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Direct alcohol fuel cells are claiming to be one of the primary clean power sources to attain a sustainable future. In the present study, PtPd core‐shell bimetallic nanoparticles (CSNPs) were synthesized by the polyol method. The shell was adjusted by adding an increased amount of Pd precursor on pre‐synthesized Pt nanoparticles. The morphology and atomic structure of the PtPd CSNPs were characterized by X‐ray diffraction and high‐resolution scanning transmission electron microscopy. PtPd CSNPs were successfully supported on Vulcan XC‐72 carbon and verified by scanning electron microscopy. The electrocatalysts were tested by cyclic voltammetry in an alkaline medium for the activity performance to ethanol oxidation reaction. The stability along with the presence of poisoning carbonaceous species was investigated by chronoamperometry and voltammetry cycles. Also, the cyclic durability was analysed. The results confirmed that the catalytic performance depends on the elemental composition of PtPd CSNPs, showing the optimum catalytic properties to PtPd (1 : 0.5)/C than commercial Pt/C. [ABSTRACT FROM AUTHOR]

Owing to the advantages of large energy density, excellent conversion efficiency, and safety for storage, direct ethanol fuel cells (DEFCs) possess an extensive range of applications in alkaline mediums. In this study, we successfully synthesize the PdSn nanoparticles (NPs) with a different molar ratio of Pd/Sn by a simple one‐step method. The alloyed PdSn NPs present higher electrocatalytic activity and better stability than that of the commercial Pd/C toward ethanol oxidation reaction (EOR). Especially, the PdSn@NP‐2 displayed the best electrocatalytic performance among the as‐prepared samples, the current density for EOR in the alkaline condition of which can even approach 2463.8 mA mg−1, approximately 3.6 times of the commercial Pd/C (700 mA mg−1). Meanwhile, on the base of the electrochemical measurement, it is also observed that increasing temperature and concentrations of KOH/C2H5OH for PdSn NPs positively affect on the current density of the above samples. [ABSTRACT FROM AUTHOR]

Bimetallic nanoparticles are often superior candidates for a wide range of technological and biomedical applications owing to their enhanced catalytic, optical, and magnetic properties, which are often better than their monometallic counterparts. Most of their properties strongly depend on their chemical composition, crystallographic structure, and phase distribution. However, little is known of how their crystal structure, on the nanoscale, transforms over time at elevated temperatures, even though this knowledge is highly relevant in case nanoparticles are used in, e.g., high-temperature catalysis. Au-Fe is a promising bimetallic system where the low-cost and magnetic Fe is combined with catalytically active and plasmonic Au. Here, we report on the in situ temporal evolution of the crystalline ordering in Au-Fe nanoparticles, obtained from a modern laser ablation in liquids synthesis. Our in-depth analysis, complemented by dedicated atomistic simulations, includes a detailed structural characterization by X-ray diffraction and transmission electron microscopy as well as atom probe tomography to reveal elemental distributions down to a single atom resolution. We show that the Au-Fe nanoparticles initially exhibit highly complex internal nested nanostructures with a wide range of compositions, phase distributions, and size-depended microstrains. The elevated temperature induces a diffusion-controlled recrystallization and phase merging, resulting in the formation of a single face-centered-cubic ultrastructure in contact with a body-centered cubic phase, which demonstrates the metastability of these structures. Uncovering these unique nanostructures with nested features could be highly attractive from a fundamental viewpoint as they could give further insights into the nanoparticle formation mechanism under non-equilibrium conditions. Furthermore, the in situ evaluation of the crystal structure changes upon heating is potentially relevant for high-temperature process utilization of bimetallic nanoparticles, e.g., during catalysis. [ABSTRACT FROM AUTHOR]

Alloyed Pd‐based nanostructured materials have been demonstrated as highly active fuel cell anode electrocatalysts for the alcohol oxidation reaction. Challenges remain in the controlled synthesis of freestanding PdM alloys catalysts through optimization of their interfacial and surface structures, which can prevent degradation and poor durability. Herein, we present an oil‐bath‐based approach to synthesize PdxSny nanoparticles (NPs) with L‐ascorbic acid (AA) as a reducing agent and cetyltrimethylammonium bromide as a structure‐directing agent. PdxSny NPs (x/y=0.66, 0.83, and 1.11) show a particular freestanding shape. Among the three alloys, Pd20Sn24 (x/y=0.83) NPs have the best electrocatalytic activity (2018 mA mg−1) toward the ethanol oxidation reaction (EOR). The enhanced performance of PdxSny NPs might be attributed to i) a change in the electron structure of Pd, ii) varied interatomic distance within a unit cell, and iii) weak adsorption of in‐situ generated oxygen‐containing (e. g. *OH and Pd−O) or carbon‐containing (e. g. *CH3CHOH, *CH3CHO, and *CH3CO) intermediate species. Experimental data proposed that higher catalytic temperature, higher pH values, and higher ethanol concentration should accelerate each step of electrooxidation of the EOR. [ABSTRACT FROM AUTHOR]

This 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. [ABSTRACT FROM AUTHOR]

Boron‐doped carbon nanocage (BC‐2) was used as carrier to anchor palladium nanoparticles and enhanced the catalytic performance for the ethanol oxidation reaction. The BC‐2 was synthesized via thermal treatment the predesigned compound containing cobalt and boron at 900 °C with the help of hydrogen and acid washing process. Palladium nanoparticles can be loaded on the BC‐2 supports (Pd/BC‐2) for ethanol oxide reaction (EOR). The BC‐2 support has the following characteristics: (i) The hollow structure contains highly order nanoporous to offer more channel and space in catalysis process; (ii) boron‐doped carbon structures can supply abundant activity sites for stabilizing palladium nanoparticles; (iii) the unique three‐dimensional architecture can prevent the agglomeration and inactivation of metal catalysts. The Pd/BC‐2 catalyst displays higher catalytic activities 3614.11 mA mg−1 toward the peak current density compared to that of Pd/C (804.39 mA mg−1). [ABSTRACT FROM AUTHOR]

Zirconium oxide has been proposed as an alternative to carbon supports due to its high electrochemical stability at high electrode potential values. However, its low electrical conductivity has limited its use. In this work, we successfully overcome this issue by synthesizing Pt electrocatalysts directly on ZrO2 supports. The ZrO2 supports were obtained through a sol‐gel method at 350 °C (ZrO2‐350) and 500 °C (ZrO2‐500) calcination temperatures, obtaining surface areas of 82 and 92 m2 g−1 and crystalline phases corresponding to the tetragonal and mixture of tetragonal and monoclinic phases, respectively. Pt nanoparticles synthesized directly on ZrO2 had particle sizes of 3.0±0.3 nm and 6.0±0.8 nm for Pt/ZrO2‐350 and Pt/ZrO2‐500, respectively. Pt/ZrO2‐350 and Pt/ZrO2‐500 presented similar onset potentials (−0.34 V and −0.33 V) and current densities (249.3 mA mg−1 and 255.8 mA mg−1) than a commercial Pt/C (−0.39 V, 277.5 mA mg−1) during the electro‐oxidation of 2 M methanol in alkaline medium. Regarding catalyst stability, Pt/ZrO2‐500 kept 96 % of its initial current after 500 cycles, while Pt/C maintained 49 % of its initial current. [ABSTRACT FROM AUTHOR]

In this work, the effect of Pt−Ni(OH)2 nanoparticles on the activity and reaction pathway of glycerol oxidation was studied. For this purpose, small Pt (4±0.2 nm) and Pt−Ni(OH)2 nanoparticles (4.7±0.4 nm) supported on Vulcan carbon were synthesized. Ni(OH)2 were found in the vicinity of Pt modifying the lattice parameter, inter‐planar distance and binding energy of Pt. Electrochemical evaluation indicated that Pt−Ni(OH)2/C had better electrocatalytic activity than Pt/C offering a higher current density (almost 45 mA mg−1), and lower onset (−0.3 V) and oxidation peak potentials (0.04 V). The improved activity was associated to the OH groups found in the vicinity of Pt active sites, facilitating the charge transfer due to a bifunctional mechanism. The in situ evaluation confirmed that the incorporation of Ni(OH)2 led to higher electron transfer due to short‐chain byproducts such as glycolate, mesoxalate and formate, which were found at the oxidation peak potential. Electrocatalytic activity of Pt−Ni(OH)2/C and Pt/C for glycerol electro‐oxidation is analyzed by spectroelectrochemical experiments using surface‐enhanced Raman spectroscopy. This analysis confirmed that the capability of Pt−Ni(OH)2 for achieving a higher current density than Pt/C was related to its ability to oxidize glycerol, while Pt/C tends to form glyceraldehyde and glyoxylates. [ABSTRACT FROM AUTHOR]

Abstract: Here, we built Ru‐decorated Pt/C nanoparticles with different coverage degrees (θRu) by wall‐jet configuration for the first time, and we investigated their catalytic properties towards glycerol electrooxidation in acidic medium. Moreover, we used the most active catalysts as the anode in electrolysis to produce carbonyl compounds. The use of an electrochemical cell in wall‐jet configuration allows for the controlling of electrodeposition through easily handling parameters; namely, the θRu is controlled by changing the concentration of the metallic precursor, speed, and volume of injection onto a Pt/C‐modified glassy carbon electrode under applied potential. Excess of Ru on a Pt surface inhibits glycerol dissociative adsorption, which limits further electrooxidation; whereas low θRu do not provide surface oxygen species to the anodic reaction. Hence, intermediates θRu reveal active catalysts – namely, θRu=0.42 shifts the onset potential 170 mV towards lower values and increases 1.65‐fold the current density at 0.5 V. The stability of this catalyst is also enhanced by maintaining a more constant current density during successive potential cycles in the presence of glycerol and by avoiding Ru leaching from the surface. The electrolysis on Ru‐decorated Pt/C is shown to lead the reaction towards formic acid (‘high oxidation state’), decreasing the amounts of glyceradehyde, glycolic acid, and dihydroxyacetone, as a result of the improved catalytic properties. [ABSTRACT FROM AUTHOR]

In this work, PdMo/C and Pd/C nanocubes were synthesized and used for the electro-oxidation of ethylene glycol. The XRD patterns revealed that the Pd/C nanocubes had an average crystallite size of 10.9 nm, whereas the PdMo/C nanoparticles were amorphous. HRTEM images indicated the presence of only cubic-shaped nanoparticles for Pd/C nanocubes and semispherical nanoparticles for PdMo/C with sizes of 9 and 2 nm, respectively. XPS and line-scan EDX spectroscopy confirmed the presence of Pd and Mo in the PdMo/C nanocatalyst, and Mo was determined to be incorporated with Pd in the form MoO3. The Pd/C nanocubes exhibited a current density that was 9.3 times higher than commercial Pd/C, demonstrating the superior activity of the (100) facet. The combined effects of the amorphous structure and the presence of molybdenum oxides enhanced the activity of PdMo/C, which demonstrated a 1.5-fold increase current density with respect to the Pd/C nanocubes and a 12-fold increase compared to commercial Pd/C. [ABSTRACT FROM AUTHOR]

Bimetallic nanoparticles are of interest since they lead to many interesting electrical, chemical, catalytic, and optical properties. They are particularly important in the field of catalysis since they show superior catalytic properties than their monometallic counterparts. The structures of bimetallic nanoparticles depend mainly on the synthesis conditions and the miscibility of the two components. In this work, PdPt alloyed-bimetallic nanoparticles (NPs) were synthesized through the polyol method, and characterized using spherical aberration (Cs) corrected scanning transmission electron microscopy (STEM). High-angle annular dark-field (HAADF)-STEM images of bimetallic nanoparticles were obtained. The contrast of images shows that nanoparticles have an alloy structure with an average size of 8.2 nm. Together with the characterization of nanoparticles, a systematic molecular dynamics simulations study focused on the structural stability and atomic surface segregation trends in 923-atom PdPt alloyed-bimetallic NPs was carried out. [ABSTRACT FROM AUTHOR]