Synthesis Of Pt Nanoparticles Research Articles

Pt Catalysts Prepared via Top-down Electrochemical Approach: Synthesis Methodology and Support Effects

The synthesis of Pt nanoparticles and catalytically active materials using the electrochemical top-down approach involves dispersing Pt electrodes in an electrolyte solution containing alkali metal cations and support material powder using an alternating pulsed current. Platinum is dispersed to form particles with a predominant crystallographic orientation of Pt(100) and a particle size of approximately 7.6±1.0 nm. The dispersed platinum particles have an insignificant content of PtOx phase (0.25±0.03 wt.%). The average formation rate was 9.7±0.5 mg cm−2 h−1. The nature of the support (carbon material, metal oxide, carbon-metal oxide hybrid) had almost no effect on the formation rate of the Pt nanoparticles as well as their crystallographic properties. Depending on the nature of the support material, Pt-containing catalytic materials obtained by the electrochemical top-down approach showed good functional performance in fuel cell technologies (Pt/C), catalytic oxidation of CO (Pt/Al2O3) and electrochemical oxidation of methanol (Pt/TiO2-C) and ethanol (Pt/SnO2-C).

Role of polyvinylpyrrolidone in the polyol synthesis of platinum nanoparticles.

In this work, platinum (Pt) nanoparticles (NPs) were prepared via the reduction of Pt salts in an ethylene glycol induced polyol process with an altered polyvinylpyrrolidone (PVP)/Pt molar ratio. With the systematic elucidation of the hydrodynamic size in a liquid; the solid-state size and morphology, crystal structure, surface chemical state and thermal decomposition behavior of the synthesized Pt NPs; as well as the reducing dynamic of Pt cations, the role of PVP in the polyol synthesis of Pt NPs is clarified for the first time. It was found that the amount of PVP does not affect the reducing dynamic of Pt cations, but the chemical state of PVP capped on Pt NPs and the resultant particle size significantly depend on the initial PVP/Pt molar ratio in the precursor solution. Dense-packed PVP via the chemisorption of carbonyl oxygen on the surface of Pt NPs occurs in the case of a higher PVP/Pt ratio, suppressing particle growth and resulting in smaller Pt NPs. On the contrary, the chemical structure of PVP is tuned by the cleavage of the N-C bond and results in the chemisorption of the N atom on the surface of Pt NPs, which promotes the production of larger Pt NPs when a lower PVP/Pt ratio is applied.

Synthesis of Pt nanoparticles with gelatin-assisted green route to improve sensitization of cancer cells to X-Ray irradiation

This study aimed to develop a novel radiosensitizer consisting of platinum nanoparticles (Pt NPs) as a high-atomic-number element in order to maximize the generation of ROS under ionizing radiation at the tumor site. Pt NPs were produced via a green and facile method in the presence of gelatin (Gel) as both reducing and stabilizing agent. After determining the physical structure and chemical composition of Pt@Gel NPs by STEM, FeSEM, EDS, DLS, XRD and FTIR, in vitro cytotoxicity on human umbilical vein endothelial cells (HUVEC) and breast cancer cell line (4T1) was evaluated by MTT assay. Finally, ROS generation assay, calcein AM/PI staining assay and clonogenic test were performed on 4T1 cells under X-Ray irradiation to evaluate the radioenhancment efficiency of Pt@Gel. The prepared NPs exhibited spherical and uniform shapes and narrowly distributed sizes in addition to an acceptable radiosensitization capability. The nanosystem provided higher levels of intracellular ROS in malignant cells and enhanced cancer cell death rate under X-Ray irradiation. Overall, the findings suggested that Pt@Gel could be a safe and effective alternative to existing radiosensitizers and potentially be employed for the treatment of breast cancer.

Controllable synthesis of Pt nanoparticles on graphene oxide nanosheets and its application for electrochemical determination of dopamine

AbstractEstablishing effective strategies to improve the performance of catalyst is a major area of interest within the field of electrochemical detection. In this paper, the nanocomposites of Pt catalyst with different morphologies decorated GO surface were successfully synthesized. The feature and diversity of Pt nanoparticles were confirmed by transmission electron microscope. The electrocatalytic performance and electroactive area of various modified electrodes were examined by cyclic voltammetry. According to Randles‐Sevick equation, the active area of electrode modified with the shape of concave cube Pt nanoparticles is the largest. Moreover, compared with the other common stable planes, the concave cube Pt nanoparticles bound by high‐index facets have the strongest current response. Furthermore, dopamine can be detected by amperometry at a typical working potential of 0.2 V (versus SCE) with a detection limit of 0.74 μM (at the signal‐to‐noise ratio of 3), over two wide linear ranges (3 μM–0.7 mM and 0.7 mM–4 mM). The sensing electrode also exhibited good reproducibility, stability and selectivity for dopamine determination.

THE INFLUENCE OF LIGHT ON THE BIOSYNTHESIS OF PT AND AU NANOPARTICLES BY SHEWANELLA ONEIDENSIS MR-1

Shewanella oneidensis MR-1 is a metal-reducing bacterium widely used in dissimilatory reduction and recovery of precious metals. It has previously been used for the photo-induced reduction of Au(III) to Au(0), but to date there are no reports for the photo-induced reduction of Pt(IV). This study investigated whether light could be used to stimulate the synthesis of Pt nanoparticles (PtNPs) in S. oneidensis MR-1. The synthesis of AuNPs and PtNPs by S. oneidensis MR-1 both at dark and under white light was verified by UV-Vis spectroscopy and transmission electron microscopy (TEM). The results indicated that light significantly influences the synthesis of both Au and Pt nanoparticles. Under light conditions, the synthesis of AuNPs and PtNPs was induced within 24 hours, and the concentration increased exponentially over time. While being exposed to dark conditions, the reduction appeared to be a slower process (i.e., 48 hours for Au and more than 72 hours for Pt). The size and cellular localization of the NPs synthesized in above mentioned conditions also differed. To the best of our knowledge, this is the first report that the synthesis of PtNPs by S. oneidensis MR-1 can be induced by light, which could be a cost-effective and an environmentally friendly alternative to chemical synthesis.

A Systematic Investigation of Carbon Pretreatment for the Synthesis of Platinum Nano-Catalysts for Oxygen Reduction Reaction

The synthesis of electrocatalysts for low- and high temperature fuel cells is dependent on many different factors that determine the activity of the produced catalysts. One important and highly underrepresented factor in literature are carbon pretreatments, which have a strong impact on the electrochemical activity of the produced catalyst. A web of science search showed that less than 1% of the articles working with the synthesis of Pt-based catalysts for the Oxygen reduction reaction (ORR) contain information on carbon pretreatments. In recent years no articles on the topic of carbon pretreatment for the synthesis of Pt-based ORR catalyst have been published.However, different forms (as powder, nano tubes, etc.) of carbon are commonly used as support material for Pt-based catalysts. Previous work has shown the importance of pretreatment of carbon supports to change the surface-active groups, enhancing the dispersion and reducing agglomeration of Pt-nanoparticles [1]. Oxidizing treatments are known to change the surface groups and decreasing the BET surface area [2]. Furthermore, carbon pretreatments can effectively reduce impurities present in as-purchased carbon [3].A systematic study of pretreatments of Vulcan XC72-R and Ketjen 300 have been carried out followed by the synthesis of supported Pt-nanoparticles using XPS, XRD, TEM, BET and RDE techniques. We found that the presence of sulfur in the surface strongly correlates with the ECSA of the supported Pt catalyst. This talk will elaborate on the effect of pretreatments on the carbon support, the synthesis of Pt nanoparticles and its impact on the resulting electrochemical performance: Compared to as received carbon, the Pt mass activity could be increased by a factor 4, exceeding the mass activity of comparable commercial Pt/C electrocatalysts.[1] Bimetallic Pt–Sn catalysts supported on activated carbon I. The effects of support modification and impregnation strategy - A. Erhan Aksoylu; M. Madalena A. Freitas; Jose L. Figueiredo[2] The effect of pretreatment of Vulcan XC-72R carbon on morphology and electrochemical oxygen reduction kinetics of supported Pd nano-particle in acidic electrolyte - Senthil Kumar, S. M.; Soler Herrero, Jaime; Irusta, Silvia; Scott, Keith[3] Effect of the carbon pre-treatment on the properties and performance for nitrobenzene hydrogenation of Pt/C catalysts - Torres, G. C.; Jablonski, E. L.; Baronetti, G. T.; Castro, A. A.; De Miguel, S. R.; Scelza, O. A.; Blanco, M. D.; Peña Jiménez, M. A.; Fierro, J. L.G. Figure 1

Surface Coordination Decouples Hydrogenation Catalysis on Supported Metal Catalysts

Surface Coordination Decouples Hydrogenation Catalysis on Supported Metal Catalysts

TEMPO-oxidized cellulose for in situ synthesis of Pt nanoparticles. Study of catalytic and antimicrobial properties

In this work, platinum nanoparticles (PtNPs) were synthesized by a modified polyol process using TEMPO-oxidized nanocellulose (TOCN) as a stabilizing and co-reducing agent. Different ratios of TOCN nanocellulose to Pt4+ ions were studied to establish the optimum stabilizing effect of PtNPs. The effect of different pH of aqueous TOCN suspensions on the morphology of PtNPs was also examined. It was proved that PtNPs can be obtained solely in the presence of TOCN without the use of an additional reducing agent or ethylene glycol. The morphology and structural properties of the nanocellulose‑platinum nanoparticles composites were assessed using spectroscopic, microscopic and diffraction techniques, The catalytic performance in 4-nitrophenol reduction was evaluated. Significant differences in reaction rate constants k were found depending on the pH of the TOCN suspension applied during Pt4+ reduction. The crucial effect of reaction conditions on PtNPs performance was confirmed in tests of antibacterial efficacy against E. coli.

Thermal synthesis of Pt nanoparticles on carbon paper supports

A thermal method of synthesis and fixation of Pt nanoparticles (Pt NPs) on carbon paper is proposed in this paper. Carbon paper was coated with H2PtCl6 by simple immersion in an ethanol solution containing the Pt precursor. Thereafter, H2PtCl6 was decomposed in inert atmosphere into Pt NPs by applying a temperature of 600 °C. Formed Pt NPs were able to oxidize the surrounding carbon fiber surface. This local thermal oxidation of carbon promoted the generation of nano-roughness and Pt NPs were embedded in the carbon fiber, thus favoring their fixation on carbon paper. Pt load can be easily controlled by the number of coating processes applied. The proposed method combines the advantage of achieving small size nanoparticles (5–10 nm) with enhanced fixation of Pt NPs when compared with electrochemical synthesis. The optimal number of coatings applied was three, which produced a complete coverage of carbon paper surface (with a Pt load of 0.18 mg cm−2).

Structural and Electrochemical Characteristics of Platinum Nanoparticles Supported on Various Carbon Carriers

Graphene-like materials have attracted significant attention as alternative catalyst carriers due to the broad possibilities of changing their shape, composition, and properties. In this study we investigated the structural and electrochemical characteristics of platinum electrocatalysts supported on reduced graphene oxide (rGO), including those modified with amine functionalities, nitrogen heteroatoms (rGO-Am), and oxygen enriched (rGO-O). Synthesis of Pt nanoparticles (20 wt.%) on the graphene-like nanomaterials surface was carried out using a modified polyol procedure. The Pt20/rGO-Am showed a lower Pt nanoparticles size together with high Pt utilization and EASA values compared to rGO-supported catalysts and the Pt/C reference sample due to the uniform distribution of nucleation centers on the surface of graphene nanoparticles, and the greater ability of these centers to electrically bond with platinum.

Synthesis of Pt nanoparticles with the aid of PVA for highly active and stable alcohol electro-oxidation

Synthesis of Pt nanoparticles with the aid of PVA for highly active and stable alcohol electro-oxidation

In situ laser synthesis of Pt nanoparticles embedded in graphene films for wearable strain sensors with ultra-high sensitivity and stability

Carbon-based materials have recently attracted tremendous attention for their applications in highly sensitive wearable devices for human motion monitoring. Embedding rare metal nanoparticles such as Au, Ag, and Pt has been proved to significantly improve the sensitivity of the carbon-based strain sensors. However, the existing method to prepare nanoparticles usually involves multi-step, time-consuming procedures. Here, we report a facile one-step laser process to synthesize porous 3D graphene structures embedded with Pt nanoparticles. This is achieved by irradiating an ultraviolet (355 nm) picosecond laser on a film formed with a mixture of polybenzimidazole (PBI) and Pt(acac)2 solution to simultaneously induce the formation of graphene and reduction of the Pt precursor. The assembled strain sensor with loaded Pt nanoparticles in laser-induced graphene (Pt/LIG) demonstrates ultra-high sensitivity (a gauge factor, GFmax ≈ 489.3) and a wide strain range up to 20%. Additionally, the strain sensor with an optimized concentration of Pt(acac)2 has low hysteresis, minor lag errors, and a highly stable response (>5000 cycles). Various human motion signals are detected, from subtle physical activities (including chewing muscles movement, pulse beating) to large-scale limb track (finger bending, knee movement, and waist extending). This one-step laser process is facile, rapid, and potentially scalable for the mass production of high-performance wearable strain sensors.

Synthesis of Pt Nanoparticles by Cavitation Bubble Plasma and Hydrogen Production by Pt/TiO2 in Glycerol Aqueous Solution

Synthesis of Pt Nanoparticles by Cavitation Bubble Plasma and Hydrogen Production by Pt/TiO2 in Glycerol Aqueous Solution

Nucleation/growth of the platinum nanoparticles under the liquid phase synthesis

The need to reduce platinum content in PEMFC catalyst layers has sparked a new wave of interest in ways to control the microstructure of Pt/C catalysts, which must combine high platinum surface area and activity. A comparative study of platinum nanoparticle nucleation/growth under a liquid-phase synthesis of Pt/C materials, with formaldehyde and formic acid being used as reducing agents, has been carried out. Analysis of the color change in the reaction medium and the in situ spectral-kinetic studies performed with absorption spectroscopy, were used as methods to study the reactions kinetics. The effect of the synthesis temperature on the features of the Pt(IV) reduction stages, nucleation/growth of Pt(0) nanoparticles, as well as on the size of the resulting Pt nanoparticles were studied. The role of the ethylene glycol and its derivatives, formed in the reaction medium at high pH, in the processes of Pt(IV) reduction and in the Pt(0) nanoparticles formation, is shown. The positive effect of the dispersed carbon support on the morphological characteristics of the resulting Pt/C catalysts is demonstrated, with carbon being introduced into the reaction medium in the initial stage of the synthesis. The roles of homogeneous and heterogeneous phase formation in the synthesis of Pt nanoparticles and Pt/C materials in the liquid phase are estimated.

Synthesis and characterization of Pt/graphene-CNTs electrocatalyst for direct methanol fuel cell

In the present work we report a facile method for the synthesis of Pt nanoparticles supported reduced graphene oxide (rGO) and multi-walled carbon nanotubes (MWCNTs) nanocomposite by an in-situ chemical reduction. The incorporation of MWCNTs to rGO leads to decrease in agglomeration between rGO sheets due to π – π interactions and higher loading of Pt nanoparticles. In this process, a mixture of exfoliated graphene oxide, CNTs and chloroplatinic acid was treated with a mixture of hydrazine hydrate and ammonium hydroxide at 95° C in an oil bath for 1 h. Pt nanoparticles of 4-6 nm size were homogeneously dispersed on rGO-CNTs nanocomposite as revealed by TEM analysis. Cyclic voltammetry measurements depict an anodic current density of 11.74 mA/cm2 that could be obtained using Pt/rGO-CNTs catalyst and 6.2 mA/cm2 using Pt/rGO catalyst during methanol oxidation, indicating that the catalytic activity of Pt/rGO-CNTs catalyst is almost 2 times higher than that of Pt/rGO catalyst. The electrochemical stability of Pt/rGO-CNTs catalyst was also found to be much higher as compared with that of Pt/rGO catalyst. Thus, Pt/rGO-CNTs catalyst has the potential to be used in the preparation of a promising anode material for direct methanol fuel cell. Copyright © 2016 VBRI Press

Electrochemical synthesis of Pt nanoparticles on ZrO2/MWCNTs hybrid with high electrocatalytic performance for methanol oxidation

Zirconia supported on multi-walled carbon nanotubes (ZrO2/MWCNTs) as carriers was synthesized with hydrothermal method, and then ternary Pt-ZrO2/MWCNTs hybrid was prepared by electrodeposition with aims to enhance electron and proton conductivity, specific surface as well as active site, and also oxidize the adsorbed CO on Pt surface and synergistically improve electrocatalytic activity and stability for the oxidation of methanol. The synthetic conditions of Pt-ZrO2/MWCNTs, such as mass ratio of ZrO2/MWCNTs, deposition cycle of Pt, were screened, respectively. The catalytic performance of Pt-ZrO2/MWCNTs hybrid for methanol oxidation was investigated by cyclic voltammetry, electrochemical impedance spectroscopy, and chronoamperogram test. The results showed that Pt-ZrO2/MWCNTs hybrid exhibited significantly lower charge transfer resistance and better toxicity resistance compared with the commercial Pt/C(20 wt%)-SA. Meanwhile, the ECSA (42.25 m2/g) of Pt-ZrO2/MWCNTs hybrid is higher than that of other related materials. Therefore, the as-prepared Pt-ZrO2/MWCNTs hybrid is a promising electro-catalyst for the application of direct methanol fuel cell.

Green synthesis of Pt nanoparticles and their application in the oxygen reduction reaction

Green synthesis of Pt nanoparticles and their application in the oxygen reduction reaction

Insights from In Situ Studies on the Early Stages of Platinum Nanoparticle Formation.

Understanding the formation of nanomaterials down to the atomic level is key to rational design of advanced materials. Despite their widespread use and intensive study over the years, the detailed formation mechanism of platinum (Pt) nanoparticles remains challenging to explore and rationalize. Here, various in situ characterization techniques, and in particular X-ray total scattering with pair distribution function (PDF) analysis, are used to follow the structural and chemical changes taking place during a surfactant-free synthesis of Pt nanoparticles in alkaline methanol. Polynuclear structures form at the beginning of the synthesis, and Pt-Pt pair distances are identified before any nanoparticles are generated. The structural motifs best describing the species formed change with time, e.g., from [PtCl5-PtCl5] and [PtCl6-Pt2Cl6-PtCl6] to [Pt2Cl10-Pt3Cl8-Pt2Cl10]. The formation of these polynuclear structures with Pt-Pt coordination before the formation of the nanoparticles is suggested to account for the fast nucleation observed in the synthesis.

The influence of dielectric permittivity of water on the shape of PtNPs synthesized in high-pressure high-temperature microwave reactor

In this paper, a novel method for the synthesis of Pt nanoparticles (PtNPs) using a microwave autoclave reactor is proposed. For benchmarking, the obtained results are compared with the traditional, batch method. A novel process window is proposed, which is the application of high-temperature and high-pressure. The main finding is that this only brings advantage, when the ionic strength of the system is enough low. It is explained, that at high pressure and high temperature, water behaves like only a slightly polar solvent, approaching a subcritical state. This reduces the electrostatic stabilization of the particles. Moreover, a change in the Pt particle shape is observed under high pressure and temperature conditions, suggesting that additional physical–chemical processes are involved.

Synthesis of Pt Nanoparticles Enveloped with Flexible Zeolitic Imidazolate Framework

We report the synthesis of Pt nanoparticles (NPs) covered with a zeolitic imidazolate framework (ZIF-7). The hybrid materials were characterized by powder X-ray diffraction measurements and transmi...