A hybrid Ag/TiO2 nanoarray-based in situ charge transfer toward multi-functional active-platform

Designing an efficient heteronanostructure array for surface-enhanced Raman scattering (SERS) to enable ultrasensitive and reproducible detection of analytes and degrading organic contaminants provides new perspectives for chemical and biological detection at trace levels and environmental remediation. Here, we design and fabricate a heterostructure consisting of Ag nanoparticles (NPs) in-situ grown on high-density arrays of vertical TiO₂ nanorods (NRs) (denoted Ag/TiO₂ NRs). As a result, compared with pristine TiO₂ NRs, the as-obtained Ag/TiO₂ NR substrate possesses a SERS activity for detecting rhodamine 6G (R6G) with a detection limit as low as 10⁻¹² M and an enhancement factor up to 1.2 × 10¹⁰. In addition, the substrate exhibits the highest degradation rates of R6G of 82% under illumination with visible light and an excellent self-cleaning effect under UV-assisted light. Such remarkable enhanced efficacy of the binary Ag/TiO₂ NRs nanocomposites may be attributed to the i) appropriate band alignment based on the synergistic effect of Ag decorated on TiO₂ NRs; ii) a large adhesion area and the localized surface plasmon resonance (LSPR) of Ag; and iii) high-density and engineering hotspots in the active platform. These properties make the heterostructure Ag/TiO₂ NR platform promising candidate for detecting analytes and photocatalytic applications.     

Fabrication and evolution of multilayer silver nanofilms for surface-enhanced Raman scattering sensing of arsenate

Surface-enhanced Raman scattering (SERS) has recently been investigated extensively for chemical and biomolecular sensing. Multilayer silver (Ag) nanofilms deposited on glass slides by a simple electroless deposition process have been fabricated as active substrates (Ag/GL substrates) for arsenate SERS sensing. The nanostructures and layer characteristics of the multilayer Ag films could be tuned by varying the concentrations of reactants (AgNO₃/BuNH₂) and reaction time. A Ag nanoparticles (AgNPs) double-layer was formed by directly reducing Ag⁺ ions on the glass surfaces, while a top layer (3rd-layer) of Ag dendrites was deposited on the double-layer by self-assembling AgNPs or AgNPs aggregates which had already formed in the suspension. The SERS spectra of arsenate showed that characteristic SERS bands of arsenate appear at approximately 780 and 420 cm^-1, and the former possesses higher SERS intensity. By comparing the peak heights of the approximately 780 cm^-1 band of the SERS spectra, the optimal Ag/GL substrate has been obtained for the most sensitive SERS sensing of arsenate. Using this optimal substrate, the limit of detection (LOD) of arsenate was determined to be approximately 5 μg·l^-1.     

Microwave-assisted green synthesis of Ag/reduced graphene oxide nanocomposite as a surface-enhanced Raman scattering substrate with high uniformity

A nanocomposite of silver nanoparticles/reduced graphene oxide (Ag/rGO) has been fabricated as a surface-enhanced Raman scattering (SERS) substrate owing to the large surface area and two-dimensional nanosheet structure of rGO. A facile and rapid microwave-assisted green route has been used for the formation of Ag nanoparticles and the reduction of graphene oxide simultaneously with L-arginine as the reducing agent. By increasing the cycle number of microwave irradiation from 1 and 4 to 8, the mean diameters of Ag nanoparticles deposited on the surface of rGO increased from 10.3 ± 4.6 and 21.4 ± 10.5 to 41.1 ± 12.6 nm. The SERS performance of Ag/rGO nanocomposite was examined using the common Raman reporter molecule 4-aminothiophenol (4-ATP). It was found that the Raman intensity of 4-ATP could be significantly enhanced by increasing the size and content of silver nanoparticles deposited on rGO. Although the Raman intensities of D-band and G-band of rGO were also enhanced simultaneously by the deposited Ag nanoparticles which limited the further improvement of SERS detection sensitivity, the detectable concentration of 4-ATP with Ag/rGO nanocomposite as the SERS substrate still could be lowered to be 10⁻¹⁰ M and the enhancement factor could be increased to 1.27 × 10¹⁰. Furthermore, it was also achievable to lower the relative standard deviation (RSD) values of the Raman intensities to below 5%. This revealed that the Ag/rGO nanocomposite obtained in this work could be used as a SERS substrate with high sensitivity and homogeneity.     

Nanostructured Tin Oxide as a Surface‐Enhanced Raman Scattering Substrate for the Detection of Nitroaromatic Compounds

Sensing of low concentrations of two nitroaromatic compounds, 1,2‐dinitrotoluene and 2‐nitrophenol, is presented. The sensing mechanism is based on surface‐enhanced Raman scattering (SERS) using nanostructured tin oxide as the SERS‐active substrate. The SnO_x nanostructures are synthesized by a simple solgel method and doped with Ag and Au. The Raman signal of a low concentration of the analyte, otherwise extremely weak, becomes significant when the analytes are attached to these substrates. Doping of SnO_x nanopowders with Ag and Au leads to a further increase in the Raman intensities. This study demonstrates the scope of ceramic–metal nanocomposites as convenient solid‐state SERS sensors for low‐level detection.     

Application of In Situ Surface-Enhanced Raman Spectroscopy (SERS) to the Study of Citrate Oxidation on Silica-Supported Silver Nanoparticles

Surface-enhanced Raman spectroscopy (SERS) was used to characterize citrate anions adsorbed on nanometer-sized particles of Ag supported on SiO₂. The magnitude of the surface-enhancement effect was determined to be ～3 × 10² on the as-prepared samples of Ag/SiO₂. Upon heating in air above 373 K, the citrate anions undergo oxidation to uni- and bidentate carbonate species and then decomposition to CO₂ and adsorbed O atoms. In the SERS of Ag/SiO₂, a very strong enhancement of the ν(C=O) signal for the bidentate CO₃ species was observed for temperatures between 398 and 448 K, which is accompanied by an increase in the UV–vis absorbance of the sample at the frequency of the laser line used for Raman spectroscopy. This phenomenon is attributed to an increase in the surface-enhancement effect caused by clustering of the Ag nanoparticles as they sinter at elevated temperatures. The present investigation shows that the proper interpretation of in situ SERS spectra requires an understanding of the changes occurring in the UV–vis spectrum of the sample.     

Micro/nano-structured graphitic carbon nitride–Ag nanoparticle hybrids as surface-enhanced Raman scattering substrates with much improved long-term stability

Surface-enhanced Raman scattering (SERS) substrates with high SERS activity and stability are important for SERS sensors. A facile method was developed to fabricate efficient and stable SERS substrates by combining Ag nanoparticles (NPs) and micro-scale sheeted graphitic carbon nitride (g-C₃N₄). The g-C₃N₄/Ag NPs hybrid could provide a great number of hot spots and concentrated the analyte by the π–π stacking interaction between analyte molecules and g-C₃N₄, making a dramatic Raman enhancement. Moreover, the g-C₃N₄/Ag NPs hybrid uniformly immobilized Ag NPs on the surface and edges of g-C₃N₄ sheets by an interaction between Ag NPs and g-C₃N₄, leading to much improved long-term stability. This could be explained in terms of the electron–donor effect of g-C₃N₄, which was further confirmed by density functional theory calculations. The inherent Raman enhancing effect of g-C₃N₄ itself also contributed to the total SERS responses. Due to multiple enhancement contributions, the g-C₃N₄/Ag NPs hybrid exhibited a strong Raman enhancement effect for with an enhancement factor of 4.6 × 10⁸ (evaluated by using crystal violet as a probe), and possessed wide adaptability from dyes, pesticides to bio-molecules.     

Fabrication of 2D titanium carbide MXene/Au nanorods as a nanosensor platform for sensitive SERS detection

As an emerging label-free detection technology, surface-enhanced Raman scattering (SERS) has been used for biological detection, food safety, and environmental pollution owing to its high sensitivity, specificity and rapid response. However, traditional SERS substrates are unstable, prone to agglomeration, and demonstrate low productivity and high production cost. In this work, hybrids of a two-dimensional electron gas (2DEG) Ti₃C₂T_x monolayer and Au nanorods (AuNRs) were fabricated via self-assembly. Ti₃C₂T_x:AuNRs ratios were prepared, and each hybrid's SERS activity was evaluated through 4-aminothiophenol (pATP) detection. The Ti₃C₂T_x/AuNRs-1 substrate exhibited the weakest SERS performance, whereas the Ti₃C₂T_x/AuNRs-3 substrate had the best SERS activity enhancement, with a pATP limit of detection (LOD) of 10⁻⁹ M. When 30 sites on substrates were selected for SERS detection, the relative standard deviation (RSD) was found to be only 7.18 %, revealing the good performance sensitivity and high reproducibility of the Raman signal. The sensitivity of Ti₃C₂T_x/AuNRs-3 was also assessed with respect to a hazardous chemical, 1,2-bis (4-pyridyl) ethylene (BPE), revealing an LOD of 10⁻¹² M. For thiram, the LOD of Ti₃C₂T_x/AuNRs-3 was 10⁻⁸ M, which is considerably lower than the 1 ppm industry safety standard. A relative standard deviation RSD of 7.94 % indicates the high reproducibility and uniformity of the Raman signal of thiram for Ti₃C₂T_x/AuNRs-3. Compared with the LODs of 10⁻⁵ M and 10⁻⁶ M for commercial substrates T-SERS and Au nanorod arrays (AuNRAs), respectively, the 10⁻⁸ M LOD of our synthesized Ti₃C₂T_x/AuNRs indicates good sensitivity. Three kinds of pesticides were detected by Ti₃C₂T_x/AuNRs, and only Raman signal of thiram can be found, revealing the good selectivity for thiram. These results for Ti₃C₂T_x/AuNRs suggest its potential to serve as a novel SERS platform.     

A novel graphene-like titanium carbide MXene/Au–Ag nanoshuttles bifunctional nanosensor for electrochemical and SERS intelligent analysis of ultra-trace carbendazim coupled with machine learning

A new bifunctional intelligent nanosensing platform based on graphene-like titanium carbide MXene (Ti₂C MXene)/Au–Ag nanoshuttles (NSs) for both electrochemical and surface-enhanced Raman scattering (SERS) intelligent analysis of ultra-trace carbendazim (CBZ) residues in tea and rice coupled with machine learning (ML) was successfully designed. Ti₂C MXene was synthesized by selectively etching Al layers of Ti₂AlC with hydrofluoric acid and high-temperature calcination. Ti₂C MXene/Au–Ag NSs prepared by the ultrasonic dispersion of graphene-like Ti₂C MXene into Au–Ag NSs solution under dark conditions displayed large and rough surface, enhanced conductivity, excellent electrochemical response, prominent Raman enhancement, and high stability. The ML via different algorithms such as artificial neural network, support vector machine, and relevance vector machine (RVM) for the intelligent analysis of CBZ was contrasted and discussed. RVM displayed more superiority for the electrochemical analysis of CBZ in a wide linear range of 0.006 – 9.8 μM with low limit of detection (LOD) of 0.002 μM and SERS detection of CBZ in the wide linear range of 0.033 – 10 μM with low LOD of 0.01 μM. This will provide a new bifunctional intelligent sensing platform via different ML algorithms for improving accuracy of sensor via mutual verification of two or more methods of detection and a new bifunctional nanosensing platform based on the development of graphene-like nanohybrid for food and agro-products safety.     

Structure of the silver containing diamond like carbon films: Study by multiwavelength Raman spectroscopy and XRD

In the present study structure of silver containing diamond like carbon (DLC:Ag) films deposited by reactive magnetron sputtering was investigated by X-ray diffractometry (XRD) and multiwavelength Raman spectroscopy. In the case of the DLC:Ag films containing low amount of silver, crystalline silver oxide prevails over silver. While at higher Ag atomic concentrations formation of the silver crystallites of the different orientations was observed. Surface enhanced Raman scattering (SERS) effect was detected for high Ag content in the films. For UV excited Raman spectra sp³ bonded carbon related Raman scattering T peak at ~ 1060 cm^− 1 was detected only for the films with the highest amount of silver (34.3 at.%). The dependence of the Raman scattering spectra parameters such as position of the G peak, G peak full width at half maximum (FWHM(G)), D/G peak area ratio on Ag atomic concentration in DLC:Ag film as well as Raman scattering spectra excitation wavelength were studied. The dependence on Ag amount in film was more pronounced in the case of the Raman scattering spectra excited by higher wavelength laser beam, while in the case of the spectra excited by 325 nm and 442 nm laser beams only weak dependence (or no dependence) was observed. Overall tendency of the decrease of the dispersion of the G peak with the increase of Ag atomic concentration was found. Thus sp³/sp² bond ratio in DLC:Ag film decreased with the increase of Ag atomic concentration in the films.     

A multifunctional Ag/TiO2/reduced graphene oxide with optimal surface-enhanced Raman scattering and photocatalysis

A multifunctional Ag/TiO₂/reduced graphene oxide (rGO) ternary nanocomposite was prepared by a one-step photochemical reaction with TiO₂ and Ag nanoparticles successively deposited on reduced graphene oxide. The structure, morphology, composition, optical, and photoelectrochemical properties of Ag/TiO₂/rGO were investigated in detail. Meanwhile, the ternary nanocomposite possessed much higher adsorption capacity to organic dyes compared with bare TiO₂ and binary Ag/TiO₂, which would help to its use for surface-enhanced Raman scattering detection and photocatalytic degradation. Due to the charge transfer between rGO and organic dyes and enhanced electromagnetic mechanism of Ag, Ag/TiO₂/rGO nanocomposites as surface-enhanced Raman scattering substrates demonstrated dramatically improved sensitivity and good uniformity. The detection limit of rhodamine 6G (R6G) was as low as 10⁻⁹ mol/L, and the relative standard deviation values of the intensities remained below 5%. Most importantly, the synergistic coupling effect of three components extended the photoresponse range and accelerated separation of the electron-hole pairs, leading to greatly improved photocatalytic activity under simulated sunlight. The maximum rate constant (k, 0.06243 min⁻¹) of Ag/TiO₂/rGO was 50 and four times higher than that of TiO₂ and Ag/TiO₂, respectively.     

Enhanced mechanical properties and bactericidal activity of polypropylene nanocomposite with dual‐function silica–silver core‐shell nanoparticles

Dual‐function silica–silver core‐shell (SiO₂@Ag) nanoparticles (NPs) with the core diameter of 17 ± 2 nm and the shell thickness of about 1.5 nm were produced using a green chemistry. The SiO₂@Ag NPs were tested in vitro against gram‐positive Staphylococcus aureus (S. aureus) and gram‐negative Escherichia coli (E. coli), both of which are human pathogens. Minimal inhibitory concentrations of the SiO₂@Ag NPs based on Ag content are 4 and 10 μg mL^?1 against S. aureus and E. coli, respectively. These values are similar to those of Ag NPs. SiO₂@Ag NPs were for the first time incorporated to a commodity polypropylene (PP) polymer. This yielded an advanced multifunctional polymer using current compounding technologies i.e., melt blending by twin‐screw extruder and solvent (toluene) blending. The composite containing 5 wt % SiO₂@Ag NPs (0.05 wt % Ag) exhibited efficient bactericidal activity with over 99.99% reduction in bacterial cell viability and significantly improved the flexural modulus of the PP. Anodic stripping voltammetry, used to investigate the antibacterial mechanism of the composite, indicated that a bactericidal Ag⁺ agent was released from the composite in an aqueous environment. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Novel synthesis method and microstructure evolution of Ti3C2(OH)2/K2Ti8O17 nanocomposites as an effective surface enhanced Raman scattering substrate

In this paper, we have developed a mild and facile approach using KOH solution as etchants to corrode Ti₃SiC₂ at room temperature, fabricating novel Ti₃C₂(OH)₂/K₂Ti₈O₁₇ nanocomposites with open network structures and abundant surface functional groups. The as-produced products obtain the excellent surface enhanced Raman scattering (SERS) performance in the determination of crystal violet (CV), rhodamine 6G (R6G) and methylene blue (MB) dye molecules. The enhancement factors of the three can be calculated to be 3.98 × 10⁵, 1.78 × 10⁵ and 5.27 × 10⁵, and the Raman signals can be detected at the concentrations as low as 10^?6 M, 10^?8 M and 10^?6 M, respectively, suggesting the potential for reliable SERS substrates. In this regard, this work provides a new strategy for exploring and synthesizing MAX phase-derived nanomaterials as promising SERS substrates for high-sensitive molecular detection.     

α-Fe2O3/Ag核壳结构纳米复合颗粒的制备及SESR性能

用籽晶法,以甲醛为还原剂、3-氨丙基三乙氧基硅烷(APS)为改性剂,在Ag［(NH₃)₂］⁺溶液中制备α-Fe₂O₃/Ag核壳结构复合粉体。采用XRD、TEM和EDX对样品进行表征,系统研究了APS改性剂、醇水比等对复合纳米颗粒包覆效果及性能的影响;并用吡啶(Py)为探针,研究了α-Fe₂O₃/Ag核壳纳米颗粒作为拉曼衬底时的拉曼增强性能相似文献   

C60-polymer nanocomposites: evidence for interface interaction

Polyaniline-fullerene (PA-C₆₀) composites have been studied by Surface Enhanced Raman scattering (SERS) spectroscopy and X-ray diffraction. They were obtained by mixing solutions of polyaniline-emeraldine base (PA-EB) and C₆₀, as well as by chemical synthesis from aniline, sulfuric acid and potassium dichromate, with addition of C₆₀. The Raman bands peaking at 1330-1370 cm⁻¹, associated with a protonated structure were used as indicative for changes of the PA-EB phonon spectrum resulting from C₆₀ doping. The two types of compounds show different SERS spectra, also dependent on the metallic support used (Au or Ag). Variation of the SERS spectra with the type of metallic support is related to a chemical interface interaction between composite and metal. In mixture samples, a doped polymeric chain (with ionically attached C₆₀⁻) was evidenced by an increased fraction of quinoid rings. The SERS spectra of the chemically synthesized PA-C₆₀ reveals the existence of two polymeric structures: a doped PA (doped with C₆₀⁻ ions) and an undoped one, the latter with a structure of ‘pendant chain’ type. Structural (XRD) data reveal the presence of C₆₀ nano-zones, with a lattice parameter increase of 0.3-0.6%, attributed to slight oxidation. Detailed analysis of the fcc(111) line asymmetry suggests, in mixture samples, a boundary zone with an ‘expanded’ lattice, induced by ionic interface effects.     

Synthesis and characterization of coaxial silver/silica/polypyrrole nanocables

Double‐shelled coaxial nanocables of silver nanocables with SiO₂ and polypyrrole (PPy; Ag/SiO₂/PPy) were synthesized by a simple method. The thickness of the outer PPy shell could be controlled by the amount of pyrrole monomer. The silver nanocables encapsulated in the interior of the hollow PPy nanotubes were obtained by the removal of the midlayer SiO₂. By the silver‐mirror reaction, flowerlike Ag nanostructures could be formed on the surface of the Ag/SiO₂/PPy multilayer nanocable. The application of the as‐prepared Ag/SiO₂/PPy–Ag composites in surface‐enhanced Raman scattering (SERS) was studied with Rhodamine B (Rh B) as a probe molecule. We found that the composites could be used as SERS substrates and that they exhibited excellent enhancement ability. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Conjugated polymer mediated synthesis of nanoparticle clusters and core/shell nanoparticles

Two water soluble conjugated polymers, poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and ammonium ion stabilized poly(phenylene vinylene) (P2), are found to be able to reduce noble metal ions to zero-valent metals via a direct chemical deposition technique. Au nanoparticle clusters can be obtained through reduction of Au³⁺ ions by PEDOT:PSS and the electronic coupling between them can be controlled by HAuCl₄ concentration. Core/shell Ag/polymer nanostructures are prepared from reduction of Ag⁺ ions by P2, which have a ppb detection limit for 4-MBA using surface-enhanced Raman spectroscopy (SERS). This conjugated polymer mediated synthesis of metal nanoparticles may open a new avenue for fabricating nanomaterials and nanocomposites with tunable optical properties that are dominated by their structure and electronic coupling between nanoparticles.     

Naturally inspired SERS substrates fabricated by photocatalytically depositing silver nanoparticles on cicada wings

Densely stacked Ag nanoparticles with an average diameter of 199 nm were effectively deposited on TiO₂-coated cicada wings (Ag/TiO₂-coated wings) from a water-ethanol solution of AgNO₃ using ultraviolet light irradiation at room temperature. It was seen that the surfaces of bare cicada wings contained nanopillar array structures. In the optical absorption spectra of the Ag/TiO₂-coated wings, the absorption peak due to the localized surface plasmon resonance (LSPR) of Ag nanoparticles was observed at 440 nm. Strong Surface-enhanced Raman scattering (SERS) signals of Rhodamine 6G adsorbed on the Ag/TiO₂-coated wings were clearly observed using the 514.5-nm line of an Ar⁺ laser. The Ag/TiO₂-coated wings can be a promising candidate for naturally inspired SERS substrates.     

Ag@CoFe2O4/Fe2O3 nanorod arrays on carbon fiber cloth as SERS substrate and photo-Fenton catalyst for detection and degradation of R6G

In this study, Ag nanoparticles loaded CoFe₂O₄/Fe₂O₃ nanorod arrays on carbon fiber cloth have been successfully fabricated by a hydrothermal route followed by a calcination treatment and photochemical reduction process. The as-prepared composite has been characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS). The obtained Ag@CoFe₂O₄/Fe₂O₃ nanorod arrays show excellent SERS performance, which provides enhancement factors (EF) as high as about 1.2 × 10⁸ for Rhodamine 6G (R6G). The SERS signals collected over a 20?µm × 20?µm area show relative standard deviation lower than 12%, suggesting good SERS signal uniformity. In addition, the Ag@CoFe₂O₄/Fe₂O₃ nanorod arrays can be used as an effective photo-Fenton catalyst photocatalytical degradation of R6G. It was found that 99.15% of R6G can be degraded in an hour. This bifunctional composite that can act both as SERS substrates and as photo-Fenton catalyst would facilitate the cleaning and recycling of SERS substrates for reusing through a photocatalytic process, as well as facilitate the integration of rapid detection and effective degradation of organic pollutants.     

MAX phase-derived woolen ball-like K2Ti8O17 with excellent surface-enhanced Raman scattering property

In surface-enhanced Raman scattering (SERS) applications, the MAX phase is typically acid etched to address deficiencies, while the more accessible alkali corrosion products are neglected. The woolen ball-like K₂Ti₈O₁₇ (KTO) nanomaterial is synthesized via an efficient hydrothermal surface corrosion reaction between KOH solution and MAX phase Ti₂AlN, which exhibits excellent SERS capabilities to the contaminating dyes. The enhancement factors are 2.33 × 10⁵, 1.04 × 10⁵ and 2.22 × 10⁵ with lowest limits of detection of 10⁻⁷ M, 10⁻⁶ M and 10⁻⁷ M for crystal violet, rhodamine 6G and methylene blue, respectively, indicating that KTO is a highly desired candidate of SERS substrate material. Meanwhile, KTO shows excellent SERS performance for chrysoidine in simulated seawater, which proves its practical application value. The excellent SERS performance of KTO is attributed to the charge transfer mechanism, which is made possible by the appropriate energy band structure and the robust adsorption capacity. In conclusion, a novel method for the synthesis of KTO is investigated and its reaction process and enhancement mechanism are exhaustively characterized and described. The woolen ball-like KTO exhibits remarkable SERS properties and potential applications.     

Hybrid diamond/graphite films: Morphological evolution,microstructure and tribological properties

Diamond films were deposited on silicon substrate by microwave plasma enhanced chemical vapor deposition (MPCVD) using H₂ and CH₄ gas mixture. The morphological evolution process was characterized systematically by means of field-emission scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy. Special attention has been paid to the influence of the methane concentrations on the microstructures of diamond films, which shows a gradual transition from nanocrystalline to microcrystalline films, and finally displays a hybrid diamond-graphite nanostructure with the length of a few micrometers. Finally, the friction behaviour of the hybrid films was studied. The value of the friction coefficient of the hybrid films is 0.10 and the corresponding wear resistance is below 1.9 × 10^− 7 mm³/N·m in diamond composites/Al₂O₃ sliding system in ambient atmosphere under dry sliding conditions. It is a convenient path to synthesize hybrid diamond/graphite nanostructures by MPCVD depending on higher methane concentrations in the absence of nitrogen or argon. The structure is appropriate for the potential applications as high efficient mechanical tools.