Core-shell structured tungsten–tungsten carbide as a Pt catalyst support and its activity for methanol electrooxidation

Obradović, Maja D.; Babić, Biljana; Radmilović, Velimir; Krstajić, N.V.; Gojković, S.Lj.

doi:10.1016/j.ijhydene.2012.04.114

Cited by 22 publications

(12 citation statements)

References 37 publications

(45 reference statements)

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“…Some recent studies indicate that this decay of the currents is due to the presence of tungstate species formed by chemical oxidation of WC, which are deposited on the Pt particles, partially blocking the Pt H UPD process. These W oxides are prone to suffer hydrogen intercalation/deintercalation processes, which in the case of the catalyst with higher WC content results in the appearance of the significant redox peak at 0.2 to 0.3 V . These processes have been represented by the following reactions:

true normalW O_{3} + x Pt - {normalH}^{+} \to H_{x} normalW O_{3} + x Pt

true H_{x} normalW O_{3} \to W O_{3} + {x normalH}_{x} + x {normale}^{-}

…”

Section: Resultsmentioning

confidence: 99%

Activity and Electrochemical Stability of Pt‐ and Pt₂Ni‐α‐WC/C Catalysts for the Oxygen Reduction Reaction in Acid Media

Bott‐Neto¹,

Ticianelli²

2018

ChemElectroChem

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The activity and electrochemical stability of Pt and Pt2Ni alloy nanoparticles supported on carbon (Pt/C, Pt2Ni/C) or on hexagonal tungsten carbide/carbon powders (Pt‐α‐WC/C, Pt2Ni‐α‐WC/C) were investigated for the oxygen reduction reaction (ORR) in 0.1 M HClO4. The composites were extensively characterized by different physicochemical techniques, after which the electrochemical active surface area and the electrocatalytic activity for ORR were investigated, before and after being submitted to accelerated stress tests (AST). Results of rotating ring‐disk electrode experiments have indicated that Pt2Ni‐α‐WC 20 wt.%/C presents the highest initial specific activity (SA) for ORR, about 1.8 times higher than that of a Pt/C catalyst, but also the largest loss of specific activity caused by the AST. This is assigned to a strong catalyst degradation and consequent elimination of positive effects of Ni over Pt in the electrocatalysis of ORR. Although the mass activity of Pt/C electrode was higher after 12000 AST cycles, the specific activity of Pt‐α‐WC20 wt.%/C is more stable, indicating that beneficial interactions between Pt and the WC/WOx phases are maintained along the AST.

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true normalW O_{3} + x Pt - {normalH}^{+} \to H_{x} normalW O_{3} + x Pt

true H_{x} normalW O_{3} \to W O_{3} + {x normalH}_{x} + x {normale}^{-}

…”

Section: Resultsmentioning

confidence: 99%

Activity and Electrochemical Stability of Pt‐ and Pt₂Ni‐α‐WC/C Catalysts for the Oxygen Reduction Reaction in Acid Media

Bott‐Neto¹,

Ticianelli²

2018

ChemElectroChem

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“…Nosač je sintentizovan metodom sol-gel polikondenzacije rezocinola i formaldehida u prisustvu (NH 4 ) 2 WO 4 kao izvora volframa i cetiltrimetilamoniumbromida kao površinski aktivne supstance [7,11,20]. Uzorak je termički tretiran na 900 °C tokom 1 h u atmosferi Ar, a zatim još dodatna 2 h na 95 °C u atmosferi H 2 .…”

Section: Eksperimentalni Deounclassified

“…Nakon sušenja tokom noći na vazduhu i sobnoj temperaturi ispitivane su karakteristike ovako pripremljenog tankog sloja praha metodom ciklične voltametrije u 0,10 mol dm -3 H 2 SO 4 , u atmosferi N 2 . Pre svih elektrohemijskih merenja elektroda je pripremljena cikliziranjem tokom 15 min u oblasti potencijala od 0,04 do 1,15 V. Elektrohemijski aktivna površina Pt na katalizatoru Pt/W-C je određena merenjem količine naelektrisanja anodnog rastvaranja Cu koji je prethodno nataložen na potpotencijalu 0,33 V iz rastvora 2,0×10 -3 mol dm -3 CuSO 4 u 0,10 mol dm -3 H 2 SO 4 [5,20].…”

Section: Eksperimentalni Deounclassified

“…Rezultati XRD analize uzoraka nosača W-C i katalizatora Pt/W-C prikazani su na slici 1 zajedno sa referentnim spektrima za W, WC i W 2 C (JCPDS kartice 04--0806, 25-1047 i 20-1315). Prisutni maksimumi na difraktogramima ukazuju da uzorak W-C sadrži metalni volfram i karbide volframa WC i W 2 C. Analiza uzorka TEM-om visoke rezolucije je ukazala na bimodalnu raspodelu čestica volframa na ugljeničnom nosaču, sa veličinom čestica oko 2 i iznad 5 nm [20]. Kristalna struktura manjih čestica odgovara karbidu, dok čestice veli-čine iznad 5 nm sadrže metalni volfram u centru koji je obavijen verovatno volfram-karbidom.…”

Section: Karakterizacija W-c I Pt/w-c Metodom Xrdunclassified

“…Ciklični voltamogram katalizatora Pt/W-C prikazan je na slici 2b, dok je voltamogram komercijalnog katalizatora Pt/C, snimljen pri istim uslovima, prikazan na slici 2c. Vrednosti gustine struje su izračunate po jedinici površine Pt, koja je određena na osnovu količine naelektrisanja desorpcije adsorbovanog monosloja Cu [5,20]. Specifična površina Pt u uzorku Pt/W-C iznosi 41 m 2 g -1 što odgovara prosečnoj veličini nanočestica Pt od 6,8 nm.…”

Section: Elektrohemijska Karakterizacija W-c I Pt/w-cunclassified

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Effect of tungsten carbide in carbon Pt catalyst support on electrochemical oxygen reduction in acid solution

Obradović

Babić

Krstajić

et al. 2013

Hem Ind

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Tungsten carbide was synthesized by calcination of carbon cryogel with embedded tungsten in a form of metatungstate. This material was used as a support for Pt nanoparticles. XRD pattern of W-C support indicates the presence of WC, W2C, and unreacted W, as well as graphitized carbon. According to the previous TEM analysis of W-C support, it contains particles with core-shell structure, where W particle was covered with the shell of a mixture of WC and W2C. The average Pt grain size calculated from XRD pattern was about 6 nm. Cyclic voltammogram of W-C support was recorded within potential range relevant for its application as a catalyst support in fuel cells. Pair of anodic/cathodic peaks close to the negative potential limit could be ascribed to the intercalation of hydrogen within hydrous tungsten oxide, which is always present on the surface of WC in aqueous solutions. Cyclic voltammogram of Pt/W-C indicated that tungsten oxide species are present on tungsten carbide shell as well as on the surface of Pt nanoparticles. Pt surface is only partially covered by hydrous tungsten oxide. Hydrogen intercalation in hydrous tungsten oxide is enhanced in the presence of Pt nanoparticles. Also, the presence of hydrated tungsten oxide leads to the decrease of OH chemisorbed on Pt surface. Stripping of underpotentially deposited copper was used for the assessment of Pt surface area and the specific surface area of Pt was estimated to 41 m2 g-1. Electrochemical oxygen reduction reaction was examined on the synthesized Pt/W-C catalyst and compared with the results on the commercial Pt/C catalyst. It was found that the current densities at Pt/W-C are almost double as those on Pt/C. The Tafel plots for both catalysts are characterized with two Tafel slopes: -0.060 V dec-1 at low current densities, and -0.120 V dec-1 at high current densities. From the rotational dependence of the reaction rate, it was found that oxygen reduction on both Pt/W-C and Pt/C follows the first order kinetics with respect to O2 and that four electrons are transferred per O2 molecule. The results show that the presence of tungsten carbide in support material i.e. hydrous tungsten oxide on Pt surface, leads to promotion of oxygen reduction on the Pt/W-C catalyst. It was assumed that oxophilic hydrated tungsten oxide hinders OH adsorption on Pt surface, thus increasing Pt surface area available for O2 adsorption and its electrochemical reduction

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Milestones of Electrocatalyst Development for Direct Alcohol Fuel Cells

Nguyen

Pham

Huynh³

et al. 2023

Advanced Sustainable Systems

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With increasing energy demands and environmental issues, renewable energy‐related conversion systems have gained significant attention as a potential substitute for traditional fossil fuel‐based energy technologies. First introduced by S.W.Grove in 1838, fuel cells have been extensively developed into many different types, and direct alcohol fuel cells (DAFCs) are of interest as a potential power source because of their large power density, quick start, simplicity, and nearly zero emission. However, the high cost and poor catalytic efficiency of current catalysts are primary barriers to commercializing DAFCs. Designing advanced nanocatalysts for both anode and cathode electrodes is of crucial importance for practical DAFC development; however, a brief evaluation of current progress in electrocatalyst development for the alcohol oxidation reaction (AOR) and oxygen reduction reaction (ORR) is still very little. Herein, recent advances in fuel cell catalysts, mainly focusing on several most active areas (i.e., Pt‐ and Pt‐free‐based catalysts, metal‐free carbon, carbon‐based nonprecious metal composites) are concisely summarized. Also, challenges and prospects for DAFCs are highlighted to supply a comprehensive view for further designing high‐performance DAFC catalysts.

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Core-shell structured tungsten–tungsten carbide as a Pt catalyst support and its activity for methanol electrooxidation

Cited by 22 publications

References 37 publications

Activity and Electrochemical Stability of Pt‐ and Pt₂Ni‐α‐WC/C Catalysts for the Oxygen Reduction Reaction in Acid Media

Activity and Electrochemical Stability of Pt‐ and Pt₂Ni‐α‐WC/C Catalysts for the Oxygen Reduction Reaction in Acid Media

Effect of tungsten carbide in carbon Pt catalyst support on electrochemical oxygen reduction in acid solution

Milestones of Electrocatalyst Development for Direct Alcohol Fuel Cells

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Core-shell structured tungsten–tungsten carbide as a Pt catalyst support and its activity for methanol electrooxidation

Cited by 22 publications

References 37 publications

Activity and Electrochemical Stability of Pt‐ and Pt2Ni‐α‐WC/C Catalysts for the Oxygen Reduction Reaction in Acid Media

Activity and Electrochemical Stability of Pt‐ and Pt2Ni‐α‐WC/C Catalysts for the Oxygen Reduction Reaction in Acid Media

Effect of tungsten carbide in carbon Pt catalyst support on electrochemical oxygen reduction in acid solution

Milestones of Electrocatalyst Development for Direct Alcohol Fuel Cells

Contact Info

Product

Resources

About

Activity and Electrochemical Stability of Pt‐ and Pt₂Ni‐α‐WC/C Catalysts for the Oxygen Reduction Reaction in Acid Media

Activity and Electrochemical Stability of Pt‐ and Pt₂Ni‐α‐WC/C Catalysts for the Oxygen Reduction Reaction in Acid Media