PtPd Bimetallic Nanoparticles Research Articles

Deposition of Pd, Pt, and PdPt Nanoparticles on TiO2 Powder Using Supercritical Fluid Reactive Deposition: Application in the Direct Synthesis of H2O2.

In this study, we investigated the catalytic properties of mono- and bimetallic palladium (Pd) and platinum (Pt) nanoparticles deposited via supercritical fluid reactive deposition (SFRD) on titanium dioxide (TiO2) powder. Transmission electron microscopy analyses verified that SFRD experiments performed at 353 K and 15.6 MPa enabled the deposition of uniform mono- and bimetallic nanoparticles smaller than 3 nm on TiO2. Electron-dispersive X-ray spectroscopy demonstrated the formation of alloy-type structures for the bimetallic PdPt nanoparticles. H2O2 is an excellent oxidizing reagent for the production of fine and bulk chemicals. However, until today, the design and preparation of catalysts with high H2O2 selectivity and productivity remain a great challenge. The focus of this study was on answering the questions of (a) whether the catalysts produced are suitable for the direct synthesis of hydrogen peroxide (H2O2) in the liquid phase and (b) how the metal type affects the catalytic properties. It was found that the metal type (Pd or Pt) influenced the catalytic performance strongly; the mean productivity of the mono- and bimetallic catalysts decreased in the following order: Pd > PdPt > Pt. Furthermore, all catalysts prepared by SFRD showed a significantly higher mean productivity compared to the catalyst prepared by incipient wetness impregnation.

Enhanced Mass Activity and Durability of Bimetallic Pt-Pd Nanoparticles on Sulfated-Zirconia-Doped Graphene Nanoplates for Oxygen Reduction Reaction in Proton Exchange Membrane Fuel Cell Applications.

Developing highly active and durable Pt-based electrocatalysts is crucial for polymer electrolyte membrane fuel cells. This study focuses on the performance of oxygen reduction reaction (ORR) electrocatalysts composed of Pt-Pd alloy nanoparticles on graphene nanoplates (GNPs) anchored with sulfated zirconia nanoparticles. The results of field emission scanning electron microscopy and transmission electron microscopy showed that Pt-Pd and S-ZrO2 are well dispersed on the surface of the GNPs. X-ray diffraction revealed that the S-ZrO2 and Pt-Pd alloy coexist in the Pt-Pd/S-ZrO2-GNP nanocomposites without affecting the crystalline lattice of Pt and the graphitic structure of the GNPs. To evaluate the electrochemical activity and reaction kinetics for ORR, we performed cyclic voltammetry, rotating disc electrode, and EIS experiments in acidic solutions at room temperature. The findings showed that Pt-Pd/S-ZrO2-GNPs exhibited a better ORR performance than the Pt-Pd catalyst on the unsulfated ZrO2-GNP support and with Pt on S-ZrO2-GNPs and commercial Pt/C.

An innovative immunochromatographic assay employing Pt-Pd bimetallic nanoparticles as labels for the detection of foot-and-mouth disease virus serotype O

ObjectiveWe created a novel, high sensitivity immunochromatographic assay that allows for clear and precise quantitative analysis by employing innovative bimetallic nanoparticles with peroxide-like activity as markers for the preparation of the test strip. MethodsInitially, we synthesized Pt-Pd bimetallic nanoparticles through the reduction of K2PtCl4 and Na2PdCl4 using ascorbic acid (AA) in an ultrasonic water bath. These bimetallic nanoparticles were then utilized to label purified antigens from the foot-and-mouth disease virus (FMDV) type O (FMDV-146S), resulting in the creation of antigen-captured nanomarkers. Upon completion of the antigen–antibody reaction, we introduced a color-developing agent (3,3′,5,5′-tetramethylbenzidine) for cascade amplification, significantly enhancing detection sensitivity while ensuring clear and accurate quantitative analysis. ResultsThe quantitative detection sensitivity achieved was 1:28/test, with a linear range spanning from 1:26 ∼ 1:29 /test. For FMDV type O positive serum, the detection sensitivity reached 96.7 %. Furthermore, this method exhibited a 95 % detection sensitivity for FMDV negative serum, FMDV type A and type AsiaⅠ positive sera, as well as sera positive for other common viral diseases in animals. In comparison to the OIE-recommended LPB-ELISA, this approach displayed higher correlation (correlation coefficient = 0.909). Innovation was at the core of establishing this immunochromatographic assay based on Pt-Pd bimetallic nanoparticles for the detection of FMDV antibodies. ConclusionThe findings revealed a striking 24-fold improvement in sensitivity when compared to colloidal gold, accompanied by a strong correlation coefficient (R2 > 0.9). This suggests a robust and consistent linear association in the results. This method represents a significant advancement in the field of rapid immunochromatographic assays, offering a promising alternative application for bimetallic nanoparticles.

Fractal Design of Hierarchical PtPd with Enhanced Exposed Surface Atoms for Highly Catalytic Activity and Stability.

Hierarchical assembly of arc-like fractal nanostructures not only has its unique self-similarity feature for stability enhancement but also possesses the structural advantages of highly exposed surface-active sites for activity enhancement, remaining a great challenge for high-performance metallic nanocatalyst design. Herein, we report a facile strategy to synthesize a novel arc-like hierarchical fractal structure of PtPd bimetallic nanoparticles (h-PtPd) by using pyridinium-type ionic liquids as the structure-directing agent. Growth mechanisms of the arc-like nanostructured PtPd nanoparticles have been fully studied, and precise control of the particle sizes and pore sizes has been achieved. Due to the structural features, such as size control by self-similarity growth of subunits, structural stability by nanofusion of subunits, and increased numbers of exposed active atoms by the curved homoepitaxial growth, h-PtPd displays outstanding electrocatalytic activity toward oxygen reduction reaction and excellent stability during hydrothermal treatment and catalytic process.

PtPd NPs-functionalized metal-organic framework-derived α-Fe2O3 porous spindles for efficient low-temperature detection of triethylamine.

In recent years, metal-organic framework (MOF) derivatives have gradually become ideal materials for gas sensors due to their controllable composition, diverse structures and open metal sites. In this research, a simplified hydrothermal method was applied to successfully prepare MOF-derived α-Fe2O3 spindles, and an in situ reduction method was then utilized to deposit Pt, Pd and PtPd bimetallic nanoparticles (NPs) on the α-Fe2O3 spindles. The effects of noble metals Pt, Pd and PtPd on the gas-sensing properties of Fe2O3 were systematically examined. The PtPd/α-Fe2O3 sensor has enhanced gas-sensing performance for triethylamine (TEA), especially at PtPd content of 1.5 wt% and mass ratio of Pt : Pd = 90 : 10, where the response of the sensor to 100 ppm TEA at a lower temperature of 150 °C is 442, which is 34 times higher than that of the original α-Fe2O3 (response of 13). Additionally, the sensor demonstrated improved response/recovery properties and very respectable selectivity, repeatability, long-term stability within 30 days and lower detection limit (500 ppb) at 150 °C. Combining the results of XPS and O2-TPD, the enhanced gas-sensing properties of PtPd bimetallic-modified α-Fe2O3 over monometallic (Pt or Pd) modified α-Fe2O3 were analyzed, which can be attributed to the chemical and electronic sensitization of noble metals and the synergistic effect of the PtPd bimetallic NPs, resulting in more surface defects and enhanced oxygen adsorption capacity of the sensing material. This work provided an effective gas-sensing material for the low-temperature detection and analysis of triethylamine gas.

PEDOT-embellished Ti3C2Tx nanosheet supported Pt-Pd bimetallic nanoparticles as efficient and stable methanol oxidation electrocatalysts.

Exploiting high-efficiency and durable electrocatalysts toward the methanol oxidation reaction (MOR) is crucial for the advancement of direct methanol fuel cells (DMFCs). Herein, we demonstrate the loading of platinum-palladium bimetallic nanoparticles (Pt-Pd NPs) onto poly(3,4-ethylenedioxythiophene) (PEDOT)-embellished titanium carbide (Ti3C2Tx) nanosheets as the electrocatalyst (Ti3C2Tx/PEDOT/Pt-Pd) via a facile and rapid chemical reduction-assisted one-pot hydrothermal process. The structural and morphological analyses of Ti3C2Tx/PEDOT/Pt-Pd indicate that the three-dimensional (3D) hybrid structure formed between PEDOT and Ti3C2Tx provides a sizable active surface and more active sites, which enhances the homogeneous dispersion of the Pt-Pd NPs and facilitates mass transfer. The Schottky junctions formed between PEDOT and Pt-Pd NPs contribute to charge transfer. The electronic effects and synergistic interactions between the support and catalyst favor the electrocatalytic activity of the catalyst. The electrochemical test results reveal that the Ti3C2Tx/PEDOT/Pt-Pd catalyst has prominent electrocatalytic capability for the MOR. Compared with Ti3C2Tx/Pt-Pd and commercial Pt/C catalysts, the Ti3C2Tx/PEDOT/Pt-Pd catalyst has a larger electrochemical activity surface area (ECSA = 122 m2 g-1) and higher mass activity (MA = 1445.4 mA mg-1), as well as better CO tolerance and more reliable long-term durability (a peak current density retention of 71% after 5200 s).

Catalytic oxidation of propane over Pt-Pd bimetallic nanoparticles supported on TiO2

The oxidation of propane to CO2 was performed by means of Pt-Pd nanoparticles supported on TiO2. The catalyst activities were evaluated through conversion versus temperature, where propane conversion profiles and reaction rates followed the order Pt-Pd/TiO2 > Pt/TiO2 > Pd/TiO2. It is proposed that the oxidation of propane on Pt-Pd/TiO2 catalysts occurs not only on Pt0 and Pd0 sites but also on Pt2+, Pd2+ and Ti3+ones, improving the oxidation pathway of propane as shown by Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) and X-ray Photoelectron Spectroscopy (XPS). Propane uptake and Lewis and Brönsted acidity type on the Pt-Pd/TiO2 catalyst were four times higher than on Pt/TiO2 and Pd/TiO2 as observed by FTIR-pyridine thermo-desorption. Ab-initio calculations showed that Pt enhanced the Brönsted acidity of the interface favoring a dissociative oxygen adsorption, whereas the bimetallic system presented more acidic Lewis sites which correlate with the catalytic activity. Then, hydrogen adsorption could be considered as a chemical reactivity descriptor for the oxidation of propane. Likewise, the higher activity of the Pt-Pd/TiO2 catalyst was explained by considering that the Pt-Pd catalyzed reduction of Ti4+ to Ti3+created oxygen vacancies that enhanced the mobility of lattice oxygen of the TiO2 support and its transfer to the propane species adsorbed on the Pt-Pd bimetallic nanoparticles.

Thermo-responsive catalysts based on bimetallic alloyed Pt-Pd supported on mesoporous silica: Controllable hydrogen generation from ammonia borane

The ultrafine and highly dispersed bimetallic Pt-Pd nanoparticles are successfully anchored on mesoporous silica nanoparticles (MSN). The [email protected] catalyst exhibits excellent catalytic performance in the hydrogen from ammonia borane (AB). When the [email protected] nanoparticles were grafted with luminescent material and smart thermo-responsive polymer, a smart catalyst could be fabricated. The smart catalyst exhibits the thermo-responsive catalytic performance and switchable luminescence. For example, the composite catalyst displays high catalytic activity in hydrolysis of AB at 25 °C. However, it shows much lower catalytic activity when the temperature increases to 35 °C. The smart catalysts could be potentially applied in the self-protection device of dehydrogenation. When the system of dehydrogenation is under high temperature environment, the smart composite catalyst could automatically restrain the production of H2 for the purpose of safety.

Direct Imaging of the Atomic Mechanisms Governing the Growth and Shape of Bimetallic Pt-Pd Nanocrystals by In Situ Liquid Cell STEM.

Understanding the atomic mechanisms governing the growth of bimetallic nanoalloys is of great interest for scientists. As a promising material for photocatalysis applications, Pt-Pd bimetallic nanoparticles (NPs) have been in the spotlight for many years due to their catalytic performance, which is typically superior to that of pure Pt NPs. In this work, we use in situ liquid cell scanning transmission electron microscopy to track the exact atomic mechanisms governing the formation of bimetallic Pt-Pd NPs. We find that the formation process of the bimetallic Pt-Pd is divided into three stages. First, the nucleation and growth of ultrasmall primary nanoclusters are formed by the agglomeration of Pt and Pd atoms. Second, the primary nanoclusters are involved in a coalescence process to form two types of bigger agglomerates, namely, amorphous (a-NC) and crystalline (c-NC) nanoclusters. In the third stage, these clusters undergo a coalescence process leading to the formation of Pt-Pd NPs, while, in parallel, monomer attachment continues. We found that the third stage contains three types of coalescence processes, a-NC-a-NC, a-NC-c-NC, and c-NC-c-NC coalescence, which eventually give rise to crystalline bimetallic alloys. However, each type of coalescence gave distinct NPs in terms of shape and defects. Our results thus reveal the exact growth mechanisms of bimetallic alloys on the atomic scale, unravel the origin of their structure, and overall are of key interest to tailor the structure of bimetallic NPs.

Improved Oxygen Reduction on GC-Supported Large-Sized Pt Nanoparticles by the Addition of Pd

PdPt bimetallic nanoparticles on carbon-based supports functioning as advanced electrode materials have attracted attention due to their low content of noble metals and high catalytic activity for fuel cell reactions. Glassy carbon (GC)-supported Pt and PdPt nanoparticles, as promising catalysts for the oxygen reduction reaction (ORR), were prepared by the electrochemical deposition of Pt and the subsequent spontaneous deposition of Pd. The obtained electrodes were examined using X-ray Photoelectron Spectroscopy (XPS), Atomic Force Microscopy (AFM), and electroanalytical techniques. An XPS analysis of the PdPt/GC with the highest ORR performance revealed that the stoichiometric ratio of Pd: Pt was 1:2, and that both Pt and Pd were partially oxidized. AFM images of PdPt2/GC showed the full coverage of GC with PdPt nanoparticles with sizes from 100–300 nm. The ORR activity of PdPt2/GC in an acid solution approached that of polycrystalline Pt (E1/2 = 0.825 V vs. RHE), while exceeding it in an alkaline solution (E1/2 = 0.841 V vs. RHE). The origin of the improved ORR on PdPt2/GC in an alkaline solution is ascribed to the presence of a higher amount of adsorbed OH species originating from both PtOH and PdOH that facilitated the 4e-reaction pathway.

Multishell SnO2 Hollow Microspheres Loaded with Bimetal PdPt Nanoparticles for Ultrasensitive and Rapid Formaldehyde MEMS Sensors.

Low-cost and real-time formaldehyde (HCHO) monitoring is of great importance due to its volatility, extreme toxicity, and ready accessibility. In this work, a low-cost and integrated microelectromechanical system (MEMS) HCHO sensor is developed based on SnO2 multishell hollow microspheres loaded with a bimetallic PdPt (PdPt/SnO2-M) sensitizer. The MEMS sensor exhibits a high sensitivity to HCHO ((Ra/Rg - 1) % = 83.7 @ 1 ppm), ultralow detection limit of 50 ppb, and ultrashort response/recovery time (5.0/7.0 s @ 1 ppm). These excellent HCHO sensing properties are attributed to its unique multishell hollow structure with a large and accessible surface, abundant interfaces, suitable mesoporous structure, and synergistic catalytic effects of bimetal PdPt. The well-defined multishell hollow structure also shows fascinating capacities as good hosts for noble metal loading. Therefore, PdPt bimetallic nanoparticles can be employed to construct a synergistic sensitizer with a high content and good dispersity on this multishell hollow structure, further exhibiting a reduced working temperature and ultrasensitive detection of HCHO. This PdPt/SnO2-M-based MEMS sensor presents a unique and highly sensitive means to detect HCHO, establishing its great promise for potential application in environmental monitoring.

Highly active PdPt bimetallic nanoparticles synthesized by one-step bioreduction method: Characterizations, anticancer, antibacterial activities and evaluation of their catalytic effect for hydrogen generation

Metallic nanoparticles (MNPs) have important applications in medicine and technology. Bimetallic NPs, which are among the metallic nanoparticles, are of great interest due to their properties. An innovative method by green synthesis has been developed to obtain bimetallic NPs. Aromatic plants are used in this synthesis method. One of the plants used for green synthesis is Nigella sativa and it has a unique place among plants for use as medicine. In this study, the synthesis of Palladium–Platinum bimetallic nanoparticles (PdPt NPs) and the catalytic, antibacterial, and anticancer activity of synthesized PdPt NPs by green synthesis method using Nigella sativa seed extract are reported. The synthesized PdPt NPs were characterized by Fourier Transform Infrared Spectrophotometer (FTIR), Transmission Electron Microscopy (TEM), X-ray diffraction (XRD), and UV–Vis spectrometry techniques. The catalytic activity of PdPt NPs was determined by performing sodium borohydride (NaBH4) hydrolysis experiments. According to the results obtained, Turnover Frequency (TOF), activation energy, entropy, and enthalpy values were found to be 1664.76 h−1, 13.93 kJ/mol, −119.02 J/mol.K, and 11.43 kJ/mol, respectively. It was determined that PdPt NPs are highly effective catalysts for hydrogen production. PdPt NPs (200 μg/mL) were determined to have antibacterial activity of 57.58%, 64.42%, 48.68%, and 58.77% against Escherichia coli, Staphylococcus aureus, Methicillin-resistant Staphylococcus aureus, and Bacillus subtilis bacteria, respectively. In addition, the cytotoxic effects of PdPt NPs, MTT against human breast cancer cell line (MDA-MB-231), human endometrial carcinoma cell line (Ishikawa, ISH), human cervical cancer cell line (HeLa), L929-Murine fibroblast cell line test, and IC50 values were calculated. The IC50 values of PdPt NPs applied against MDA-MB-231, ISH, and HeLa cancer cell lines were calculated as 9.1744 ± 1.566 μg/mL, 12.2431 ± 1.132 μg/mL, 18.1963 ± 1.730 μg/mL, respectively. No significant cytotoxic effect was observed in healthy L929-murine fibroblasts. Green synthesis of PdPt NPs was determined to have significant advantages over chemical approaches. The biogenic PdPt NPs synthesized in this study suggest the design of bio-based bimetallic catalysts with high catalytic performance to prevent environmental pollution.

Electrocatalytic activity of bimetallic PtPd on cerium oxide-modified carbon nanotube for oxidation of alcohol and formic acid

• Bimetallic PtPd nanoparticles on CeO 2 modified CNT were prepared by reduction . • Effective catalysts provide better electrocatalytic performance towards oxidations. • High current density and durability compared to commercial Pt/C were found. This paper proposes an approach for the fabrication of an anode electrocatalyst for application as a fuel cell catalyst. It comprises three components, multiwall carbon nanotube (CNT), ceria oxide (CeO 2 ), and metal (i.e., Pt and/or Pd), using the reduction method for preparation. The characterization of the prepared catalysts was determined by transmission electron microscopy (TEM), X-ray diffraction, and Raman spectroscopy. The electrocatalytic performance of the prepared catalysts was examined by electrochemical measurements, e.g., cyclic voltammetry, chronoamperometry and CO stripping voltammetry. Among the catalysts, the obtained 1Pt1Pd − CeO 2 /CNT electrocatalyst provides a high electrochemical surface area, as well as high oxidation activity and durability for the oxidation of methanol, ethanol, and formic acid. The enhancement of the catalytic activity is attributed to changes in the surface electronic structures of Pt, Pd, and CeO 2 on the CNT surface that incrementally effect the active sites for oxidation. A required catalytic performance for these oxidations were observed with small-size and high-dispersion of the metal i.e.1Pt1Pd (3.34 nm) on the CeO 2 /CNT support nanocomposite. The results also show substantial improvement in the kinetics for oxidations and mass transfer efficiency owing to the catalyst structure. Therefore, the prepared catalysts have promising potential for application in low-temperature fuel cells.

Electrochemically simultaneous detection of ascorbic acid, sulfite and oxalic acid on Pt-Pd nanoparticles/chitosan/nitrogen doped graphene modified glassy carbon electrode: A method for drug quality control

Methods that can directly and sensitively quantify a set of correlative substances lack of chromophores in pharmaceuticals are persistently desired. Here, by facile preparation of Pt-Pd nanoparticles/chitosan/nitrogen-doped graphene (N-Gra) nanocomposite, we establish an electroanalytical method for simultaneous detection of ascorbic acid (AA), sulfite and oxalic acid (OA) that are closely involved with Vitamin C injection, a widely-used clinical drug. One-step electrodeposition of Pt-Pd bimetallic nanoparticles on chitosan/N-Gra decorated glassy carbon electrode was proposed to construct a well-performing electrocatalyst possessing notable electrochemical activity to the electrooxidation of both sulfite and OA. The electrocatalytic ability was evidenced by the increased current response and decreased oxidation overpotential. More importantly, sufficiently electrochemical resolution of multiple oxidative peaks allowed simultaneous quantitation of the three species of interest. The peak currents measured by differential pulse voltammetry were linear to the analytical concentration of AA, sulfite, and OA, yielding good linear ranges of 2 ~ 400 μM, 8 ~ 600 μM, and 1.5 ~ 500 μM, respectively. Correspondingly, the limit of detection was 0.97 μM, 5.5 μM, and 0.84 μM. This work opens a vista for multiplex assays of pharmaceuticals, including drug principal ingredient, toxic preservative, and decomposed impurity without chromatographic separation, and thus holds promise for the overall quality control for clinical drug.

Bimetallic PtPd nanoparticles relying on CoNiO2 and reduced graphene oxide as a most operative electrocatalyst toward ethanol fuel oxidation

Of late, fuel cells have drawn great attentions owing to high-energy demands, fossil fuel depletion and worldwide environmental pollution. Direct ethanol fuel cell (DEFC) constituted as one of the most promising sources of green energy, howbeit the ethanol oxidation reaction (EOR) sluggish kinetic is one of the essential challenges toward the commercialization of DEFCs. Herein, we introduce bimetallic catalyst on CoNiO2 modified reduced graphene oxide (rGO) to completely exploit the advantages of nano-surface structures as well as the reduction of Pt and Pd loading in fuel cells. With the combined advantages of PtPd, CoNiO2 and rGO, a significant enhancement in electrocatalytic behavior, stability and CO poisoning tolerance of PtPd have been observed. Regarding the implications, PtPd/CoNiO2/rGO is greatly preferable than Pt/CoNiO2/rGO and Pd/CoNiO2/rGO in terms of high electroactive surface area (ECSA), electro-catalytic activity, and lower onset potential (Eons) towards the EtOH oxidation in alkaline media. Furthermore, the chronoamperometry curve (CA) illustrated 77% after 3600 s which is dramatically soared compared with the other electrodes (≤40%), demonstrating the high stability of the PtPd bimetallic nanoparticle electrocatalyst. Ultimately, PtPd/CoNiO2/rGO nanocomposite is found to be an excellent anode electrocatalyst for application in DEFCs.

Characterization and Electrocatalytic Features of PtPd and PdPt Bimetallic Nanoparticles for Methanol Electro‐oxidation

AbstractThis work entails a comprehensive study on PtPd, and PdPt bimetallic nanoparticles (BNPs) supported on Vulcan XC‐72 carbon towards methanol oxidation reaction (MOR) in alkaline media. BNPs with different compositions were synthesized using a flexible and facile polyol method through a heterogeneous nucleation process. The homogeneous BNPs were characterized by SEM, XRD, HR‐TEM and XRF to analyse the crystallographic structure and verified the controlled characteristics. The electrochemical properties and stability were investigated using cyclic voltammetry and chronoamperometry, respectively. As a consequence of the electrocatalysts’ controlled composition, a direct correlation between the catalytic activity and the shift in the PtO/PdO reduction potential was observed. The optimal electrocatalyst that overcomes the catalytic performance of PdPt structure, also showed an improvement in the CO anti‐poisoning ability was PtPd (1 : 0.5)/C with a current density of 12.56‐fold higher than of commercial Pt/C. This study about different Pt/Pd structures may provide valuable information for developing new and efficient electrocatalysts towards MOR.

Tuning the porosity of sulfur-resistant Pd-Pt/MCM-41 bimetallic catalysts for partial hydrogenation of soybean oil-derived biodiesel

Partial hydrogenation of soybean oil-derived fatty acid methyl esters was studied using MCM-41 mesoporous silica-supported Pd-Pt bimetallic catalysts with tunable porosity under mild reaction conditions (100 °C, 0.4 MPa H2, 4 h). This process produced partially hydrogenated fatty acid methyl esters (H-FAME) as a new type of high-quality biodiesel fuel enriched in monounsaturated fatty acid methyl esters (mono-FAME), which is a potential source for formulating high blends of biodiesel fuel with petrodiesel. MCM-41 supports with various structural properties and morphologies were synthesized by self-assembly with different amounts of ammonia solution as a mineralizing agent. Bimetallic Pd-Pt nanoparticles with a Pd/Pt atomic ratio of 4 were stepwise impregnated on three MCM-41 supports, resulting in a series of Pd-Pt/MCM-41 bimetallic catalysts with tunable porosity (0.89–1.79 cm3 g−1), average pore size (3.2–8.5 nm), and particle size (0.12–0.62 μm). The Pd-Pt/MCM-41 catalyst prepared with the least amount of ammonia produced the best partial hydrogenation conversion of polyunsaturated FAME into mono-FAME, ascribed to nano-aggregation resulting in a dual-pore system containing large pores for fast molecular diffusion; a high turnover frequency (1920 h−1), larger k1 rate constant (0.60 gcat−1h−1), and smaller k2 rate constant (0.37 gcat−1h−1) were obtained. Furthermore, this Pd-Pt/MCM-41 catalyst exhibited excellent sulfur resistance in the synthesis of H-FAME, even though the feedstocks contained approximately 5 ppm of sulfur contaminates. These results demonstrate that the sulfur-resistant Pd-Pt/MCM-41 bimetallic catalysts with stable and dual pore system are beneficial for obtaining higher quality BDF to reduce our reliance on fossil fuels.

Effect of Pd on the Electrocatalytic Activity of Pt towards Oxidation of Ethanol in Alkaline Solutions

The understanding of electrocatalytic activity and poisoning resistance properties of Pt and Pd nanoparticles, recognized as the best electrocatalysts for the ethanol oxidation reaction, is an essential step for the commercialization of direct ethanol fuel cells (DEFCs). In this paper, mono and bimetallic Pt and Pd nanoparticles with different atomic ratios have been synthesized to study their electrocatalytic properties for an ethanol oxidation reaction in alkaline solutions. The different nanoparticles were physiochemically characterized by transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The electrochemical characterization was performed by cyclic voltammetry and chronoamperometry measurements. The electrochemical measurements indicate that Pt nanoparticles have much higher electrocatalytic activity for ethanol oxidation than Pd nanoparticles. The studies with bimetallic PtPd nanoparticles showed a significant impact of their composition on the ethanol oxidation. Thus, the highest electrocatalytic activity and poisoning resistance properties were obtained for Pt3Pd2 nanoparticles. Moreover, this study demonstrates that the poisoning of the catalyst surface through ethanol oxidation is related to the prevalence of the acetaldehyde–acetate route and the polymerization of acetaldehyde through aldol condensation in the alkaline media.

NIR Stimulus-Responsive PdPt Bimetallic Nanoparticles for Drug Delivery and Chemo-Photothermal Therapy.

The combination of chemotherapy and phototherapy has attracted increasing attention for cancer treatment in recent years. In the current study, porous PdPt bimetallic nanoparticles (NPs) were synthesized and used as delivery carriers for the anti-cancer drug doxorubicin (DOX). DOX@PdPt NPs were modified with thiol functionalized hyaluronic acid (HA-SH) to generate DOX@PdPt@HA NPs with an average size of 105.2 ± 6.7 nm. Characterization and in vivo and in vitro assessment of anti-tumor effects of DOX@PdPt@HA NPs were further performed. The prepared DOX@PdPt@HA NPs presented a high photothermal conversion efficiency of 49.1% under the irradiation of a single 808 nm near-infrared (NIR) laser. Moreover, NIR laser irradiation-induced photothermal effect triggered the release of DOX from DOX@PdPt@HA NPs. The combined chemo-photothermal treatment of NIR-irradiated DOX@PdPt@HA NPs exerted a stronger inhibitory effect on cell viability than that of DOX or NIR-irradiated PdPt@HA NPs in mouse mammary carcinoma 4T1 cells in vitro. Further, the in vivo combination therapy, which used NIR-irradiated DOX@PdPt@HA NPs in a mouse tumor model established by subcutaneous inoculation of 4T1 cells, was demonstrated to achieve a remarkable tumor-growth inhibition in comparison with chemotherapy or photothermal therapy alone. Results of immunohistochemical staining for caspase-3 and Ki-67 indicated the increased apoptosis and decreased proliferation of tumor cells contributed to the anti-tumor effect of chemo-photothermal treatment. In addition, DOX@PdPt@HA NPs induced negligible toxicity in vivo. Hence, the developed nanoplatform demonstrates great potential for applications in photothermal therapy, drug delivery and controlled release.

Synthesis and application of dendritic Pt-Pd bimetallic nanoparticles in imprinted electrochemical sensor for the determination of florfenicol

In this work, the formation mechanism of dendritic Pt-Pd bimetallic nanoparticles (NPs) with perpendicular pore channels in aqueous medium was investigated using hexadecylpyridinium chloride (HDPC) and hexamethylenetriamine (HTM) as structure-directing agents. The results indicated that reaction temperature impacted the properties of the bimetallic components and the particle diameter, while the amount of ascorbic acid (AA) and reaction time impacted the diameter and the amount of HTM determined the pore size. Porous N-doped graphene (N-P-r-GO) was used to load the dendritic Pt-Pd NPs to form a porous and three-dimensional structure on glassy carbon electrode (GCE). As a result, Pt-Pd NPs-N-r-GO / GCE was obtained. Florfenicol (FOL) was imprinted on the modified electrodes using cyclic voltammetry (CV) since indole-5-carboxylic acid was a novel monomer, and FOL functions as a template molecule. The molecularly imprinted polymer (MIP) / Pt-Pd NPs-N-r-GO / GCE was successfully obtained by eluting the template molecule from the polymer, and Fe(CN)63−/4− was used to detect the impedance signal for the recognition of FOL. This sensor exhibited excellent response for FOL in the linear range of 5.0 × 10-8 ∼ 8.0 × 10-6 mol L-1 with detection limit of 1.0 × 10-9 mol L-1. The obtained sensor also exhibited excellent response for FOL detection in real samples.