Hybrid nanostructures composed of semiconductor and plasmonic metal components are receiving extensive attention. They display extraordinary optical characteristics that are derived from the ...simultaneous existence and close conjunction of localized surface plasmon resonance and semiconduction, as well as the synergistic interactions between the two components. They have been widely studied for photocatalysis, plasmon‐enhanced spectroscopy, biotechnology, and solar cells. In this review, the developments in the field of (plasmonic metal)/semiconductor hybrid nanostructures are comprehensively described. The preparation of the hybrid nanostructures is first presented according to the semiconductor type, as well as the nanostructure morphology. The plasmonic properties and the enabled applications of the hybrid nanostructures are then elucidated. Lastly, possible future research in this burgeoning field is discussed.
(Plasmonic metal)/semiconductor hybrid nanostructures are currently of increasing interest owing to their rich and attractive physical and chemical properties derived from localized plasmon resonance and semiconduction. In this article, the preparation, properties, and applications of this type of hybrid nanostructure are reviewed. Future directions in this field are also discussed.
The photochemical production of fuels using sunlight is an innovative way for meeting the quickly increasing energy demands. One of the largest challenges is to develop high‐performance ...photocatalysts that can meet the requirements of practical applications. Owing to their intriguing localized surface plasmon resonances, noble metal nanoparticles and nanostructures show a great potential for enhancing the photocatalytic efficiency and thereby have attracted rapidly growing interest recently. Here, for the first time, the latest achievements in the utilization of plasmons in driving CO2 reduction and N2 fixation into high‐value products are comprehensively described. The involved plasmonic enhancement mechanisms in the two types of reactions are fully illustrated. A particular emphasis is given to the outlook on the direction and prospects for future work in this topic.
Photocatalytic solar‐to‐fuel conversion is of high potential in tackling energy shortage and environmental issues. The emerging applications of plasmons in the enhancement of the conversion efficiency toward practical relevance have recently gathered much attention. A focused overview of the recent studies in the use of plasmons for the photocatalytic CO2 reduction and N2 fixation is provided.
The fixation of atmospheric N2 to NH3 is an essential process for sustaining life. One grand challenge is to develop efficient catalysts to photofix N2 under ambient conditions. Herein we report an ...all-inorganic catalyst, Au nanocrystals anchored on ultrathin TiO2 nanosheets with oxygen vacancies. It can accomplish photodriven N2 fixation in the “working-in-tandem” pathway at room temperature and atmospheric pressure. The oxygen vacancies on the TiO2 nanosheets chemisorb and activate N2 molecules, which are subsequently reduced to NH3 by hot electrons generated from plasmon excitation of the Au nanocrystals. The apparent quantum efficiency of 0.82% at 550 nm for the conversion of incident photons to NH3 is higher than those reported so far. Optimizing the absorption across the overall visible range with the mixture of Au nanospheres and nanorods further enhances the N2 photofixation rate by 66.2% in comparison with Au nanospheres used alone. This work offers a new approach for the rational design of efficient catalysts toward sustainable N2 fixation through a less energy-demanding photochemical process compared to the industrial Haber–Bosch process.
Evolution of the sizes and plasmonic properties of (Au core)−(Ag shell) nanorods is studied. Four plasmon bands are observed on the core−shell nanorods and their properties are investigated. The ...lowest‐energy one belongs to the longitudinal dipolar plasmon mode, the second‐lowest‐energy one belongs to the transverse dipolar plasmon mode, and the two highest‐energy ones are ascribed to octupolar plasmon modes.
The efficient use of solar energy has received wide interest due to increasing energy and environmental concerns. A potential means in chemistry is sunlight-driven catalytic reactions. We report here ...on the direct harvesting of visible-to-near-infrared light for chemical reactions by use of plasmonic Au–Pd nanostructures. The intimate integration of plasmonic Au nanorods with catalytic Pd nanoparticles through seeded growth enabled efficient light harvesting for catalytic reactions on the nanostructures. Upon plasmon excitation, catalytic reactions were induced and accelerated through both plasmonic photocatalysis and photothermal conversion. Under the illumination of an 809 nm laser at 1.68 W, the yield of the Suzuki coupling reaction was ∼2 times that obtained when the reaction was thermally heated to the same temperature. Moreover, the yield was also ∼2 times that obtained from Au–TiO x –Pd nanostructures under the same laser illumination, where a 25-nm-thick TiO x shell was introduced to prevent the photocatalysis process. This is a more direct comparison between the effect of joint plasmonic photocatalysis and photothermal conversion with that of sole photothermal conversion. The contribution of plasmonic photocatalysis became larger when the laser illumination was at the plasmon resonance wavelength. It increased when the power of the incident laser at the plasmon resonance was raised. Differently sized Au–Pd nanostructures were further designed and mixed together to make the mixture light-responsive over the visible to near-infrared region. In the presence of the mixture, the reactions were completed within 2 h under sunlight, while almost no reactions occurred in the dark.
Gold nanocrystals have attractive plasmon-enabled photothermal conversion properties, which have been widely employed for photothermal therapy and solar energy harvesting. For practical applications, ...the mass-normalized photothermal conversion performance is often desired to be known for Au nanocrystals with different shapes and sizes and for different nanomaterials. We study the photothermal conversion performances of differently shaped and sized Au nanocrystals and compare them with those of PbS nanocrystals, carbon black, and organic dyes at the same mass concentrations. Both the mass-normalized extinction cross section and the photothermal conversion efficiency of Au nanocrystals decrease as their size is increased. The photothermal conversion performance of carbon black is comparable to that of relatively small Au nanocrystals, while the photothermal conversion performance of organic dyes and PbS nanocrystals is inferior to that of Au nanocrystals. Our results are useful for the design of Au nanocrystals and the choice of nanomaterials for photothermal applications.
Hydrogen detection is crucial for the safety of all hydrogen‐related applications. Compared to electrical hydrogen sensors, which usually suffer from possible electric sparks, optical hydrogen ...sensors offer advantages of remote and contact‐free readout and therefore the avoidance of spark generation. Herein, bimetallic Au/Pd nanostructure monolayers that exhibit ultrasensitive plasmonic response to hydrogen are reported. Bimetallic Au/Pd nanostructures with continuous and discontinuous Pd shells are prepared. The plasmonic response to hydrogen is monitored by measuring the extinction spectra of the ensemble Au/Pd nanostructures deposited on glass slides. Introduction of hydrogen induces red plasmon shifts, which become larger for the nanostructures with thicker Pd shells. For the nanostructures with continuous Pd shell, the plasmon shift can reach 56 nm at the hydrogen volume concentration below the explosion limit. The plasmon resonance wavelength displays an excellent linear dependence on the hydrogen volume concentration below 1%. The detection limit in the experiments reaches 0.2%. The nanostructures with discontinuous Pd shell show smaller plasmon shifts than those with continuous Pd shell. The extinction measurements on the ensemble nanostructures supported on transparent substrates and the unprecedentedly large plasmon shifts and sensitivity make the results very promising for the development of practical optical hydrogen sensors.
The plasmonic response of bimetallic Au/Pd nanostructures to hydrogen is systematically investigated. Red plasmon shifts larger than 50 nm are observed when Au/Pd nanostructure monolayers are exposed to hydrogen at the volume concentration below the explosion limit. The facile measurements and ultrasensitive plasmonic response make the bimetallic nanostructures very promising for the development of practical optical hydrogen sensors.
The control of the emission from electric and magnetic dipoles is highly desired for the development of optic chips. Although the emission of electric dipole has been successfully controlled by ...plasmonic nanoantenna, the control of magnetic dipole emission is relatively difficult. Here, we systematically study the effect of electric and magnetic modes of Au nanocups on the emission of electric and magnetic dipoles. The emission of electric dipole can be enhanced by both the electric and magnetic mode of the Au nanocup, while the emission of the magnetic dipole is only increased by the magnetic mode. The enhancement exhibits wavelength dependence. The wavelength of the largest enhancement is determined by the resonance wavelength of electric and magnetic modes. The enhancement values for electric and magnetic dipoles are determined by the near-field electric and magnetic field enhancements, respectively. More importantly, the emission pattern of magnetic dipole is greatly modified by the magnetic mode of Au nanocup. The directional emission of magnetic dipole is first time realized by use of the magnetic mode of the Au nanocup. Our findings deepen the understanding of the plasmon-controlled emission of electric and magnetic dipoles and will be very helpful to the development of the nanophotonic chips.
Food safety is a constant concern for humans. Besides adulteration and contamination, another major threat comes from the spontaneous spoilage of perishable products, which is basically inevitable ...and highly dependent on the temperature history during the custody chain. For advanced quality control and assessment, time–temperature indicators (TTIs) can be deployed to document the temperature history. However, the use of TTIs is currently limited by either relatively high cost or poor programmability. Here we describe a general, kinetically programmable, and cost-efficient TTI protocol constructed from plasmonic nanocrystals. We present proof-of-principle demonstrations that our TTI can be specifically tailored and thus used to track perishables, dynamically mimic the deteriorative processes therein, and indicate product quality through sharp-contrast multicolor changes. The flexible programmability of our TTI, combined with its substantially low cost and low toxicity, promises a general applicability to each single packaged item of a plethora of perishable products.
Ovarian cancer (OC) is the most lethal malignant gynecological tumor type for which limited therapeutic targets and drugs are available. Enhanced mitochondrial oxidative phosphorylation (OXPHOS), ...which enables cell growth, migration, and cancer stem cell maintenance, is a critical driver of disease progression and a potential intervention target of OC. However, the current OXPHOS intervention strategy mainly suppresses the activity of the electron transport chain directly and cannot effectively distinguish normal tissues from cancer tissues, resulting in serious side effects and limited efficacy.
We screened natural product libraries to investigate potential anti-OC drugs that target OXPHOS. Additionally, LC-MS, qRT-PCR, western-blot, clonogenic assay, Immunohistochemistry, wound scratch assay, and xenograft model was applied to evaluate the anti-tumor mechanism of small molecules obtained by screening in OC.
Gossypol acetic acid (GAA), a widely used gynecological medicine, was screened out from the drug library with the function of suppressing OXPHOS and OC progression by targeting the leucine-rich pentatricopeptide repeat containing (LRPPRC) protein. Mechanically, LRPPRC promotes the synthesis of OXPHOS subunits by binding to RNAs encoded by mitochondrial DNA. GAA binds to LRPPRC directly and induces LRPPRC rapid degradation in a ubiquitin-independent manner. LRPPRC was overexpressed in OC, which is highly correlated with the poor outcomes of OC and could promote the malignant phenotype of OC cells in vitro and in vivo. GAA management inhibits cell growth, clonal formation, and cancer stem cell maintenance in vitro, and suppresses subcutaneous graft tumor growth in vivo.
Our study identified a therapeutic target and provided a corresponding inhibitor for OXPHOS-based OC therapy. GAA inhibits OC progression by suppressing OXPHOS complex synthesis via targeting LRPPRC protein, supporting its potential utility as a natural therapeutic agent for ovarian cancer.
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