PtNi Alloy Nanoparticles Research Articles

A Strategy for Designing a Concave Pt–Ni Alloy through Controllable Chemical Etching

This corrosion: Octahedral Pt-Ni alloy nanoparticles (NPs) are converted into concave Pt(3)Ni NPs by a coordination-assisted chemical-etching process. The corroded concave Pt-Ni NPs have a higher density of low-coordinate atoms in steps sites, a decisive property in heterogeneous catalysis.

PtNi alloy nanoparticles supported on carbon-doped TiO2 nanotube arrays for photo-assisted methanol oxidation

To develop anode catalysts for photo-assisted direct methanol fuel cell (PDMFC), carbon-doped TiO2 nanotube arrays-supported PtNi alloy nanoparticles with different Pt/Ni atomic ratio (PtNi/C-TiO2NTs) prepared by pulsed electrodeposition method are evaluated as catalysts for photo-assisted methanol oxidation. The cyclic voltammetry (CV) and chronoamperometry results show that the PtNi/C-TiO2NTs prepared at tonPt:tonNi:=10:7 (ton is the current-on time) with a Pt:Ni atomic ratio of 6.1:5.7 presents the highest catalytic activity for methanol oxidation both in the dark and under illumination. In addition, according to the results obtained from the CO stripping voltammetry and electrochemical impedance spectroscopy (EIS) tests, it was found that the light play an accelerative role in the oxidation of methanol on PtNi/C-TiO2NTs under illumination. The effect of illumination which enhancing the catalytic activity of PtNi/C-TiO2NTs are attributed to (1) methanol and the intermediates be oxidized directly on C-TiO2NTs for the light-induced catalytic effect; (2) more abundant oxygen-donating species be produced on C-TiO2NTs in the presence of light; (3) less COads adsorbing on catalysts due to the presence of stronger metal–support interactions between PtNi alloy nanoparticles and C-TiO2NTs under illumination.

Carboxyl Multi-Wall Carbon Nanotubes Supported Pt-Ni Alloy Nanoparticles as Cathode Catalyst for Microbial Fuel Cells

Carboxyl Multi-Wall Carbon Nanotubes Supported Pt-Ni Alloy Nanoparticles as Cathode Catalyst for Microbial Fuel Cells

Identical Location Scanning Electron Microscopy: A Case Study of Electrochemical Degradation of PtNi Nanoparticles Using a New Nondestructive Method

The electrochemical degradation of PtNi and PtCu alloy nanoparticles is studied with a new, nondestructive variant of scanning electron microscopy (SEM). The method allows for observation of the same site (same nanoparticle) before and after electrochemical treatment, hence the name identical location SEM, IL-SEM. The method was complemented with other techniques such as energy-dispersive X-ray spectroscopy (EDS) and electrochemical thin film rotating disk electrode (TF-RDE) measurements. During initial potential cycling, the combined results show Ni or Cu dissolution and an increase in the electrochemical surface area (ESA). After accelerated degradation test (ADT), however, morphological changes (visible roughening) of the catalyst surface and a decrease in oxygen reduction reaction (ORR) specific activity are observed. In contrast to transmission electron microscopy (TEM and IL-TEM), the major advantage of SEM and IL-SEM is the ability to study surface phenomena rather than the bulk characteristic of a...

Electrocatalytic Oxygen Reduction on Dealloyed Pt1-xNix Alloy Nanoparticle Electrocatalysts

The synthesis, structural, and compositional characterization as well as the electrocatalytic oxygen reduction (ORR) activity of a number of carbon-supported Pt x Ni1−x (x = 1.00–0.14) nanoparticles in acidic electrolyte are reported. A number of different low-temperature colloidal synthesis routes were employed to prepare monodisperse, single-phase Pt-Ni alloy nanoparticles. The catalysts were characterized using XRD, TEM, and ICP-OES techniques, subsequently electrochemically dealloyed and, in their dealloyed state, tested for their Pt mass-based ORR activity, specific Pt surface area-based ORR activity. Additional 4,000 voltage cycles were applied to investigate the durability of the electrocatalysts in terms of their electrochemically active surface area and their final ORR activity. It is found that Pt-Ni alloys exhibit a distinctly different dealloying and ORR stability behavior compared to Pt-Co or Pt-Cu alloy nanoparticles. In particular, Pt-Ni alloys require longer cycling times to unfold their full ORR activity. A distinct ORR activity maximum was uncovered for Pt-Ni nanoparticle alloys with initial Ni contents in the neighborhood of 70–75 at.% consistent with results from dealloyed macroscopic Pt-Ni thin films.

One-Step Electrochemical Synthesis of PtNi Nanoparticle-Graphene Nanocomposites for Nonenzymatic Amperometric Glucose Detection

We report a facile one-step ultrasonication-assisted electrochemical method to synthesize nanocomposites of graphene and PtNi alloy nanoparticles (NPs) and their uses for highly selective nonenzymatic glucose detection. We have demonstrated that the obtained nanocomposites exhibit a collection of unique features including well-dispersed NPs with alloy features, high NP loading, and effective reduction of graphene oxide (GO). And the resulting nanoelectrocatalyst shows significantly improved electrochemical performance in nonenzymatic amperometric glucose detection, compared to a number of control electrode materials including the PtNi NP-chemically reduced GO nanocomposites fabricated in two steps (chemical reduction of GO followed by the electrodeposition of metal NPs). Under the physiological condition, the response current of the sensor is linear to glucose concentration up to 35 mM with a sensitivity of 20.42 μA cm(-2) mM(-1) at a substantially negative potential (i.e., -0.35 V). Operation under this potential eliminates the impact from the oxidation of common interfering species. This sensor with excellent sensitivity and selectivity also allows for reproducible detection of glucose in human urine samples.

Enhanced methanol electro-oxidation activity of PtNi alloy nanoparticles on the large surface area porous carbon

A kind of porous carbon (AC-K) with high surface area 2972 m2/g was obtained by treating activated carbon (AC) with KOH, which was investigated as the support for direct methanol fuel cell. PtNi nanoparticles were synthesized by chemical reduction with hydrazine using PVP as a stabilizer and deposited onto AC-K to produce PtNi/AC-K catalyst. Pt/AC-K and Pt/AC catalysts were also prepared under similar condition with the same nominal metal loading 20 wt.%. Their structures, morphologies, and electrocatalytic properties were investigated and compared. X-ray diffraction shows the alloy formation for Pt and Ni for PtNi/AC-K catalyst. Transmission electron microscopy reveals Pt/AC-K has a lower degree of agglomeration than Pt/AC. Moreover, PtNi/AC-K consists of nanoparticles with the lowest average particle size and best dispersion among the three catalysts. Nitrogen sorption at 77 K indicates that the potassium hydroxide activation can remarkably increase specific surface area and micropore volumes, which may be favorable for anchoring metal nanoparticle. Pt alloying with Ni may also contribute to the smaller particle size and better dispersion. Consequently, the activities of methanol oxidation investigated by cyclic voltammograms follow the order of PtNi/AC-K > Pt/AC-K > Pt/AC. Hence, the porous carbon AC-K and the corresponding catalyst PtNi/AC-K show great potential as support and less expensive electrocatalyst respectively for methanol electrooxidation in alkaline media in direct methanol fuel cells.

Electrocatalytic Activity of Carbon-Supported Pt-Ni Alloy Nanoparticles for Oxygen Reduction in PEMFCs

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Functional multi-walled carbon nanotube/polysiloxane composite films as supports of PtNi alloy nanoparticles for methanol electro-oxidation

We demonstrate the use of molecular monolayers to enhance the nucleation of electrocatalytically active PtNi alloy nanoparticles onto the multi-walled carbon nanotubes (MWCNTs). After the siloxane was polymerized on the nanotube surfaces, the carbon nanotubes were embedded within the polysiloxane shell with a hydrophilic amino group situated outside. Subsequent deposition of PtNi nanoparticles led to high density of 3–10 nm diameter PtNi alloy nanoparticles uniformly deposited along the length of the carbon nanotubes. The presence of MWCNTs and PtNi in the composite films was confirmed by transmission electron microscopy (TEM), X-ray diffraction (XRD) and energy dispersion X-ray spectra analysis (EDS). The electrocatalytic activity of the PtNi-modified MWCNT/polysiloxane (PtNi/Si-MWCNT) composite electrode for electro-oxidation of methanol was investigated by cyclic voltammetry (CV), and excellent electrocatalytic activity can be observed.

A new simple preparation of platinum-nickel alloy nanoparticles and their characterization as an electrocatalyst for methanol oxidation

Pt-Ni alloy nanoparticles were produced by casting 2 or 10 mM H2PtCl6 solutions on a Ni column. The apparent particle size for the resultant Pt-Ni alloys increased with the concentration of the H2PtCl6 solution, while the content of Pt in the alloy decreased. The potential sweeps of 5 cycles in an H2SO4 aqueous solution for Pt-Ni (2 mM)/Ni and Pt-Ni (10 mM)/Ni electrodes led to electrochemical behavior similar to a polycrystalline Pt electrode, suggesting the formation of a few thin Pt layers on each Pt-Ni alloy surface. In electrochemical measurements, both Pt-Ni/Ni electrodes showed more negative onset potential of methanol oxidation and slower degradation of oxidation current of methanol than the polycrystalline Pt electrode. X-ray photoelectron spectroscopy of both Pt-Ni/Ni electrodes showed the shift of Pt4f peaks to a higher binding energy, suggesting that the increase in the d vacancy in the balance band 5d orbital of Pt contributed to the improved electrocatalytic activity and durability of the Pt-Ni/Ni electrodes.