Local Surface Plasma Resonance Effect Research Articles

SnO2 tetragonal nanonails with enhanced optical and photoelectric performances via localized surface plasmon resonance effect of Au nanoparticles

Enhanced optical and photoelectric characteristics of semiconductors via Localized Surface Plasma Resonance (LSPR) effect strategy has drawn extensive attentions and researches in the fields of semiconductor industry. Specially, Au/SnO2 tetragonal nanonails (TNs) Schottky heterojunctions have been innovatively synthesized by modified CVD and hydrothermal methods. Au/SnO2 TNs Schottky heterojunction fabricated at the volume ratio of 0.5/45 HAuCl4/Water (0.5 Au/SO) exhibits the remarkable photocurrent density about of 52.8 μA cm−2 at 0.5 V vs. Ag/AgCl, which is about of 1.5 and 1.2 times than that of SO-550 (36.4 μA cm−2) and 0.7 Au/SO (44.8 μA cm−2) photoelectrodes, respectively. Optical absorption properties of all Au/SnO2 TNs Schottky heterojunctions have obviously improved in ultraviolet–visible regions due to the strong LSPR effect of Au nanoparticles (NPs). Au NPs also act as photosensitizers, which can generate more high-energy active electrons by LSPR excitation and then inject into CB of SnO2 TNs photoelectrode. This process can effectively enhance separation and transportation efficiencies of photogenerated charge carriers, further improving photoelectric performances of Au/SnO2 TNs Schottky heterojunctions. This work can provide novel strategies to synthesize one-dimensional metallic oxide photoelectrodes and Schottky heterojunctions, and further laying the foundation for exploring the interface/surface novel effects of heterojunctions at the applications of catalysis, sensors or detection fields.

Controllable Preparation of Gold Nanocrystals with Different Porous Structures for SERS Sensing.

Porous Au nanocrystals (Au NCs) have been widely used in catalysis, sensing, and biomedicine due to their excellent localized surface plasma resonance effect and a large number of active sites exposed by three-dimensional internal channels. Here, we developed a ligand-induced one-step method for the controllable preparation of mesoporous, microporous, and hierarchical porous Au NCs with internal 3D connecting channels. At 25 °C, using glutathione (GTH) as both a ligand and reducing agent combined with the Au precursor to form GTH-Au(I), and under the action of the reducing agent ascorbic acid, the Au precursor is reduced in situ to form a dandelion-like microporous structure assembled by Au rods. When cetyltrimethylammonium bromide (C16TAB) and GTH are used as ligands, mesoporous Au NCs formed. When increasing the reaction temperature to 80 °C, hierarchical porous Au NCs with both microporous and mesoporous structures will be synthesized. We systematically explored the effect of reaction parameters on porous Au NCs and proposed possible reaction mechanisms. Furthermore, we compared the SERS-enhancing effect of Au NCs with three different pore structures. With hierarchical porous Au NCs as the SERS base, the detection limit for rhodamine 6G (R6G) reached 10-10 M.

Drastic performance enhancement of photoluminescence and water electrolysis by local-magnetic-field-assisted LSPR of Ag NPs and NCs

A novel method is presented for drastically improving the local surface plasma resonance (LSPR) effect of noble metal nanoparticles (NPs) and nanoclusters (NCs). This is realized by magnetizing particles comprising a ferrimagnetic core and a noble metal nanoshell. In this study, we prepared Fe3O4 @SiO2 @Ag composite particles. Ag NPs and NCs had the size of 10–15 nm and 2–3 nm, respectively. The photoluminescence (PL) intensities of ZnO and YAG:Ce substrates coated with the magnetic composite particles increased by 160 % and 50 %, respectively, after magnetization under a magnetic field of 18 mT compared to the unmagnetized state. The activity of Ni-foam-based-Fe3O4 @SiO2 @Ag working electrode for water electrolysis was also significantly improved after magnetization. The increasing rate of current density after magnetization was 226 mA∙cm−2/0.1 V, which is higher than 158 mA∙cm−2/0.1 V before the magnetization. The mechanism for drastic performance enhancement of PL and water electrolysis postulates that after magnetization, the remanence of the ferrimagnetic Fe3O4 core provides a local magnetic field to strengthen the local electric field in the confined area of Ag NPs/NCs. It was confirmed by the higher intensity of peaks in Raman spectroscopy and contributed to the enhancement of LSPR effect. This efficient and practical approach to magnetization-induced LSPR improvement has potential application prospects in LSPR-related fields.

Fabrication of a high-performance photoelectrochemical aptamer sensor based on Er-MOF nanoballs functionalized with ionic liquid and gold nanoparticles for aflatoxin B1 detection

One of the most dangerous mycotoxins is Aflatoxin B1 (AFB1) that is commonly found in food. Thus, AFB1 has been considered as a serious food safety concern. Herein, using Er-MOF nanoballs assembled with gold nanoparticles (AuNPs) as photoactive elements, a photoelectrochemical aptasensor with high analytical performance was developed for sensing AFB1. Er-MOFs nanoballs were prepared by using ionic liquid as a ligand and Er3+ as a metal center through a solvothermal method. Chloroauric acid was reduced in-situ onto Er-MOF nanoballs to form Er-MOF@AuNPs nanocomposites. AuNPs can effectively enhance the photocurrent of Er-MOF nanoballs attributed to their excellent conductivity and local surface plasma resonance effect. In addition, they can provide active sites for immobilizing more biorecognition elements that can further enhance the sensing performance. Through self-assembling reaction, thiol-functionalized hairpin DNA (hDNA) was immobilized onto an Er-MOF@AuNPs-based interface to construct a photoelectrochemical biosensing platform. As the AFB1 aptamers labeled with gold nanoparticles (AuNPs-Apt) were selectively recognized, the photocurrent response can be further amplified. Due to the high affinity of AFB1 and its aptamer (Apt), when Apt is reacted with AFB1, it causes AuNPs-Apt detaching from the PEC aptasensing interface, and thus a reduced photocurrent response is generated. Under optimized conditions, the changes of photocurrent before and after recognition of AFB1 exhibits a linear response from 0.005 to 10.0 ng mL−1. In addition, the limit of detection obtained was 19.6 fg mL−1. This PEC aptasensor provides relatively high selectivity, reproducibility and accuracy in the determination of AFB1 in real corn samples.

CuO Nanozymes as Multifunctional Signal Labels for Efficiently Quenching the Photocurrent of ZnO/Au/AgSbS2 Hybrids and Initiating a Strong Fluorescent Signal in a Dual-Mode Microfluidic Sensing Platform.

A novel dual-mode microfluidic sensing platform based on CuO nanozymes as a photoelectrochemical (PEC)-fluorescent (FL) multifunctional signal label was developed for ultrasensitive neuron specific enolase (NSE) detection. Herein, ZnO/Au/AgSbS2 hybrids, possessing excellent PEC properties, were first exploited as a sensing matrix to provide a stable photocurrent. The controlled synthesis of photoactive ZnO nanoflowers (NFs) was successfully conducted using a microfluidic reactor in the scale of seconds. Furthermore, the photocurrent of ZnO NFs decorated by Au and AgSbS2 nanoparticles significantly improved, owing to the local surface plasma resonance effect of Au and matching band structure between ZnO and AgSbS2. A strategy of catalytic oxidation ascorbic acid (AA) by CuO nanozymes was proposed to quench the PEC signals and initiate FL signals. CuO nanoparticles growing on conductive carbon spheres (CuO@CSs) as secondary antibodies' labels could efficiently catalyze the oxidation of AA to achieve a PEC "signal-off" state. Then, the produced dehydroascorbic acid reacting with o-phenylenediamine opportunely generated a strong FL signal. Importantly, wide linear ranges of 0.0001-150 ng/mL for the PEC technique and 0.001-150 ng/mL for the FL method with a low detection limit of 0.028 and 0.25 pg/mL, respectively, could guarantee the sensitive detection of NSE.

Convex fiber-tapered seven core fiber-convex fiber (CTC) structure-based biosensor for creatinine detection in aquaculture.

The purpose of this article is to propose an optical fiber sensor probe based on the localized surface plasma resonance (LSPR) technique for the detection of creatinine in aquaculture. The sensing probe is functionalized through the use of gold nanoparticles (AuNPs), niobium carbide (Nb2CTx) MXene, and creatinase (CA) enzyme. The intrinsic total internal reflection (TIR) mechanism is modified to increase the evanescent field intensity using a heterogeneous core mismatch and tapering probe structure (i.e., convex fiber-tapered seven core fiber-convex fiber (CTC) structure). Strong evanescent fields can stimulate AuNPs and induce the LSPR effect, thereby increasing probe sensitivity. The specific recognition is enhanced by Nb2CTx MXene adsorbing more active CA enzymes. The developed sensor probe has a sensitivity and limit of detection of 3.1 pm/µM and 86.12 µM, respectively, in the linear range of 0-2000µM. Additionally, the sensor probe's reusability, reproducibility, stability, and selectivity were evaluated, with satisfactory results obtained with impact for areas like food protein, marine life and healthcare.

S-Scheme/Type-1 heterostructure stimulated WO3/g-C3N4-WS2 ternary photocatalyst with improved charge transfer mechanism for full solar spectrum photocatalysis

Combination of liquid ultrasonication and facile hydrothermal approach were used for synthesis of novel highly efficient WO3/g-C3N4-WS2 ternary photocatalyst. The presence of noble metal free WS2 as cocatalyst induced localized surface plasma resonance (LSPR) and extended the light utilizing spectrum of the ternary composite towards the NIR. An electrochemical property reveals that it follows combined S-Scheme/Type-1 mode of changer transfer mechanism in the ternary. Transient photocurrent validated the excitation of charge carriers in the presence of light with 18.18% increases in photocurrent for ternary. Formation of internal electric field at the interface of heterojunction restricted the recombination rate. The reduction in the charge transfer resistance by the introduction of WS2 was established through LSPR effect. Pore size varies from 2 to 30 nm confirms mesoporous structure. Highest donor density of 4.24 × 1023 was found in WOCNS. This has significantly enhanced photocatalysing ability and established successful degradation of both MB and MO under the direct sunlight and artificial NIR light source. AQY of WOCNS composite was found to be 66.67% higher than pristine g-C3N4 in the NIR region. The dominance of reactive oxygen species (ROS) such as superoxide radicals (.O2-) and holes (h+) were primarily responsible for decomposition of MB and MO. The ternary exhibited high stability and reusability with a removal efficiency of 87% for up to 5th consecutive cycles. This study demonstrates the novel S-scheme/Type-1 strategy for harnessing full solar spectrum with application towards water purification and industrial wastewater treatment.

Preparation of a Bi12O15Cl6@W18O49@g-C3N4/PDI heterojunction with dual charge transfer paths and its photocatalytic performance for phenolic pollutants

A novel plasmonic Bi12O15Cl6@W18O49@g-C3N4/PDI photocatalyst with dual charge transfer paths was prepared via a solvothermal method using W18O49 nanowires grown on Bi12O15Cl6 nanosheets, followed by loading graphitic carbon nitride/ pyromellitic acid dianhydride (g-C3N4/PDI) onto the resulting Bi12O15Cl6@W18O49 via simple calcination. The heterojunction displayed outstanding photocatalytic performance in the degradation of bisphenol A (BPA) under simulated sunlight illumination, achieving an efficiency of 100% with respect to the removal of BPA (10 ppm) within 30 min. The results of five recycling experiments and an X-ray diffraction analysis before and after degradation showed that the photocatalyst had a relatively stable structure and properties. The investigation of the mechanism regarding the enhanced activity of the plasmonic photocatalyst revealed that dual charge transfer paths and the localized surface plasma resonance effect significantly improved the photogenerated electron transport efficiency and light absorption capacity of the Bi12O15Cl6@W18O49@g-C3N4/PDI composite, which can effectively activate molecular oxygen, producing superoxide radicals and hydroxyl radicals. This study provides a novel platform for the application of the localized surface plasmon resonance effect in photocatalysis via the development of a photocatalyst with dual charge transfer paths.

Precise Preparation of Various Morphological Silver Sulfide Nanostructures, Investigation of Formation Mechanism, and Comparative Study of Photothermal Performance for Cancer Treatment

AbstractAs a bio‐nanomaterial with low toxicity, Ag2S has attracted more and more attention due to its intensive absorption of near‐infrared (NIR) light. Meanwhile, it has become a novel and excellent photothermal transduction agent due to its local surface plasma resonance effect. However, little research is conducted with respect to the influences of factors such as shapes on photothermal property. In this paper, a novel and convenient strategy is proposed to prepare three shapes of Ag2S (i.e., hollow nanospheres, nanoplates, and porous nanoplates), and their formation mechanisms are revealed through various characterizations. Furthermore, the in vitro capabilities of hollow Ag2S nanospheres are compared with nanoplates and porous nanoplates as photothermal transduction agents for theranostic applications. All these Ag2S nanostructures can absorb and convert 808 nm NIR light into heat. Among them, porous Ag2S nanoplates possess the highest photothermal conversion efficiency, whereas hollow Ag2S nanospheres have the maximum temperature difference. In addition, hollow Ag2S nanospheres exhibit the highest cellular uptake and the best treatment effect. Combined, it can be concluded that hollow Ag2S nanospheres are promising candidates for cancer treatment.

Design and preparation of Ag modified expanded graphite based composite phase change materials with enhanced thermal conductivity and light-to-thermal properties

Phase change materials (PCMs) is an excellent performance candidate for thermal energy storage and utilization. However, low thermal conductivity and low light-to-thermal conversion efficiency of PCMs are the serious limitation factors for highly efficient energy storage and photothermal conversion. In this paper, we reported a novel composite PCM based on lauric acid (LA) as the PCM supported by Ag nanoparticles modified expanded graphite (Ag-EG). The composite PCM of Ag-EG/LA possessed good energy thermal storage properties, which melted at 47.2 °C with the latent heat of 129.5 J/g at the LA maximum loading of 70.2%. Meanwhile, based on the high thermal conductivity and local surface plasma resonance effect of Ag, the composite (Ag-EG/LA) exhibits improved thermal conductivities (2.85 W/(m•K)) and high light-to-thermal energy conversion efficiency (η=81.2%). Moreover, the TGA and thermal cycles test results shown that Ag-EG/LA have good thermal stability and reliability. Hence, this novel composite of Ag-EG/LA could be potentially applicated in solar energy harvesting system and electric devices for thermal energy management.

Local surface plasma resonance effect enhanced Z-scheme ZnO/Au/g-C3N4 film photocatalyst for reduction of CO2 to CO

Local Surface Plasma Resonance (LSPR) effect enhanced Z-scheme ZnO/Au/g-C3N4 micro-needles film (3-ZAC) has been prepared for the photoreduction of CO2 into CO under UV–vis light irradiation. Photoreduction experiments show that 3-ZAC has the excellent photocatalytic performance and reusability. The CO production can be achieved 689.7 μmol/m2 after 8 h reaction time, which is 4.5 higher than that of the pure ZnO film. 13C isotope test shows that CO is produced from CO2 by photoreduction. DFT calculations confirm that build-in electric field formed at g-C3N4/ZnO interface effectively promoted the electron transfer efficiency in Z-scheme interface. FDTD simulations prove that Au NPs not only act as electron-transfer bridge, but also as LSPR excited source to speed up the separation of electron-hole pairs. In-situ FTIR technique was used to investigate the CO2 photoreduction process. The above characteristics together maximize the electron transfer efficiency, which causes the material has enhanced photocatalytic performance.

Ag-DNA@ZIF-8 membrane: A proton conductive photoswitch

Proton conductive metal-organic frameworks (MOFs) and further control of proton conduction are desired for advanced applications such as sensors and smart devices. Herein, the membrane of ZIF-8 co-modified by sliver nanoparticles and single-strand DNA (Ag-DNA@ZIF-8) is designed for proton conduction, which is switchable by light. In Ag-DNA@ZIF-8 membranes, light illumination can decrease the proton conductivity by 5 orders of magnitude. This decrement attributes to the heat from local surface plasma resonance effect that make water molecules break away from the pristine hydrogen-bonded network in DNA@ZIF-8, thus cutting off the proton transport pathway. The proton conductivity is reversible since when light turn off the water molecules can rebind with DNA again. The method of achieving highly switchable proton conductive MOFs by light is promising for the development of MOFs-based smart devices.

Novel all-solid-state Z-scheme SnO2/Pt/In2O3 photocatalyst with boosted photocatalytic performance on water splitting and 2,4-dichlorophenol degradation under visible light

Fabricating Z-scheme photocatalytic system is of great significance for water splitting and degradation of organic pollutants. However, it is highly challenging to select suitable materials to form Z-scheme photocatalysis systems due to the harsh requirement for band edge levels alignment and interfacial contact. In this work, a novel all-solid-state Pt-bridge SnO2/Pt/In2O3 Z-scheme photocatalyst was prepared by an ingenious in situ deposition and photo-reduction protocol. The physicochemical properties of prepared materials were characterized via SEM, TEM, BET, DRS, PL, and EIS. It is revealed that the visible light absorption capacity of prepared composites was remarkably enhanced due to the localized surface plasma resonance effect of Pt nanoparticles. Moreover, such Pt nanoparticles act as the electron mediator of photogenerated carriers, and the photogenerated electron hole pairs of SnO2/Pt/In2O3 Z-scheme photocatalysts can be effectively separated, which hence reserving the most favorable reductive and oxidative reaction sites. The photocatalytic degradation efficiency of 2,4-dichlorophenol (50 mg L−1) over SnO2/Pt/In2O3 under visible light reaches 90% in 180 min, and the optimal photocatalytic H2 generation rate reaches 967.018 μmol h−1 g−1, respectively more than 9.36 and 19.40 times higher than that of pure In2O3 (103.358 μmol h−1 g−1) and SnO2 (49.847 μmol h−1 g−1). In addition, the stability experiments showed that the H2 generation rate of the SnO2/Pt/In2O3 Z-scheme photocatalyst after five cycles has only decreased by 8.96%. This work not only demonstrates a facile and eco-friendly strategy to prepare highly active and stable photocatalyst, but provides a new viewpoint about designing and constructing novel Z-scheme photocatalytic materials.

Ag-graphene/PEG composite phase change materials for enhancing solar-thermal energy conversion and storage capacity

In view of the excellent characteristic of thermal energy storage, phase change materials (PCMs) are of great significance for improving the efficiency of solar thermal energy utilization. However, the direct thermal effect of visible-light (40% of solar radiation) is very low. In order to improve the capabilities of visible-light absorption and photothermal conversion, we reported novel and efficient sunlight-driven PCMs based on polyethylene glycol (PEG) supported by Ag nanoparticle-functionalized graphene nanosheets (Ag–GNS). The multi-folded layered structure provides Ag–GNS a large surface area to support PEG for achieving the shape stability before and after phase transition. Meanwhile, based on the local surface plasma resonance effect of Ag, Ag has high visible light selective absorption and infrared reflectance, which can give Ag–GNS enhanced light absorption capacity and reduced thermal radiation. So Ag–GNS/PEG can harvest sunlight and convert light to thermal energy with significantly higher efficiency (η = 88.7–92.0%). Moreover, Ag–GNS/PEG composites exhibit enhanced thermal conductivities (49.5–95.3%), high energy storage densities (>166.1 J/g), high thermal energy storage/release rates and outstanding form-stable properties. Therefore, this novel sunlight-driven composite can be potentially used for clean and efficient utilization of solar energy.

Visible-Light-Induced Effects of Au Nanoparticle on Laccase Catalytic Activity.

A deep understanding of the interaction between the nanoparticle and enzyme is important for biocatalyst design. Here, we report the in situ synthesis of laccase-Au NP (laccase-Au) hybrids and its catalytic activity modulation by visible light. In the present hybrid system, the activity of laccase was significantly improved (increased by 91.2% vs free laccase) by Au NPs. With a short time visible light illumination (λ > 420 nm, within 3 min), the activity of laccase-Au hybrids decreased by 8.1% (vs laccase-Au hybrid without light), which can be restored to its initial one when the illumination is removed. However, after a long time illumination (λ > 420 nm, over 10 min), the catalytic activity of laccase-Au hybrids consecutively decreases and is not reversible even after removing the illumination. Our experiments also suggested that the local surface plasma resonance effect of Au NPs causes the structure change of laccase and local high temperature near the Au NPs. Those changes eventually affect the transportation of electrons in laccase, which further results in the declined activity of laccase.

The Optical Property and Sensitivity of Ag Nanoparticles Deposited Ultra-Thin Diamond-Like Carbon Films

Ag nanoparticles (NPs) had most prominent local surface plasma resonance effect (LSPR) among the all metals. Diamond-like carbon (DLC) film had good biological compatibility, wear resistance, corrosion-resisting and high transmission ability in the visible and near-infrared range. Since the Ag NPs were easily oxidized in air,a new LSPR interface between them and an ultra-thin DLC films was formed by means of a plasma enhanced chemical vapor deposition (PECVD). The morphologies and properties of the Ag NPs deposited ultra-thin DLC films were studied by using Raman spectrometer, X-ray photoelectron spectrometer (XPS) , field emission scanning electron microscope (FESEM) and atomic force microscope (AFM) and so on. And the optical tramsmission sensitivity of the new LSPR interface was also examined. The results indicated that the DLC films deposited in a shorter time had a higher sp3bond content of carbon atoms and more sensitive to refractive index of surrounding media. Moreover, to obtain the optimal morphologies and the sensing property, the deposition time for forming the DLC films should be controlled within 30 seconds.

Optical properties of Ag doped ZnO nanocrystals prepared by hydrothermal and photodeposition method

Ag/ZnO nanocomposites have been synthesized by facile hydrothermal and photodeposition method. The effect of different concentration of Ag on the luminous intensity of ZnO was studied. The morphology, structure and optical properties of Ag/ZnO were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence (PL), respectively. The XRD patterns show that intensities of diffraction peaks of Ag/ZnO were enhanced. The weak diffraction peak at 38.28° can be assigned to Ag2O when the concentration of Ag increased to 0.09 M. PL results demonstrate that the UV luminous intensity of ZnO was significantly influenced by the concentration of Ag. The UV luminous intensity of Ag/ZnO nanocomposites increased by 11 times as compared with undoped ZnO when the concentration of Ag was 0.03 M due to the local surface plasma resonance effect of Ag nanoparticles.

Study on the Preparation of Silver Nanoparticles Coated with Diamond-Like Carbon Film and their Properties

Ag nanoparticles (NPs) have prominent local surface plasma resonance effect (LSPR), and Ag NPs exhibit sharpest and strongest bands among all metals. Diamond-like carbon (DLC) film have good biological compatibility and also have high transmissibility in the visible and near-infrared region. A new LSPR interface between Ag NPs and ultra-thin DLC film was formed by Plasma Enhanced Chemical Vapor Deposition. The morphologies and properties of the Ag NPs coated with DLC film were studied with SEM and AFM. The results indicated that the thickness of DLC film increased with the deposition time. LSPR peak became sharper after depositing for 1 or 2 min. DLC film was prior to nucleate on the surface of Ag NPs, and it has high content of sp2 bonds near the interface. The sensitivity of new LSPR interface deposited for 20s was about the half of the sensitivity of bare Ag NPs and the sensitivity significantly decreased with deposition time. This result is helpful to understand the behavior of the new LSPR interface and to improve its sensitivity.