Rapid synthesis of Pt-based alloy/carbon nanotube catalysts for a direct methanol fuel cell using flash light irradiation

Park, Sung Hyeon; Jung, Hye Mi; Um, Sukkee; Song, Yong Won; Kim, Kwang Ho

doi:10.1016/j.ijhydene.2012.06.004

Cited by 27 publications

(21 citation statements)

References 22 publications

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“…It has generally been known that CO poisoning increases I b , which in turn decreases the I f /I b ratio. 19,42,43 Therefore, a high value of I f /I b implies relatively complete oxidation of methanol to carbon dioxide. In this work, the Pt 100 /MWCNT catalyst exhibited the highest electrochemical reaction when compared to the other structures (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…19 In our previous work, the pulse number, width, and gap were optimized at 3 times, 5 ms, and 5 ms, respectively, and a total pulse energy of 60 J/cm 2 was chosen to form uniform and well dispersed Pt-alloy nanoparticles on the MWCNTs. 19 After flash light irradiation, the Pt-alloy nanoparticle/MWCNT catalysts were mixed with 3.5 mL of ethanol (> 99.9% purity, Samchun. Co) and 0.7 mL of a 5 wt% Nafion solution (MW = 1100, perfluorinated ion exchange resin, 5 wt% solution, DuPont Co.).…”

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confidence: 99%

“…All CV experiments were conducted at room temperature at a scan rate of 50 mV/s from −0.3 V to 1.0 V (vs. Ag/AgCl); each sample was scanned five times. 19 A glassy carbon electrode (GCE, I.D 3 mm, O.D 6 mm, CHI Co.) was polished to a mirror finish with 0.05 μm alumina. Five microliters of the catalyst slurries and 5 μL of a 5 wt% Nafion solution were then loaded onto the surface of the electrode.…”

mentioning

confidence: 99%

“…[5][6][7][8][9][10][11][12][13][14][15][16][17] In particular, Pt-Ru-Mo is considered to be one of the best Pt-based alloy catalysts. [18][19][20][21] However, the synthesis of this metal alloy is quite challenging when compared to the fabrication of pure metal nanoparticles due to the difficulty in forming a uniform material. Furthermore, controlling the concentration of each metal in the metal alloy nanoparticles is important.…”

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confidence: 99%

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An Investigation into Methanol Oxidation Reactions and CO, OH Adsorption on Pt-Ru-Mo Catalysts for a Direct Methanol Fuel Cell

Park

Joo

Kim

2014

J. Electrochem. Soc.

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The electrochemical performance of pure Pt and Pt-based alloy nanoparticle catalysts with various Pt, Ru and Mo concentrations is investigated. Pure Pt, Ru, and Mo are first deposited on multi-walled carbon nanotubes (MWCNTs) using a E-beam evaporator (MEP5000, SNTEK), and Pt-based alloy nanoparticles are subsequently formed on the MWCNTs via flash light irradiation. Several microscopic and spectroscopic techniques, including X-ray diffractometry, scanning electron microscopy, and Raman spectroscopy are employed to characterize the catalysts. Cyclic voltammetry experiments are also performed to measure the electrochemical reactions of the Pt-based alloy nanoparticle/MWCNT catalysts. To verify the experimental results, a computational simulation analysis is conducted using molecular dynamics and the application of density functional theory. From the experimental and analytical findings, it is concluded that the Pt 43 -Ru 43 -Mo 14 /MWCNT structure exhibits the best electrochemical performance for the oxidation of methanol.The phenomenon of CO poisoning is a critical problem in the field of direct methanol fuel cells (DMFCs). CO poisoning occurs at pure Pt catalyst sites on the DMFC anode during the methanol oxidation reaction. The oxidation of methanol to carbon dioxide proceeds via a six-electron transfer process as follows: 1-4 Pt + CH 3 OH → Pt(CO) ads + 4H + + 4e − [1.1] Pt + H 2 O → Pt(OH) ads + H + + e − [1.2] Pt(CO) ads + Pt(OH) ads → CO 2 + 2Pt + H + + e − [1.3]Strongly adsorbed CO can gradually occupy all active Pt sites according to reaction 1.1. In order to remove the Pt(CO) ads species, the production of Pt(OH) ads by reaction 1.2 is needed so that reaction 1.3 may occur. However, the formation of Pt(OH) ads is difficult due to its high electrochemical potential (0.7 V vs. reversible hydrogen electrode (RHE)). A promising approach to solve this issue is to form M(OH) ads (M = metal) species that have a low electrode potential. For example, water dissociation can occur on Ru sites with the formation of Ru(OH) ads species at a potential as low as 0.2 V vs. RHE. 3 Various metals (e.g., Ru, Ni, Mo, Sn, Rh, Pd) that are compatible with Pt have been proposed for the fabrication of binary, ternary, and quaternary catalysts. [5][6][7][8][9][10][11][12][13][14][15][16][17] In particular, Pt-Ru-Mo is considered to be one of the best Pt-based alloy catalysts. 18-21 However, the synthesis of this metal alloy is quite challenging when compared to the fabrication of pure metal nanoparticles due to the difficulty in forming a uniform material. Furthermore, controlling the concentration of each metal in the metal alloy nanoparticles is important. For example, it has been reported that excessive concentrations of Mo has a deleterious effect on methanol oxidation. [21][22][23] In this study, we fabricated Pt-Ru-Mo/MWCNT catalysts with various metal atomic ratios in a short period of time (millisecond) using the flash light irradiation method under ambient conditions at room temperature. 14,15 The optimum atomic ratio of...

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Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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An Investigation into Methanol Oxidation Reactions and CO, OH Adsorption on Pt-Ru-Mo Catalysts for a Direct Methanol Fuel Cell

Park

Joo

Kim

2014

J. Electrochem. Soc.

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“…PtRu-Mo) presents best catalytic activities for alcohol electro-oxidation, which may be attributed to the electronic effect, bifunctional mechanism, and hydrogen spillover effect. [36][37][38] The effect of molybdenum is nowadays an issue open to discussion, but there are gas-phase studies applied to catalytic hydrogenation of toluene, such as that carried out in the gas phase by Zosimova et al 36 Based on XRD, SEM, TEM and XEDS analyses performed in this study, a spillover mechanism is proposed in which the MoOx acts as a stabilizer of the proton that is previously dissociated on the platinum surface. Our electrochemical results show that the best results toward MeOH oxidation correspond to the Pt/Mo/C bhr catalyst, which presents a slight slope in the electrical double layer, indicative of the presence of Mo oxide phase at the surface; this presence is corroborated by the increase in the reduction current on the reverse scan.…”

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confidence: 92%

Study of the Electrochemical Activities of Mo-Modified Pt Catalysts, for Application as Anodes in Direct Methanol Fuel Cells: Effect of the Aggregation Route

Reyes

Hernandez-Maya

Ocampo

et al. 2014

J. Electrochem. Soc.

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Electrocatalysts with constant metallic composition, consisting of carbon-supported platinum and molybdenum phases, were synthesized following the thermolysis (thr) and borohydride (bhr) reduction methods and using different metallic precursors. The obtained electrocatalysts were characterized by X-ray energy-dispersive spectrometry, X-ray diffraction and high resolution transmission electron microscopy. Their activities were studied by cyclic voltammetry. Different surface structures were obtained and the electrochemical activities toward methanol oxidation were compared. Pt, MoO 2 and MoO 3 phases were well identified with the characterization techniques used. However, the electrochemical responses obtained from both sample series were considerably different, suggesting that the arrangement and relationships between active phases strongly depend on the synthesis method and aggregation sequence of the metallic precursors, and being the cause of different catalytic activities and stabilities of molybdenum oxide phases. The bhr method offered higher activity than the thr method. Among the sample series obtained by bhr method, the catalyst obtained by platinum deposition on the previously synthesized molybdenum on carbon, led to the highest overall activity. Fuel Cells represent one of the most promising options for generating electricity with high efficiency and low environmental impact. The Direct-Methanol Fuel Cell (DMFC) is a low-temperature cell where methanol is directly supplied as fuel to the anode compartment, without any previous reforming. Furthermore, methanol can be stored and transported in liquid phase, it can be obtained from biomass, and its complete oxidation can yield a high energy density.1 Platinum has been recognized as the most active catalyst for the methanol oxidation reaction and it has been employed in the formulation of such materials. However, the formation of different organic intermediates, adsorbed on Pt surfaces during methanol electrooxidation, causes the poisoning of active sites and decreases the catalyst efficiency. Several studies indicate that the modification of the Pt catalyst with other transition metal can lead to good results in oxidizing methanol at a low potential (lower than in pure Pt). 2On the other hand, it is well known that bimetallic materials show increased activity toward the CO electro-oxidation reaction, yielding CO 2 . Studies on catalytic effects that take place on bimetallic surfaces, obtained from pure metals and modified by the deposition of a second metal, are closely related to the technological development of low temperature fuel cells. Some researchers have emphasized the use of CO as a test molecule to show the electronic effect associated with this reaction. The CO desorption energy is apparently related to strong intermetallic bonds and mixed orbitals of the active phases. Hence, a catalyst with high activity toward methanol oxidation must also have high activity for CO oxidation.3 This activity is explained by some authors in terms of the so-cal...

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Synthesis of Nitrogen‐Doped Porous Carbon Nanocubes as a Catalyst Support for Methanol Oxidation

et al. 2016

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Nitrogen-doped porousc arbon nanocubes with ah igh surface area synthesized by carbonizing Prussian blue nanocubes coated with poly(fururyla lcohol) were used to support Pt nanoparticles as an electrocatalyst for the oxidation of methanol. The resulting catalyste xhibited excellent electrocatalytic activity and electrochemical stability, owning to its high surface area, au niform dispersion of Pt particles, and enhanced interaction between the particles and the support.Direct methanol fuel cells (DMFCs) are considered someo ft he most promising energy sourcesf or portable devices and mobile applications. [1] However,t heir applications on al arge scale are limited by the high costs associated with the use of noble metal electrocatalysts (e.g. Pt)a nd the operational durability of the anode. [2] Thus, increasing the catalytic activity of Pt-based catalysts and decreasing the Pt loading are very important for the development of DMFCs. [3] Carbon black supported Pt or Pt-based alloys have been widely investigated and used as electrocatalysts for the electro-oxidation of methanol. [4] However,P tn anoparticles (NPs) can be trapped in the deep cracks of carbon black, which thus reduces the utilization of Pt. [5] To tackle these issues, improving the dispersion of Pt or Pd-baseda lloys in ap orouss upport is ap romising way to increase the utilization of Pt catalyst. Differentc arbon materials including carbon nanotubes, [6] graphene, [7] and nanoporous carbon [8] have been studied to improve the activities and stabilities of catalysts.Recently,m etal-organic frameworks (MOFs) have attracted increasing attention, because they can act as versatile precursors to preparec arbon,c arbon-metal composite, and metaloxide materials with high specific surfacea reas. [9] In particular, MOF-derived carbon materials show high specific surface areas, variousm orphologies, and heteroatom doping, which Supporting Information for this article can be foundu nder http:// dx.

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Rapid synthesis of Pt-based alloy/carbon nanotube catalysts for a direct methanol fuel cell using flash light irradiation

Cited by 27 publications

References 22 publications

An Investigation into Methanol Oxidation Reactions and CO, OH Adsorption on Pt-Ru-Mo Catalysts for a Direct Methanol Fuel Cell

An Investigation into Methanol Oxidation Reactions and CO, OH Adsorption on Pt-Ru-Mo Catalysts for a Direct Methanol Fuel Cell

Study of the Electrochemical Activities of Mo-Modified Pt Catalysts, for Application as Anodes in Direct Methanol Fuel Cells: Effect of the Aggregation Route

Synthesis of Nitrogen‐Doped Porous Carbon Nanocubes as a Catalyst Support for Methanol Oxidation

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