A Highly-Durable CO-Tolerant Poly(vinylphosphonic acid)-Coated

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A Highly-Durable CO-tolerant Poly(vinylphosphonic acid)coated Electrocatalyst Supported on a Nanoporous Carbon Zehui Yang, Isamu Moriguchi, and Naotoshi Nakashima ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.5b06826 • Publication Date (Web): 25 Jan 2016 Downloaded from http://pubs.acs.org on February 1, 2016

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ACS Applied Materials & Interfaces

A Highly-Durable CO-tolerant Poly(vinylphosphonic acid)-coated Electrocatalyst Supported on a Nanoporous Carbon Zehui Yanga, Isamu Moriguchib and Naotoshi Nakashima*a,c,d a

Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744

Motooka, Nishi-ku, Fukuoka 819-0395, Japan b

Division of Chemistry and Materials Science, Graduate School of Engineering, Nagasaki

University, 1-14 Bunkyo-Machi, Nagasaki 852-8521, Japan c

International Institute for Carbon Neutral Energy Research (WPI-I2CNER), Kyushu University,

Fukuoka 819-0395, Japan d

Japan Science and Technology Agency (JST), Core Research for Evolutionary Science and

Technology (CREST), 5 Sanbancho, Chiyoda-ku, Tokyo, 102-0075, Japan KEYWORDS: Direct methanol fuel cells, Durability, CO poisoning, Nanoporous carbon, Poly(vinylphosphonic acid).

1 Environment ACS Paragon Plus


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ABSTRACT

To commercialize the direct methanol fuel cells (DMFCs), the durability of the anodic electrocatalyst needs to be highly considered, especially under high temperature and methanol concentration conditions. The low durability caused by the carbon corrosion as well as the carbon monoxide (CO) poisoning of the platinum nanoparticles (Pt-NP) leading to the decrease of the active Pt-NPs and increase in the inactive Pt-NPs covered by CO species. In this study, we deposited nanoporous

Pt-NPs carbon

poly(vinylphosphonic

on

poly[2,2’-(2,6-pyridine)-5,5’-bibenzimidazole]

(NanoPC)

and

coated

acid)

(PVPA).

The

the

as-synthesized durability

of

(PyPBI)-wrapped

electrocatalyst the

with

as-synthesized

NanoPC/PyPBI/Pt/PVPA was tested in 0.1M HClO4 electrolyte at 60 oC by cycling the potential from 1.0 to 1.5 V vs. RHE, and the results indicated that the NanoPC/PyPBI/Pt/PVPA showed an ~5 times better durability by comparison with that the commercial CB/Pt. The methanol oxidation reaction (MOR) of the electrocatalyst was tested before and after the potential cycling in the presence of 4M or 8M methanol at 60 oC and found that the CO-tolerance of the electrocatalyst was ~3 times higher than that of the commercial CB/Pt. Such a higher CO tolerance is due to the coating of the PVPA, which was proved by an EDX mapping measurement. The NanoPC/PyPBI/Pt/PVPA showed a high durability and CO tolerance under high temperature and high methanol concentration conditions indicating that the electrocatalyst would be used in real fuel applications.


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INTRODUCTION Energy consumption that has relied on the combustion of the fossil fuels is forecast to have a serious impact on the world’s future economics and ecology. Electrochemical energy productions are considered as an alternative energy sources because those energy consumptions are recognized to be more environmentally friendly and sustainable. Batteries (lead-acid battery, lithium battery), fuel cells (PEFCs, SOFC, PAFC, AFC), and electrochemical capacitors (ECs) are the hot systems for the electrochemical energy productions.

1

The fuel cells, especially the

direct methanol fuel cells (DMFCs), have received a lot of attention due to the higher energy density (5.04 KWh/L), easy storage and transportation compared with the hydrogen fuel cells (0.53 KWh/L). 2-9 Also the direct conversion of methanol has a voltage similar (2CH3OH+3O2→ 2CO2+4H2O+6e-, E=1.19 V) to that of hydrogen (E=1.23 V). However, the DMFCs still suffer from three problems on the anode side; namely, i) the carbon monoxide (CO) poisoning of the platinum nanoparticles (Pt-NPs), which is generated from the uncompleted methanol oxidation reaction (MOR),

10-15

ii) the sluggish methanol oxidation reaction (MOR) compared to the

hydrogen oxidation reaction (HOR) 16-18 and iii) the low durability of the electrocatalyst in terms of Pt stability and carbon corrosion, which degrades the fuel cell performance. 19-20 Recent studies have indicated that alloying transition metals (e.g., Ru) with Pt is an effective way to eliminate the CO-poisoning, because the generated CO and CO-like species from the uncompleted oxidation of methanol were reacted with the OH group formed via the reaction between Ru and H2O which has a lower reaction potential than that of the Pt. 21-27 However, the Ru-Pt alloyed electrocatalyst is limited in real DMFC applications since the Ru metal will dissolve rapidly by potential cycling in the acidic medium and migrate from the anode to the



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cathode through the membrane during the real DMFC operation, resulting in severe degradation in fuel cell performance and shortened lifetime of the DMFC.

28

Thus, it is of importance to

develop and design a new method to address the CO poisoning problem in the DMFCs. Recently, we reported that poly(vinylphosphonic acid) (PVPA) plays an important role in enhanced CO tolerance of the electrocatalyst due to the acceleration of the reaction between Pt and H2O to form the Pt(OH)ads that consumes the CO poisoned Pt, namely, Pt(CO)ads.

29

We

have proved that the amount of the PVPA is also important in further CO tolerance enhancement. 30-31

Moreover, the durability was improved because of the polymer wrapping which decelerated

the carbon corrosion process of the electrocatalyst and stabilized the Pt-NPs. Both the durability and CO tolerance in previous reports were measured at room temperature, which is different from the real operating conditions of the DMFCs. Thus, the study at higher temperatures that satisfied actual DMFC conditions from industry is needed. In this study, we describe the methanol oxidation reaction (MOR) and durability of an electrocatalyst composed of poly[2,2’-(2,6-pyridine)-5,5’-bibenzimidazole] (PyPBI)-wrapped nanoporous carbon (NanoPC), PVPA (denoted as NanoPC/PyPBI/Pt/PVPA, the preparation of the electrocatalyst is shown in Figure 1) evaluated at high temperature (60 oC) under high methanol concentrations (4M and 8M), which are similar to practical operations of the DMFCs.

Figure 1. Schematic illustration of the preparation procedure of the NanoPC/PyPBI/Pt/PVPA.


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EXPERIMENTAL SECTION Materials: Used materials are described in the Supporting Information (see also refs. #29-31). NanoPC was synthesized based on a previous report. 32 The synthetic procedure of the poly[2,2’(2,6-pyridine)-5,5’-bibenzimidazole] (PyPBI) was reported by Xiao et al and Li et al. NanoPC/PyPBI/Pt was synthesized according to our previous report.

35

33-34

The

The PVPA coating

process was described in the previous report. 31 Milli-Q water was used for the preparation of all the aqueous solutions and further purification is not needed for all the received chemicals. Characterization: Detailed procedures using X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), TEM micrographs, X-ray diffraction (XRD), scanning transmission electron microscopy (STEM) and STEM-energy dispersive X-ray (EDX) are described in Supporting Information (see also refs. #29-31). The electrochemical measurements (cyclic voltammetry, methanol oxidation reaction and CO stripping), the fabrication of the membrane electrode assembly (MEA) and the fuel cell performance testing were reported previously. 31, 36 Durability test: The experimental setup of this study is shown in Figure S1. The temperature of the vessel measured by a thermometer was ~57 ˚C. The serious durability test was measured using the protocol from the Fuel Cell Commercialization Conference of Japan (FCCJ), which was tested in N2-saturated 0.1M HClO4 at 60 oC without any rotation). The potential was held at 1.0 V vs. RHE for 30 s, and then increased to 1.5 V vs. RHE with a scan rate of 0.5 V/s followed by a potential-decrease to 1 V vs. RHE. This process was cycled, and after every 1,000 potential cycles, cyclic voltammetry (CV) was measured three times to evaluate the average ECSA value (see Supporting information, Figure S2).



RESULTS AND DISCUSSION (b)

Intensity

Intensity

(a)

410

405 400 395 Binding Energy / eV

390

140

135 130 Binding Energy / eV

125


65

(d)

Intensity

(c)

Intensity

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85


65

85

Figure 2. XPS narrow scan in the regions of the N1s (a) and P2p (b), Pt4f for the NanoPC/PyPBI/Pt/PVPA (c) and CB/Pt (d) and their deconvolution curves. The XPS measurement of the electrocatalyst is shown in Figure 2 and the commercial CB/Pt was used as a control electrocatalyst (for the survey scan, see the Supporting Information, Figure S3). From Figure 2a, a clear peak was observed at ~400 eV due to the N1s from the PyPBI. 37-40 Meanwhile, a sharp peak appeared at 133 eV, as shown in Figure 2b, coming from the P2p on the PVPA indicating the successful coating of the PVPA.

41-42

Also, two obvious peaks at 71.4 and

75.0 eV appeared that were attributed to the 4f7/2 and 4f5/2 of the metal Pt, respectively.

17, 43

In

addition, the Pt4f peak of the NanoPC/PyPBI/Pt/PVPA (Figure 2c) showed that the composition 6 Environment ACS Paragon Plus

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ratio of the Pt(0), Pt(II) and Pt(IV) was 65:17:18 which was similar to that of the commercial CB/Pt (57:19:24) as shown in Figure 2d.

Figure 3. (a) TGA curve of the NanoPC/PyPBI/Pt (blue line) and NanoPC/PyPBI/Pt/PVPA (red line) measured under flowing air (100 mL/min) at the heating rate of 5 oC/min. (b) TEM image of the NanoPC/PyPBI/Pt/PVPA and the particle size distribution histogram of 100 particles (inset). The amount of the PVPA was evaluated from the TGA analysis as shown in Figure 3a, in which the Pt amounts of the NanoPC/PyPBI/Pt and NanoPC/PyPBI/Pt/PVPA were 49.9 wt% and 42.8 wt%, respectively. The decrease in the Pt amount before and after PVPA coating was due to the additional PVPA which was calculated to be 14.4 wt%. The higher PVPA in the composite was attributed to the higher specific surface area.

31

The diameter of the Pt-NP calculated from

the TEM image shown in Figure 3b was 2.3±0.2 nm which was almost comparable to the Pt size of the NanoPC/PyPBI/Pt.

35

As a control electrocatalyst, the diameter of the Pt-NP in the



commercial CB/Pt was 3.9 ± 0.6 nm (Figure S4). The diameter of the Pt-NP of the NanoPC/PyPBI/Pt/PVPA calculated from the XRD based on the Scherrer equation (D=Kλ/(βcosθ), K is the shape factor, λ is the X-ray wavelength, β is the diffraction peak at half the maximum intensity, and θ is the diffraction angle.) was also smaller than that of the commercial CB/Pt as shown in Figure S5 and Table S1.

0.4

0.5

(a)

0.5

(b)

0.4

0.1 0

Current / mA

0.2

Current / mA

Current / mA

0.3 0.2 0.1 0

-0.1 -0.1 -0.2

(c)

0.4

0.3

0.3 0.2 0.1

-0.2 0

0.2 0.4 0.6 0.8 1 Potential / V vs. RHE

1.2

-0.3

0


0 0.7

1.2

0.8 0.9 1 Potential / V vs. RHE

1.1

Figure 4. CO stripping voltammograms of the NanoPC/PyPBI/Pt/PVPA (a) and CB/Pt (b) before durability test at the scan rate of 50 mV/s at 60 oC. (c) Magnification of the CO stripping profile in the range of 0.7 ~ 1.1 V vs. RHE. 0.2

0.2

(a)

110

(b) 0.1

0 -0.1

1st 10,000th 20,000th 30,000th 40,000th 50,000th

-0.2 -0.3

Current / mA

0.1

0 -0.1

1st 2000th 4000th 6000th 8000th 10,000th

-0.2 -0.3

0


1.2

Normalized ECSA / %

100

Current / mA

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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1.2


CB/Pt NanoPC/PyPBI/Pt/PVPA

90 80 70 60 50 40 30

0

(c)

0 10 20 30 40 50 Number of Potential cycling (*10 3)

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Figure 5. CV curves of the NanoPC/PyPBI/Pt/PVPA (a) and CB/Pt (b) after different potential cycling tests. (c) Normalized ECSAs of the NanoPC/PyPBI/Pt/PVPA (red line) and CB/Pt (black line) as a function of the number of potential cycles in the range of 1.0 ~ 1.5 V vs. RHE at 60 oC.

In order to evaluate the CO tolerance of the electrocatalyst at high temperature, the CO stripping was carried out at 60 ˚C and the result is shown in Figure 4, in which a sharp peak was observed at ~0.9 V vs. RHE as shown in Figure 4 (a, b) due to the oxidation of the CO species absorbed

on

the

Pt

surfaces.

The

CO

oxidation

peak

of

the

electrocatalyst

(NanoPC/PyPBI/Pt/PVPA) that appears at 877 mV shows a negative shift compared to that of the commercial CB/Pt (950 mV), indicating that the onset potential of the CO oxidation on the electrocatalyst was lower than that of the commercial CB/Pt. 44 This result demonstrated that the NanoPC/PyPBI/Pt/PVPA has a higher CO tolerance probably due to the PVPA layer on the electrocatalyst that would weaken the binding energy between the Pt-NPs and CO species and thus accelerated the formation of the Pt(OH)ads that consumed the Pt(CO)ads.

29

The initial

electrochemical surface area (ECSA) was calculated from the 2nd cycle based on equation (1), 4546

ECSA=QH/210 ×(Pt loading amount on the electrode) (1) where QH is the charge calculated from the CV curve based on the electro-adsorption of the hydrogen on the surface of the Pt-NPs. The initial ECSAs of the electrocatalyst and commercial CB/Pt were 52.3 and 62.0 m2/gPt, respectively. The ECSA of the prepared NanoPC/PyPBI/Pt/PVPA decreased by ~17% compared to that (63.7 m2/gPt) of the previously reported NanoPC/PyPBI/Pt,

35

which would be due to the

coating of the active Pt surface that would affect the hydrogen adsorption. The long-term



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durability was evaluated in an N2-saturated 0.1 M HClO4 electrolyte at 60 oC by potential cycling in the range of 1.0 ~1.5 V vs. RHE in order to accelerate the carbon corrosion, whose protocol was proposed by the Fuel Cell Commercialization of Japan (FCCJ). 47 The durability tested at 60 o

C was due to the real operational conditions of the DMFC. One obvious peak (hydroquinone-

quinone (HQ/Q) redox peak) was found at 0.6 V vs. RHE for both the NanoPC/PyPBI/Pt/PVPA and CB/Pt indicating the carbon corrosion. 48-49 As can be seen in Figure 5b, the CB/Pt showed a pronounced HQ/Q peak even after 10,000 cycles. In contrast, the NanoPC/PyPBI/Pt/PVPA showed a smaller HQ/Q peak even after 50,000 potential cycles as shown in Figure 5a, suggesting that serious carbon corrosion occurred on the CB. The reduced carbon corrosion of the NanoPC/PyPBI/Pt/PVPA was attributed to the protection by the two polymers, i.e., PyPBI and PVPA.

Figure 6. TEM images of the NanoPC/PyPBI/Pt/PVPA (a) and CB/Pt (b) after durability test at 60 oC and their particle size distribution histograms of 100 particles (inset).


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The normalized ECSAs of the two electrocatalysts are shown in Figure 5c. After 10,000 potential cycles in the range of 1.0 to 1.5 V vs. RHE at 60 oC, the commercial CB/Pt was found to exhibit an ~70% decrease in the initial ECSA, while, for the NanoPC/PyPBI/Pt/PVPA, an ~70% decrease

was

observed

even

after

50,000

potential

cycles,

indicating

the

NanoPC/PyPBI/Pt/PVPA has a 5 times higher durability compared to the commercial CB/Pt. After the durability test, ex-situ TEM was used to examine the morphologies of the two electrocatalysts, and the results are shown in Figure 6. The NanoPC/PyPBI/Pt/PVPA still possessed a homogeneous Pt-NP dispersion with a diameter of 4.2±0.6 nm (Figure 6a). In contrast, in the commercial CB/Pt, Pt aggregation was observed and the diameter of the Pt-NPs increased to 5.2±0.8 nm (Figure 6b). MOR is the anodic reaction in the real DMFCs and the CO species generated during the MOR poison the Pt-NP, which leads to the covered Pt-NPs becoming inactive. Thus, the CO poisoning is still a serious problem in the DMFCs. The CO tolerance can be evaluated from the ratios of the If and Ib in the MOR curves, 50-51 where Ib and If are the reverse anodic and reverse anodic peaks, respectively, as used in the following equation. 11, 52-53 Anodic peak (If): 54 Pt(CH3OH)ads + H2O → CO2 + 6H2O + 6e- (2) Pt(CH3OH)ads → Pt(CO)ads+ 4H+ + 4ePt + H2O → Pt(OH)ads + H+ + e-

(3) (4)

Reverse anodic peak (Ib): Pt(OH)ads + Pt(CO)ads → Pt + CO2 + H+ + e- (5)



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The higher If/Ib ratios indicate a higher CO tolerance. As shown in Figure 7 (a, b), the MOR of the two electrocatalysts including NanoPC/PyPBI/Pt/PVPA and Pt/CB was measured in the presence of 4M and 8M methanol before and after the durability test at 60 oC that simulates practical operating conditions of the DMFCs, in which highly concentrated methanol (4M or 8M) was fed to the DMFC anode side to solve the sluggish MOR.

55

Based on the MOR curves, the

If/Ib ratios were calculated and the result is shown in Table 1, in which the CO tolerance of the


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5

5

Pt

4

Current / mA/µg

Current / mA/µg

Pt

(a)

4M-before 8M-before 4M-after 8M-after

3 2 1

0.4 0.6 0.8 1 1.2 Potential / V vs. RHE

4 3 2

0 0.2

1.4

0.3

0.3

0.4 0.6 0.8 1 1.2 Potential / V vs. RHE

1.4

0.3 0.4 0.5 0.6 Potential / V vs. RHE

0.7

(d)

Pt

Current / mA/µg

Current / mA/µg

Pt

(c)

0.2

0.1

0 0.2

0.3 0.4 0.5 0.6 Potential / V vs. RHE

0.2

0.1

0 0.2

0.7

5

5 (f) Pt

(e) 4

Mass activity / mA/µg

Pt

(b)

1

0 0.2

Mass activity / mA/µg

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


3 2 1 0

4 8 Methanol concentration / M

4 3 2 1 0

4 8 Methanol concentration / M

Figure 7. Methanol oxidation reaction (MOR) curves measured in an N2-saturated 0.1M HClO4 with 4M (red line) and 8M (black line) methanol at 60 oC of the NanoPC/PyPBI/Pt/PVPA (a) and CB/Pt (b) before (solid line) and after (dotted line) the durability test. Magnified MOR



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curves in the range of 0.27 ~ 0.6 V vs. RHE for the NanoPC/PyPBI/Pt/PVPA (c) and CB/Pt (d). Mass activities of the NanoPC/PyPBI/Pt/PVPA (e) and CB/Pt (f) as a function of the methanol concentration before (red column) and after (black column) the durability test.

Figure 8. STEM (left) and EDX mapping for C, N, P and Pt (right) of the NanoPC/PyPBI/Pt/PVPA after the durability test.

Table 1. Comparisons of the NanoPC/PyPBI/Pt/PVPA and CB/Pt for CO tolerance (If/Ib ratio) before and after the durability test. NanoPC/PyPBI/Pt/PVPA

CB/Pt

(If/Ib ratio)

(If/Ib ratio)

4M (before durability)

2.86

0.91

8M (before durability)

2.52

0.87

4M (after durability)

1.78

0.69

8M (after durability)

1.72

0.60


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NanoPC/PyPBI/Pt/PVPA measured before the durability test in the presence of 4M and 8M methanol was found to exhibit an ~3 times higher CO tolerance compared to the commercial CB/Pt. Such a high CO tolerance of the NanoPC/PyPBI/Pt/PVPA was due to the PVPA-coating which accelerated the water adsorption to form the Pt(OH)ads according to equation (4), and weakened the binding energy between the Pt-NPs and CO species. The If/Ib values of the NanoPC/PyPBI/Pt/PVPA decreased by 37.6% and 32.6% for the 4M methanol and 8M methanol after

the

durability

test,

respectively.

Interestingly,

the

CO

tolerance

of

the

NanoPC/PyPBI/Pt/PVPA was still ~3 times higher than that of the commercial CB/Pt even after the durability test due to the presence of the PVPA, which agreed with the result shown by the EDX mapping (Figure 8 and Figure S6). Also the PVPA layer on the NanoPC/PyPBI/Pt/PVPA was stable for long (~28 h) due to the strong multipoint base-acid interaction between the PyPBI and PVPA. The onset potential of the two electrocatalysts after durability test shows negative shifts as shown in Figure 7(c, d). However, the onset potentials of the NanoPC/PyPBI/Pt/PVPA before and after the durability test were lower than those of the commercial CB/Pt, indicating a more active MOR on the NanoPC/PyPBI/Pt/PVPA. The mass activities before and after the durability test are summarized in Figure 7 (e, f). The mass activities of the NanoPC/PyPBI/Pt/PVPA and CB/Pt decreased by ~35% after the durability test. However, the mass activities of the NanoPC/PyPBI/Pt/PVPA were ~2 times higher compared to the commercial CB/Pt, suggesting an enhanced MOR.



1

120 133 mW/cm 2

100

0.6

80

0.4

60 40

0.2 0

20 0

Power density / mW/cm 2

140

0.8 Potential / V

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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0 0.2 0.4 0.6 0.8 1 1.2 Current density / A/cm 2

Figure 9. Polarization I-V and power density curve of the MEA fabricated from the NanoPC/PyPBI/Pt/PVPA under 70 oC with 8M methanol (9 mL/min) and 100%RH humidified air (200 mL/min) for the anode and cathode, respectively. Accordingly, the MEA fabricated from two GDEs containing the NanoPC/PyPBI/Pt/PVPA and Nafion 117 was tested under 70 oC with 100%RH as shown in Figure 9. The maximum power density reached 132 mW/cm2 which was ~1.6 times higher than that of the previously reported commercial CB/Pt (81 mW/cm2). 36 CONCLUSIONS In conclusion, we compared the CO tolerance and durability of as-synthesized NanoPC/PyPBI/Pt/PVA with the commercial CB/Pt under high methanol concentration (4M, 8M) and high temperature (60˚C) that simulates operating conditions from industry. The obtained interesting features are: i) the NanoPC/PyPBI/Pt/PVPA was revealed to show an ~5 times higher durability for the carbon corrosion compared to the commercial CB/Pt, ii) the CO tolerance of the NanoPC/PyPBI/Pt/PVPA evaluated from the methanol oxidation reaction (MOR) was ~3 times better than that of the commercially available CB/Pt before and after the potential cycling test, and iii) the mass activity of the NanoPC/PyPBI/Pt/PVPA was ~2 times higher than that of


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the commercial CB/Pt. Such a high durable and CO tolerant electrocatalyst is suitable for real applications in the DMFCs. This study provides significant information about the design and fabrication of a DMFC anodic electrocatalyst with a high performance. ASSOCIATED CONTENT Supporting information. TEM images of the CB/Pt before durability. XRD patterns of the NanoPC/PyPBI/Pt/PVPA and CB/Pt. EDX mapping of the NanoPC/PyPBI/Pt/PVPA before durability testing. This material is available free of charge via the Internet at http://pubs.acs.org. AUTHOR INFORMATION Corresponding Author *E-mail: [email protected] Author Contributions The manuscript was written through contributions of all authors. All authors have given approval to the final version of the manuscript. Notes The authors declare no competing financial interest. ACKNOWLEDGMENTS We thank Ms. X. J. Yu at Kyushu University for her support in measuring an EDX mapping image. This work was supported in part by the project “Advanced Research Program for Energy and Environmental Technologies” commissioned by the New Energy and Industrial Technology Development Organization (NEDO), the Nanotechnology Platform Project (Molecules and Materials Synthesis) of the Ministry of Education, Culture, Sports, Science and Technology 17 Environment ACS Paragon Plus


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(MEXT) Japan and the Japan Science and Technology Agency (JST) through its Center of Innovation Science and Technology-based Radical Innovation and Entrepreneurship Program (COI Program). Z.H. Yang acknowledges China Scholarship Council (CSC) for their support. REFERENCES 1.

Winter, M.; Brodd, R. J., What Are Batteries, Fuel Cells, and Supercapacitors? Chem.

Rev. 2004, 104, 4245-4270. 2.

Zhao, X.; Yin, M.; Ma, L.; Liang, L.; Liu, C.; Liao, J.; Lu, T.; Xing, W., Recent Advances

in Catalysts for Direct Methanol Fuel Cells. Energy Environ. Sci. 2011, 4, 2736-2753. 3.

Koenigsmann, C.; Wong, S. S., One-Dimensional Noble Metal Electrocatalysts: a

Promising Structural Paradigm for Direct Methanol Fuel Cells. Energy Environ. Sci. 2011, 4, 1161-1176. 4.

Ahmad, H.; Kamarudin, S. K.; Hasran, U. A.; Daud, W. R. W., A Novel Hybrid Nafion-

PBI-ZP Membrane for Direct Methanol Fuel Cells. Int. J. Hydrogen Energy 2011, 36, 1466814677. 5.

Li, X.; Chen, W.-X.; Zhao, J.; Xing, W.; Xu, Z.-D., Microwave Polyol Synthesis of

Pt/CNTs Catalysts: Effects of pH on Particle Size and Electrocatalytic Activity for Methanol Electrooxidization. Carbon 2005, 43, 2168-2174. 6.

Heinzel, A.; Barragán, V. M., Review of the State-of-The-Art of the Methanol Crossover

in Direct Methanol Fuel Cells. J. Power Sources 1999, 84, 70-74. 7.

Paoletti, C.; Cemmi, A.; Giorgi, L.; Giorgi, R.; Pilloni, L.; Serra, E.; Pasquali, M.,

Electro-Deposition on Carbon Black and Carbon Nanotubes of Pt Nanostructured Catalysts for Methanol Oxidation. J. Power Sources 2008, 183, 84-91. 8.

Bosco, J. P.; Sasaki, K.; Sadakane, M.; Ueda, W.; Chen, J. G., Synthesis and


Page 19 of 25

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Characterization of Three-Dimensionally Ordered Macroporous (3DOM) Tungsten Carbide: Application to Direct Methanol Fuel Cells†. Chem. Mater. 2010, 22, 966-973. 9.

Bahrami, H.; Faghri, A., Review and Advances of Direct Methanol Fuel Cells: Part II:

Modeling and Numerical Simulation. J. Power Sources 2013, 230, 303-320. 10.

Alia, S. M.; Zhang, G.; Kisailus, D.; Li, D.; Gu, S.; Jensen, K.; Yan, Y., Porous Platinum

Nanotubes for Oxygen Reduction and Methanol Oxidation Reactions. Adv. Funct. Mater. 2010, 20, 3742-3746. 11.

Ding, L. X.; Wang, A. L.; Li, G. R.; Liu, Z. Q.; Zhao, W. X.; Su, C. Y.; Tong, Y. X.,

Porous Pt-Ni-P Composite Nanotube Arrays: Highly Electroactive and Durable Catalysts for Methanol Electrooxidation. J. Am. Chem. Soc. 2012, 134, 5730-5733. 12.

Lv, H.; Peng, T.; Wu, P.; Pan, M.; Mu, S., Nano-Boron Carbide Supported Platinum

Catalysts with much Enhanced Methanol Oxidation Activity and CO Tolerance. J. Mater. Chem. 2012, 22, 9155-9160. 13.

Li, W.; Liang, C.; Zhou, W.; Qiu, J.; Zhou, Z.; Sun, G.; Xin, Q., Preparation and

Characterization of Multiwalled Carbon Nanotube-supported Platinum for Cathode Catalysts of Direct Methanol Fuel Cells. J. Phys. Chem. B 2003, 107, 6292-6299. 14.

Su, F.; Zeng, J.; Bao, X.; Yu, Y.; Lee, J. Y.; Zhao, X. S., Preparation and Characterization

of Highly Ordered Graphitic Mesoporous Carbon as a Pt Catalyst Support for Direct Methanol Fuel Cells. Chem. Mater. 2005, 17, 3960-3967. 15.

Xue, X.; Ge, J.; Tian, T.; Liu, C.; Xing, W.; Lu, T., Enhancement of the Electrooxidation

of Ethanol on Pt-Sn-P/C Catalysts Prepared by Chemical Deposition Process. J. Power Sources 2007, 172, 560-569. 16.

Huang, H.; Wang, X., Recent Pprogress on Carbon-based Support Materials for



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 20 of 25

Electrocatalysts of Direct Methanol Fuel Cells. J. Mater. Chem. A 2014, 2, 6266-6291. 17.

Zhou, Z.; Wang, S.; Zhou, W.; Wang, G.; Jiang, L.; Li, W.; Song, S.; Liu, J.; Sun, G.; Xin,

Q., Novel Synthesis of Highly Active Pt/C Cathode Electrocatalyst for Direct Methanol Fuel Cell. Chem. Commun. 2003, 9, 394-395. 18.

Wang, C. H.; Du, H. Y.; Tsai, Y. T.; Chen, C. P.; Huang, C. J.; Chen, L. C.; Chen, K. H.;

Shih, H. C., High Performance of Low Electrocatalysts Loading on CNT Directly Grown on Carbon Cloth for DMFC. J. Power Sources 2007, 171, 55-62. 19.

Sharma, S.; Pollet, B. G., Support Materials for PEMFC and DMFC Electrocatalysts—A

Review. J. Power Sources 2012, 208, 96-119. 20.

Liu, H.; Song, C.; Zhang, L.; Zhang, J.; Wang, H.; Wilkinson, D. P., A Review of Anode

Catalysis in the Direct Methanol Fuel Cell. J. Power Sources 2006, 155, 95-110. 21.

Wakisaka, M.; Mitsui, S.; Hirose, Y.; Kawashima, K.; Uchida, H.; Watanabe, M.,

Electronic Structures of Pt−Co and Pt−Ru Alloys for CO-Tolerant Anode Catalysts in Polymer Electrolyte Fuel Cells Studied by EC−XPS. J. Phys. Chem. B 2006, 110, 23489-23496. 22.

Maiyalagan, T.; Alaje, T. O.; Scott, K., Highly Stable Pt-Ru Nanoparticles Supported on

Three-Dimensional Cubic Ordered Mesoporous Carbon (Pt-Ru/CMK-8) as Promising Electrocatalysts for Methanol Oxidation. J. Phys. Chem. C 2012, 116, 2630-2638. 23.

Franceschini, E. A.; Planes, G. A.; Williams, F. J.; Soler-Illia, G. J. A. A.; Corti, H. R.,

Mesoporous Pt and Pt/Ru Alloy Electrocatalysts for Methanol Oxidation. J. Power Sources 2011, 196, 1723-1729. 24.

Polo, A. S.; Santos, M. C.; de Souza, R. F. B.; Alves, W. A., Pt–Ru–TiO2

Photoelectrocatalysts for Methanol Oxidation. J. Power Sources 2011, 196, 872-876. 25.

Gu, Y.-J.; Wong, W.-T., Nanostructure PtRu/MWNTs as Anode Catalysts Prepared in a


Page 21 of 25

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Vacuum for Direct Methanol Oxidation. Langmuir 2006, 22, 11447-11452. 26.

Xue, X.; Ge, J.; Liu, C.; Xing, W.; Lu, T., Novel Chemical Synthesis of Pt–Ru–P

Electrocatalysts by Hypophosphite Deposition for Enhanced Methanol Oxidation and CO Tolerance in Direct Methanol Fuel Cell. Electrochem. Commun. 2006, 8, 1280-1286. 27.

Paik, Y.; Kim, S. S.; Han, O. H., Methanol Behavior in Direct Methanol Fuel Cells.

Angew. Chem. Int. Ed. 2008, 47, 94-96. 28.

Wang, S.; Cochell, T.; Manthiram, A., Boron-Doped Carbon Nanotube-supported Pt

Nanoparticles with Improved CO Tolerance for Methanol Electro-Oxidation. Phys. Chem. Chem. Phys. 2012, 14, 13910-13913. 29.

Yang, Z.; Berber, M. R.; Nakashima, N., A Polymer-Coated Carbon Black-based Fuel

Cell Electrocatalyst with High CO-Tolerance and Durability in Direct Methanol Oxidation. J. Mater. Chem. A 2014, 2, 18875-18880. 30.

Yang, Z.; Hafez, I. H.; Berber, M. R.; Nakashima, N., An Enhanced Anode based on

Polymer-Coated Carbon Black for use as a Direct Methanol Fuel Cell Electrocatalyst. ChemCatChem 2015, 7, 808-813. 31.

Yang, Z.; Kim, C.; Hirata, S.; Fujigaya, T.; Nakashima, N., Facile Enhancement in CO-

Tolerance of a Polymer-Coated Pt Electrocatalyst Supported on Carbon Black: Comparison between Vulcan and Ketjenblack. ACS Appl. Mater. Interfaces 2015, 7, 15885-15891. 32.

Moriguchi, I.; Nakahara, F.; Furukawa, H.; Yamada, H.; Kudo, T., Colloidal Crystal-

Templated Porous Carbon as a High Performance Electrical Double-layer Capacitor Material. Electrochem. Solid-State Lett. 2004, 7, A221-A223. 33.

Xiao, L.; Zhang, H.; Jana, T.; Scanlon, E.; Chen, R.; Choe, E. W.; Ramanathan, L. S.; Yu,

S.; Benicewicz, B. C., Synthesis and Characterization of Pyridine-based Polybenzimidazoles for



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 22 of 25

High Temperature Polymer Electrolyte Membrane Fuel Cell Applications. Fuel Cells 2005, 5, 287-295. 34.

Li, Q.; Jensen, J. O.; Savinell, R. F.; Bjerrum, N. J., High Temperature Proton Exchange

Membranes based on Polybenzimidazoles for Fuel Cells. Prog. Polym. Sci. 2009, 34, 449-477. 35.

Yang, Z.; Moriguchi, I.; Nakashima, N., Durable Pt Electrocatalyst Supported on a 3D

Nanoporous Carbon Shows High Performance in a High-Temperature Polymer Electrolyte Fuel Cell. ACS Appl. Mater. Interfaces 2015, 7, 9800-9806. 36.

Yang, Z.; Nakashima, N., A simple Preparation of very High Methanol Tolerant Cathode

Electrocatalyst

for

Direct

Methanol

Fuel

Cell

based

on

Polymer-Coated

Carbon

Nanotube/Platinum. Sci. Rep. 2015, 5, art. no. 12236. 37.

Hafez, I. H.; Berber, M. R.; Fujigaya, T.; Nakashima, N., Enhancement of Platinum Mass

Activity on the Surface of Polymer-wrapped Carbon Nanotube-Based Fuel Cell Electrocatalysts. Sci. Rep. 2014, 4, art. no. 6295. 38.

Fujigaya, T.; Hirata, S.; Nakashima, N., A Highly Durable Fuel Cell Electrocatalyst based

on Polybenzimidazole-Coated Stacked Graphene. J. Mater. Chem. A 2014, 2, 3888-3893. 39.

Fujigaya, T.; Okamoto, M.; Nakashima, N., Design of an Assembly of Pyridine-

Containing Polybenzimidazole, Carbon Nanotubes and Pt Nanoparticles for a Fuel Cell Electrocatalyst with a High Electrochemically Active Surface Area. Carbon 2009, 47, 32273232. 40.

Okamoto,

M.;

Fujigaya,

T.;

Nakashima,

N.,

Design

of

an

Assembly

of

Poly(benzimidazole), Carbon Nanotubes, and Pt Nanoparticles for a Fuel-Cell Electrocatalyst with an Ideal Iinterfacial Nanostructure. Small 2009, 5, 735-740. 41.

Berber, M. R.; Fujigaya, T.; Sasaki, K.; Nakashima, N., Remarkably Durable High


Page 23 of 25

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Temperature Polymer Electrolyte Fuel Cell Based on Poly(vinylphosphonic acid)-doped Polybenzimidazole. Sci. Rep. 2013, 3, art. no. 1764. 42.

Berber, M. R.; Fujigaya, T.; Nakashima, N., High-Temperature Polymer Electrolyte Fuel

Cell using Poly(vinylphosphonic acid) as an Electrolyte shows a Remarkable Durability. ChemCatChem 2014, 6, 567-571. 43.

Bae, G.; Youn, D. H.; Han, S.; Lee, J. S., The Role of Nitrogen in a Carbon Support on

the Increased Activity and Stability of a Pt Catalyst in Electrochemical Hydrogen Oxidation. Carbon 2013, 51, 274-281. 44.

Yang, M.; Guarecuco, R.; Disalvo, F. J., Mesoporous Chromium Nitride as High

Performance Catalyst Support for Methanol Electrooxidation. Chem. Mater. 2013, 25, 17831787. 45.

Wang, D.; Xin, H. L.; Hovden, R.; Wang, H.; Yu, Y.; Muller, D. A.; Disalvo, F. J.;

Abruña, H. D., Structurally Ordered Intermetallic Platinum-Cobalt Core-Shell Nanoparticles with Enhanced Activity and Stability as Oxygen Reduction Electrocatalysts. Nat. Mater. 2013, 12, 81-87. 46.

Sun, S.; Zhang, G.; Geng, D.; Chen, Y.; Li, R.; Cai, M.; Sun, X., A Highly Durable

Platinum Nanocatalyst for Proton Exchange Membrane Fuel Cells: Multiarmed Starlike Nanowire Single Crystal. Angew. Chem. Int. Ed. 2011, 50, 422-426. 47.

Ohma, A.; Shinohara, K.; Iiyama, A.; Yoshida, T.; Daimaru, A. In Membrane and catalyst

performance targets for automotive fuel cells by FCCJ membrane, catalyst, MEA WG, ECS Trans. 2011, 41, 775-784. 48.

Zana, A.; Speder, J.; Reeler, N. E. A.; Vosch, T.; Arenz, M., Investigating the Corrosion of

High Surface Area Carbons during Start/Stop Fuel Cell Conditions: A Raman Study.



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 24 of 25

Electrochim. Acta 2013, 114, 455-461. 49.

Zhao, X.; Hayashi, A.; Noda, Z.; Kimijima, K.; Yagi, I.; Sasaki, K., Evaluation of Change

in Nanostructure through the Heat Treatment of Carbon Materials and their Durability for the Start/Stop Operation of Polymer Electrolyte Fuel Cells. Electrochim. Acta 2013, 97, 33-41. 50.

Zhao, Y.; Fan, L.; Zhong, H.; Li, Y.; Yang, S., Platinum Nanoparticle Clusters

Immobilized

on

Multiwalled

Carbon

Nanotubes:

Electrodeposition

and

Enhanced

Electrocatalytic Activity for Methanol Oxidation. Adv. Funct. Mater. 2007, 17, 1537-1541. 51.

Sun, S.; Zhang, G.; Gauquelin, N.; Chen, N.; Zhou, J.; Yang, S.; Chen, W.; Meng, X.;

Geng, D.; Banis, M. N.; Li, R.; Ye, S.; Knights, S.; Botton, G. A.; Sham, T.-K.; Sun, X., Singleatom Catalysis Using Pt/Graphene Achieved through Atomic Layer Deposition. Sci. Rep. 2013, 3, art. no. 1775. 52.

Liao, S.; Holmes, K.-A.; Tsaprailis, H.; Birss, V. I., High Performance PtRuIr Catalysts

Supported on Carbon Nanotubes for the Anodic Oxidation of Methanol. J. Am. Chem. Soc. 2006, 128, 3504-3505. 53.

Yu, L. H.; Kuo, C. H.; Yeh, C. T., Poly(vinylpyrrolidone)-Modified Graphite Carbon

Nanofibers as Promising Supports for PtRu Catalysts in Direct Methanol Fuel Cells. J. Am. Chem. Soc. 2007, 129, 9999-10010. 54.

Samant, P. V.; Rangel, C. M.; Romero, M. H.; Fernandes, J. B.; Figueiredo, J. L., Carbon

Supports for Methanol Oxidation Catalyst. J. Power Sources 2005, 151, 79-84. 55.

Gao, M. R.; Gao, Q.; Jiang, J.; Cui, C. H.; Yao, W. T.; Yu, S. H., A Methanol-Tolerant

Pt/CoSe2 Nanobelt Cathode Catalyst for Direct Methanol Fuel Cells. Angew. Chem. Int. Ed. 2011, 50, 4905-4908.


Page 25 of 25

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(3.6 cm*7.2 cm)


A Highly-Durable CO-Tolerant Poly(vinylphosphonic acid)-Coated

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