Triangular Nanoplates Research Articles

Simultaneous detection of enrofloxacin and chloramphenicol antibiotics using surface-enhanced Raman spectroscopy combined with triangular silver nanoplates

The emergence of antibiotic residues in the environment and food requires the development of sensitive and selective detection methods for monitoring these contaminants. In fact, many different types of antibiotics will be used simultaneously to prevent diseases in livestock and aquatic animals, causing antibiotic residues in food and the environment. Rapid and accurate simultaneous analysis of multiple antibiotics at low concentrations remains a major challenge in in the field of rapid detection. This study presents a sensitive and selective method for the simultaneous detection of two widely used antibiotics, enrofloxacin and chloramphenicol, by combining surface-enhanced Raman spectroscopy (SERS) with triangular silver nanoplates. Triangular silver nanoplates (TAgNPls) in the form of colloid were simply synthesized by chemical reduction method and then used as an effective SERS substrate, enhancing the Raman signals of the target antibiotics and enabling the detection of these antibiotics at trace levels. It was found that with a SERS substrate assembled from the above TAgNPls, the antibiotics enrofloxacin and chloramphenicol could be detected with detection limits of 2.6 µg/L and 4.3 µg/L, respectively. In addition, this SERS substrate also allows simultaneous detection of the above two antibiotics in one analytical sample with concentrations as low as 10 µg/L for both substances. The proposed method holds promise for addressing concerns related to antibiotic contamination in various environments and food sources, contributing to the advancement of analytical techniques for the trace detection of pharmaceutical residues.

Mellitic Acid-Supported Synthesis of Anisotropic Nanoparticles Used as SERS Substrate.

A method for the synthesis of a new SERS substrate-anisotropic silver nanoparticles using mellitic acid as a new capping agent is presented. The synthesis is free of toxic substances and does not require special temperature or lighting conditions. Moreover, it is fast, easy, and inexpensive. Depending on the concentration of silver ions and nanoparticle seeds, four different colloids were obtained, representing the evolution of nanoparticle growth along different paths from the first common stage. One of the synthesized colloids consists mainly of triangular nanoplates, while the other consists of polyhedral NPs. The analysis of the synthesis process together with the observation of TEM images and UV-vis extinction spectra enabled the proposal of the mechanism of interaction of mellitic acid molecules as the capping agent. The ability of mellitic acid molecules to form a hydrogen bond network, together with a ratio of silver ions to the mellitic acid concentration, turned out to be crucial for determining the shape of the NPs. All obtained colloids strongly enhance the Raman spectra of analyte molecules, thus proving their applicability as efficient new SERS substrates. For the one that enhanced the spectra the most, the detection limit was set at 10-9 M. Using it as a SERS substrate enables the identification of a trace amount of a designer drug, i.e., 4-chloromethcathinone (4-CMC, clephedrone). For the first time, SERS spectra of this substance, illegal in many countries, are presented.

(Invited) Plasmonic Nanofabrication of Chiral Nanodisk Ensembles

Chiral plasmonic nanostructures attract attention because those could be applied to enantioselective chemical sensors, optical isolators, light sources for circularly polarized light (CPL), metasurfaces, and metamaterials. In many cases, chiral plasmonic nanostructures are fabricated by a top-down method such as electron beam lithography (EBL). Since EBL is time-consuming and expensive, we have developed photoelectrochemical methods in which a site-selective reaction is driven by optical near field generated around anisotropic metal nanoparticles under right- or left-CPL. As anisotropic metal precursors for preparation of chiral nanoparticles, we have used gold or silver nanocuboids, nanorods, nanocubes, and triangular or hexagonal nanoplates so far.1-5 In the present work we demonstrate that laterally isotopic, circular nanodisks can also be used as precursors for the preparation of chiral nanostructures.We prepared ensembles of circular gold nanodisks on a glass plate by a nanosphere lithography method. A glass plate was coated with a gold thin film, and an array of polystyrene spheres (500 nm diameter) was prepared on the gold film. The polystyrene spheres were etched by oxygen plasma, and the exposed gold film was etched by argon ion milling. As a result, an ensemble of gold nanodisks (~200 nm diameter) was obtained. Each nanodisk was capped with a polystyrene cone, and the cap was removed by sonication in toluene if necessary. We used both capped and uncapped nanodisk ensembles. The ensemble was irradiated with visible right- or left-CPL in the presence of silver ions and sodium citrate. The obtained Au-Ag nanostructures exhibited circular dichroism (CPL), indicating that the nanostructures have chirality. Initial deposition at arbitrary site may break the geometric symmetry, resulting in the growth into chiral structures. Saito, K.; Tatsuma, T. Nano Lett. 2018, 18, 3209–3212.Morisawa, K.; Ishida, T.; Tatsuma, T. ACS Nano 2020, 14, 3603–3609.Shimomura, K.; Nakane, Y.; Ishida, T.; Tatsuma, T. Appl. Phys. Lett. 2023, 122, 151109.Homma, T.; Sawada, N.; Ishida, T.; Tatsuma, T. ChemNanoMat 2023, 9, e202300096.Ishida, T.; Isawa, A.; Kuroki, S.; Kameoka, Y.; Tatsuma, T. Appl. Phys. Lett. 2023, 123, 061111.

Engineering the Blackbody Absorption of the Au-Branch-on-Au-Plate Heterostructures.

Utilizing the strong ligand control effects of l-cysteine (l-Cys), the growth of Au on Au triangular nanoplate (AuTN) seeds was continuously tuned from layer-by-layer (the Frank-van der Merwe) to layer-plus-island (the Stranski-Krastanov), and island (the Volmer-Weber) growth modes, leading to the formation of a series of Au-on-AuTN heterostructures. Within the window of VW growth mode (featured by the growth of Au spikes and branches on AuTNs), the effective localized surface plasmon resonance (LSPR) coupling led to the selective strengthening of the "valley" absorptions, leading to smooth and flat absorption curves. Interestingly, through engineering the number/density, size, and branching degree of the Au branches, except for the black color, full spectrum absorption within 400-1300 nm wavelength was achieved on Au-branch-on-AuTN structures. Mechanistic studies revealed that the blackbody absorption property of the Au-branch-on-AuTN originates from the well-balanced intraparticle LSPR couplings among the neighboring Au branches. The tunable blackness and the full spectrum absorption property made the Au-branch-on-AuTN heterostructure a suitable candidate for various plasmonic-related applications, such as a wide spectrum light absorber, photoacoustic imaging contrast agent, and photothermal therapy medium. In addition, our strong ligand control in Au-branch-on-AuTN heterostructures could be extended to other hybrid systems with diverse material combinations, so long as to find the proper strong ligand.

Fabrication of SERS composite substrates using Ag nanotriangles-modified SiO2 photonic crystal and the application of malachite green detection

A novel surface-enhanced Raman scattering (SERS) composite substrates on the basis of Ag triangular nanoplates(Ag TNPs)-modified SiO2 photonic crystals (PC) is fabricated and applied to the SERS detection of malachite green (MG). It consists of uniformly arranged Ag TNP@SiO2, a new PC. Notably, Ag TNP are uniformly aligned on the SiO2 surface, forming a three-dimensional high-density hotspot nanostructure. With the tip “hot spots” of Ag TNPs, Bragg diffraction of SiO2 and coupling enhancement between Ag TNPs and SiO2, the SERS enhancement of this composite substrates was multiplied. The effect on the SERS of Ag TNP@SiO2 composite substrate was systematically optimized by tuning Ag TNP size, size of SiO2 microspheres, coverage of Ag TNPs on SiO2 and fabrication method of Ag TNPs and PC. Moreover, the uniform of SERS composite substrates and Raman signal was dramatically increased by the method of vertical deposition. Eventually, the SERS composite substrates were employed in MG detection. Its broad detection range of 1 pM–1 μM and low limit of detection (LOD) of 0.49 pM indicated acceptable sensitivity and repeatability. This work illustrates the promising applicability in food safety analysis based on SERS composite substrates composed by Ag TNP@SiO2 with numerous SERS enhancements and excellent stability.

Insight into the size-dependent activity in Ag/SiO2 catalyzed hydrogenation of dimethyl oxalate to methyl glycolate

Methyl glycolate (MG) is an important building block for synthesizing biodegradable material of polyglycolic acid. Hydrogenation of coal-based dimethyl oxalate (DMO) to MG is quite promising, where Ag-based catalysts exhibited excellent selectivity. Here, a series of Ag/SiO2-x catalysts with particle sizes of 1.4–13.5 nm were prepared, which showed significant structural sensitivity in DMO hydrogenation. For Ag nanoparticles of 1.4–2.7 nm, the turnover frequency (TOF) was linearly increased with the surface electron density of silver, but when the Ag nanoparticles further enlarged, no significant variation of TOF was observed. Combining DFT calculation and experimental results of the model catalyst, triangular nanoplate, it was deduced that the Ag (111) played a dominant role in DMO hydrogenation to MG, originating from the benefited MG desorption as well as promoted dissociation of H2 and DMO. This understanding about Ag particle size effect may provide guidance for designing efficient catalysts for DMO hydrogenation to MG.

Radially polarized light in single particle optical extinction microscopy identifies silver nanoplates

Quantifying the optical extinction cross section of a single plasmonic nanoparticle (NP) has recently emerged as a powerful method to characterize the NP morphometry, i.e., size and shape, with a precision comparable to electron microscopy while using a simple optical microscope. Here, we enhance the capabilities of extinction microscopy by introducing a high numerical aperture annular illumination coupled with a radial polarizer to generate a strong axial polarization component. This enables us to probe the NP response to axial polarized light, and, in turn, to distinguish flat-lying nanoplates from other geometries. Polarization-resolved optical extinction cross sections were acquired on 219 individual colloidal silver NPs of a nominally triangular nanoplate shape but, in practice, exhibiting heterogeneous morphometries, including decahedrons and non-plate spheroids. An unsupervised machine learning cluster analysis algorithm was developed, which allowed us to separate NPs into different groups, owing to the measured differences in cross sections. Comparison of the measurements with a computational model of the absorption and scattering cross section accounting for nanoplates of varying geometries beyond simple triangles provided insight into the NP shape of each group. The results provide a significant improvement of polarization-resolved optical extinction microscopy to reconstruct NP shapes, further boosting the utility of the method as an alternative to electron microscopy analysis.

Microwave-synthesized aluminum, gallium and indium-substituted stannite nanocrystal absorbers for solar cell applications

A novel family of Cu2FeXS4-x (X = Sn, Al, Ga & In) semiconductors with tetragonal stannite crystal structurehave been designed by a simple microwave assisted method. The impact of microwave power on the morphological, structural,spectroscopic and electrochemical properties were investigated. X-ray Diffraction (XRD) clearly revealed that the complete substitution of Sn (0.69 Å) with Al (0.54 Å), Ga (0.62 Å) and In (0.80 Å) did not affect the tetragonal arrangement of the stannite crystal structure except for a slight peak shift. High resonance scanning and transmission electron microscopy (HRSEM and HRTEM) revealed nano bullets, hexagonal prism, triangular nanoplates and spherical morphology with nanocrystal sizes ranging from 8 to 13 nm for CFXS nanocrystals. The UV–visible spectroscopy shows strong light absorption in the whole visible range with band gaps of between 1.2 and 1.6 eV suggesting its potential application as an absorber in thin film solar cells. Doctor blading method was used to coat CFXS nanocrystal inks on CdS coated ZnO nanorod arrays to fabricate a superstrate solar cell devices with the architecture ITO/ZnONRs/CdS/CFXS/Ag. The solar cell devices fabricated with copper iron tin sulfide (CFTS), copper iron aluminium sulfide (CFAS), copper iron gallium sulfide (CFGS) and copper iron indium sulfide (CFIS) absorbers displayed a power conversion efficiency (PCE) of 0.21%, 0.15%, 0.58% and 0.41% respectively. The photovoltaic response exhibited by the novel materials is quite positive and this shows that they can in fact be utilized to design solar cells with strong photovoltaic properties.

Near-Infrared Responsive Ag@Au Nanoplates with Exceptional Stability for Highly Sensitive Colorimetric and Photothermal Dual-Mode Lateral Flow Immunoassay.

Lateral flow immunoassay (LFIA) has played a vital role in point-of-care (POC) testing on account of its simplicity, rapidity, and low cost. However, the low sensitivity and difficulty of quantitation limit its further development. Sensitive markers with new detection modes are being developed to dramatically improve LFIA's performance. Herein, a ligand-complex approach was proposed to uniformly coat a thin layer of Au onto Ag triangular nanoplates (Ag TNPs) without etching the Ag cores, which not only retain the unique optical properties from Ag TNPs but also acquire the surface stability and biocompatibility of gold. The localized surface plasmon resonance absorption of these Ag@Au TNPs could be finely adjusted from visible (550 nm) to the second near-infrared region (NIR-II) (1100 nm), and even longer, by simply adjusting the ratio between edge length and thickness. Utilizing the Ag@Au TNPs as new markers for LFIA, a highly sensitive colorimetric and photothermal dual-mode detection of the SARS-CoV-2 nucleocapsid protein was achieved with a very low background. The Ag@Au TNPs showed an exceedingly high photothermal conversion efficiency of 61.4% (ca. 2 times higher than that of Au nanorods), endowing the LFIA method with a low photothermal detection limit (40 pg/mL), which was 25-fold lower than that of the colorimetric results. The generality of the method was further verified by the sensitive and accurate analysis of cardiac troponin I (cTnI). This method is robust, reproducible, and highly specific and has been successfully applied to SARS-COV-2 detection in 35 clinical samples with satisfactory results, demonstrating its potential for POC applications.

Naked-eye rapid recognition of tyrosine enantiomers using silver triangular nanoplates as colorimetric probe

Recognizing and quantifying enantiomers of chiral molecule is of great importance in chemical, biological and pharmaceutical fields. Herein, we presented one simple-yet-efficient method of sensing tyrosine (Tyr) enantiomers. In this sensing, silver triangular nanoplates (AgTNPs) were used as colorimetric probes. L-Tyr quickly induced the color of AgTNPs solution to change from dark blue to light gray, whereas D-Tyr induced no change of the AgTNPs solution color. The obvious color change enables the naked eye to recognize Tyr enantiomer. The visual method was used to detect the enantiometric excess value of L-Tyr in the whole range (−100 % ∼ 100 %). This chiral sensing can be finished within 5 min using one simple ultraviolet–visible spectrometer or naked eye. Furthermore, the mechanism of this chiral sensing was explored. It was confirmed that this chiral sensing was based on AgTNPs’ intrinsic chirality. This chiral sensing is rapid, simple, and low-cost, and has great potential for chiral determination of Tyr.

Shearing-induced formation of Au nanowires.

Shearing-induced nucleation is known in our daily lives, yet rarely discussed in nano-synthesis. Here, we demonstrate an unambiguous shearing-induced growth of Au nanowires. While in static solution Au would predominately deposit on pre-synthesized triangular nanoplates to form nano-bowls, the introduction of stirring or shaking gives rise to nanowires, where an initial nucleation could be inferred. Under specific growth conditions, CTAB is responsible for stabilizing the growth materials and the resulting oversaturation promotes shearing-induced nucleation. At the same time, all Au surfaces are passivated by ligands, so that the growth materials are diverted to relatively fresher sites. We propose that the different degrees of "focused growth" in active surface growth could be represented by watersheds of different slopes, so that the subtle differences between neighbouring sites would set course to opposite pathways, with some sites becoming ever more active and others ever more inhibited. The shearing-induced nuclei, with their initially ligand-deficient surface and higher accessibility to growth materials, win the dynamic inter-particle competition against other sites, explaining the dramatic diversion of growth materials from the seeds to the nanowires.

Silver Triangular Nanoplates as Analytical Reagents in Optical Molecular Absorption Spectroscopy: Possibilities and Prospects

Silver Triangular Nanoplates as Analytical Reagents in Optical Molecular Absorption Spectroscopy: Possibilities and Prospects

Early Detection of Carcinoembryonic Antigen Using Hollow Nanospheres Improves the Outcome of Pediatric Solid Tumors

A sandwich electrochemical immunosensor was developed for sensitive detection of carcinoembryonic antigen (CEA) using hollow nanospheres composite material loaded with gold nanoparticles as the signal tag and gold triangular nanoplate as the substrate material. Samples obtained from pediatric solid tumor tissue and their blood samples were used to detect CEA using this nanoparticle. The hollow nanospheres constructed in this study, provided abundant reaction sites and high catalytic activity, while the loading of Au NPs enhances conductivity and biocompatibility. The immunosensor has good analytical ability in detecting CEA in the mass concentration range of 1 pg/mL to 50 ng/mL, with a low detection limit (LOD) of 0.37 pg/mL. This novel method provides a valuable tool for rapid clinical detection of CEA in the context of pediatric solid tumors.

AgTNP@TiO2@Ag core-satellite composites for sensitive sensing and in situ monitoring photodegradation of organic dyes by portable Raman spectrometer

The development of sensitive, reliable, and robust substrates for surface-enhanced Raman spectroscopy (SERS) heavily relies on the creation of numerous hot spots. In this study, we propose a simple approach to fabricate core-satellite composites composed of AgTNP@TiO2@Ag, where Ag triangular nanoplates (AgTNPs) act as the cores, TiO2 serves as the interlayer, and Ag nanoparticles are deposited around them to form Ag satellites. By adjusting the amount of AgNO3, we precisely control the coverage of Ag nanoparticles on AgTNP@TiO2@Ag, thus fine-tuning their SERS sensitivity. Various characterization techniques were employed to examine their composition, morphology, and crystal structure. Thanks to the abundant hot spots created by the Ag satellites, these composites exhibit significantly enhanced SERS sensitivity and they demonstrate the capability to detect methylene blue (MB) at a concentration of 10−10 M by portable Raman spectrometer. Moreover, the AgTNP@TiO2@Ag composites effectively enable in situ SERS monitoring of the photodegradation reaction of MB. Overall, the novel AgTNP@TiO2@Ag composites prepared in this study exhibit high SERS sensitivity and excellent photocatalytic performance, making them highly valuable for environmental detection and ecological restoration purposes.

Apparent symmetry rising induced by crystallization inhibition in ternary co-crystallization-driven self-assembly

The concept of apparent symmetry rising, opposite to symmetry breaking, was proposed to illustrate the unusual phenomenon that the symmetry of the apparent morphology of the multiply twinned particle is higher than that of its crystal structure. We developed a unique strategy of co-crystallization-driven self-assembly of amphiphilic block copolymers PEO-b-PS and the inorganic cluster silicotungstic acid to achieve apparent symmetry rising of nanoparticles under mild conditions. The triangular nanoplates triply twinned by orthogonal crystals (low symmetry) have an additional triple symmetry (high symmetry). The appropriate crystallization inhibition of short solvophilic segments of the block copolymers favors the oriented attachment of homogeneous domains of hybrid nanoribbons, and consequently forms kinetic-controlled triangular nanoplates with twin grain boundaries.

Solid-Phase Spectrometric Determination of Organic Thiols Using a Nanocomposite Based on Silver Triangular Nanoplates and Polyurethane Foam.

Adsorption of silver nanoparticles on polymers may affect the processes in which they participate, adjusting the analytical characteristics of methods for the quantitation of various substances. In the present study, a composite material based on silver triangular nanoplates (AgTNPs) and polyurethane foam was proposed for chemical analysis. The prospects of its application for the solid-phase/colorimetric determination of organic thiols were substantiated. It was found that aggregation of AgTNPs upon the action of thiols is manifested by a decrease in the AgTNPs' localized surface plasmon resonance band and its significant broadening. Spectral changes accompanying the process can be registered using household color-recording devices and even visually. Four thiols differing in their functional groups were tested. It was found that their limits of detection increase in the series cysteamine < 2-mercaptoethanol < cysteine = 3-mercaptopropionic acid and come to 50, 160, 500, and 500 nM, respectively. The applicability of the developed approach was demonstrated during the analysis of pharmaceuticals and food products.

Limits of antibacterial activity of triangular silver nanoplates and photothermal enhancement thereof for Bacillus subtilis

Currently, nanoparticles are being actively explored for antimicrobial applications involving variety of pathogens. Bacillus subtilis is a major concern considering its sporulation and biofilm formation capability which involves high bacteria loadings. Also, there is natural ability of B subtilis to adapt and develop resistance to the silver nanoparticles alone. So, this study reports the limits of antibacterial activity of triangular silver nanoplates (∆AgNPs) and further photothermal enhancement for B. subtilis ATCC 6051 for considerably high bacterial load of 2.5 × 107 to 5 × 108 CFU/ml.Triangular silver nanoplates were synthesized using one pot synthesis method and showed significant photothermal response i.e., ∼36 °C temperature rise on near infrared irradiation as well as photothermal stability. Triangular silver nanoplates alone showed absolute destruction for 2.5 × 107 CFU/ml initial B. subtilis load in 5 min. Whereas, for further higher bacterial loads, the antibacterial efficacy of ∆AgNPs is observed to be insignificant. For higher initial bacterial loads of 5 × 107 CFU/ml and 5 × 108 CFU/ml, photothermally enhanced triangular silver nanoplates resulted in complete destruction of bacteria in about 5 and 10 min, respectively. Antibacterial efficacy and mechanism of the destruction assessed via scanning electron microscopy and LIVE/DEAD assay confirmed morphological deformities. Further the generation of higher levels of reactive oxygen species is also confirmed due to photothermal activation of ∆AgNPs. The study concludes that ∆AgNPs alone are effective only up to bacterial load of 2.5 × 107 CFU/ml. Whereas, for higher bacterial loads of B. subtilis, photothermally activated ∆AgNPs lead to irreversible damage due to multiple targeting mechanisms leading to absolute elimination in short span of 5–10 min for the chosen irradiation conditions.Ultimately, this study demonstrates photothermally enhanced silver nanoplates as a potential antimicrobial agent for considerably high bacterial loads of B. subtilis. Overall, the broader window of considered high bacterial loadings and its irradiation by this technique shows the full-proof nature of photothermal applications for scenarios involving high cell density such as biofilms and wound infections etc. Further, the concept may be useful for sterilization or decontamination of samples, devices, etc. because B. subtilis and its spores are the challenges during sterilization.

MoS2 embedded triangular silver nanosheets modified MOF-808 as electrochemical sensing platform for highly sensitive simultaneous detection of ACOP and 4-AP

The detection of acetaminophen (ACOP) and its toxic hydrolyzed product p-aminophenol (4-AP) is very significant for clinical diagnosis and quality control of drug formulation. In this study, a novel electrochemical sensor based on MoS2 embedding triangular Ag nanoplates (Tri-AgNPs) coated MOF-808 was developed for simultaneous and sensitive detection of ACOP and 4-AP. The morphology and structure MOF-808@MoS2/Tri-AgNPs nanocomposite were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and so on. The electrochemical and electrocatalytic properties of the composite electrode were evaluated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The experimental results demonstrated that the constructed sensor had excellent electrochemical performance for ACOP and 4-AP detection due to the synergistic interaction among MOF-808, MoS2 and Tri-AgNPs. The proposed sensor exhibited a wide linear range (1–450 μM) and low limits of detection for detection of ACOP (0.054 μM) and 4-AP (0.046 μM). At the same time, the sensor also showed outstanding repeatability, reproducibility, stability and selectivity. In addition, MOF-808@MoS2/Tri-AgNPs/GCE was also employed to determine ACOP and 4-AP in acetaminophen tablets and Yellow River water samples with satisfactory recovery rates, which indicated the feasibility of the developed electrochemical sensor in the actual sample analysis.

Close-packed small nanocubes assemblies as efficient SERS substrates

Silver-based nanostructures, especially the anisotropic ones such as triangular nanoplates, nanorods, nanocubes or silver nanowires, are used as Surface enhanced Raman scattering substrates for different analytes sensing, with outstanding results, in terms of the limit of detection (LOD), as well as the enhancement factor (EF), being applicable for early clinical diagnosis of cancer, trace level detection of different organic pollutants, or for the pesticides’ detection, and even explosives. Among all these shapes, cubes like nanoparticles (AgNCs) can generate intense hot-spots due to their corners and edges, due to some additional plasmonic modes that occur at different resonance wavelengths in the spectrum, thus, improving SERS sensitivity.In this work we have successfully synthesized silver AgNCs of 60 nm, that were then assembled on a planar silicon substrate, and use it as a simple SERS substrate towards Rh6G dye. We were able to obtain an averaged calculated EF of 1.78 × 108, with a limit of detection of 4. 16 × 10−12 M. Furthermore, the effect of nanocubes’ configurations was investigated through the numerical calculations, being revealed that the edge-to-edge arrangement exhibits the highest EF of about 109, followed by the edge-to-face (8.6 × 108) and face-to-face (9 × 107) arrangements, in good agreement with experimental calculated value, ∼108, considering the frequency of appearance of each configuration.Our studies related to the use of assemblies of smaller AgNCs on planar silicon surface, with no further nanostructuration process, as SERS based substrates towards one of the most known analyte molecules, as well as an organic dye pollutant, are very encouraging, giving the chance to explore the emerging properties of small nanocubes towards low concentration detection of different organic molecules, thus showing great applicability in both scientific research and practical application, like water pollutants or even foodborne pathogen detection.

Triangular silver nanoplates-BiVO4 composite for the photocatalytic CO2 reduction under irradiating LED light source

In this study, triangular silver nanoplates (TagNPts)/BiVO4 nanomaterials were prepared by hydrothermal method and are used as a photocatalyst in a photoreaction system to convert carbon dioxide into methane and carbon monoxide. The as prepared material was characterized using X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and ultraviolet–visible spectrometer (UV–vis). The absorbance increases in the visible light region due to the incorporation of nano-silver (triangular plate) metal and pulls electrons, reduces the recombination rate of electron-hole pairs, and improves the photoreduction activity. The transmittance ratio is measured and the specific wavelengths of blue LED 412–505 nm and green LED 427–622 nm are measured. It shows that the irradiation of targeted wavelength bands will increase the absorbance and effectively reduces the recombination of electron-hole pairs. The best performance in this study was achieved after irradiating blue light source with 0.9% TAgNPts/BiVO4. The cumulative production of photoreduced carbon monoxide is 30.11 μmol g−1 and the quantum yield is 0.07%. After a green light source, the cumulative carbon monoxide yield using 0.9 wt% TAgNPts/BiVO4 is 24.77 μmol g− and the quantum yield is 0.06%.