A Highly Order‐Structured Membrane Electrode Assembly with Vertically Aligned Carbon Nanotubes for Ultra‐Low Pt Loading PEM Fuel Cells

PEFC electrodes manufactured using inkjet printing are investigated. Cell performance, Tafel slope, reaction order and local oxygen transport resistance of electrodes with varying Pt loadings of 0.014 to 0.113 mg/cm 2 are studied in order to understand the nonlinear relationship between loading and performance. The performance increase with Pt loading was substantially reduced above Pt loadings of 0.08 mg/cm 2 . Electrochemical active area of the electrodes decreased from 66.4 to 40.4 m 2 /g as the Pt loading increased from 0.026 to 0.113 mg/cm 2 . Below the transition voltage of 0.8 V i R f ree , the Tafel slope was found to be a function of the Pt loading and oxygen partial pressure. The kinetic performance dependence on p O 2 was quantified by measuring the total reaction order. Oxygen transport resistance evaluated from limiting current experiments revealed its dependence on the inlet relative humidity of the reactants. The local oxygen transport resistance was found to drop from 5.93 ± 3.16 s/cm to 3.43 ± 1.67 s/cm as the humidity increased from 50% to 90%. Hydrogen polymer electrolyte fuel cells (PEFCs) are a zero emission and efficient energy conversion technology for transportation, stationary and electronic applications. The current generation of fuel cell vehicles provide quick start-up, long-range and increased durability. The high and unstable cost of platinum (Pt), which is the commonly used catalyst, however hinders its commercial prospects, especially when compared to the internal combustion engine. The cost of Pt is responsible for over 34% of the fuel cell stack cost.1 Less than 10-20% of the catalyst is however estimated to be utilized during the operation of a conventional catalyst layer (CL) due to mass and charge transport limitations.2 Re-designing the CL to improve these transport limitations has the potential to achieve better Pt utilization, i.e., generate more current per gram of catalyst. The CL fabrication process governs its utilization efficiency, microstructure and Pt loading in the electrodes.The effect of Pt loading on electrodes manufactured by spraying, using film applicators, sputtering as well as inkjet printing has been studied in the literature. [3][4][5][6][7][8][9][10][11][12][13][14][15] Results show that fuel cell performance is severely degraded at low Pt loading, 3,6,12,16 and that an optimal value of Pt loading exists above which the performance gains are not very significant. 4,12 The reason for the reduced performance of low loading electrodes has thus far mainly been attributed to a high oxygen mass transport resistance at the reaction site. 12,[17][18][19][20][21][22] The source of this resistance is still under debate. Oxygen dissolution in the ionomer, 23 densification of the ionomer layer near the ionomer/Pt interface, 24 and catalyst/oxygen interactions at the catalyst site 20 have been proposed as causes for this local mass transport barrier. These results indicate that in order to understand the performance degradation of low loading electrodes, and to comp...

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“…Refs. 5,7,8,11,12. Even for conventional electrodes, the oxygen reaction order has usually been reported only at open circuit voltage, e.g. Refs.…”

mentioning

confidence: 99%

Analysis of Inkjet Printed PEFC Electrodes with Varying Platinum Loading

Shukla

Stanier

Saha

et al. 2016

J. Electrochem. Soc.

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“…In addition, well-aligned carbon nanotubes (WACNTs) with highly ordered CNT structures are advantageous compared with randomly oriented CNTs because WACNTs can better improve the stability of catalyst, the catalytic activity and anti-electrochemical oxidation [14,15]. Tian et al prepared membrane electrode assembly (MEA) by using vertically aligned carbon nanotubes (VACNTs) as Pt support material, and the PEM fuel cell with the MEA showed an excellent performance with ultra-low Pt loading down to 35 lg cm À2 which was comparable to that of the commercial Pt catalyst on carbon powder with 400 lg cm À2 [16]. Although Pt/WACNTs display the promising electrode materials, these advantages have not been adequately validated.…”

Section: Introductionmentioning

confidence: 75%

Atomistic investigation on the diffusion mechanism of Pt nanoclusters on well-aligned multi-walled carbon nanotubes

Feng

2015

Computational Materials Science

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“…To overcome the above problems, new generation electrodes, namely ordered CLs have been proposed [107], developed, widely studied in the laboratory [108][109][110][111][112][113][114][115][116][117][118][119][120][121][122][123], and even commercialized [124,125]. In this section, the recent progress in the fabrication of CLs, the efforts to resolve and optimize the microstructure, and new trends in CL designs are reviewed.…”

Section: Catalyst Layermentioning

confidence: 99%

“…Ordered CLs can be broadly divided into three types: (1) ordered carbon phase, such as ordered carbon nanotubes [109,113,120,121], ordered carbon nanofibers [117,137], and ordered mesoporous carbon [112,116,119,122,123]; (2) ordered Nafion ® nanofibers [115,118]; (3) ordered Pt thin film [124,125] or network [110].…”

Section: Ordered Design Of Catalyst Layermentioning

confidence: 99%

Recent Progress on the Key Materials and Components for Proton Exchange Membrane Fuel Cells in Vehicle Applications

Wang

Peng

et al. 2016

Energies

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Fuel cells are the most clean and efficient power source for vehicles. In particular, proton exchange membrane fuel cells (PEMFCs) are the most promising candidate for automobile applications due to their rapid start-up and low-temperature operation. Through extensive global research efforts in the latest decade, the performance of PEMFCs, including energy efficiency, volumetric and mass power density, and low temperature startup ability, have achieved significant breakthroughs. In 2014, fuel cell powered vehicles were introduced into the market by several prominent vehicle companies. However, the low durability and high cost of PEMFC systems are still the main obstacles for large-scale industrialization of this technology. The key materials and components used in PEMFCs greatly affect their durability and cost. In this review, the technical progress of key materials and components for PEMFCs has been summarized and critically discussed, including topics such as the membrane, catalyst layer, gas diffusion layer, and bipolar plate. The development of high-durability processing technologies is also introduced. Finally, this review is concluded with personal perspectives on the future research directions of this area.

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A Highly Order‐Structured Membrane Electrode Assembly with Vertically Aligned Carbon Nanotubes for Ultra‐Low Pt Loading PEM Fuel Cells

Cited by 175 publications

References 38 publications

Analysis of Inkjet Printed PEFC Electrodes with Varying Platinum Loading

Analysis of Inkjet Printed PEFC Electrodes with Varying Platinum Loading

Atomistic investigation on the diffusion mechanism of Pt nanoclusters on well-aligned multi-walled carbon nanotubes

Recent Progress on the Key Materials and Components for Proton Exchange Membrane Fuel Cells in Vehicle Applications

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