticles was achieved through adjusting the HGN core sizes, Cu2O shell thicknesses, and morphologies related to structure-directing agents. The morphology-dependent plasmonic band red-shifts across the visible and near-infrared spectral regions were observed from experimental extinction spectra and theoretical simulation based on the finite-difference time-domain method. Moreover, the hollow Au-Cu2O core-shell nanoparticles with synergistic optical properties exhibited higher photocatalytic performance in the photodegradation of methyl orange when compared to pristine Cu2O and solid Au-Cu2O core-shell nanoparticles under visible-light irradiation due to the efficient photoinduced charge separation, which could mainly be attributed to the Schottky barrier and plasmon-induced resonant energy transfer. Such optical tunability achieved through the hollow cores and structure-directed shells is of benefit to the performance optimization of metal-semiconductor nanoparticles for photonic, electronic, and photocatalytic applications.

The Effects of Gold Nanoparticles Deposition on the Surface of TiO2 Nanorods for Solar Water Splitting Applications

Plasmonic gold nanostructures offer a promising route to improving the solar energy conversion efficiency of semiconductors. This paper reports that the presence of gold nanoparticles (NPs) on the surface of TiO2 nanorods leads to an enhanced photocurrent for the photoelectrochemical (PEC) water splitting performance and discusses the origins of this enhancement from the results of various characterization techniques. The results show that plasmon-induced resonant energy transfer is responsible for the light harvesting enhancement at the energies below the band edge of TiO2. These results may provide a general approach to overcoming the low optical absorption of semiconductor structures, while further reducing the charge recombination losses.

Nanoscopic imaging of energy transfer from single plasmonic particles to semiconductor substrates via STEM/EELS

Localized surface plasmon resonances (LSPRs), the collective oscillations of conduction electrons in metallic nanoparticles, can produce intense near-fields at the resonance wavelengths. Plasmonic nanoparticles have been incorporated in the design of photovoltaic (PV) and photocatalytic devices, where they have been shown to enhance solar energy harvesting efficiency. Research has shown that the addition of plasmonic nanoparticles improves the efficiency of solar light harvesting via one or more of the following mechanisms1: (1) LSPR excitation leads to an increase in path length for incoming light via scattering, thereby increasing light absorption by the semiconductors; (2) energy transfer from the decay of an LSPR directly creates an electron-hole pair in the semiconductor, a process known as plasmon-induced resonant energy transfer (PIRET). Its efficiency relies on the overlap between the LSPR emission and the band gap absorption of the semiconductor2; (3) direct electron transfer (DET) from the nanoparticle to a semiconductor, in which an LSPR decays, through Landau damping, into a “hot” electron that may then scatter into the semiconductor if it has sufficient energy to overcome the Schottky barrier formed at the interface3. Mechanism (1) is only effective for photon energies above the band gap, while mechanism (2) and (3) involve photons with energies below or above the band gap, therefore, are of particular interest and importance. However, despite its importance, little is known about how PIRET and DET operate at the nanoscale, particularly at the level of a single nanoparticle.

Enhanced Production of Solar-Fuels By Plasmonic Metal/Semiconductor Photocatalyst Heterostructures

Earth’s dependence on fossil fuels for providing the majority of the world’s energy is problematic due to the finite nature of fossil fuels and the release of greenhouse gases and other pollutants during their combustion. As such, sustainable, carbon-neutral fuels are needed as a long-term replacement for fossil fuels. One promising approach is direct solar energy-to-chemical fuel conversion by photocatalysis. Examples of fuels produced include H2 from photocatalytic water splitting or photocatalytic reduction of CO2 to methanol or methane. However, current photocatalyst materials suffer from a combination of problems such as poor charge carrier lifetimes and mobility, poor photostability in water, wide bandgaps that allow only UV light absorption, and/or an inactive surface for carrying out redox reactions. Forming heterostructures made of plasmonic metals (i.e. Au, Ag, or Cu) and semiconductor photocatalyst materials can serve to enhance overall photocatalytic performance versus the photocatalyst alone. This enhancement comes from photonic mechanisms like visible or NIR light absorption or scattering by plasmonic metal nanostructures and plasmonic enhancement mechanisms of direct transfer of “hot” electrons from the plasmonic metal to the photocatalyst and plasmon-induced resonant energy transfer from plasmonic metal to photocatalyst through dipole-dipole interactions. This poster summarizes our latest research on determining the nature of these enhancement mechanisms and progress towards high efficiency photocatalytic production of solar-fuels.

Plasmon Induced Resonant Energy Transfer and Hot Electron Injection in Plasmon Enhanced Photocatalysis

Localized surface plasmon resonance (LSPR) is ideal for improving solar energy harvesting because of the strong, tunable absorption and scattering cross sections. The energy stored in the collective electron oscillations can be transferred to a semiconductor, allowing photoconversion at wavelengths near and above the band edge of the semiconductor. In this presentation we will investigate the mechanisms and optimization of plasmon enhanced photocatalysis using a combined transient absorption and action spectrum/IPCE analysis. Specifically, by controlling the spectral overlap, energy band alignment, and thickness of insulating barriers in metal@semiconductor nanostructures the two possible energy transfer pathways, hot electron injection and plasmon induced resonant energy transfer, are mapped out as well as the corresponding charge relaxation dynamics. A connection is made between the initial plasmonic energy transfer measured on ultrafast time scales to the resulting enhancement in photocatalysis, guiding the efficient design of plasmon enhanced photocatalysts.

Plasmon-induced photonic and energy-transfer enhancement of solar water splitting by a hematite nanorod array

Plasmonic metal nanostructures offer a promising route to improve the solar energy conversion efficiency of semiconductors. Here we show that incorporation of a hematite nanorod array into a plasmonic gold nanohole array pattern significantly improves the photoelectrochemical water splitting performance, leading to an approximately tenfold increase in the photocurrent at a bias of 0.23 V versus Ag|AgCl under simulated solar radiation. Plasmon-induced resonant energy transfer is responsible for enhancement at the energies below the band edge, whereas above the absorption band edge of hematite, the surface plasmon polariton launches a guided wave mode inside the nanorods, with the nanorods acting as miniature optic fibres, enhancing the light absorption. In addition, the intense local plasmonic field can suppress the charge recombination in the hematite nanorod photoanode in a photoelectrochemical cell. Our results may provide a general approach to overcome the low optical absorption and spectral utilization of thin semiconductor nanostructures, while further reducing charge recombination losses.

Plasmon-Enhanced Solar Energy Harvesting

Solar energy can be directly converted to electrical energy via photovoltaics. Alternatively, solar energy can be converted and stored in chemical fuels through photoelectrochemical cells and photocatalysis (see front cover image), allowing continued power production when the sky is cloudy or dark. The conversion of solar energy is regulated by four processes: light absorption, charge separation, charge migration, and charge recombination. An individual material cannot be optimized for all four processes. Incorporation of plasmonic nanostructures with semiconductors offers an alternative route to improve the solar energy conversion efficiency. One enhancement mechanism is a so called photonic enhancement, the other one is plasmonic energy transfer enhancement. Two different mechanisms of plasmonic energy transfer enhancement are discussed: plasmon-induced resonant energy transfer (PIRET) from the metal to the semiconductor and direct electron transfer (DET). Plasmonic nanostructures can be designed with orders of magnitude larger EM field enhancements, creating the possibility of highly efficient photocatalysts and solar cells.

Ag@Cu2O Core-Shell Nanoparticles as Visible-Light Plasmonic Photocatalysts

Compared to pristine Cu2O nanoparticles (NPs), Ag@Cu2O core-shell NPs exhibit photocatalytic activity over an extended wavelength range because of the presence of localized surface plasmon resonance (LSPR) in the Ag core. The photocatalysis action spectra and transient absorption measurements show that the plasmonic energy is transferred from the metal to the semiconductor via plasmon-induced resonant energy transfer (PIRET) and direct electron transfer (DET) simultaneously, generating electron–hole pairs in the semiconductor. The LSPR band of Ag@Cu2O core-shell NPs shows a red-shift with an increase in the Cu2O shell thickness, extending the light absorption of Ag@Cu2O heterostructures to longer wavelengths. As a result, the photocatalytic activity of the Ag@Cu2O core-shell NPs is varied by modulation of the shell thickness on the nanometer scale. This work has demonstrated that the Ag@Cu2O core-shell heterostructure is an efficient visible-light plasmonic photocatalyst, which allows for tunable light ab...