Electrochemical oxidation of ammonia by multi-wall-carbon-nanotube-supported Pt shell–Ir core nanoparticles synthesized by an improved Cu short circuit deposition method

Morita, Seitaro; Kudo, Eiji; Shirasaka, Ryo; Yonekawa, Minoru; Nagai, Keiji; Ota, Hikaru; N.-Gamo, Mikka; Shiroishi, Hidenobu

doi:10.1016/j.jelechem.2015.12.017

Cited by 20 publications

(3 citation statements)

References 69 publications

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“…Overall, the AOR activity of the optimal PtIrNi 1 /SiO 2 -CNT-COOH catalyst (∼0.40 V onset potential, peak current density 124.0 A g –1 ) is superior or comparable to those of many reported catalysts, such as the CeO 2 -modified Pt catalyst (onset potential: ∼0.50 V), Pt-decorated highly porous flowerlike Ni particles (onset potential: ∼0.50 V), PtIr/CNT (atomic ratio of Pt/Ir = 4:1, onset potential: ∼0.38 V), PtIr/N-reduced graphene oxide (rGO) (molar ratio of Pt/Ir = 1:3, onset potential: ∼0.37 V), PtRh/C (molar ratio of Pt/Rh = 9:1, onset potential: ∼0.44 V), CuPtRh nanowires (mass ratio of Pt/Ru = 7:1, onset potential: ∼0.49 V), and PtIrZn (mass ratio of Pt/Ir = 8:2, onset potential: ∼0.30 V) . Detailed comparisons in terms of onset potential and/or peak current density can be found in Table S4.…”

Section: Resultsmentioning

confidence: 74%

Ternary PtIrNi Catalysts for Efficient Electrochemical Ammonia Oxidation

Pillai

et al. 2020

ACS Catal.

139

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Ammonia (NH3) has proved to be an effective alternative to hydrogen in low-temperature fuel cells via its direct ammonia oxidation reaction (AOR). However, the kinetically sluggish AOR has prohibitively hindered the attractive direct ammonia fuel cell (DAFC) applications. Here, we report an efficient AOR catalyst, in which ternary PtIrNi alloy nanoparticles well dispersed on a binary composite support consisting of porous silicon dioxide (SiO2) and carboxyl-functionalized carbon nanotube (PtIrNi/SiO2-CNT-COOH) through a sonochemical-assisted synthesis method. The PtIrNi alloy nanoparticles, with the aid of abundant OHad provided by porous SiO2 and the improved electrical conductivity by CNTs, exhibit remarkable catalytic activity for the AOR in alkaline media. It is evidenced by a lower onset potential (∼0.40 V vs reversible hydrogen electrode (RHE)) at room temperature than that of commercial PtIr/C (ca. 0.43 V vs RHE). Increasing NH3 concentrations and operation temperatures can significantly enhance AOR activity of this PtIrNi nanoparticle catalyst. Specifically, the catalyst at the temperature of 80 °C exhibits a much lower onset potential (∼0.32 V vs RHE) and a higher peak current density, indicating that DAFCs operated at a higher temperature are favorable for increased performance. Constant-potential density functional theory (DFT) calculations showed that the Pt–Ir ensembles on {100}-terminated surfaces serve as the active site. The introduction of Ni raises the center energy of the density of states projected onto the group d-orbitals of surface sites and thus lowers the theoretical onset potential for *NH2 dehydrogenation to *NH compared to Pt and Pt3Ir alloy.

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Section: Resultsmentioning

confidence: 74%

Ternary PtIrNi Catalysts for Efficient Electrochemical Ammonia Oxidation

Pillai

et al. 2020

ACS Catal.

139

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“…The less amount Pt 2+ and no Pt 4+ binding indicated that the reduced Pt can anchor on the N‐rGO substrate. It is a similar situation to Ir4 f, containing of more Ir 0 (61.8, 65.2 eV) and some Ir 3+/4+ (63.5, 66.8 eV) . The metal state in the catalysts can facilitate their electrocatalytic activity.…”

Section: Resultsmentioning

confidence: 82%

High Mass and Specific Activity for Ammonia Electro‐oxidation through Optimization of Dispersion Degree and Particle Size of Pt‐Ir Nanoparticles over N‐Doped Reductive Graphene Oxide

Zhou

Zhang

et al. 2018

ChemistrySelect

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Platinum and iridium co-supported on N-doped reductive graphene oxide (N-rGO) electrocatalysts (PtÀIr/N-rGO) were synthesized and investigated for ammonia electro-oxidation reaction (AOR) in alkaline media. Pt and Ir particles were deposited over the N-rGO substrate through a potentiodynamic electrodeposition method. The deposition parameters, lower potential limit (E L ) and scan rate, play a vital role on the dispersion degree and particle size of PtÀIr bimetallic nanoparticles over N-rGO. Additionally, the comparable current densities and a better poisoning inhibition are obtained compared to the commercial Pt (20 wt%)/C indicating that a synergistic effect among Pt, Ir and N-rGO substrate is existing in favour on the electrocatalytic activity. The N-rGO substrate with more active sites, higher excellent electrochemical activity and well dispersion for Pt and Ir particles anchoring is a suitable substrate for AOR and would be extended to other catalytic reactions.[a] Dr.

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“…Briefly, this technique includes two steps: (1) loading the functional groups with the MNP precursor via ion exchange, for example, a metal salt or metal complex ions, and (2) formation of MNPs by chemical reduction of the metal precursor. Additionally, due to the dramatic decrease of the redox potential on the nanometer scale for several metals, it has been possible to oxidize some superficial atoms of the MNPs by another metal such as gold or platinum by a procedure known as galvanic displacement [10,25,26].…”

Section: Introductionmentioning

confidence: 99%

Metal nanoparticle–carbon nanotubes hybrid catalysts immobilized in a polymeric membrane for the reduction of 4-nitrophenol

et al. 2019

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In this work, the synthesis of silver and copper nanoparticles and bimetallic silver-platinum and copper-platinum nanoparticles, in previously functionalized multi-walled carbon nanotubes (MWCNT), was carried out using the intermatrix synthesis for the charge of the first metal, and a galvanic replacement for the deposition of a second metal to form the bimetallic NPs. Well-controlled small size NPs were obtained as demonstrated by TEM, with a homogeneous distribution and mean particle diameters of ca. 2.9 nm. The hybrid MNPs/MWCNTs catalysts were characterized by FTIR, TEM and XPS. The metal content was determined by TGA and validated via FAAS. Thereupon, the metal-MWCNTs hybrid catalysts were incorporated into a polymeric membrane (PM) and characterized by SEM. The effects of the hybrid catalyst-polymeric support interactions and the role of the MNPs/MWCNTs/PM materials as heterogeneous catalysts were evaluated from the catalytic performance on the reduction of 4-nitrophenol as a model reaction. An apparent rate constant normalized by the metal content of 1706.7 s −1 mol −1 was achieved for the best system (Ag-PtNPs/MWCNTs/PMR) along with a decrease in the percentage of conversion from 95% (first cycle) to 80% (third cycle). Results indicated that the catalytic activity depends mainly on the MNPs size and the metal content in the catalyst. The catalytic activity of the MNPs/MWCNTs was only 3 times higher than for the MNPs/MWCNTs/PMs catalysts, with the former presenting the advantage of being easily recovered from the reaction medium, thus, demonstrating the capability to perform an efficient and sustainable process.

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Electrochemical oxidation of ammonia by multi-wall-carbon-nanotube-supported Pt shell–Ir core nanoparticles synthesized by an improved Cu short circuit deposition method

Cited by 20 publications

References 69 publications

Ternary PtIrNi Catalysts for Efficient Electrochemical Ammonia Oxidation

Ternary PtIrNi Catalysts for Efficient Electrochemical Ammonia Oxidation

High Mass and Specific Activity for Ammonia Electro‐oxidation through Optimization of Dispersion Degree and Particle Size of Pt‐Ir Nanoparticles over N‐Doped Reductive Graphene Oxide

Metal nanoparticle–carbon nanotubes hybrid catalysts immobilized in a polymeric membrane for the reduction of 4-nitrophenol

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