A review on methanol crossover in direct methanol fuel cells: challenges and achievements

Ahmed, Mahmoud; Dinçer, İbrahim

doi:10.1002/er.1889

Cited by 234 publications

(136 citation statements)

References 135 publications

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“…Platinum nanoparticles used as catalysts also agglomerate during fuel cell use further reducing their activity [4]. In addition with DMFCs, methanol crossover from the 3 anode to the cathode due to unideal membrane materials causes a mixed potential and poisons the catalyst in the cathode with the intermediate product CO [5].…”

Section: Introductionmentioning

confidence: 99%

Highly efficient cathode catalyst layer based on nitrogen-doped carbon nanotubes for the alkaline direct methanol fuel cell

Kanninen

Borghei

Sorsa

et al. 2014

Applied Catalysis B: Environmental

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Section: Introductionmentioning

confidence: 99%

Highly efficient cathode catalyst layer based on nitrogen-doped carbon nanotubes for the alkaline direct methanol fuel cell

Kanninen

Borghei

Sorsa

et al. 2014

Applied Catalysis B: Environmental

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“…As methanol is a small, polar and neutral molecule, it can easily penetrate the ionexchange membrane along with water and protons [18] and it is transported to the cathode due to concentration and pressure gradients over the membrane and by the electro-osmotic drag induced by the proton flow in the acidic DMFC [19]. When methanol reaches the cathode, it is instantly oxidized in the high potential releasing electrons causing oxidative current and electrode depolarization, that is the cathode and thus the cell voltage is decreased.…”

Section: Methanol Crossover In Dmfcmentioning

confidence: 99%

“…The cathode catalyst can be modified so that it is not active for MOR or poisoned by CO, thus decreasing the cathode depolarization and increasing the ORR activity (like nitrogen-modified carbon materials (Publication III), Fe porphyrins [28] or transition metal sulfides [29]. A large effort has been directed in designing new membrane materials that would have high conductivity with good mechanical stability and selectivity toward water and protons [18]. The membrane material should also be available in dispersion form so that it can easily be used as the CL binder.…”

Section: Methanol Crossover In Dmfcmentioning

confidence: 99%

Silicon nanograss as micro fuel cell gas diffusion layer

et al. 2010

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Direct methanol fuel cells (DMFC) produce electrical energy directly from chemical energy. They are a promising candidate for power sources of portable devices due to the high energy density of methanol and the quick recharging procedure by fuel insertion. However, the problem areas of the DMFC are the slow electro-oxidation of methanol and the permeated methanol reacting at the cathode. New catalysts are constantly searched but they are often tested only for catalytic activity and the DMFC testing is omitted even though the catalyst layer (CL) structure has a large impact on the performance. Miniaturization of the system is also necessary for portable applications. Silicon etching can be used to fabricate small structures for fuel cells replacing or enhancing the functions of laboratory-scale components.In the first part of this thesis, new catalysts for the DMFC are studied with the emphasis on the CL structure. Different carbon supports for the anode were studied: standard carbon black and alternative few-walled carbon nanotubes (FWCNT) and graphitized carbon nanofiber (GNF). The alternative supports showed better DMFC performance but their stability was lower than with carbon black. However, the CL formed with GNF showed a very porous structure enhancing the mass transfer, so that higher binder content could be used improving the stability to the level of carbon black and the performance by 30%. The FWCNTs were also investigated as a platform for enzymatic methanol oxidation by studying the electrochemical properties of an immobilized cofactor pyrroloquinoline quinone (PQQ). A large amount of PQQ was adsorbed having a strong redox response and good stability in a wide pH window. For the cathode, a methanol-tolerant, Pt-free nitrogen-doped FWCNTs were tested in an alkaline DMFC as such testing is not often made. Its performance was remarkably 4 times better than with Pt when synthetic air was used as the oxidant.In the second part of thesis, an integrated gas diffusion layer (GDL) consisting of Si nanoneedles (nanograss) was tested in a micro fuel cell (MFC). The layer functioned properly at low current densities. For high power applications, a standard carbon cloth GDL was tested with the nanograss as a contact surface reducing the resistance between the GDL and the flow field. The use of the nanograss improved the MFC performance and stability. Finally, the MFCs were used as a catalyst testing platform and the results were compared with a similar test in a laboratory-scale DMFC. The results varied showing that the DMFC components also have a large impact on catalyst testing.Keywords direct methanol fuel cell, carbon nanomaterials, micro fuel cells, catalyst layer Tiivistelmä Suorametanolipolttokennot (SMPK) tuottavat sähköenergiaa suoraan kemiallisesta energiasta. Ne ovat lupaava vaihtoehto kannettavien laitteiden voimanlähteeksi, koska metanolilla on korkea energiatiheys ja lataaminen tapahtuu nopeasti polttoainelisäyksellä. SMPK:lla on kuitenkin rajoitteina metanolin hidas hapetusreaktio ja katodi...

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“…At present, the commercialization of DMFCs is hindered by several issues, including crossover of methanol from anode to cathode 3,4 , as well as the dependence on precious Pt catalyst for methanol oxidation and oxygen reduction reactions 5,6 . Methanol transported through the membrane will be electrochemically oxidized at the cathode, thus reducing the cathodic reactant.…”

mentioning

confidence: 99%

Emerging methanol-tolerant AlN nanowire oxygen reduction electrocatalyst for alkaline direct methanol fuel cell

Lei

Wang²,

et al. 2014

Sci Rep

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Replacing precious and nondurable Pt catalysts with cheap materials is a key issue for commercialization of fuel cells. In the case of oxygen reduction reaction (ORR) catalysts for direct methanol fuel cell (DMFC), the methanol tolerance is also an important concern. Here, we develop AlN nanowires with diameters of about 100-150 nm and the length up to 1 mm through crystal growth method. We find it is electrochemically stable in methanol-contained alkaline electrolyte. This novel material exhibits pronounced electrocatalytic activity with exchange current density of about 6.52 3 10 28 A/cm 2 . The single cell assembled with AlN nanowire cathodic electrode achieves a power density of 18.9 mW cm 22 . After being maintained at 100 mA cm 22 for 48 h, the AlN nanowire-based single cell keeps 92.1% of the initial performance, which is in comparison with 54.5% for that assembled with Pt/C cathode. This discovery reveals a new type of metal nitride ORR catalyst that can be cheaply produced from crystal growth method. D irect methanol fuel cell (DMFC) is one of the most attractive power sources for portable and vehicular applications due to the simplicity of the system and the adaptability of the liquid fuel 1,2 . At present, the commercialization of DMFCs is hindered by several issues, including crossover of methanol from anode to cathode 3,4 , as well as the dependence on precious Pt catalyst for methanol oxidation and oxygen reduction reactions 5,6 . Methanol transported through the membrane will be electrochemically oxidized at the cathode, thus reducing the cathodic reactant. And in intermediate reactions during this process, for instance the adsorption of carbon monoxide onto the catalyst surface, the cathode will also be poisoned, which further lowers its performance [7][8][9] . Thus, the methanol-tolerant oxygen reduction reaction (ORR) catalysts have attracted much attention in recent years. One of the effective approaches is the nanostructured Pt alloy since Pt is the most effective electrocatalyst for ORR reaction. Pt-Pd Alloy Nanoflowers 10 , Pt/CoSe 2 Nanobelt 11 , core-Shell Pt decorated PdCo 12 and numbers of Pt alloy nanoparticles [13][14][15][16] fall into this category. Although great advances have been achieved for the improvement of methanol tolerance, a high usage of Pt metal is still of great concern for further practical applications of DMFCs.In recent years, some promising non-precious catalysts have been developed towards oxygen reduction reaction, including Co or Fe-based macrocyclic compounds , and even nitrogen-doped graphene 21,22 . The transition metal nitride catalysts also displayed methanol-tolerance for ORR reactions. In comparison with a sharp ORR current decrease of ,80% for commercial Pt/C catalyst after the addition of a 3 M methanol at 90 s in the LSV test, it was reported that a sulfur-nitrogen Co-doped carbon foam catalyst has no noticeable decrease under the same test condition 23 . The similar behavior was also found for sulfur-nitrogen Co-doped graphene oxide 24 and Co-doping c...

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A review on methanol crossover in direct methanol fuel cells: challenges and achievements

Cited by 234 publications

References 135 publications

Highly efficient cathode catalyst layer based on nitrogen-doped carbon nanotubes for the alkaline direct methanol fuel cell

Highly efficient cathode catalyst layer based on nitrogen-doped carbon nanotubes for the alkaline direct methanol fuel cell

Silicon nanograss as micro fuel cell gas diffusion layer

Emerging methanol-tolerant AlN nanowire oxygen reduction electrocatalyst for alkaline direct methanol fuel cell

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