In-Plane Channel-Structured Catalyst Layer for Polymer Electrolyte

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In-plane Channel-structured Catalyst Layer for Polymer Electrolyte Membrane Fuel Cells Dong-Hyun Lee, Wonhee Jo, Seongmin Yuk, Jaeho Choi, Sungyu Choi, Gisu Doo, Dong Wook Lee, and Hee-Tak Kim ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.7b16433 • Publication Date (Web): 17 Jan 2018 Downloaded from http://pubs.acs.org on January 21, 2018

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ACS Applied Materials & Interfaces

In-plane Channel-structured Catalyst Layer for Polymer Electrolyte Membrane Fuel Cells Dong-Hyun Lee†, Wonhee Jo†, Seongmin Yuk†, Jaeho Choi†, Sungyu Choi†, Gisu Doo†, Dong Wook Lee† and Hee-Tak Kim *, †, §

†

Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of

Science and Technology (KAIST), Daejeon 34141, Republic of Korea §

Advanced Battery Center, KAIST Institute for the NanoCentury, Korea Advanced Institute

of Science and Technology (KAIST), 335 Gwahangno, Yuseong-gu, Daejeon 34141, Republic of Korea Corresponding Author * E-mail: (H.-T. Kim) [email protected] Author contribution

The manuscript was written through contributions of all authors. All authors have given approval to the final version of the manuscript.

Keywords:

Polymer electrolyte membrane fuel cell, catalyst layer, in-plane channel,

surface pattern, mass transport

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ABSTRACT: In this study, we present a novel catalyst layer (CL) with in-plane flow channels to enhance the mass transports in polymer electrolyte membrane fuel cells (PEMFCs). The CL with in-plane channels on its surface is fabricated by coating a CL slurry onto a surface-treated substrate with the inverse line pattern and transferring the dried CL from the substrate to a membrane. The membrane electrode assembly (MEA) with the inplane channel-patterned CL (IC-CL) has superior power performances in high current densities compared with an un-patterned, flat CL (FCL), demonstrating a significant enhancement of the mass transport property by the in-plane channels carved in the CL. The performance gain is more pronounced when the channel direction is perpendicular to the flow field direction, indicating that the in-plane channels increase the utilization of the CL under the rib area. An oxygen transport resistance analysis shows that both molecular and Knudsen diffusion can be facilitated with the introduction of the in-plane channels. The direct CL patterning technique provides a platform for the fabrication of advanced CL structures with a high structural fidelity and design flexibility and a rational guideline for designing high performance CLs.


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1. Introduction Fuel cells have been regarded as a promising candidate for an environment-friendly power generation system. Among the various fuel cell systems, a polymer electrolyte membrane fuel cell (PEMFC) has several advantages such as a moderate operation temperature, high power density and high mechanical robustness due to the use of a flexible polymer electrolyte membrane.

1-4

For those reasons, PEMFCs have been intensively studied

for decades and are commercialized for stationary and automotive applications.

5-7

A current

issue in relation to the application of PEMFCs is to reduce the amounts of expensive catalysts required without performance losses. However, reducing the Pt loading in a MEA is generally accompanied by a considerable loss in power performance of the MEA due to increased kinetic and mass transport polarizations. advanced catalysts with a higher activity

11-15

8-10

Therefore, the development of

and advanced catalyst layer (CL) structures

with enhanced mass transport properties is highly important in achieving low-Pt loaded CLs. 16-19

Mass transport in a PEMFC system is a complex process in which two phases are transported through pores on various scales. Gas transport in CL, Knudsen diffusion through the meso/macro pores of a CL and film diffusion through a thin ionomer film covered with Pt particles have been of great interest for low Pt-loaded MEAs; however, the mass transport of the CL is also affected by the flow field and gas diffusion layer (GDL). It is typically exampled by channel/rib effect, which is one of the deep-routed problems of PEMFCs. Under the rib area of the flow plate, the GDL is compressed due to contact pressure. Mass transport in such a case is difficult and the underlying CL area is inhibited.

20-24

Recently, Yoshida et

al. reported a 3-D fine mesh flow field which alleviated the channel/rib effect due to a minimized flow field/GDL contact area.

25

However, even for a mesh type flow field, GDL



compression cannot be completely avoided because an electrical contact between the flow filed and GDL is indispensable. In this work, we present an in-plane channel-structured, patterned CL (PCL) to improve the power performance of a low Pt-loaded MEA. The key feature of the CL is that in-plane channels are carved into the CL improving the utilization of the portion of the CL under the compressed GDL. A line pattern was directly formed in the CL by spraying a CL slurry onto an-inverse-patterned mold and transferring the CL to a membrane. Figure 1 illustrates the structural features of the CL developed in this work. The in-plane channels in the CL provide an efficient in-plane mass transport between the CL segments under the compressed and uncompressed GDL. Previously, there were a few attempts to fabricate a patterned CL structure by forming a patterned membrane surface and subsequent CL coating on the membrane surface

26-31

However, the patterned CL structure derived from the

patterned membrane does not have a high structural fidelity due to the structural changes of the membrane that change during the CL coating and drying process. Compared with the previous CL patterning techniques, the current fabrication method can have a higher structural fidelity due to the use of a dimensionally stable substrate for the CL patterning. We demonstrate that the in-plane channel-structured CL can significantly improve the power performance of a low Pt-loaded MEA as a result of the enhanced gas and water transport, and the direct CL patterning strategy can be a versatile platform for advanced fuel cell development.


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Figure 1. Schematic illustration of the in-plane channel structured CL and the in-plane mass transport through the in-plane channels

2. Results and Discussion How to fabricate an in-plane channel-structured PCL with a high structural fidelity is a major challenge. Because of the high fragility of the porous CL, it is difficult to carve a pattern in the CL without causing any structural damages. To address this problem, a novel fabrication strategy based on the coating the CL onto a patterned substrate and the decal transfer of the PCL to a membrane was developed as illustrated in Figure 2a. A patterned poly(urethane acrylate) (PUA) substrate was produced from a silicon master mold by the nanoimprint technique.

32, 33

The uniformity of the patterned PUA thickness determines the

quality of the resulting CL; a variation in the thickness leads to a larger pressure on a thicker portion during the decal transfer resulting in a localized collapse of the CL. To obtain a high thickness uniformity of the PUA substrate, the spin coating process was used. Figure 2b and c show that the fabricated PUA substrate has a well-defined channel structure and highly uniform in thickness. In addition, a pressure distribution layer (fluorinated ethylene polymer (FEP) film)

was inserted during the decal transfer process to alleviate the pressure



distribution. Another important step for high-quality CL patterning is the surface treatment of the PUA substrate.

Figure 2. Fabrication of the in-plane channel-structured PCL. (a) Fabrication process, (b) surface and (c) cross-sectional SEM images of the patterned PUA substrate, (d) decal-transfer results for the non-treated and hydrophobic-treated patterned PUA substrates, (e) digital image of the PCL, (f) surface SEM image of the PCL, (g) surface and (h) cross-sectional SEM image of the pattern of the PCL, and (i) cross-sectional SEM image of the CCM with the PCL

This step enables the proper wetting of the CL ink and easy detachment of the dried CL from the PUA substrate. For the surface modification, hydroxyl surface functional groups were first formed on the patterned PUA by oxygen plasma treatment, and then, a C8H4F13SICl3


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which form a chemical bond with a hydroxyl group, was deposited with the chemical vapor deposition method. After the surface treatment, the water contact angle was changed from 87o to 98o shown in Figure S1 confirming the surface modification. The typical effect of the surface modification is shown in Figure 2d; the CL coated onto the hydrophobic-treated PUA substrate was perfectly transferred to the membrane, which is in contrast with the partial CL transfer for the untreated PUA substrate. The transferred PCL of the catalyst coated membrane (CCM) showed a vivid prism on its surface (Figure 2e) indicating the formation of a regular pattern. The structures of the PCL and the resulting CCM were investigated with scanning electron microscopy (SEM). As shown in Figure 2f, highly ordered, regularly arranged in-plane channels were successfully formed in the PCL. The surface of the PCL was highly porous as observed for conventional CLs (Figure 2g). No local densification or local deterioration was observed for the PCL after the decal transfer. For the PCL, the channel depth, width, and spacing were 1.8, 1.5, and 2.6 µm according to the SEM image (Figure 2h). These values are close to those of the silicon master pattern (depth: 1.8 µm; width: 1.5 µm; spacing: 2.7 µm), indicating the high structural fidelity for the CL patterning method, which is not achievable with the previous fabrication strategies. The cross-sectional SEM image of the CCM (Figure 2i) shows that the PCL is highly uniform in thickness (3.0±0.4 µm), and it forms a tight interfacial bond with the membrane. For comparison, an un-patterned, flat CL (FCL) with the same Pt loading was prepared. The SEM images of the FCL and the corresponding CCM are shown in Figure S2. The thickness of the FCL was 2.4±0.2 µm. The effect of the in-plane channels in the CL on the power performance is a major interest of this work. To demonstrate the effect, the direction of the in-plane channel was arranged to be perpendicular or parallel to the direction of the single serpentine flow field;



which are denoted as PE-PCL and PA-PCL, respectively (Figure 3a). FCL may have a channel/rib effect due to the localized compression of the GDL under the rid area. In the case of the PA-PCL, the in-plane channels in the PCL do not cross the rib area. Therefore, inplane mass transport through the channels between the CL segments under the channel and rib area is not allowed; however, the patterned structure can influence the mass transport of the CL in the thickness direction, which is denoted as the ‘through-plane effect’. On the other hand, the PE-PCL configuration provides in-plane channels which cross the rib and channel


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area, thus leading to in-plane mass transport between the CL segments under the rib and channel area, denoted as the ‘in-plane effect’. Figure 3. (a) Three different cell configurations: FCL, PA-PCL (Channel direction in PCL and flow field direction are parallel with each other), and PE-PCL (Channel direction in PCL and flow field direction are perpendicular with each other). iV polarization curves and power density curves for FCL, PA-PCL, and PE-PCL at (b) 50% and (c) 100 % RH (Error bar indicates a voltage fluctuation during galvanostatic measurements at each current density). Oxygen gains measured at (d) 50% and (e) 100% RH.

The proton conduction and catalytic activity of the CL were carefully controlled so as to not interfere with the mass transport effect. The proton conduction resistance of the CL



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(RCL) and the ohmic resistance (Rohm) were measured from the AC impedances at an open circuit voltage (OCV) under a H2/N2 (anode/cathode) environment.

34

Rohm, the major

contributions of which are membrane resistance and interfacial resistances, was determined from the intercept of the high frequency impedances on the x-axis in the Nyquist plot. As shown in Figure S3a, the intercepts for the three cells were nearly identical because of the use of the same membrane and membrane/CL interface structure. RCL corresponds to three times of the distance between the high frequency intercept and the intercept of the asymptotic line extending from the slightly sloping low frequency impedances on the x-axis. 34, 35 The values for RCL were close with each other (0.0147 for FCL, 0.0190 for PA-PCL, and 0.0166 Ωcmଶ for PE-PCL) and quite smaller than those for Rohm (0.0563 for FCL, 0.0535 for PA-PCL, and 0.0551 Ωcmଶ for PE-PCL) because of the thin CL thicknesses. Therefore, proton transport in the CL does not influence the difference in the power performance capabilities among the three cells. The electrochemical surface area (ECSA) of the CL was measured with the cyclic voltammetry (CV) technique.

35

From the amount of charge for the electro-adsorption of

hydrogen on the Pt surface, the values for ESCA were quantified. As shown in Figure S3b, the CV curves of FCL, PA-PCL, and PE-PCL were nearly the same indicating similar ECSA values for the CLs (54.8 for FCL, 55.1 for PA-PCL, and 58.7 m2 g-1 for PE-PCL). These electrochemical analyses confirm that the CLs compared in this work have similar proton conduction properties and catalytic activities. Also, pore size distribution was measured for FCL and PCL by using mercury porosimetry test. As shown in Figure S4, the micro and meso-pore structures are nearly identical for the two CLs because of the use of same CL slurry and drying condition. The only difference is the appearance of micron sized pores for PCL due to the in-plane channels. Therefore, all CLs were appropriately designed to investigate the effect of the in-plane channels on the mass transport properties.


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Figures 3b and c show the i-V polarization curves for the FCL, PA-PCL, and PEPCL at 50 and 100% relative humidity (RH), respectively. The polarizations were measured at a stoichiometry of 1.5/1.5 for a H2/Air feed and at an absolute pressure of 180 kPa. The purpose of the comparison of the two RH conditions was to understand how the in-plane channels in the CL affect the water flooding behavior. The relatively low air stoichiometry of 1.5 was chosen to amplify the mass transport resistance for a clearer detection of the in-plane channel effect. Overall, the power performances were indifferent in the low current density regime but were largely varied in the high current density regime depending on the CL structure and cell configuration. In detail, at 50% RH, the iV curves of the three cells overlap with each other below 0.6 A cm-2, which indicates that the kinetic polarization and ohmic polarization of the cells were nearly identical as expected from the impedance and CV analyses. Above 0.6 A cm-2, the PE-PCL exhibited higher power performances than that of the FCL and PA-PCL, which is indicative of a smaller mass transport polarization. However, the PA-PCL did not show a considerable improvement compared with the FCL. Therefore, at 50% RH, the in-plane effective was clearly observed, but the through-plane effect was not apparent. At 100% RH, the in-plane channel effect was more pronounced. Below 0.2 A cm-2, the iV polarizations were identical as observed for the 50% RH results. Above 0.2 A cm-2, the PE-PCL and PA-PCL showed higher power performances than that of the FCL demonstrating that both the in-plane and through-plane effect exist at the high RH operation. The error bars in the iV polarization curves indicate the degree of voltage fluctuation during the galvanostatic measurement at each current density. The voltage fluctuation reflects the dynamic process of liquid water accumulation and removal and thus, it is an indicator of water flooding. The voltage fluctuation during the measurement time scale is illustrated in Figure S5. The polarization curves at 100% RH showed larger error bars than those at 50% RH indicating more significant water flooding at the higher RH condition. Fig. 3b and c show



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that at a fixed current density, the voltage fluctuation was reduced on the order of FCL > PAPCL > PE-PCL indicating that the in-plane channel can effectively mitigate water flooding. The comparison between the FCL and PA-PCL illustrates the through-plane effect. At 100% RH, it is clear that mass transport can be facilitated by the through-plane effect. In contrast, at 50% RH, the through-plane effect was not apparent. These results suggest that water removal from the CL can be facilitated by the channeled structure. Due to the expanded outer surface area of the PCL, water evaporation from the CL to the bulk gas phase can be promoted. The in-plane effect is demonstrated by the comparison between the PA-PCL and PE-PCL. Regardless of the RH conditions, the PE-PCL exhibited higher power performances than that of the PA-PCL, which verifies the presence of the in-plane effect. The large difference in cell voltages at 50% RH indicates that gas transport from the channel area to the rib area can lead to a higher utilization of the CL segments under the rib area at the high current densities. At 100% RH, the in-plane effect was more pronounced; the power performance enhancement and the reduction of the error bar size with the perpendicular configuration became more significant at the higher RH. It means that the in-plane channels crossing the channel and rib area can improve both the overall gas and water transports. Further confirmation of the in-plane and through-plane effects came in the form of an oxygen gain, which is indicative of mass transport polarization.

36

Figure 3d and e compare

the oxygen gains for the FCL, PA-PCL, and PE-PCL at 50% and 100% RH, respectively. The oxygen gain was exponentially increased with the current density due to an increased mass


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Figure 4. (a) Total O2 transport resistances, (b) molecular diffusion resistances, and (c) sum of Knudsen and film diffusion resistances for the FCL, PA-PCL, and PE-PCL at various temperatures

transport polarization. At 50% RH, the oxygen gains of the PE-PCL were higher than those of the PCL and PA-PCL in all the current densities investigated. In addition, the FCL and PA-PCL did not show any difference in oxygen gains. On the other hand, at 100% RH, the oxygen gains decreased in this order: FCL > PA-PCL > PE-PCL. These results again verify



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that the in-plane effect contributes to both the gas and water transport, and the through-plane effect contributes to mainly water transport, which are in good agreement with the iV polarization analysis results. After the iV polarization measurements, the cells were disassembled, and the structures of the PCLs were investigated with SEM to ensure the preservation of the in-plane channel structure under the cell compression. The cross-sectional SEM image of the PCL after the cell operation (Figure S6) shows that the in-plane channel structures were preserved. To understand the mechanism of the observed in-plane and though-plane effects of the channeled CL structure, gas transport resistances of each CL were analyzed with the limiting current method. Total gas transport resistance (‫்ݎ‬௢௧௔௟ ) of the MEA generally includes three additive contributions: the molecular diffusion resistance (‫ݎ‬ெ஽ ) from the O2 transport through the macropores in GDL; the Knudsen diffusion resistance (‫ݎ‬௄஽ ) from the O2 transport through the mesopores in microporous layer of the GDL and CL, and the film diffusion resistance (‫ݎ‬௙௜௟௠ ) from the O2 transport through the ionomer thin film covering the catalyst surfaces. The ‫ݎ‬ெ஽ and the sum of ‫ݎ‬௄஽ and ‫ݎ‬௙௜௟௠ (‫ݎ‬௢௧௛௘௥௦ ) can be quantified with a limiting current method with two diluted O2 feeds with a N2 and He balance gas.

37-39

Because the

microstructures of the FCL and PCL were quite similar as indicated by the impedance and CV analysis, it can be assumed that ‫ݎ‬௙௜௟௠ is identical for the CLs, and any difference in

r୭୲୦ୣ୰ୱ is attributed to the difference in ‫ݎ‬௄஽ . Figure 4a, b, and c compare the ‫ݎ‬௧௢௧௔௟ , ‫ݎ‬ெ஽ , and ‫ݎ‬௢௧௛௘௥௦ ( ‫ݎ‬௄஽ + ‫ݎ‬௙௜௟௠ ), respectively. To increase the reliability of the analysis, these resistances were measured at various temperatures. The value for ‫ݎ‬௧௢௧௔௟ was decreased in the following order: FCL > PAPCL > PE-PCL (Figure 4a), which was consistent with the iV polarization and O2 gain analysis results. Of interest, the comparison of ‫ݎ‬ெ஽ (Figure 4b) shows that the PE-PCL was


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considerably smaller than the FCL and PA-PCL. It indicates that the depressed molecular diffusion due to the compressed GDL can be restored by providing the in-plane gas transport channel. Because molecular diffusion to the CL segments under the compressed GDL cannot be enhanced for the PA-PCL, the indifference in the ‫ݎ‬ெ஽ between the FCL and PA-PCL was resulted in. On the other hand, for the PA-PCL and PE-PCL, the ‫ݎ‬௢௧௛௘௥௦ values were quite similar with each other and considerably smaller than those of the FCL. It can be understood as such that the in-plane channel structured CL permits the Knudsen diffusion from not only the top surfaces but also the side walls of the patterned CL. Due to the expanded diffusion surface, the effective diffusion distance through the CL can be shortened for the PCL structures irrespective of the orientation. Therefore, the observed mass transport enhancement by the in-plane channel structure is two-fold: both molecular diffusion and Knudsen diffusion are accelerated. The double effects provide a guide for the design of low Pt loaded fuel cells. The expanded outer surface of the CL and the in-plane channel connecting the compressed and uncompressed areas independently and additively improve the mass transport properties. Based on this understanding, novel high-performance CL structures could be designed in a more rational manner.

3. Conclusion In summary, we developed a direct CL patterning method and invented an in-plane channel structured CL. By using the surface treatment of the patterned substrate for the CL coating, a patterned CL with a high structural fidelity was fabricated. The comparison among the flat CL and the two patterned CLs with different in-plane channel directions with respect to the flow field direction shows that the in-plane channel in the CL, which connects the portion of the CL under the flow channel and that under the rib, can provide facile gas and



water transport to the CL under the rib. The oxygen transport resistance analysis indicates that the in-plane channels enhance both molecular and Knudsen diffusion in the CL. These results demonstrate that the direct CL patterning strategy can be an effective platform for achieving advanced CL structures with a high structural fidelity.

4. Experimental methods Preparation of the patterned substrate. A patterned PUA substrate was fabricated by spincoating a curable PUA solution (MINS-311RM) on a PET film (SKC KOREA) at 1000 rpm for 1 min. and putting a patterned PDMS master mold on the PUA cast followed by a UV curing for 10 min. After removing the PDMS mold from the patterned PUA layer on the PET film, the PUA surface was subjected to O2 plasma treatment (MyPL-150, APPLASMA) and a subsequent chemical vapor deposition of a hydrophobic chemical (C8H4F13SICl3, SIT8174.0, Gelest Inc.) under vacuum at room temperature for 3 min. Fabrication of the patterned CL and MEA. Cathode CLs were formed on the patterned and surface-treated PUA substrate mounted on a hot plate (150oC) by spraying a CL ink comprised of a Pt/C catalyst (46.9 wt% Pt, Tanaka Kikinzoku Kogyo) and Nafion solution (D520™, Dupont) with a solid content of 3 wt%. The cathode CL ink was homogenously dispersed by tip sonication for 2 h before use. The ionomer/carbon ratio (I/C ratio) of the ink was set to 1.0. After the CL coating, the CL on the PUA substrate was annealed at 130oC for 4 h to remove the residual solvents. An anode CL was formed on a FEP film by casting the same CL slurry mixed with a ball milling process and dried at 60 oC in an oven for 12 h. CCM was fabricated with a decal-transfer method. The stack of the cathode CL on the PUA substrate, a Nafion 211 membrane (25μm thickness, Dupont™), and the anode CL on the


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polyimide substrate was pressed at 130oC at 25 atm for 10 min., and the PUA and polyimide substrates were removed from the laminate. The active area of the CCM was 12.25 cm2 Field emission-scanning electron microscopy (FE-SEM, Sirion, FEI) was used to characterize the structures of the patterned substrates and patterned CLs. The pore size distributions of FCL and PCL were measured by using mercury porosimeter (MicroActive AutoPore V9600). The Pt loading of the CLs was 0.166 ± 0.004 mgPt cm-2. A single cell was assembled with the CCM, a pair of GDLs (JNT20-A3, JNTG), a pair of hard gaskets, a pair of graphite blocks with a single serpentine flow field, and a pair of end plates with 8 screws. The single cells were clamped to 75 kgf cm-1 torque pressure. Single cell operation. The break-in and iV polarization test were performed with a fuel cell test station (Scitech Korea). Break-in was conducted by injecting a constant flow of H2/O2 (300/1000sccm) to the cell and sweeping the cell voltage between 0.07 and 1.2 V at 50 mV s1

10 times. The iV polarization curve was measured at 80oC with an absolute pressure of 180

kPa and at a relative humidity of 50% and 100%. The stoichiometry of the feed gases was 1.5 for both H2 and air. For the current densities below 400 mA cm-2, constant H2 (57 sccm) and air (137 sccm) flow rates, which are equivalent to a stoichiometry of 1.5 at 400 mA cm-2, were used. The iV polarization curves were obtained by stepping up the current density at an increment of 10mA cm-2 which enabled the cell to stabilize at which time the cell voltage was measured. For the stabilization, two minutes were spent at each current density below 0.1A cm-2 and three minutes above 0.1 A cm-2. Electrochemical analysis. Electrochemical characterization was conducted with a potentiostat (HCP-803, BioLogics Science Instrument). To quantify the proton transport resistance of the CL, electrochemical impedance spectroscopy (EIS) was measured at OCV with a H2/N2 (counter/working, 500/1500 sccm) feed. Electro chemical surface area (ECSA)



was calculated from a cyclic voltammetry (CV) measurement for the single cells under a H2 (anode, 100 sccm) / N2 (cathode, 0 sccm) atmosphere. The oxygen transport resistances of the CLs were obtained with a limiting current method; linear sweep voltammetry was measured for the single cells from OCV to 0.15 V at a scan rate of 5 mV s-1 at various temperatures (50, 60, 70 and 80 oC) and at a relative humidity of 90 %, with injecting excess amounts of hydrogen (500 sccm) and diluted oxygen (1% oxygen in nitrogen or helium, 650 sccm) at an absolute pressure of 150 kPa to the anode and cathode, respectively.

ASSOCIATED CONTENT Supporting Information The Supporting Information is available free of charge on the ACS Publications website at DOI: Water contact angle of patterned substrate; Cross-section SEM images of the FCL and after cell operation PCL; Electrochemical analysis results

AUTHOR INFORMATION * E-mail: (H.-T. Kim) [email protected] * Group website: eed.kaist.ac.kr Notes The authors declare no competing financial interest. ACKNOWLEDGMENT


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This work was supported by the Korea Institute of Energy Technology Evaluation and Planning(KETEP) and the Ministry of Trade, Industry & Energy(MOTIE) of the Republic of Korea (No.20173010032100)



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