Search Results (479)

The importance and challenges of ethylene detection based on combustion-type low-cost commercial sensors for agricultural and industrial applications are well-established. This work summarizes the significant progress in ethylene detection based on an innovative Gas Metal Oxide Semiconductor (GMOS) sensor and a new catalytic composition of metallic nanoparticles. The paper presents a study on ethylene and ethanol sensing using a miniature catalytic sensor fabricated by Complementary Metal Oxide Semiconductor–Silicon-on-Insulator–Micro-Electro-Mechanical System (CMOS-SOI-MEMS) technology. The GMOS performance with bimetallic palladium–platinum (Pd-Pt) and monometallic palladium (Pd) and platinum (Pt) catalysts is compared. The synergetic effect of the Pd-Pt catalyst is observed, which is expressed in the shift of combustion reaction ignition to lower catalyst temperatures as well as increased sensitivity compared to monometallic components. The optimal catalysts and their temperature regimes for low and high ethylene concentrations are chosen, resulting in lower power consumption by the sensor. Full article

Hydrogen peroxide (H₂O₂) is an important industrial chemical that is widely applied in many areas. The direct synthesis of H₂O₂ from H₂ and O₂ has proved to be a green and economic pathway. Pd-based bimetallic catalysts, due to their superior catalytic performances in this reaction, have attracted intensive attention. Herein, Tetrakis(hydroxymethyl)phosphonium chloride (THPC) was adopted as the protective ligand to immobilize Pd-Au alloy nanoparticles onto activated carbon (AC). The varied Pd/Au molar ratios demonstrated homogeneously distributed Pd-Au nanoalloys with average particle sizes ranging from 3.51 to 5.75 nm. The optimal ratio was observed over the Pd₃Au₁/AC-THPC catalyst with a maximum H₂O₂ productivity of 165 mol/(kg_Pd·h) and selectivity of 82.3% under ambient pressure. The relationship between the electronic structure and catalytic activity indicated Pd⁰ was the active site, while the presence of Au inhibited H₂O₂ degradation rate. This research could help in the design efficient bimetallic catalysts for the direct synthesis of H₂O₂. Full article

This report introduces a high-performance bimetallic electrocatalyst for the oxygen reduction reaction (ORR) featuring a 20 wt.% platinum content. The PtCu-based catalyst combines de-alloyed nanoparticles (NPs) supported on nitrogen-doped carbon. Enhanced uniformity in NP distribution significantly boosts the catalyst performance. Nitrogen-doped carbon provides active centers for NP deposition, which is confirmed by HAADF-STEM and EDX. The PtCu/CN catalyst achieves over 5.6 times the ORR mass activity and two times the stability under pulse cycling compared to commercial Pt/C. Uniquely, the study examines bimetallic NPs and local nano-sites before and after stress testing using IL-TEM. In situ analysis of PtCu/CN microstructure revealed two primary degradation mechanisms, (i) partial dissolution of NPs and (ii) NP agglomeration, with the C–N support significantly mitigating these effects through strong NP–support interactions. The findings underscore the prospects of bimetallic PtCu catalysts with nitrogen-doped support by showcasing exceptional ORR activity and durability. Full article

The conversion of CO₂ through the electrochemical reduction reaction (ECO₂RR) into chemicals or fuels is regarded as one of the effective ways to decrease atmospheric CO₂ concentrations. In this study, a Cu-Sn bimetallic electrocatalyst (ER-Sn_mCu_nO_x-t/CC) was successfully prepared via a chemical foaming method and electrochemical reduction. SEM showed that ER-Sn₁Cu₁O_x-500 nanoparticles were uniformly distributed on the carbon cloth, which benefited from foaming. The XPS results demonstrated the synergistic interaction between Cu and Sn and the existence of oxygen vacancies originating from the electroreduction. Due to the above features, ER-Sn₁Cu₁O_x-500/CC achieved 84.1% FE for HCOOH at −1.1 V vs. RHE, and the corresponding J_HCOOH was up to 32.4 mA·cm⁻² in the H-type cell. Especially in the flow cell, ER-Sn₁Cu₁O_x-500/GDE could reach a high J_HCOOH of 190 mA·cm⁻² at −1.1 V vs. RHE and maintained J_HCOOH higher than 100 mA·cm⁻² for 24 h with a formic acid selectivity over 70%, indicating both excellent catalytic activity and high HCOOH selectivity. In situ FTIR results revealed that synergism between Cu and Sn could regulate the adsorption of intermediates, thus enhancing the catalytic performance of ER-Sn₁Cu₁O_x-500 for ECO₂RR. Full article

Catalytic hydrogenolysis of lignin to produce high-value monophenols has emerged as a pivotal strategy in modern biorefineries. In this study, we synthesized spherical nitrogen-doped porous carbon (SNCB) materials by using Al/Co-BTC as a precursor, introducing melamine as a supplementary carbon and nitrogen source, and activating the material with NaOH solution. The SNCB framework was decorated with Cu-Pd bimetallic nanoparticles, exhibiting outstanding catalytic activity in the hydrogenolytic depolymerization of organosolv lignin. The Cu-Pd@SNCB catalyst exhibited remarkable activity, attributed to the hierarchical porous structure of SNCB that facilitated metal nanoparticle dispersion and reactant accessibility. The synergistic effect between Cu as the reactive site for reactant adsorption and Pd as the reactive site for H₂ adsorption enhanced the catalytic activity of the catalyst. Systematically optimized conditions (2 MPa H₂, 270 °C, 3 h) yielded 43.02 wt% phenolic monomers, with 4-(3-hydroxypropyl)-2,6-dimethoxyphenol dominating the product profile at 46.3% selectivity. The catalyst and its reaction products were analyzed using advanced characterization techniques, including XPS, XRD, TEM, SEM, BET, GC-MS, GPC, 2D HSQC NMR, and FT-IR, to elucidate the reaction mechanism. The mechanism proceeds through: (1) nucleophilic substitution of the β-O-4 hydroxyl group by MeOH, followed by (2) simultaneous hydrogenolytic cleavage of C_β-O and C_α-O bonds mediated by Cu-Pd@SNCB under H₂ atmosphere, which selectively produces 4-(3-hydroxypropyl)-2,6-dimethoxyphenol and 4-propyl-2,6-dimethoxyphenol. This study proposes a bimetallic synergistic mechanism, offering a general blueprint for developing selective lignin valorization catalysts. Full article

This study presents an easy and rapid two-step electrodeposition method for the synthesis of a novel hierarchical dendritic AuPt bimetallic nanocomposite electrode. Ascorbic acid served as both a reducing and directing agent, while a roughened carbon substrate facilitated the formation of the unique dendritic nanostructure. The structural and compositional properties of the synthesized material were comprehensively characterized using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), selected area electron diffraction (SAED), and transmission electron microscopy (TEM). The resulting nanocomposite exhibited a significantly enhanced specific surface area of 6.97 m² g⁻¹, compared to commercial Pt/C. Electrochemical investigations demonstrated superior electrocatalytic activity and durability for methanol oxidation in the prepared AuPt nanocomposite electrode, suggesting its promising potential for fuel cell applications. Full article

Ru–Zn catalysts exhibit excellent catalytic performance for the selective hydrogenation of benzene to cyclohexene and has been utilized in industrial production. However, the structure–performance relationship between Ru–Zn catalysts and benzene hydrogenation remains lacking. In this work, we focused on the evolution of Ru–Zn nanoparticles with size and Ru/Zn ratio. The structures of Ru nanoparticles and Ru–Zn bimetallic nanoparticles with different sizes were determined by the minima-hopping global optimization method in combination with density functional theory and high-dimensional neural network potential. Furthermore, we propose the growth mechanism for Ru nanoparticles and evolution processes for Ru–Zn bimetallic nanoparticles. Additionally, we analyzed the structural stability, electronic properties, and adsorption properties of Zn atoms. This work provides valuable reference and guidance for future theoretical research and applications. Full article

As cyanide ion (CN⁻), an ecologically harmful pollutant, has received incessant attention with growing industrialization on a global scale, the capability of on-site monitoring of CN⁻ contamination becomes increasingly crucial. In this work, we have fabricated a simplistic plasmonic-sensing platform for CN⁻, which can be combined with the human naked eye for visual monitoring. The main sensor part consisted of β-Cyclodextrin (β−CD)-decorated gold-rich silver bimetallic alloy nanoparticles (β−CD-Ag/Au-rich alloy NPs), while a sensing analysis was performed by a spectrophotometer or smartphone, where optical data gathered by its camera were analyzed by RGB color sensing. Upon the introduction of various CN⁻ quantities into β−CD-Ag/Au-rich alloy NPs, the spectral peak of the surface plasmon resonance (SPR) shifted from 488 nm to 496 nm. This redshift indicated a strong etching reaction between alloy NPs and CN⁻, demonstrating a ultrahigh detection sensitivity, i.e., a limit of detection (LOD) of 0.24 nM. During the formation of metal-cyano complexes in the CN⁻-induced etching response of β−CD-Ag/Au-rich alloy NPs, we observed a naked-eye discernible color change from brownish-red to colorless, allowing for naked-eye monitoring. The smartphone could also analyze the colorimetric response for such an etching process via RGB color sensing, demonstrating a LOD of 1.35 nM, being still less than the maximum concentration (1.91 nM) in drinking water, which is allowable by the World Health Organization (WHO). The straightforwardness and very high sensitivity of the proposed technique for CN⁻ detection using alloy nanoparticles with a smartphone may hold promise for simplistic, affordable in-field examinations of CN⁻ in water. Full article

This study focuses on the design of a novel electrode for an energy storage system utilizing EDEN (electrochemical-based decarbonizing energy) technology. This technology implies a chlor-alkali electrochemical cell with dual functionality: first, the electrolysis of water and NaCl to produce hydrogen (H₂) and chlorine (Cl₂), and subsequently, the utilization of these products in an H₂/Cl₂ fuel cell to generate electricity. Bimetallic RuPt nanoparticles have been synthesized on Vulcan carbon (C-V) from organometallic precursors to be used as electrocatalysts. Characterization includes transmission electron microscopy (TEM), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), and powder X-ray diffraction (XRD). The RuPt/C-V-based electrode demonstrated notable performance in the target reversible electrochemical cell, acting as the anode for electrolysis and as the cathode in fuel-cell mode. Testing in a 3D-printed electrochemical cell revealed high efficiency, with a coulombic efficiency exceeding 96% for hydrogen production, yielding 11.75 mg·Wh⁻¹ and achieving a power output of approximately 4.5 mW·cm⁻² in H₂/Cl₂ fuel-cell operation. Full article

Anion exchange membrane fuel cells (AEMFCs) are versatile power generation devices that can be fed by both gaseous (H₂) and liquid fuels. The development of sustainable, efficient, and stable catalysts for the oxidation of hydrogen (HOR) and oxygen reduction (ORR) under alkaline conditions remains a challenge currently facing AEMFC technology. Reducing the loading of PGMs is essential for reducing the overall cost of AEMFCs. One strategy involves exploiting the synergistic effects of two metals in bimetallic nanoparticles (NPs). Here, we report that the activity for the HOR and the ORR can be finely tuned through surface engineering of carbon-supported PdAu-PVA NPs. The activity for both ORR and HOR can be adjusted by subjecting the material to heat treatment. Specifically, heat treatment at 500 °C under an inert atmosphere increases the crystallinity and oxophilicity of the nanoparticles, thereby enhancing anodic HOR performance. On the contrary, heat treatment significantly lowers ORR activity, highlighting how reduced surface oxophilicity plays a major role in increasing active sites for ORR. The tailored activity in these catalysts translates into high power densities when employed in AEMFCs (up to 1.1 W cm⁻²). Full article

This study investigates silver (Ag), copper oxide (CuO), and bimetallic Ag/CuO nanoparticles (NPs) synthesized using Cistus creticus L. extract, focusing on their synthesis, physicochemical characteristics, and antioxidant activity. Green synthesis methods utilizing plant extracts offer environmentally benign routes for nanoparticle fabrication, attracting significant interest across multiple fields. NP formation was confirmed by UV/Vis and total X-ray fluorescence (TXRF) spectroscopy, while dynamic and electrophoretic light scattering (DLS, ELS) characterized particle size and ζ-potential, respectively. AgNPs exhibited the smallest particle size (30.8 ± 8.81 nm), while CuONPs had the largest (44.07 ± 19.19 nm). For Ag/CuONPs, the ζ-potential value was −77.9 ± 2.99 mV. Morphological and structural analyses performed using transmission electron microscopy (TEM), selected area electron diffraction (SAED), and X-ray diffraction (XRD) revealed that AgNPs were spherical, while CuONPs and Ag/CuONPs exhibited spherical and polymorphic structures. Colloidal stability studies over 60 days demonstrated that the NPs were highly stable, indicating their suitability for pharmaceutical and cosmetic applications. Antioxidant activity, assessed via the DPPH assay, demonstrated that CuONPs had the highest free radical scavenging activity. By systemically comparing Ag, CuO, and bimetallic Ag/CuONPs synthesized from Cistus creticus L. extract, this study provides valuable insights for the development of tailored nanomaterials with diverse applications in pharmaceutics and cosmetics. Full article

A fiber-reinforced SPR sensor based on silver-nucleated gold-shell bimetallic nanoparticles and graphene oxide was developed and applied to human IgG detection. The refractive index (RI) sensitivity of the Ag@Au/GO fiber SPR sensor is as high as 4715.9 nm/RIU in the RI range of 1.333–1.365. Staphylococcus aureus protein A (SPA) can specifically recognize and bind to the fragment crystallizable (Fc) of the antibody; it facilitates the highly targeted immobilization of the antibody. SPA and rabbit anti-human IgG were immobilized on the surface of the Ag@Au/GO fiber SPR sensor for the detection of different concentrations of human IgG with a sensitivity of 0.53 nm/μg/mL and detection limits of 0.037 μg/mL. This biosensor based on the mixed structure of GO and Ag@Au combined the common advantages of the two materials. Therefore, our study provides a simple platform for biological analysis and has a good application prospect. Full article

SnO₂-based semiconductor gas-sensing materials are regarded as some of the most crucial sensing materials, owing to their extremely high electron mobility, high sensitivity, and excellent stability. To bridge the gap between laboratory-scale SnO₂ and its industrial applications, low-cost and high-efficiency requirements must be met. This implies the need for simple synthesis techniques, reduced energy consumption, and satisfactory gas-sensing performances. In this study, we utilized a surfactant-free simple method to modify SnO₂ nanoparticles with PdPt noble metals, ensuring the stable state of the material. Under the synergistic catalytic effect of Pd and Pt, the composite material (1.0 wt%-PdPt-SnO₂) significantly enhanced its response to HCHO. This modification decreased the optimal working temperature to as low as 180 °C to achieve a response value (R_a/R_g = 8.2) and showcased lower operating temperatures, higher sensitivity, and better selectivity to detect 10 ppm of HCHO when compared with pristine SnO₂ or single noble metal-decorated SnO₂ sensors. Stability tests verified that the gas sensor signals based on PdPt-SnO₂ nanoparticles exhibit good reliability. Furthermore, a portable HCHO detector was designed for practical applications, such as in newly purchased cushions, indicating its potential for industrialization beyond the laboratory. Full article

The thermal stability of bimetallic nanoparticles plays a crucial role in their performance in applications in catalysis, biotechnology, and materials science. In this study, we employ molecular dynamics simulations to investigate the melting behavior of Au-Pd nanoparticles with cuboctahedral, icosahedral, and decahedral geometries. Using a tight-binding potential, we systematically explore the effects of particle size and composition on the melting transition. Our analysis, based on caloric curves, Lindemann coefficients, and orientational order parameters, reveals distinct premelting behaviors influenced by geometry. Larger particles exhibit a coexistence of a pseudo-crystalline core and a partially melted shell, but, in decahedra and icosahedra, melting of the core occurs unevenly, with twin boundaries promoting the melting of one or two of the tetrahedral subunits before the rest of the particle. Notably, icosahedral nanoparticles display higher thermal stability, while both icosahedral and decahedral structures exhibit localized melting within twin boundaries. Additionally, we generate HAADF-STEM simulations to aid the interpretation of in situ electron microscopy experiments. Full article

The arrival of nanotechnology in the field of metal castings is considered a promising approach to significantly improve the quality, performance and lifetime of castings. A better understanding of the implementation of nanotechnology in the metal casting process and its dynamics is essential for the successful production of metal matrix nanocomposite castings. This review focuses on past and present techniques for metal matrix nanocomposite castings to facilitate future fabrication processes and improve the performance of casting products. The advantages, limitations, difficulties and optimal processing conditions of nanocomposite castings are presented and thoroughly discussed. Both types of metal matrix nanocomposites (i.e., ferrous and nonferrous metallic matrices, are discussed in the present review), as well as nanocomposites in the working surface layer and interlayer of bimetallic materials. Significant improvements in the surface microstructure and shear strength of bimetallic bearings are achieved using nanoparticles as additions to the surface working layer and interlayer areas. Special emphasis is given to the factors affecting these fabrication processes in achieving high-quality products. The dispersion of nanoparticles in the metallic matrix is another critical issue, which is discussed comprehensively. Moreover, the strengthening mechanisms that evolve due to the incorporation of nanoparticles in the metallic matrices, which deserve separate attention, are discussed. The economic and political factors that simultaneously lead to evolutionary and drastic changes in metal matrix nanocomposite castings are also considered. Finally, the present article indicates future fabrication routes and describes the development of metal matrix nanocomposite castings under the influence of nanotechnology after incorporating the novel casting opportunities presented by nanotechnology. Full article