Enhancement of high temperature PEMFC stability using catalysts based on Pt supported on SiC based materials

Lobato, Justo; Zamora, Héctor; Plaza, Jorge; Cañizares, Pablo; Rodrigo, Manuel A.

doi:10.1016/j.apcatb.2016.06.011

Cited by 46 publications

(39 citation statements)

References 29 publications

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“…On the one hand distribution of catalyst on the electrode can play a role, but on the other hand also the properties of support material may have an influence on the electrocatalytic properties. 45 For instance, rGO has a lower electrical conductivity than carbon black or MWCNT. 30 In case of Pt on titanium dioxide, Huang et al 35 also measured lower mass transport limited currents during ORR measurements than for Pt/C.…”

Section: Resultsmentioning

confidence: 99%

Stability of Pt Nanoparticles on Alternative Carbon Supports for Oxygen Reduction Reaction

Schonvogel

Hülstede

Wagner

et al. 2017

J. Electrochem. Soc.

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Pt supported on carbon black, commonly used as PEM fuel cell catalyst, underlies electrochemical instabilities in terms of carbon corrosion and platinum degradation. To better understand the influence of the support on nature and extent of catalyst aging, Pt was synthesized on four different substrates: Carbon black, multiwalled carbon nanotubes (MWCNTs), reduced graphene oxide (rGO) and a nanocomposite of indium tin oxide with rGO (ITO-rGO). The four Pt catalysts and the separate supports were studied on their durability using an accelerated stress test (AST, −0.02-1.40 V SHE ). Comparable platinum degradation was shown by losses of electrochemically active surface area (EASA) and activity for oxygen reduction reaction (ORR) and by identical location transmission electron microscopy (IL-TEM). With respect to the supports, highest instability of carbon black was observed investigating the double layer capacitance and amounts of hydroquinone (HQ) species. MWCNTs showed the lowest degradation. Thus, AST provoked strongly different extents of support aging but similar Pt degradation. In view of complex FC catalyst degradation mechanism, only negligible Pt detachment caused by support degradation and rather dominating Pt dissolution and agglomerationadditionally evidenced by IL-TEM-is assumed here. Regarding ITO-rGO, neither carbon support nor platinum stabilization by ITO nanoparticles has been observed. Proton exchange membrane fuel cells (PEMFCs) are attractive for stationary, portable and automotive applications.1,2 Short response times and simple cell design with low weight and solid electrolyte membranes are some advantages of PEMFCs, especially for the automotive sector. Good performance and high lifetimes are two important criteria for commercialization of fuel cells. Low temperature PEMFCs can reach power densities about 680 mWcm −2 , 3 higher than the power densities of other fuel cell types.1 However, a challenge is the loss of performance with operation time.2,4 The better understanding of physical, thermal, mechanical, chemical and electrochemical processes, leading to the aging of fuel cell components, is indispensable and is therefore one main issue of current fuel cell research. 2,[5][6][7][8] Platinum supported on carbon black represents the commonly used catalyst in fuel cells. Under PEMFC conditions at low pH values and cell voltages of around 1.0 V during no-load or 1.4 V during startstop operation, 9 dissolution of platinum becomes relevant. Pt oxides are formed at potentials higher than 0.6 V SHE , 10 whereas Pt oxides or metallic Pt can dissolve.2 Dissolved Pt underlies Ostwald ripening or simply leaves the cell with the exhaust water stream. Pt ions can migrate into the membrane and be reduced to metallic platinum. 11Especially at potentials above 0.95 V SHE oxygen atoms can replace Pt atoms, so that potential cycling can lead to significant changes of the catalyst particle structure. 2Also instabilities of the catalyst support can result in a reduction of cell performance. Corrosion of carbo...

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Section: Resultsmentioning

confidence: 99%

Stability of Pt Nanoparticles on Alternative Carbon Supports for Oxygen Reduction Reaction

Schonvogel

Hülstede

Wagner

et al. 2017

J. Electrochem. Soc.

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“…Vulcan XC-72 is a popular catalyst support typically used in the HT-PEMFC literature. Groups such as Zamora and associates have investigated alternative carbon based supports [117,118] as well as silicon carbide [119][120][121] in phosphoric acid doped PBI based systems. In their works they evaluated the use of several types of carbon based supports including Vulcan XC-72, carbon nanofibers, and carbon nanospheres.…”

Section: Orr Catalyst Activity In Free Electrolyte: Alternative Catalystmentioning

confidence: 99%

“…The tradeoff was a significant boost in thermal and electrochemical stability along with improved mass transport characteristics of the silicon carbide based systems. In later studies, the same group investigated the use of composite titanium silicon carbide [120,121]. They found that the composite titanium silicon carbide based system showed cell performance lower but comparable to the Vulcan XC-72 based system with the highest stability when operated at 160 • C.…”

Section: Orr Catalyst Activity In Free Electrolyte: Alternative Catalystmentioning

confidence: 99%

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Catalyst, Membrane, Free Electrolyte Challenges, and Pathways to Resolutions in High Temperature Polymer Electrolyte Membrane Fuel Cells

2017

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High temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) are being studied due to a number of benefits offered versus their low temperature counterparts, including co-generation of heat and power, high tolerance to fuel impurities, and simpler system design. Approximately 90% of the literature on HT-PEM is related to the electrolyte and, for the most part, these electrolytes all use free phosphoric acid, or similar free acid, as the ion conductor. A major issue with using phosphoric acid based electrolytes is the free acid in the electrodes. The presence of the acid on the catalyst sites leads to poor oxygen activity, low solubility/diffusion, and can block electrochemical sites through phosphate adsorption. This review will focus on these issues and the steps that have been taken to alleviate these obstacles. The intention is this review may then serve as a tool for finding a solution path in the community.

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“…Microbial fuel cells (MFCs) have been well studied since the discovery of the ability of many microorganisms to donate electrons to an electrode, which opened the possibility of using these microorganisms to harvest the energy contained in the organic matter of wastewater. A lot of effort has been made from that moment, most related to study of the influence on the performance of the MFCs of electrodic materials,, cell design, carbon source and concentration of the fuel fed,, catalysts, origin of the sludge seeded, external resistance, environmental and operational conditions, decrease of the internal resistance and tolerance to real wastewaters. However, after some decades, the production of electricity yielded by individual MFCs is rather low and the key points to increase the productivity seem to be miniaturization of the MFC and then later stacking of individual mini‐cells and the development of very efficient electrogenic communities …”

Section: Introductionmentioning

confidence: 99%

Effect of sludge age on microbial consortia developed in MFCs

Mateo

Zamorano-López

Borrás

et al. 2017

J of Chemical Tech & Biotech

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BACKGROUND This work is focused on the assessment of the performance of mini‐scale air‐breathing microbial fuel cells (MFCs), by monitoring the evolution of the bio‐electrogenic activity for a period of 40 days and by comparing the microorganisms populations developed in each of the MFCs after this period. RESULTS Five MFCs were operated at sludge ages ranging from 1.4 to 10.0 days. Results showed the superb performance of the MFC operating under a sludge age of 2.5 days. Desulfuromonas, Syntrophothermus, Solitalea, Acholeplasma, Propionicimonas, Desulfobacula and Sphaerochaeta are proposed as potentially responsible for the bio‐electrogenic activity. CONCLUSIONS Microbial population analysis through Illumina amplicon sequencing demonstrated that despite all MFCs being seeded with the same mixed culture inoculum, the biological cultures developed in the suspension and the biofilm are completely different and depend strongly on sludge age. © 2017 Society of Chemical Industry

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Enhancement of high temperature PEMFC stability using catalysts based on Pt supported on SiC based materials

Cited by 46 publications

References 29 publications

Stability of Pt Nanoparticles on Alternative Carbon Supports for Oxygen Reduction Reaction

Stability of Pt Nanoparticles on Alternative Carbon Supports for Oxygen Reduction Reaction

Catalyst, Membrane, Free Electrolyte Challenges, and Pathways to Resolutions in High Temperature Polymer Electrolyte Membrane Fuel Cells

Effect of sludge age on microbial consortia developed in MFCs

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