Plasmonic Ag Research Articles

Ultrafast resonant exciton-plasmon coupling for enhanced emission in lead halide perovskite with metallic Ag nanostructures.

Integrating metal halide perovskites onto plasmonic nanostructures has recently become a trending method of enabling superior emissive performance of perovskite nanophotonic devices. In this work, we present an in-depth study on the spontaneous emission properties of hybrid systems comprising CsPbBr3 nanocrystals and silver nanostructures. Specifically, a 5.7-fold increment of the photoluminescence (PL) intensity and a 1.65-fold enhancement of the PL relaxation rate is attained when the transition energy of CsPbBr3 is spectrally resonant with the oscillational frequency of Ag nanodisks (NDs), which is attributed to the intense exciton-plasmon coupling-induced Purcell effect. Furthermore, a 540-fs ultrafast energy transfer from the CsPbBr3 excitons to Ag plasmons is revealed by femtosecond pump-probe experiments, suggesting the key mechanism responsible for the Purcell-enhanced radiative emission. Our finding offers a unique understanding of the enhanced emissive behavior in the plasmon-coupled perovskite system and paves the way for further applications.

Synthetic hybrid particles to improve the down-conversion efficiency of quantum dots via simultaneously induced scattering and plasmonic effects

Quantum dots (QDs) are promising color-conversion materials for various display applications owing to their high color purity, wavelength tunability, and high quantum yield. However, the self-quenching of QDs and internal reflection in the QD film reduce the external quantum efficiency, thereby hindering the applicability of the QD film. In this study, we propose a strategy to enhance the QD photoluminescence (PL) using hybrid particles, in which both scattering particles and plasmonic nanoparticles (NPs) are integrated. Using a facile synthetic route, we fabricated dielectric SiO2 microspheres decorated with plasmonic Ag NPs, and QDs were subsequently attached to the microsphere surface. The synthesized hybrid particles were embedded in a polymer matrix as down-conversion films. The proposed QD-embedded film exhibited up to a threefold improvement in the QDPL compared to the reference film. Along with the prominent down-conversion characteristics, the multifunctionality of our synthesized hybrid particles, such as flexibility, color tunability, and patternability, paves the way for wearable devices in a variety of practical applications.

Micelle-mediated assembly of metals in Ag@MnOx/m-SiO2 for reinforced antimicrobial activity and photothermal water evaporation

The increasing complexity of environmental pollution posed a higher requirement for the development of environment-governed functional materials. Herein, to achieve desired synergy and multiple functionalities of eco-friendly nanomaterials, a micelle-mediated metal assembly strategy was proposed to integrate plasmonic Ag nanoparticles into MnOx modified mesoporous silica hosts by metal-modified neutral dodecyl amine surfactant, correspondingly, a multifunctional mesoporous Ag@MnOx/m-SiO2 (AMSs) nanocomposite was obtained. The characterization results revealed that the introduction of Mn and alteration in the amount of Ag mediated the formation of a special mesostructure and nanometric morphology of the silica host. Bearing a low Ag loading (r.t. of Ag/Mn = 1/2), ultrafine Ag nanoparticles were embedded in the inner core of mesoporous silica nanospheres. While assembly with a higher Ag concentration affected the morphology of the obtained AMSs and resulted in rich Ag nanoparticles on the exterior surface of mesoporous silica. By this strategy, ultrafine Ag nanoparticles and well-dispersed amorphous MnOx species were coupled into the mesoporous silica to reach a special configuration and integrated functionality. The obtained AMSs-3 can effectively inactivate bacteria (E. coli, S. aureus, and P. aeruginosa) with a prolonged inhibitory effect, rapidly reduce harmful nitrophenol, as well as photothermally assist water evaporation (evaporation rate of 1.51 kg m−2 h−1, receiver efficiency of 87%). This work provides versatile environment-governing functional nanomaterials for both highly effective antimicrobial and environmental remediation.

Vibrational Spectro-Electrochemistry of Heme Proteins

Heme proteins perform a plethora of distinct cellular functions, including e.g. electron transport (ET), energy conversion, detoxification, catalysis, signaling, and gene regulation, and as such inspire a myriad of biotechnological applications. We use resonance Raman (RR) and Surface enhanced RR (SERR) spectroscopies to probe the architecture of the heme pocket in diverse heme proteins and enzymes, which is essential for the understanding of their physiological properties as well as for the evaluation of their potential for development of the 3rd generation bioelectronic devices (1,2). Moreover, plasmonic metal that gives origin to the surface enhancement of the Raman signal of the molecules found in its close proximity can serve as an electrode, thus driving electrochemical processes. In the case of heme proteins attached to plasmonic Ag electrodes, SERR spectra selectively show vibrational bands originating from the heme moiety only, which are sensitive to spin, coordination and redox state and of the heme iron. These properties that govern the catalytic performance of heme enzymes can be monitored in potential dependent manner by SERR spectro-electrochemistry.We have demonstrated that SERR spectro-electrochemistry possesses unique capacity of to i) disentangle ET processes in multi hemic proteins, such as 28 heme containing nitrite reductase, which represent a challenge for all other experimental approaches and ii) detect subtle immobilization induced structural changes in enzymes of biotechnological interest, which e.g. in the case of cytochrome P450 may prevent their successful applications (1-4). Here we show that SERRS monitoring of electrocatalytic processes by immobilized heme peroxidases, can provide information on catalytically relevant species in situ. Several members of a recently discovered family of heme dye-decolorizing peroxidases (DyPs) that possess remarkable catalytic properties in solution and high biotechnological potential, have been immobilized on biocompatible Ag electrodes. Their structural and electrocatalytic properties studied by RR, SERR spectro-electrochemistry and electrochemistry (2). The immobilized DyP from Pseudomonas putida (PpDyP), in particular, shows native structure and outstanding analytical and catalytic parameters, and hence an exceptional potential for development of 3rd generation biosensors for H2O2 detection. In terms of sensitivity, the bioelectrodes carrying immobilized PpDyP outperform HRP based counterparts reported in the literature (2,4). The biosensor based on a PpDyP variant that harbors mutations at the second shell of the heme cavity reveals further improved storage. Our work highlights the importance of integrated, multidisciplinary approach to simultaneously evaluate the structure and catalytic properties of the enzymes, which ensures faster identification and optimization of the promising candidates for biotechnological applications.

Plasmonic Ag decorated AlOOH for highly sensitive SERS detection of affinity OH groups molecules enriched in hotspots

Significant breakthroughs have been made in the development of surface-enhanced Raman scattering (SERS) substrates constructed by depositing plasmonic Ag onto nanostructured platforms. AlOOH is widely fabricated using hydrothermal, microwave, and microemulsion methods. Among these, the high catalytic activity of AlOOH prepared by the microemulsion method is derived from its high specific surface area, more active surface OH groups, and multi-active adsorption sites. And nanomaterials with such excellent properties have not yet been fabricated on a SERS-based platform to improve the Raman-enhanced properties of Ag achieving high-sensitivity detection of probe molecules especially with affinity for OH groups. The precious metal Ag has long been known to serve as traps to capture electrons and holes generated by plasmon resonance, reducing electron–hole recombination and exhibiting high activity in photocatalytic processes. In this work, to demonstrate the SERS substrate activity of the AlOOH@Ag complex, it has been successfully applied to identify congo red (CR) molecules with high sensitivity, methyl blue (MB) and methyl orange (MO), enabling trace-level detection with enhanced performance much stronger than Ag substrate.

A novel split-type photoelectrochemical biosensor based on double-strand specific nuclease-assisted cycle amplification coupled with plasmonic Ag enhanced BiVO4 performance for sensitive detection of microRNA-155

A novel split-type and signal-on photoelectrochemical (PEC) biosensor was proposed based on double-strand specific nuclease (DSN)-assisted recycling amplification coupled with photodeposited Ag enhanced BiVO4 photoanode for sensitive detection of microRNA (miRNA)− 155. In the presence of target miRNA, the capture DNA (cDNA) modified with silver nanocube（AgNC）would hybridize with the miRNA, then DSN-assisted cycle amplification was triggered, leading to the release of AgNCs. The released AgNCs were acidolyzed and photodeposited on the BiVO4 electrode. Compared with the BiVO4 electrode, an enhanced photocurrent could be achieved at this obtained BiVO4/Ag electrode. And the morphology change from worm-like nanoparticles to nanosheets after Ag photodeposition was observed for the first time. This PEC signal enhancement was mainly contributed to the synergistic action of localized surface plasmon resonance (LSPR) effect of Ag, Schottky junction formed between BiVO4 and Ag, and the formation of BiVO4 nanosheets with larger specific surface area. The PEC signal enhancement was positively related to the miRNA-155 concentration, so this method could be used to sensitively and selectively detect miRNA-155. A limit of detection of 8 aM could be achieved. This strategy does not require layer-by-layer modification of the electrode, so it is easy to operate, and owns good stability.

Perspective on plexciton based on transition metal dichalcogenides

Two-dimensional transition metal dichalcogenides (TMDCs) have outstanding physical advantages over graphene-like non-zero bandgap structures. It indicates that the monolayer TMDC material has significant light–material interaction, and it also implies that TMDCs have various application prospects in optoelectronic devices. The coupling of excitons and metal surface plasmons in monolayer TMDCs would affect the optical and electrical properties of the TMDC surface, and we revealed the improvement of surface catalytic reaction efficiency by plexcitons (coupling of excitons and plasmons) supported by recent experiments and theoretical reports. We also review the stress regulation on charge transfer excitons based on van der Waals (vdW) heterostructures composed of TMDCs, the special characteristics, and potential applications of coupling charge-transfer excitons with Ag plasmons in vdW and lateral heterostructures.

SERS Hotspot Engineering by Aerosol Self-Assembly of Plasmonic Ag Nanoaggregates with Tunable Interparticle Distance.

Surface‐enhanced Raman scattering (SERS) is a powerful sensing technique. However, the employment of SERS sensors in practical applications is hindered by high fabrication costs from processes with limited scalability, poor batch‐to‐batch reproducibility, substrate stability, and uniformity. Here, highly scalable and reproducible flame aerosol technology is employed to rapidly self‐assemble uniform SERS sensing films. Plasmonic Ag nanoparticles are deposited on substrates as nanoaggregates with fine control of their interparticle distance. The interparticle distance is tuned by adding a dielectric spacer during nanoparticle synthesis that separates the individual Ag nanoparticles within each nanoaggregate. The dielectric spacer thickness dictates the plasmonic coupling extinction of the deposited nanoaggregates and finely tunes the Raman hotspots. By systematically studying the optical and morphological properties of the developed SERS surfaces, structure–performance relationships are established and the optimal hot‐spots occur for interparticle distance of 1 to 1.5 nm among the individual Ag nanoparticles, as also validated by computational modeling, are identified for the highest signal enhancement of a molecular Raman reporter. Finally, the superior stability and batch‐to‐batch reproducibility of the developed SERS sensors are demonstrated and their potential with a proof‐of‐concept practical application in food‐safety diagnostics for pesticide detection on fruit surfaces is explored.

Nanoscale Manipulating Silver Adatoms for Aqueous Plasmonic Electrochromic Devices

AbstractPlasmonic colors are attractive building blocks for flat panel displays due to their broad color gamut and unprecedented subwavelength resolution. The exploration of reversible silver (Ag) electrodeposition for switchable plasmonic colors is considered as a promising strategy toward dynamically reconfigurable color displays. To date, the current reversible Ag electrodeposition‐based electrochromic devices are energy‐inefficient as the platforms are realized in nonaqueous electrolytes that require high working voltage. However, the high working voltage in an aqueous electrolyte leads to uncontrolled nucleation growth of Ag particles, thus rendering its application for color displays impractical. Herein, the first demonstration of the manipulation of Ag adatoms for aqueous plasmonic electrochromic devices through underpotential deposition is presented. It is shown that the Ag nanoparticles underpotential deposition not only enables a reversible voltage‐activated wide range of dynamic plasmonic color change of 100 nm, but also facilitates size control of the grown Ag nanoparticles. These findings provide a favorable and novel platform for low energy‐consumption tunable photonic and nanoplasmonic devices, as well as a simple and reliable process for rapid, scalable, and green preparation of tunable plasmonic Ag nanoparticles.

Photothermal Therapy with HER2-Targeted Silver Nanoparticles Leading to Cancer Remission.

Nanoparticles exhibiting the localized surface plasmon resonance (LSPR) phenomenon are promising tools for diagnostics and cancer treatment. Among widely used metal nanoparticles, silver nanoparticles (Ag NPs) possess the strongest light scattering and surface plasmon strength. However, the therapeutic potential of Ag NPs has until now been underestimated. Here we show targeted photothermal therapy of solid tumors with 35 nm HER2-targeted Ag NPs, which were produced by the green synthesis using an aqueous extract of Lavandula angustifolia Mill. Light irradiation tests demonstrated effective hyperthermic properties of these NPs, namely heating by 10 °C in 10 min. To mediate targeted cancer therapy, Ag NPs were conjugated to the scaffold polypeptide, affibody ZHER2:342, which recognizes a clinically relevant oncomarker HER2. The conjugation was mediated by the PEG linker to obtain Ag-PEG-HER2 nanoparticles. Flow cytometry tests showed that Ag-PEG-HER2 particles successfully bind to HER2-overexpressing cells with a specificity comparable to that of full-size anti-HER2 IgGs. A confocal microscopy study showed efficient internalization of Ag-PEG-HER2 into cells in less than 2 h of incubation. Cytotoxicity assays demonstrated effective cell death upon exposure to Ag-PEG-HER2 and irradiation, caused by the production of reactive oxygen species. Xenograft tumor therapy with Ag-PEG-HER2 particles in vivo resulted in full primary tumor regression and the prevention of metastatic spread. Thus, for the first time, we have shown that HER2-directed plasmonic Ag nanoparticles are effective sensitizers for targeted photothermal oncotherapy.

Plasmonic effect and bandgap tailoring of Ag/Ag2S doped on ZnO nanocomposites for enhanced visible-light photocatalysis

Ag/Ag2S-ZnO nanocomposites were prepared via a simple hydrothermal process followed by a plasmonic Ag+ reduction through a photo-deposition method. Ag2S was introduced to narrow the overall composite bandgap and activate the surface plasmon resonance (SPR) effect of the Ag+ cation present. The physicochemical properties of the as-synthesised catalysts were characterised by X-ray diffraction (XRD), scanning and transmission electron microscopies (SEM and TEM), Brunauer-Emmett-Teller (BET) analysis. Fourier-transform infrared spectroscopy (FTIR), Ultraviolet diffuse reflectance spectroscopy (UV–vis DRS), photoluminescence emission spectra (PL) and X-ray photoelectron spectroscopy (XPS) was conducted to investigate the photo-absorption and emission spectra of the nanocomposites. The degradation efficiency of all the synthesised catalysts (ZnO, Ag2S, Ag/ZnO and Ag2S/ZnO) prior to the final product, Ag/Ag2S/ZnO was tested and compared. Results showed that the ternary Ag/Ag2S/ZnO achieved a 98 % phenol removal compared to 50 %, 11 %, 64 % and 93 % for ZnO, Ag2S, Ag/ZnO and binary Ag2S/ZnO, respectively. The degradation kinetics followed the Langmuir-Hinshelwood model, which typically describes heterogeneous photocatalytic surface reactions. The linear fits had R2 values higher than 0.97, which confirms the degree of accuracy or statistical fitness to the kinetic model. Degradation scavenger test confirmed the holes (h+) as the main inhibitor and identified the superoxide O2•¯ radical as the main active specie responsible for the degradation. Total organic carbon analysis using the ternary Ag/Ag2S-ZnO catalyst only achieved a 74% phenol mineralization after 24 h of photocatalysis. Recyclability tests showed good phenol removal stability of Ag/Ag2S-ZnO at 41 % after five recycle runs. Hence, a synergistic degradation mechanism responsible for the efficient photo-degradation performance was proposed.

0D/2D/1D silver-decorated CuPc/Bi2MoO6 Z-scheme heterojunctions enable better visible-light-driven tetracycline photocatalysis

The pursuit of a desirable photocatalytic technology has always been accompanied by photocatalyst design and development, marking high activity, long-term stability, and low cost. Herein, an in-situ deposition approach is used to integrate plasmonic 0D Ag nanoparticles on the surface of 2D slice-like 2,9,16,23-tetranitrocopper(II) phthalocyanine (CuPc) sensitized 1D Bi2MoO6 nanofibers (Ag-CuPc/Bi2MoO6) for visible-light-induced tetracycline (TC) photocatalysis. Benefiting from the combination of 2D CuPc sensitization, and surface plasmon resonance (SPR) effect of 0D Ag nanoparticles, we experimentally find that the Ag-CuPc/Bi2MoO6 nanofibers boost the visible-light utilization efficiency, promote charge transfer, and separation, and accelerate electron redox transformation in TC photocatalysis. The superior photocatalytic activity is attributed to the strong interfacial interaction, and Z-scheme heterojunction synergy in Ag-CuPc/Bi2MoO6 nanofibers. This work opens new horizons for the delicate design of promising Z-scheme visible-light photocatalysts for the removal of antibiotics in wastewater, realizing water purifications.

Dual modification with plasmonic Ag and Co–Pi significantly promoted photoelectrochemical performances of CdS photoanodes

Dual modification with plasmonic Ag and Co–Pi significantly promoted photoelectrochemical performances of CdS photoanodes

Monosaccharide-mediated rational synthesis of a universal plasmonic platform with broad spectral fluorescence enhancement for high-sensitivity cancer biomarker analysis

BackgroundEffective and accurate screening of oncological biomarkers in peripheral blood circulation plays an increasingly vital role in diagnosis and prognosis. High-sensitivity assays can effectively aid clinical decision-making and intervene in cancer in a localized status before they metastasize and become unmanageable. Meanwhile, it is equally pivotal to prevent overdiagnosis of non-life-threatening cancer by eliminating unnecessary treatment and repeated blood draws. Unfortunately, current clinical screening methodologies can hardly simultaneously attain sufficient sensitivity and specificity, especially under resource-restrained circumstances. To circumvent such limitations, particularly for cancer biomarkers from early-onset and recurrence, we aim to develop a universal plasmonic platform for clinical applications, which macroscopically amplifies multiplexed fluorescence signals in a broad spectral window and readily adapts to current assay setups without sophisticated accessories or expertise at low cost.MethodsThe plasmonic substrate was chemically synthesized in situ at the solid–liquid interface by rationally screening a panel of reducing monosaccharides and tuning the redox reactions at various catalyst densities and precursor concentrations. The redox properties were studied by Benedict’s assay and electrochemistry. We systemically characterized the morphologies and optical properties of the engineered plasmonic Ag structures by scanning electron microscopy (SEM) and spectroscopy. The structure-fluorescence enhancement correlation was explicitly explained by the finite-difference time-domain (FDTD) simulation and a computational model for gap distribution. Next, we established an enhanced fluoroimmunoassay (eFIA) using a model biomarker for prostate cancer (PCa) and validated it in healthy and PCa cohorts. Prognosis was explored in patients subject to surgical and hormonal interventions following recommended PCa guidelines.ResultsThe monosaccharide-mediated redox reaction yielded a broad category of Ag structures, including sparsely dispersed nanoparticles (NPs) of various sizes, semi-continuous nanoislands, and crackless continuous films. Optimal broad-spectral fluorescence enhancement from green to far-red was observed for the inhomogeneous, irregularly-shaped semi-continuous Ag nanoisland substrate (AgNIS), synthesized from a well-balanced redox reaction at a stable rate mediated by mannose. In addition, different local electric field intensity distributions in response to various incident excitations were observed at the nanoscale, elucidating the need for irregular and inhomogeneous structures. AgNIS enabled a maximized 54.7-fold macroscopically amplified fluorescence and long-lasting photostability. Point-of-care availability was fulfilled using a customized smartphone prototype with well-paired optics. The eFIA effectively detected the PCa marker in cell lines, xenograft tumors, and patient sera. The plasmonic platform rendered a diagnostic sensitivity of 86.0% and a specificity of 94.7% and capably staged high-grade PCa that the clinical gold standard test failed to stratify. Patient prognosis of robotic-assisted surgeries and hormone therapies was non-invasively monitored following efficient medical interventions. The assay time was significantly curtailed on the plasmonic platform upon microwave irradiation.ConclusionsBy investigating the effects of reducing monosaccharides on the seed-mediated chemical synthesis of plasmonic Ag structures, we deduced that potent multiplexed fluorescence enhancement originated from both an adequate reducing power and a steady reduction rate. Furthermore, the inhomogeneous structure with adequate medium gap distances afforded optimal multiwavelength fluorescence enhancement, thus empowering an effective eFIA for PCa. The clinically validated diagnostic and prognostic features, along with the low sample volume, point-of-care feasibility with a smartphone, and microwave-shortened assay time, warrant its potential clinical translation for widespread cancer biomarker analysis.Graphical

Low Thresholds and Tunable Modes in Plasmon‐Assisted Perovskite Microlasers

AbstractLow‐dimensional perovskite structures are ideal materials for nano/microlasers owing to their excellent optical gain properties and high emission efficiency. But it is still a challenge to achieve single‐mode and tunable lasing behaviors in micro‐scale perovskite, especially showing ultralow thresholds in tens of µJ cm−2. In this work, CsPbBr3/Ag hemispheroids have been synthesized in a designed chemical vapor deposition (CVD) process. Benefiting from the whispering gallery resonance mode and plasmon‐enhanced light–matter interactions in well‐confined hybrid cavities, the CsPbBr3/Ag plasmonic microlasers exhibit low pump thresholds down to 35–51 µJ cm−2. Interestingly, single‐mode and two‐mode lasing behaviors are determined by the morphology of plasmonic Ag nanostructures, and lasing modes could be selectively tuned by increasing the pump fluence accompanying with dynamic competitions of photonic and plasmonic modes. Simulations of electromagnetic field have been plotted to show near‐field resonant modes for a comprehensive understanding of plasmon‐assisted lasing. These results not only provide a solution to fabricate low‐threshold plasmonic microlasers, but also advocate the prospect of all‐inorganic perovskite nanostructures as promising candidates for on‐chip integrated light sources.

Ternary Biocidal-Photocatalytic-Upconverting Nanocomposites for Enhanced Antibacterial Activity

Active antibacterial food packaging represents one of the most rapidly developing techniques in the food industry. The ability to inhibit, inactivate, kill, or maintain a low level of microbials in food products or food packages is crucial to reducing global foodborne diseases. Notably, metallic silver (Ag) and semiconducting titanium dioxide (TiO2) nanomaterials as well as their nanocomposites have been widely studied for food packaging because of their intrinsic biocidal and photocatalytic properties, respectively. However, they have inherent limitations associated with potential nanotoxicity of Ag nanoparticles and the need for ultraviolet (UV) irradiation for wide-bandgap TiO2 nanomaterials to invoke photocatalytic oxidation of microbials. In this context, upconverting nanocrystals (UCNCs) convert near infrared photons into visible and UV photons that could excite TiO2 without the use of a UV source. Herein, we designed ternary multifunctional nanocomposites composed of plasmonic Ag, photocatalytic TiO2, and upconverting NaYF4@Yb:Tm NPs as highly efficient biocidal nanomaterials under ambient light. The incorporation of UCNCs into the nanocomposites is found to be the key to enhanced antibacterial performance. Compared to Ag NP and Ag/TiO2 nanocomposite counterparts, the ternary Ag/TiO2/NaYF4@Yb:Tm nanocomposites yield superior antibacterial performance against Escherichia coli under both ambient light and solar simulator irradiation with UV photons filtered, when either applied alone or mixed with cellulose nanofibrils and then processed into films. Such multicomponent nanocomposites have great potential for use in food packaging as they reduce the amount of potentially toxic Ag used and are able to function without UV.

Dual-aptamer-based enzyme linked plasmonic assay for pathogenic bacteria detection

Development of rapid, sensitive, and selective method for pathogenic bacteria detection is of great importance for food safety, medical diagnostic, and environmental monitoring. Currently, most techniques for low numbers of bacteria detection require advanced instrumentation or skilled operators. Herein, we present a facile colorimetric detection platform for bacterial detection using Ag nanoplates as chromogenic substrate, which takes advantages of the high specificity and affinity of aptamer and the ability of catalase to hydrolyze H2O2 that can etch Ag nanoplates. By introducing catalase to the sandwich structure composed by dual-aptamer recognition strategy, bacteria detection signal is converted to the peak shift of LSPR and colorimetric change. This proposed method allows a fast naked-eye detection of S. aureus at the concentration of 60 CFU/mL based on the combination of streptavidin-biotin system and inherent sensitivity of plasmonic Ag nanoplates. Owing to the high selectivity and sensitivity, as well as the low-cost and good adaptability, this plasmonic assay is expected to be suitable for pathogenic bacteria detection in resource-limited settings.

Broadband self-powered photodetection with p-NiO/n-Si heterojunctions enhanced with plasmonic Ag nanoparticles deposited with pulsed laser ablation

Broadband self-powered photodetection with p-NiO/n-Si heterojunctions enhanced with plasmonic Ag nanoparticles deposited with pulsed laser ablation

Pulse electrodeposition of Ag, Cu nanoparticles on TiO2 nanoring/nanotube arrays for enhanced photoelectrochemical water splitting

In this paper, plasmonic Ag and Cu nanoparticles were co-deposited on TiO2 nanoring/nanotube arrays (TiO2 R/T) by using two-step pulse electrodeposition method for investigating the optical and photoelectrochemical properties, in comparison to monometallic Ag, Cu decoration. By optimizing the electrodeposition cycle times and electrolyte concentration, bimetallic Ag–Cu/TiO2 R/T-0.5 with moderate densities and sizes of Ag and Cu nanoparticles was fabricated and shows great photocatalytic potential, in which, Ag mainly facilitates the generation of hot electrons by absorbing visible light and Cu plays an important role in accelerating the separation and transportation of hot electrons. The hydrogen production rate was tested as 425 μL h−1 cm−2, which is about 1.34-fold enhanced H2 production over TiO2 R/T. Furthermore, molecular dynamics simulations were made for analyzing the interface electrostatic properties between plasmonic nanoparticles of Ag or Cu and the semiconductor TiO2. It is calculated that bimetallic Ag–Cu/TiO2/H2O system has larger interfacial Helmholtz potential than monometallic Ag/TiO2/H2O, Cu/TiO2/H2O and pure TiO2/H2O systems, accelerating the four-electron reaction occurring at the semiconductor/electrolyte interface. This research put forward a feasible and simple pulse electrodeposition method to fabricate bimetallic photoanodes for enhanced hydrogen evolution and an important analysis method of semiconductor/ metal/electrolyte interface characteristics.

Visible-light-active 1D Ag-CoWO4/CdWO4 plasmonic photocatalysts boosting levofloxacin conversion

The photocatalysis stride is highly dependent on the design and construction of photocatalysts, marking high activity, and long-term stability. A novel photocatalyst of plasmonic Ag decorated CoWO4/CdWO4 (Ag-CoWO4/CdWO4) tube-like Z-scheme heterojunction was firstly constructed via two-step electrospinning and in-situ deposition approach. Benefiting from the synergistic effects of Z-scheme heterojunctions, 1D tubular structure, and the localized surface plasmon resonance (LSPR) effect of Ag nanoparticles, the Ag-CoWO4/CdWO4 heterostructured photocatalysts showed strong visible-light absorption, high charge separation, and a photocatalytic activity enhancement in levofloxacin (LVF) photocatalysis. Experimental results reveal that ·OH, h+ and ·O2− act as reactive species, promoting and accelerating LVF oxidation. Our work gives the idea of introducing a dedicated composite photocatalyst, conquering individual materials’ intrinsic limits, for wastewater in practical applications.