Carbon supported Ag and Ag–Co catalysts tolerant to methanol and ethanol for the oxygen reduction reaction in alkaline media

Hernández-Rodríguez, M.A.; Goya, M.C.; Arévalo, M.C.; Rodrı́guez, José Luis; Pastor, E.

doi:10.1016/j.ijhydene.2016.07.188

Cited by 38 publications

(29 citation statements)

References 33 publications

(23 reference statements)

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“…The doping of one atom to another causes the rearrangement of the atom periodicity and thus changes cell parameters, causing a shift of diffraction peaks. AgCo-12 shows greater displacement, promoting improved combining of Ag and Co atoms to form alloys that act as transition zones leading to bimetal formation [ 33 , 34 , 35 ].…”

Section: Resultsmentioning

confidence: 99%

Surface Alloying in Silver-Cobalt through a Second Wave Solution Combustion Synthesis Technique

2018

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Herein, we report the synthesis of silver-cobalt nanopowders using three different modes of solution combustion synthesis, and we present the effects of the synthesis conditions on particle morphology. The synthesized nanoparticles were characterized using X-ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), UV-Visible spectrophotometer (UV-vis), Transmission electron microscopy (TEM), and X-Ray Photoelectron Spectroscopy (XPS) to understand the structural and elemental properties. When Co is synthesized over Ag in a second wave of combustion, peak shifts observed in XRD and XPS show a change in the cell parameters and prove the existence of a strong electronic interaction between Ag and Co. Better control of mixing and alloying through the second wave combustion synthesis mode (SWCS) was evident. The sequence of combustion affects the structure and composition of the material. SWCS reduces the amount of carbon content, as compared to single-stage combustion, and the combustion of carbon is followed by a rearrangement of atoms.

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Section: Resultsmentioning

confidence: 99%

Surface Alloying in Silver-Cobalt through a Second Wave Solution Combustion Synthesis Technique

2018

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“…The value of n was close to 4 for 40 wt% and 60 wt% and slightly lower (3.7) for 80 wt% Ag/C. Ag/C and Ag−Co/C catalysts with various metal contents were prepared using glycerol and borohydride as reducing agents without any stabilisers . It was found that high amount of Ag is not favourable for complete 4e − ORR, as the value of n decreased from 4 for 20 wt% Ag/C to 3.7 for 60 wt% Ag/C.…”

Section: Orr On Carbon‐supported Ag Nanoparticlesmentioning

confidence: 90%

“…It was found that high amount of Ag is not favourable for complete 4e − ORR, as the value of n decreased from 4 for 20 wt% Ag/C to 3.7 for 60 wt% Ag/C. Addition of Co increased the catalyst activity and both Ag‐based catalysts were tolerant to alcohols . Thus one may conclude that for efficient 4‐electron oxygen reduction at least 20 wt% Ag/C should be used and increasing Ag content to 60 wt% might not further increase the ORR activity.…”

Section: Orr On Carbon‐supported Ag Nanoparticlesmentioning

confidence: 99%

Oxygen Reduction Reaction on Silver Catalysts in Alkaline Media: a Minireview

2018

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The development of efficient platinum‐free catalysts for electrocatalytic oxygen reduction reaction (ORR) is one of the main challenges in the fuel cell research. Silver‐based materials are highly active towards ORR in alkaline conditions and recent achievements in improving the performance of anion exchange membrane fuel cells (AEMFCs) have provoked many scientists to study these catalysts. This minireview is focused on the ORR performance of monometallic Ag catalysts and Ag‐based composites, the electrochemical oxygen reduction behaviour of Ag‐containing alloys is outside the scope of this review. The effect of the morphology of Ag nanostructures on catalysts’ ORR activity and pathway is discussed and the role of the support material is described. The performance of AEMFCs using Ag‐based cathode catalysts is also reviewed.

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“…However, these promises have not been demonstrated on the field yet, and more research and technological developments are needed to enable the practical deployment of alkaline electrolyzers and fuel cells at the large scale. If one focuses on the case of (direct) alkaline fuel cells, one shall develop adequate anion exchange membranes/ionomers (AEM) to avoid the usage of liquid electrolytes and related issues of leakages and/or carbonation (even if the latter is not totally suppressed with AEM) , , and of performant non‐PGM electrocatalysts either for the oxygen reduction reaction, the hydrogen oxidation reaction or for the oxidation of any complex fuel (e.g., manganese oxides , doped carbons , non‐noble transition metals , , etc.). Besides, if the cost target of these materials can reasonably be achieved, their sufficient durability is also mandatory.…”

Section: Introductionmentioning

confidence: 99%

Selected Review of the Degradation of Pt and Pd‐based Carbon‐supported Electrocatalysts for Alkaline Fuel Cells: Towards Mechanisms of Degradation

et al. 2018

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It is usually believed that carbon‐supported electrocatalysts are stable in alkaline environment, owing to the better thermodynamics stability of many metals and oxides at high pH. By focusing on a selected literature review concerning Pt/C and Pd/C nanoparticles, and in particular from identical‐location transmission electron microscopy (ILTEM), it is demonstrated that this “common knowledge” is erroneous in aqueous alkaline electrolytes: both Pt/C and Pd/C suffer pronounced loss of electrochemical surface area (ECSA), and the latter is linked to the detachment of the metal nanoparticles from the carbon support. Raman and X‐ray photoelectron spectroscopy show that these severe degradations are neither linked to massive corrosion of the carbon support nor to an overall change in carbon chemistry, but instead to a very localized corrosion of the carbon in the vicinity of the metal nanoparticles, leading to nucleation and growth of solid carbonate (when the electrolyte contains alkali metal cations), which expels the metal nanoparticles from their support. The mechanisms and extent of degradation depend on the nature of the metal nanoparticles, but also on their texture and on the nature of the support onto which they are immobilized.

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Carbon supported Ag and Ag–Co catalysts tolerant to methanol and ethanol for the oxygen reduction reaction in alkaline media

Cited by 38 publications

References 33 publications

Surface Alloying in Silver-Cobalt through a Second Wave Solution Combustion Synthesis Technique

Surface Alloying in Silver-Cobalt through a Second Wave Solution Combustion Synthesis Technique

Oxygen Reduction Reaction on Silver Catalysts in Alkaline Media: a Minireview

Selected Review of the Degradation of Pt and Pd‐based Carbon‐supported Electrocatalysts for Alkaline Fuel Cells: Towards Mechanisms of Degradation

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