Search Results (27)

Metal nanoparticles (NPs) with enzyme-mimicking activities, known as nanozymes, are being actively explored for biomedical and analytical applications. Enhancing their catalytic activity and metal utilization efficiency is crucial for advancing these technologies. Here, we report an aqueous-phase, room-temperature synthesis of tetra-metallic Au@Ag-Pd-Pt NPs that exhibit superior peroxidase-like activity compared to their mono-, bi-, and trimetallic counterparts. The synthesis involves a sequential, seed-mediated approach comprising the formation of Au NP seeds, the overgrowth of a Ag shell, and the galvanic replacement of Ag with Pd and Pt ions. We systematically investigated the effects of the Au core diameter (15, 40, 55 nm), Ag precursor concentration (50–400 µM), and the Pd-to-Pt ratio on the optical and catalytic properties. By changing the particle composition, we were able to tune the absorbance maximum from 520 nm to 650 nm while maintaining high extinction coefficients (10⁹–10¹⁰ M⁻¹cm⁻¹) comparable to that of the initial Au nanoparticles. Mapping of chemical element distributions in the nanoscale range confirmed a core–shell–shell architecture with surface-enriched Pd and Pt. This structure ensures the surface-exposed localization of catalytically active atoms, yielding a more than 10-fold improvement in specific peroxidase-like activity while utilizing up to two orders of magnitude less Pt and Pd than bimetallic particles. The synthesized NPs thus combine high catalytic activity with tunable optical properties, making them promising multifunctional labels for biosensing. Full article

Enhancing the limited utilization and overall yield of Pt-based catalysts is essential for advancing proton exchange membrane fuel cell technology. Herein, we report a facile one-pot method that utilizes TEG as both a solvent and a reductant to efficiently synthesize a Pd@Pt core-shell icosahedron. By controlling the surface energy between Pd and Pt precursors, we achieved the formation of Pd@Pt core-shell icosahedra, resulting in a fourfold reduction in reaction time and an eightfold increase in yield. Moreover, the core-shell structures exhibited a significant enhancement in electrocatalytic activity, stability, and Pt utilization efficiency. In comparison to commercial Pt/C, the Pd@Pt core-shell icosahedron exhibited efficient mass activity (MA, 1.54 A mg⁻¹_Pt) and specific activity (SA, 2.24 mA cm⁻²_Pt) at 0.9 V (vs. RHE), while demonstrating excellent stability with minimal loss of activity even after 10,000 potential cycles. The Pd@Pt icosahedra configuration integrates the advantages of multiply twinned nanostructures, leading to rich electrochemical active surface sites and fast charge transport, thereby improving its catalytic performance and long-term stability during electrocatalytic reactions. Full article

Near-infrared light (NIR)-responsive metal-based nanoparticles (NPs) could be used for tumour therapy. We examined how platinum (Pt), gold (Au), and core-shell Pt-Au NPs affect the viability of human hepatocellular carcinoma (HCC) cell lines (Hep3B, HepG2, and Huh7D-12) alone and in combination with NIR exposure. In addition, the expression of immune checkpoint molecules (ICMs) on the tumour cells was analysed. We revealed that the cytotoxicity and programmed cell death induction of Au and Pt-Au NPs toward HCC cells could be enhanced by NIR with 960 nm in a different way. Pt-Au NPs were the only particles that resulted in an additional temperature increase of up to 2 °C after NIR. Regarding the tumour cell immune phenotype, not all of the cells experienced changes in immune phenotype. NIR itself was the trigger of the alterations, while the NPs did not significantly affect the expression of most of the examined ICMs, such as PD-L1, PD-L1, HVEM, CD70, ICOS-L, Ox40-L, and TNFRSF9. The combination of Pt-Au NPs with NIR resulted in the most prominent increase of ICMs in HepG2 cells. We conclude that the thermotherapeutic effect of Pt-Au NP application and NIR could be beneficial in multimodal therapy settings in liver cancer for selected patients. Full article

Platinum (Pt) and palladium (Pd) are crucial in hydrogen energy technologies, especially in fuel cells, due to their high catalytic activity and chemical stability. Pt-Pd nanoparticles, produced through various methods, enhance catalytic performance based on their size, shape, and composition. These nanocatalysts excel in direct methanol fuel cells (DMFCs) and direct ethanol fuel cells (DEFCs) by promoting alcohol oxidation and reducing CO poisoning. Pt-Pd catalysts are also being explored for their oxygen reduction reaction (ORR) on the cathodic side of fuel cells, showing higher activity and stability than pure platinum. Molecular dynamics (MD) simulations have been conducted to understand the structural and surface energy effects of PdPt nanoparticles, revealing phase separation and chemical ordering, which are critical for optimizing these catalysts. Pd migration to the surface layer in Pt-Pd alloys minimizes the overall potential energy through the formation of Pd surface monolayers and Pt-Pd bonds, leading to a lower surface energy for intermediate compositions compared to that of the pure elements. The potential energy, calculated from MD simulations, increases with a decreasing particle size due to surface creation, indicating higher reactivity for smaller particles. A general contraction of the average distance to the nearest neighbour atoms was determined for the top surface layers within the nanoparticles. This research highlights the significant impact of Pd segregation on the structural and surface energy properties of Pt-Pd nanoparticles. The formation of Pd monolayers and the resulting core–shell structures influence the catalytic activity and stability of these nanoparticles, with smaller particles exhibiting higher surface energy and reactivity. These findings provide insights into the design and optimization of Pt-Pd nanocatalysts for various applications. Full article

By controlling the structure and composition of Pt-based nanoalloys, the ethanol oxidation reaction (EOR) performances of Pt alloy catalysts can be effectively improved. Herein, we successfully synthesis sub-10 nm PdNi@PtNi nanoparticles (PdNi@PtNi NPs) with a core–shell structure by a one-pot method. The sub 10 nm core–shell nanoparticles possess more effective atoms and exhibit a synergistic effect which can lead to a shift in the d-band center and alter binding energies toward adsorbates. Due to the synergistic effect and unique core–shell structure, the PdNi@PtNi NP catalysts exhibit excellent electrocatalytic performance for ethanol oxidation reactions in alkaline, achieving 9.30 times more mass activity and 7.05 times more specific activity that of the state-of-the-art Pt/C catalysts. Moreover, the stability of PdNi@PtNi NPs was also greatly improved over PtNi nanoparticles, PtPd nanoparticles, and commercial Pt/C. This strategy provides a new idea for improving the electrocatalytic performance of Pt-based catalysts for EORs. Full article

High-efficiency and low-cost multifunctional electrocatalysts for hydrogen evolution reaction (HERs), oxygen evolution reaction (OERs) and oxygen reduction reaction (ORRs) are important for the practical applications of regenerative fuel cells. The activity trends of core–shell Ni₆@M₃₂ and Ni₆@Pt1M31 (M = Pt, Pd, Cu, Ag, Au) were investigated using the density functional theory (DFT). Rate constant calculations indicated that Ni₆@Pt₁Ag₃₁ was an efficient HER catalyst. The Volmer–Tafel process was the kinetically favorable reaction pathway for Ni₆@Pt₁M₃₁. The Volmer–Heyrovsky reaction mechanism was preferred for Ni₆@M₃₂. The Pt active site reduced the energy barrier and changed the reaction mechanism. The ORR and OER overpotentials of Ni₆@Pt₁Ag₃₁ were calculated to be 0.12 and 0.33 V, indicating that Ni₆@Pt₁Ag₃₁ could be a promising multifunctional electrocatalyst. Ni₆@Pt₁M₃₁ core–shell clusters present abundant active sites with a moderate adsorption strength for *H, *O, *OH and *OOH. The present study shows that embedding a single Pt atom onto a Ni@M core–shell cluster is a rational strategy for designing an effective multifunctional electrocatalyst. Full article

In modern agricultural practices, organophosphorus pesticides or insecticides (OPs) are regularly used to restrain pests. Their limits are closely monitored since their residual hinders the capability of acetylcholinesterase (AChE) and brings out a threatening accumulation of the neurotransmitter acetylcholine (ACh), which affects human well-being. Therefore, spotting OPs in food and the environment is compulsory to prevent human health. Several techniques are available to identify OPs but encounter shortcomings like time-consuming, operating costs, and slow results achievement, which calls for further solutions. Herein, we present a rapid colorimetric sensor for quantifying OPs in foods using TMB as a substrate, a multi-enzyme cascade system, and the synergistic property of core-shell Palladinum@Platinum (Pd@Pt) nanoparticles. The multi-enzyme cascade response framework is a straightforward and effective strategy for OPs recognition and can resolve the previously mentioned concerns. Numerous OPs, including Carbofuran, Malathion, Parathion, Phoxim, Rojor, and Phosmet, were successfully quantified at different concentrations. The cascade method established using Pd@Pt had a simple and easy operation, a lower detection limit range of (1–2.5 ng/mL), and a short detection time of about 50 min. With an R² value of over 0.93, OPs showed a linear range of 10–200 ng/mL, portraying its achievement in quantifying pesticide residue. Lastly, the approach was utilized in food samples and recovered more than 80% of the residual OPs. Full article

Metal aromatic substances play a unique and important role in both experimental and theoretical aspects, and they have made tremendous progress in the past few decades. The new aromaticity system has posed a significant challenge and expansion to the concept of aromaticity. From this perspective, based on spin-polarized density functional theory (DFT) calculations, we systematically investigated the doping effects on the reduction reactions of N₂O catalyzed by CO for M₁₃@Cu₄₂ (M = Cu, Co, Ni, Zn, Ru, Rh, Pd, Pt) core–shell clusters from aromatic-like inorganic and metal compounds. It was found that compared with the pure Cu₅₅ cluster, the strong M–Cu bonds provide more structural stability for M₁₃@Cu₄₂ clusters. Electrons that transferred from the M₁₃@Cu₄₂ to N₂O promoted the activation and dissociation of the N–O bond. Two possible reaction modes of co-adsorption (L-H) and stepwise adsorption (E-R) mechanisms over M₁₃@Cu₄₂ clusters were thoroughly discovered. The results showed that the exothermic phenomenon was accompanied with the decomposition process of N₂O via L-H mechanisms for all of the considered M₁₃@Cu₄₂ clusters and via E-R mechanisms for most of the M₁₃@Cu₄₂ clusters. Furthermore, the rate-limiting step of the whole reactions for the M₁₃@Cu₄₂ clusters were examined as the CO oxidation process. Our numerical calculations suggested that the Ni₁₃@Cu₄₂ cluster and Co₁₃@Cu₄₂ clusters exhibited superior potential in the reduction reactions of N₂O by CO; especially, Ni₁₃@Cu₄₂ clusters are highly active, with very low free energy barriers of 9.68 kcal/mol under the L-H mechanism. This work demonstrates that the transition metal core encapsulated M₁₃@Cu₄₂ clusters can present superior catalytic activities towards N₂O reduction by CO. Full article

Electrochemical CO₂ reduction reactions can lead to high value-added chemical and materials production while helping decrease anthropogenic CO₂ emissions. Copper metal clusters can reduce CO₂ to more than thirty different hydrocarbons and oxygenates yet they lack the required selectivity. We present a computational characterization of the role of nano-structuring and alloying in Cu-based catalysts on the activity and selectivity of CO₂ reduction to generate the following one-carbon products: carbon monoxide (CO), formic acid (HCOOH), formaldehyde (H₂C=O), methanol (CH₃OH) and methane (CH₄). The structures and energetics were determined for the adsorption, activation, and conversion of CO₂ on monometallic and bimetallic (decorated and core@shell) 55-atom Cu-based clusters. The dopant metals considered were Ag, Cd, Pd, Pt, and Zn, located at different coordination sites. The relative binding strength of the intermediates were used to identify the optimal catalyst for the selective CO₂ conversion to one-carbon products. It was discovered that single atom Cd or Zn doping is optimal for the conversion of CO₂ to CO. The core@shell models with Ag, Pd and Pt provided higher selectivity for formic acid and formaldehyde. The Cu-Pt and Cu-Pd showed lowest overpotential for methane formation. Full article

Nano-sized radiosensitizers can be used to increase the effectiveness of radiation-based anticancer therapies. In this study, bimetallic, ~30 nm palladium-platinum nanoparticles (PdPt NPs) with different nanostructures (random nano-alloy NPs and ordered core-shell NPs) were prepared. Scanning transmission electron microscopy (STEM), selected area electron diffraction (SAED), energy-dispersive X-ray spectroscopy (EDS), zeta potential measurements, and nanoparticle tracking analysis (NTA) were used to provide the physicochemical characteristics of PdPt NPs. Then, PdPt NPs were added to the cultures of colon cancer cells and normal colon epithelium cells in individually established non-toxic concentrations and irradiated with the non-harmful dose of X-rays/protons. Cell viability before and after PdPt NPs-(non) assisted X-ray/proton irradiation was evaluated by MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) assay. Flow cytometry was used to assess cell apoptosis. The results showed that PdPt NPs significantly enhanced the effect of irradiation on cancer cells. It was noticed that nano-alloy PdPt NPs possess better radiosensitizing properties compared to PtPd core-shell NPs, and the combined effect against cancer cells was c.a. 10% stronger for X-ray than for proton irradiation. Thus, the radio-enhancing features of differently structured PdPt NPs indicate their potential application for the improvement of the effectiveness of radiation-based anticancer therapies. Full article

Fuel cells are expected to bring change to the whole human race when commercialized, however, the sluggish kinetics of oxygen reduction reaction (ORR) severely hampers their commercial viability. Thus far, platinum (Pt) based catalysts are nearly inevitable due to the harsh redox environment of fuel cells. Thus, minimizing Pt metal loading and increasing Pt utilization is a paramount factor for realizing fuel cell technologies. In this context, herein, we developed a multi-metallic nanocatalyst (NC) comprising Pt-clusters (1 wt.%) decorated SnPd composite shell over cobalt-oxide core crystal underneath (denoted as CSPP). For optimizing the ORR performance of the as-prepared NC, we further modulated the configuration of the SnPd shell. In the optimum case, when the Sn/Pd ratio is 0.5 (denoted as CSPP 1005), the ORR mass activity (MA) is 3034.7 mA mg_Pt⁻¹ at 0.85 V vs. RHE in 0.1 M KOH electrolyte, which is 45-times higher than the commercial Johnson Matthey-Pt/C (J.M.-Pt/C; 20 wt.% Pt) catalyst (67 mA mg_Pt⁻¹). The results of physical inspections along with electrochemical analysis suggest that such high performance of CSPP 1005 NC can be attributed to the synergistic collaboration between Pt-clusters, PtPd nanoalloys, and adjacent SnPd domains, where Pt-clusters and PtPd nanoalloys promote the O₂ adsorption and subsequent splitting, while the SnPd shell favours the OH⁻ relocation step. We believe that the obtained results will open a new avenue for further exploring the high-performance Pt-based catalysts with low Pt-loading and high utilization. Full article

Colorimetric enzyme-linked immunosorbent assay (ELISA) has been widely applied as the gold-standard method for cytokine detection for decades. However, it has become a critical challenge to further improve the detection sensitivity of ELISA, as it is limited by the catalytic activity of enzymes. Herein, we report an enhanced colorimetric ELISA for ultrasensitive detection of interleukin-6 (IL-6, as a model cytokine for demonstration) using Pd@Pt core@shell nanodendrites (Pd@Pt NDs) as peroxidase nanomimics (named “Pd@Pt ND ELISA”), pushing the sensitivity up to femtomolar level. Specifically, the Pd@Pt NDs are rationally engineered by depositing Pt atoms on Pd nanocubes (NCs) to generate rough dendrite-like Pt skins on the Pd surfaces via Volmer–Weber growth mode. They can be produced on a large scale with highly uniform size, shape, composition, and structure. They exhibit significantly enhanced peroxidase-like catalytic activity with catalytic constants (Kcat) more than 2000-fold higher than those of horseradish peroxidase (HRP, an enzyme commonly used in ELISA). Using Pd@Pt NDs as the signal labels, the Pd@Pt ND ELISA presents strong colorimetric signals for the quantitative determination of IL-6 with a wide dynamic range of 0.05–100 pg mL⁻¹ and an ultralow detection limit of 0.044 pg mL⁻¹ (1.7 fM). This detection limit is 21-fold lower than that of conventional HRP-based ELISA. The reproducibility and specificity of the Pd@Pt ND ELISA are excellent. More significantly, the Pd@Pt ND ELISA was validated for analyzing IL-6 in human serum samples with high accuracy and reliability through recovery tests. Our results demonstrate that the colorimetric Pd@Pt ND ELISA is a promising biosensing tool for ultrasensitive determination of cytokines and thus is expected to be applied in a variety of clinical diagnoses and fundamental biomedical studies. Full article

The magnetic properties and the atomic scale morphology of bimetallic two-dimensional nanoislands, epitaxially grown on fcc(111) metal surfaces, have been studied by means of Magneto-Optical Kerr Effect and Scanning Tunneling Microscopy. We investigate the effect on blocking temperature of one-dimensional interlines appearing in core-shell structures, of two-dimensional interfaces created by capping, and of random alloying. The islands are grown on Pt(111) and contain a Co-core, surrounded by Ag, Rh, and Pd shells, or capped by Pd. The largest effect is obtained by Pd capping, increasing the blocking temperature by a factor of three compared to pure Co islands. In addition, for Co-core Fe-shell and Co-core Fe_xCo_1−x-shell islands, self-assembled into well ordered superlattices on Au(11,12,12) vicinal surfaces, we find a strong enhancement of the blocking temperature compared to pure Co islands of the same size. These ultra-high-density (15 Tdots/in²) superlattices of CoFe nanodots, only 500 atoms in size, have blocking temperature exceeding 100 K. Our findings open new possibilities to tailor the magnetic properties of nanoislands. Full article

An eco-friendly two-step synthetic method for synthesizing Pd@PdPt/CNTs nanoparticles was introduced and studied for the methanol oxidation reaction. The Pd@PdPt alloy core-shell structure was synthesized by preparing a surfactant-free monodispersed Pd/CNTs precursor through the hydrolysis of tetrachloropalladate (II) ion ([PdCl₄]²⁻) in the presence of carbon nanotubes (CNTs) and the subsequent hydrogen reduction and followed by a galvanic replacement reaction. This method opens up an eco-friendly, practical, and straightforward route for synthesizing monometallic or bimetallic nanoparticles with a clean surfactant-free electrocatalytic surface. It is quite promising for large-scale preparation. The Pd@PdPt/CNTs electrocatalyst demonstrated a high specific mass activity for methanol oxidation (400.2 mAmg_Pt⁻¹) and excellent stability towards direct methanol oxidation compared to its monometallic counterparts. Full article

In this study, 3%Pd/Al₂O₃, 3%Pt/Al₂O₃ and bimetallic (1%Pd + 2%Pt)/Al₂O₃ catalysts were examined in the total oxidation of methane in a temperature range of 150–400 °C. The evolution of the active component under the reaction conditions was studied by transmission electron microscopy and in situ extended X-ray absorption fine structure (EXAFS) spectroscopy. It was found that the platinum and bimetallic palladium-platinum catalysts are more stable against sintering than the palladium catalysts. For all the catalysts, the active component forms a “core-shell” structure in which the metallic core is covered by an oxide shell. The “core-shell” structure for the platinum and bimetallic palladium-platinum catalysts is stable in the temperature range of 150–400 °C. However, in the case of the palladium catalysts the metallic core undergoes the reversible oxidation at temperatures above 300 °C and reduced to the metallic state with the decrease in the reaction temperature. The scheme of the active component evolution during the oxidation of methane is proposed and discussed. Full article