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We report here, a strategy to prepare Pt/Pd nanoparticles decorated with Co-N-C materials, where Co-N-C was obtained via pyrolysis of ZIF-67 directly. As-prepared Pt/Pd/Co-N-C catalysts showed excellent ORR performance, offered with a higher limit current density (6.6 mA cm−2) and similar half-wave potential positive (E1/2 = 0.84 V) compared with commercial Pt/C. In addition to an ORR activity, it also exhibits robust durability. The current density of Pt/Pd/Co-N-C decreased by only 9% after adding methanol, and a 10% current density loss was obtained after continuous testing at 36,000 s. [ABSTRACT FROM AUTHOR]

A novel dual-dummy templates imprinted electrochemical sensor has been fabricated for the detection of patulin. Herein, 2-oxindole (2-oxin) and 6-hydroxynicotinic acid (6-HNA) as the dummy templates, 4-aminothiophenol as functional monomer, and ionic liquid (IL) as electropolymerization electrolyte are employed to prepare molecularly imprinted polymer (MIP) film. 2-Oxin and 6-HNA have multiple groups and the obtained MIP possesses different types of imprinted sites, thereby achieving a better recognition capacity than that of single-dummy imprinted film. ILs can regulate the density of molecularly imprinted film and facilitate effective molecular recognition. The composite of PtPd decorated N-doped porous carbon has good conductivity and large surface area, and can amplify the signal. With the aid of electrochemical probe [Fe(CN)6]3-/4- (0.16 V vs. SCE) patulin can be detected. Under the optimal conditions, this sensor shows a detection range from 0.01 to 10 μg L−1, with a detection limit of 7.5 × 10−3 μg L−1 (S/N = 3). Two spiked juice samples were analyzed by this method, and the recovery ranges from 94 to 99.8% with RSD values of 2.4–4.6% (n = 3), indicating that this method can be applied for the detection of patulin in real samples. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A facile, low cost and effective method was used to synthesize porous holey nitrogen-doped graphene (PHNG) with three-dimensional (3D) structure via direct pyrolysis of a mixture of urea and magnesium acetate tetrahydrate, followed by treating with hydrochloric acid to remove magnesium cations. The unique structure of PHNG significantly decreases the irreversible stacking of graphene nanosheet, favors the exposure of active edge sites, and enables more accessibility for reactants/electrolytes. The PHNG shows porous structure with a large surface area and can serve as support for nanoparticles. PtPd nanoparticles with different ratios were deposited on PHNG surface to synthesize PtPd/PHNG. The PtPd/PHNG-2 shows high direct oxidation activity towards the glucose, achieving a high sensitivity (52.526 μA mM−1 cm−2), wide linear range (100–4000 μM), fast response time (<3 s), low limit of detection (1.82 μM), as well as high selectivity. Image 1 • High surface area and porous structure of porous holey nitrogen-doped graphene. • High dispersion of PtPd nanoparticles supported on porous holey nitrogen-doped graphene. • A sensitive nonenzymatic sensor based on PtPd/porous holey nitrogen-doped graphene. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Catalysts of supported PtPd alloy NPs on 3DOM TiO 2 were synthesized. • 3DOM structure can enhance contact efficiency between soot and catalysts. • The synergic effect of binary Pt-Pd components can enhance intrinsic redox property. • The substituting of Pd for Pt can reduce usage amount of Pt and improve catalytic activity. • PtPd/3DOM-TiO 2 catalyst exhibited high catalytic activity and stability for soot combustion. Abstract The efficient nanocatalyst of three-dimensionally ordered macroporous (3DOM) TiO 2 -supported Pt-Pd nanoparticles (PtPd/3DOM-TiO 2) was easily fabricated by method of the gas bubbling-assisted membrane reduction (GBMR). The catalyst shows well-defined ordered macroporous nanostructure with the average pore size of 280 nm, and hemispherical PtPd nanoparticles (NPs) with mean particle size of 3.6 nm are well dispersed and deposited on the inner walls of 3DOM-TiO 2 support. 3DOM nanostructure can improve the contact efficiency between soot particles and catalysts, and enhances the mass transfer of soot particles through the porous catalysts. The synergic effect of Pt-Pd binary components is favorable for enhancing the intrinsic redox property originated from the strong metal (PtPd)-support (TiO 2) interaction (SMSI). Remarkably, PtPd/3DOM-TiO 2 catalyst exhibits highest catalytic activity for diesel soot combustion in comparison with those of supported single Pt or Pd NPs, i.e., its values of T 10 , T 50 and T 90 are only 262, 338 and 386 °C, respectively. And the TOF PtPd value of PtPd/3DOM-TiO 2 catalyst (1.27 × 10−3 S−1) is 4.3 times as much as that of Pd/3DOM-TiO 2 catalyst (0.29 × 10−3 S−1). In addition, PtPd/3DOM-TiO 2 catalyst shows the good stability of activity and nanostructure during five cycles of soot-TPO tests. The ternary catalyst of 3DOM TiO 2 -supported uniform Pt-Pd alloy NPs can not only decrease the usage amount of Pt, but also is potential to practical application in catalytic combustion of diesel soot particles. [ABSTRACT FROM AUTHOR]

This investigation involves synthesis of PtPd catalyst nano-particles supported on tungsten oxide (WO 3) and poly-N vinyl carbazole (PNVC) composite for validation in ethanol oxidation reaction. The tungsten oxide acquires excellent functional property by hydrogen spill over phenomenon that facilitates hydrogen tungsten bronze formation while conducting polymer enhances the charge transfer ability within the direct ethanol fuel cell framework. The catalyst nano-particles are found to be in the size range 3–5 nm, revealed from structure and morphology studies. Electrochemical characterizations derive output power density of ∼54 mW cm−2 and mass activity ∼1.9 A/mg Pt , in terms of specific current density for ethanol oxidation. Ion chromatographic analysis quantifies the reaction intermediates, acetate and carbonate to the extent of 396 and 280 ppm using 1 M ethanol solution. Self designed composite nano-structures of PtPd/PNVC-WO 3 with reduced Pt share provide astounding opportunity for the catalytic reaction to gear up to the complete oxidation kinetics. [Display omitted] • PNVC-WO 3 composite synthesized by polymerization of NVC in presence of WO 3. • PtPd over-casted on exceptional support produces mass activity 1.9 A/mg Pt. • OH-studded Pd sites and hydrogen tungsten bronze accelerates electron transport. • The pro-active PNVC-WO 3 support urges carbonate production on PtPd catalyst. • Power density of 54 mW cm−2 achieved for 33 % Pd share in the matrix. [ABSTRACT FROM AUTHOR]

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.

PtPd nanoparticles in the size range of 2–5 nm have been directly synthesized from their metal wire electrodes via a one-step plasma sputtering technique in a solution of water and methanol under atmospheric pressure. PtPd nanoparticles produced in the water/methanol solution have good dispersibility compared with those produced in water because methanol successfully reduces the aggregation of the nanoparticles during the plasma sputtering process. Further, the solution plasma technique provides a novel reaction field with a highly energetic state for the PtPd nanoparticle synthesis. KB-supported PtPd nanoparticles (PtPd/KB, 12 wt% Pt) exhibit excellent electrocatalytic activity (over 4 times mass activity compared with commercial Pt/C) and stability (maintaining 43% mass activity after 300 cycles) towards methanol electrooxidation because of their large electrochemical surface area (ECSA, that is 2.5 times greater than that of commercial Pt/C) and synergistic effect of the binary alloy. Thus, as-synthesized PtPd/KB catalysts may have potential applications in direct methanol fuel cells (DMFCs) to lower their cost and improve their cycle efficiency. [ABSTRACT FROM AUTHOR]

Rationally designing the composition and structure of metallic nanoparticles/reduced graphene oxide hybrids is highly important for synthesizing active electrocatalysts. Herein, we report a one-step method to efficiently synthesize dendritic bimetallic PtPd nanoparticles on reduced graphene oxide (DPtPd/rGO) in aqueous solution at room temperature. The proposed synthesis is performed by a simple sonication treatment of an aqueous reactive mixture containing K 2 PtCl 4 , Na 2 PdCl 4, Pluronic F127 and ascorbic acid. This method is greatly simplified compared to the traditional multi-step-seeded growth or other hydrothermal syntheses. The as-made DPtPd/rGO hybrid consists in spatially and locally separated dendritic PtPd nanoparticles well-dispersed on the surface of rGO and is an active catalyst for methanol oxidation and oxygen reduction reactions. The proposed strategy is an effective method to directly fabricate metals/rGO hybrids for electrocatalytic applications. [ABSTRACT FROM AUTHOR]

• Highly dispersed PtPd nanoparticles on graphitic nanofibers are obtained via heavy d-π overlap. • The existence of d-π overlap is revealed by both experiment results and DFT calculations. • The sample shows superior catalytic activity in oxygen reduction reaction. • The sample displays excellent catalytic durability and stability. The strong Pt-carbon interaction is a very promising way to high-performance design of electrocatalysts. However, the heavy d-π overlap, a high strength of Pt-C bonding, in sp2 bonded graphitic carbons with low level of defects is rarely reported. Herein, PtPd nanoparticles and graphitic carbon nanofibers (PtPd/CNF) have been integrated via heavy d-π overlap by an interfacial wettability approach and their formation mechanism has also been fully elucidated. The features of strong d-π overlap and high dispersion of metals offer PtPd/CNF with enhanced ORR activity (5.8 folds of specific activity than commercial Pt/C), and excellent structural stability and electrocatalytic durability. A new "heavy d-π overlap" concept, characteristics, and mechanism are proposed at an atomic-/nanoscale to clarify the generation of the predictive interaction as well as the interface charge transfer. It is believed that the study on heavy d-π overlap sheds new light on the fundamental aspects of the nature of Pt-C interaction. [ABSTRACT FROM AUTHOR]

Ethanol oxidation reaction has been studied in acidic environment over PtPd nanoparticles (NPs) grown on the molybdenum oxide-polypyrrole composite (MOPC) support. The attempt was focused on using reduced Pt loading on non-carbon support for direct ethanol fuel cell (DEFC) operated with proton exchange membrane (PEM). As revealed in SEM study, a molybdenum oxide network exists in polypyrrole caging and the presence of metal NPs over the composite matrix is confirmed by TEM analysis. Further physicochemical characterizations such as XRD, EDAX, and XPS are followed in order to understand the surface morphology and composition of the hybrid structure. Electrochemical techniques such as voltammetry, choroamperometry, and impedance spectroscopy along with performance testing of an in-house-fabricated fuel cell are carried out to evaluate the catalytic activity of the materials for DEFC. The reaction products are estimated by ion chromatographic analysis. Considering the results obtained from the above characterization procedures, the best catalytic performance is exhibited by the Pt-Pd (1:1) on MOPC support. A clear intervention of the molybdenum oxide network is strongly advocated in the EOR sequence which increases the propensity of the reaction by making the metallites more energy efficient in terms of harnessing sufficient numbers of electrons than with the carbon support.