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HRTEM structural characterization of platinum nanoparticles loaded on carbon black particles using focused ion beam milling
Materials Letters 237 (2019) 96–100
Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/mlblue
HRTEM structural characterization of platinum nanoparticles loaded on carbon black particles using focused ion beam milling Kun’ichi Miyazawa a,⇑, Shuichi Shimomura b, Masaru Yoshitake a, Yumi Tanaka a,⇑ a b
Department of Industrial Chemistry, Tokyo University of Science, Tokyo 162-0826, Japan National Institute for Materials Science (NIMS), Tsukuba 305-0044, Japan
a r t i c l e
i n f o
Article history: Received 29 October 2018 Accepted 13 November 2018 Available online 14 November 2018 Keywords: Nanoparticles Crystal structure Platinum HRTEM FIB Carbon black
a b s t r a c t The atomic structure of platinum nanoparticles (Pt NPs) loaded on the carbon black particles was investigated using high-resolution transmission electron microscopy (HRTEM). Both the side and plan view HRTEM images of the Pt NPs showed the inhomogeneously strained structures. These structures were analyzed by approximating the Pt NPs as monoclinic crystal structures, and no correlation was observed between the monoclinic lattice parameters and the Pt NP diameter. The mean unit cell volume of the Pt NPs was smaller than the unit cell volume of bulk Pt, and approximately 70% of the Pt NPs were compressively strained and the remaining 30% were expansively strained. Ó 2018 Elsevier B.V. All rights reserved.
1. Introduction Platinum nanoparticles (Pt NPs) loaded on carbon black (CB) particles are indispensable catalysts for polymer electrolyte fuel cells (PEFCs) [1]. The lattice parameter of Pt NPs has been reported to decrease with decreasing the particle diameter [2]. In our previous study [3], Pt NPs deposited on graphite particles using coaxial arc plasma deposition (CAPD) were inhomogeneously strained and the lattice parameters of Pt NPs were calculated by approximation as monoclinic lattice structures. However, no correlation was observed between the diameter of the Pt NPs and lattice parameters. Since the lattice straining of Pt NPs affects their catalytic activity [4], it is important to know how the lattice of Pt NPs is strained also in the practical catalysts. Focused ion beam (FIB) milling is a powerful method to prepare thin samples from bulk and powder materials for transmission electron microscopy (TEM) observations. For example, we prepared cross-sectioned multiwall carbon nanotubes (MWCNTs) with deposited Pt NPs using FIB and succeeded in atomic-scale structural analysis of the Pt NP-MWCNT joint interfaces [5]. In this study, we applied the FIB method for a commercial practical Pt catalyst powder to obtain thin samples that could be used for plan and side view observations by TEM. The results of detailed
⇑ Corresponding authors. E-mail addresses: [email protected] (K. Miyazawa), [email protected] (Y. Tanaka). https://doi.org/10.1016/j.matlet.2018.11.086 0167-577X/Ó 2018 Elsevier B.V. All rights reserved.
structural analyses of the Pt NPs on the practical catalysts at the atomic scale are presented herein.
2. Experimental A Pt catalyst powder TEC10E50E (Tanaka Kikinzoku KK) was used. The as-received TEC10E50E powder was ultrasonically dispersed into a mixed solution of water and isopropyl alcohol, and the dispersed TEC10E50E powder was subsequently deposited on the surface of a glassy carbon electrode. A layer of tungsten approximately 500 nm thick was coated on the deposited TEC10E50E powder using a FIB milling apparatus (FIB-SEM, Hitachi NB5000, Japan). The W-coated TEC10E50E powder was then milled to a thickness of less than 100 nm with a Ga ion beam of 40 keV. The particle diameter and monoclinic lattice parameters of Pt NPs were measured using the same methods of ref. [3]. The magnification of the TEM (JEOL JEM-2800, 200 kV, Tokyo) images was calibrated using high-purity silicon crystals (Optostar Ltd, Japan).
3. Results and discussion Fig. 1(a) shows a TEM image of the CB particles milled by FIB and the arrow indicates a layer of Pt NPs loaded on the CB particle surface. Fig. 1(b) shows a side view HRTEM image of the Pt NPs adhered to the CB particle surface. A Pt NP-CB adhesion interface is indicated by the white line. The side view images make it
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Fig. 1. (a) TEM image of the CB particles milled by FIB. (b) Side view HRTEM image of the Pt NPs adhered to the CB particle. (c) Side view HRTEM image of a Pt NP adhered to a CB particle. The (1 1 1) planar faults are indicated by the arrows. (d) FFT image of the circled area of the Pt NP in (c). (e) Plan view HRTEM image of a Pt NP adhered to the CB particle surface. (f) FFT image of the Pt NP in (e).
possible to measure the height H of the Pt NPs from the Pt NP-CB particle adhesion interfaces. Fig. 1(c) shows a side view HRTEM image of a Pt NP adhered to the CB particle surface via the (1 1 1) facet. The surface facets of 1), (1 1 0), (1 1 1), and (0 0 1) are also indicated. The fast Fourier (1 1 transform (FFT) image of the circled area of the Pt NP in Fig. 1(c) is 1) planar faults generated in the shown in Fig. 1(d). Due to the (1 1 Pt NP, many satellite spots are generated as indicated by the smaller arrows in Fig. 1(d). The observed interplanar angle between the 1) and (1 1 1) planes is 73.0°, and that between the (1 1 1) and (1 1 (0 0 2) planes is 52.5°. However, in the FCC lattice, the interplanar 1) and (1 1 1) planes is 70.5° and that angle between the (1 1 1) and (0 0 2) planes is 54.7°, indicating that the between the (1 1 Pt NP is anisotropically strained from the correct FCC structure.
Fig. 1(e) shows a plan view image of a Pt NP with an overlapped image of the CB matrix. The plan view images allow for the measurement of the area of the Pt NP-CB particle adhesion interface. The FFT image of Pt NP in Fig. 1(e) is shown in Fig. 1(f). The and (1 1 1) planes observed interplanar angle between the (0 0 2) and that between the (0 0 2) and (1 1 1) planes are 63.5° and 56.4°, respectively, indicating that the Pt NP is anisotropically strained from the correct FCC structure. Side view HRTEM images of the 69 Pt NPs with crossed lattice fringes and plan view HRTEM images of the 105 Pt NPs with crossed lattice fringes were analyzed, approximating their crystal structures as monoclinic lattices. Table 1 summarizes the lattice parameter measurements from the plan and side view Pt NPs. The values of the cube-root of the unit cell volume (V1/3) are also
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Table 1 Monoclinic lattice parameters (a, b, c, b) and cube-root of unit cell volume (V1/3) of the 69 side view Pt NPs and 105 plan view Pt NPs in TEC10E50E. Group
a (nm)
b (nm)
c (nm)
b (°)
V1/3 (nm)
Side view images Plan view images
0.377 ± 0.026 0.369 ± 0.021
0.382 ± 0.027 0.376 ± 0.019
0.415 ± 0.042 0.412 ± 0.036
94.4 ± 3.6 94.7 ± 3.9
0.389 ± 0.019 0.384 ± 0.011
Fig. 2. Histogram showing the diameter (D (nm)) distribution of the 174 Pt NPs in TEC10E50E.
included in Table 1. No significant difference was observed in the lattice parameters or V1/3 values between the two groups. The mean diameter of the 69 Pt NPs in the side view images was 3.7 ± 1.1 nm (mean ± sd), and that of the 105 Pt NPs in the plan view images was be 3.6 ± 1.1 nm. No significant difference was observed between the two mean diameters, indicating that the Pt NPs are randomly oriented on the surface of the CB particles. Considering that the structural analyses yielded similar results for both the plan and side view Pt NPs, the two analytical data sets were merged and the relationship between the monoclinic lattice parameters and particle diameter was investigated. The size distribution of the merged 174 Pt NPs is shown in Fig. 2. The mean diameter of the 174 Pt NPs was 3.6 ± 1.1 nm, which is close to the 3.3 nm diameter of the Pt NPs in TEC10E50E as measured by XRD [6]. The monoclinic lattice parameters (a, b, c, b) of the 174 Pt NPs are plotted in Fig. 3 as a function of particle diameter. Similar to Pt NPs deposited on graphite particles [3], no relationship was observed between the monoclinic lattice parameters and Pt NP diameter.
Fig. 3. Monoclinic lattice parameters a (nm), b (nm), c (nm), and b (°) of the 174 Pt NPs plotted as a function of diameter D (nm).
99
28.7 71.3 3.2 ± 2.7 3.5 ± 2.2 1.6 ± 3.8 0.386 ± 0.015 0.0579 ± 0.0069 94.5 ± 3.8 0.413 ± 0.039
b (°) c (nm)
0.372 ± 0.023 3.6 ± 1.1
b (nm) a (nm) Diameter (nm)
Table 2 Parameters measured for the 174 Pt NPs in the FIB-processed TEC10E50E.
In Fig. 4(a), the cube root of the monoclinic unit cell volume, V1/3 (nm), of the 174 Pt NPs also showed widely scattered data with no correlation with the diameter, D, of the Pt NPs. The mean value of V1/3 was 0.386 ± 0.015 nm, 1.6% smaller than the FCC lattice parameter a0 = 0.39231 nm of bulk Pt (JCPDS 00-004-0802). In the Pt NPs deposited on the graphite particles by CAPD [3], the mean value of V1/3 was 0.386 ± 0.008 nm, which coincides with the above result. The lattice strain of the Pt NPs was defined as 100(V1/3 a0)/a0 (%). Fig. 4(b) shows a wide distribution of lattice strain between 10% and 10%. Table 2 summarizes the above results. The compressive and expansive lattice strains of the Pt NPs were 3.5 ± 2.2% and 3.2 ± 2.7%, respectively. The compressed Pt NPs constituted 71.3% of the total NPs with expanded Pt NPs, comprising the rest at 28.7%. For the Pt NPs deposited on the graphite particles [3], 73% were compressed and 27% were expanded. This is similar to the results obtained in the current study. Since the lattice parameters of each Pt NP were calculated using a single FFT image of crossed lattice fringes of the Pt NPs that were randomly oriented on the CB particles, approximately 70% of the surface area of a single Pt NP was compressed and 30% of the same Pt NP was expanded on average. Furthermore, the mean unit cell volume of the Pt NPs was 0.0579 ± 0.0069 nm3, 4.2% smaller than that of bulk Pt (0.0604 nm3). Thus, it is considered that a single Pt NP on TEC10E50E, on average, has a unit cell volume approximately 4% smaller than that of bulk Pt.
V (nm3)
Fig. 4. (a) Cube root of the monoclinic unit cell volume, V1/3 (nm), of the 174 Pt NPs plotted as a function of diameter D (nm). (b) Lattice strain distribution of the Pt NPs deposited on the CB particles.
0.378 ± 0.023
V1/3 (nm)
Lattice strain (%)
Compressed lattice strains (%)
Expansive lattice strain (%)
Compressed Pt NPs (%)
Expanded Pt NPs (%)
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4. Conclusion (1) The Pt NPs loaded on CB particles of TEC10E50E were inhomogeneously strained and approximated as monoclinic structures. The monoclinic lattice parameters showed similar values for both the side and plan view lattice images. (2) The adhered Pt NPs were randomly oriented on the surface of the CB particles. (3) No correlation was observed between the monoclinic lattice parameters and diameter of the Pt NPs. (4) The mean unit cell volume of the Pt NPs was 4.2% smaller than that of bulk Pt. It was suggested that a single Pt NP had ca. 70% compressive facets and ca. 30% expansive facets on average.
Acknowledgements Part of this study was conducted at Advanced Characterization Nanotechnology Platform of the University of Tokyo and NIMS. This study is based on the results obtained from a project commissioned by the New Energy and Industrial Technology Development Organization.
References [1] S. Sepp, K. Vaarmets, J. Nerut, et al., Performance of polymer electrolyte membrane fuel cell single cells prepared using hierarchical microporousmesoporous carbon supported Pt nanoparticles activated catalysts, Electrochim. Acta 203 (2016) 221–229. [2] K.N. Leontyev, A.B. Kuriganova, N.G. Leontyev, et al., Size dependence of the lattice parameters of carbon supported platinum nanoparticles: X-ray diffraction analysis and theoretical considerations, RSC Adv. 4 (2014) 35959– 35965. [3] K. Miyazawa, M. Yoshitake, Y. Tanaka, HRTEM analyses of the platinum nanoparticles prepared on graphite particles using coaxial arc plasma deposition, J. Nanopart. Res. 19 (2017) 191 1–191 9. [4] T. Daio, A. Staykov, L. Guo, et al., Lattice strain mapping of platinum nanoparticles on carbon and SnO2 supports, Sci. Rep. 5 (2015) 13126. [5] K. Miyazawa, M. Yoshitake, Y. Tanaka, HRTEM Characterization of platinum nanoparticles deposited on various novel nanocarbons using coaxial arc plasma deposition and nanocarbon supports, Proceedings of 2017 Sustainable Industrial Processing Summit & Exhibition (SIPS 2017), Mexico, Paper Id 160. [6] V.A. Sethuraman, J.W. Weidner, A.T. Haug, et al., Importance of catalyst stability vis-à-vis hydrogen peroxide formation rates in PEM fuel cell electrodes, Electrochim. Acta 54 (2009) 5571–5582.
Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/mlblue
HRTEM structural characterization of platinum nanoparticles loaded on carbon black particles using focused ion beam milling Kun’ichi Miyazawa a,⇑, Shuichi Shimomura b, Masaru Yoshitake a, Yumi Tanaka a,⇑ a b
Department of Industrial Chemistry, Tokyo University of Science, Tokyo 162-0826, Japan National Institute for Materials Science (NIMS), Tsukuba 305-0044, Japan
a r t i c l e
i n f o
Article history: Received 29 October 2018 Accepted 13 November 2018 Available online 14 November 2018 Keywords: Nanoparticles Crystal structure Platinum HRTEM FIB Carbon black
a b s t r a c t The atomic structure of platinum nanoparticles (Pt NPs) loaded on the carbon black particles was investigated using high-resolution transmission electron microscopy (HRTEM). Both the side and plan view HRTEM images of the Pt NPs showed the inhomogeneously strained structures. These structures were analyzed by approximating the Pt NPs as monoclinic crystal structures, and no correlation was observed between the monoclinic lattice parameters and the Pt NP diameter. The mean unit cell volume of the Pt NPs was smaller than the unit cell volume of bulk Pt, and approximately 70% of the Pt NPs were compressively strained and the remaining 30% were expansively strained. Ó 2018 Elsevier B.V. All rights reserved.
1. Introduction Platinum nanoparticles (Pt NPs) loaded on carbon black (CB) particles are indispensable catalysts for polymer electrolyte fuel cells (PEFCs) [1]. The lattice parameter of Pt NPs has been reported to decrease with decreasing the particle diameter [2]. In our previous study [3], Pt NPs deposited on graphite particles using coaxial arc plasma deposition (CAPD) were inhomogeneously strained and the lattice parameters of Pt NPs were calculated by approximation as monoclinic lattice structures. However, no correlation was observed between the diameter of the Pt NPs and lattice parameters. Since the lattice straining of Pt NPs affects their catalytic activity [4], it is important to know how the lattice of Pt NPs is strained also in the practical catalysts. Focused ion beam (FIB) milling is a powerful method to prepare thin samples from bulk and powder materials for transmission electron microscopy (TEM) observations. For example, we prepared cross-sectioned multiwall carbon nanotubes (MWCNTs) with deposited Pt NPs using FIB and succeeded in atomic-scale structural analysis of the Pt NP-MWCNT joint interfaces [5]. In this study, we applied the FIB method for a commercial practical Pt catalyst powder to obtain thin samples that could be used for plan and side view observations by TEM. The results of detailed
⇑ Corresponding authors. E-mail addresses: [email protected] (K. Miyazawa), [email protected] (Y. Tanaka). https://doi.org/10.1016/j.matlet.2018.11.086 0167-577X/Ó 2018 Elsevier B.V. All rights reserved.
structural analyses of the Pt NPs on the practical catalysts at the atomic scale are presented herein.
2. Experimental A Pt catalyst powder TEC10E50E (Tanaka Kikinzoku KK) was used. The as-received TEC10E50E powder was ultrasonically dispersed into a mixed solution of water and isopropyl alcohol, and the dispersed TEC10E50E powder was subsequently deposited on the surface of a glassy carbon electrode. A layer of tungsten approximately 500 nm thick was coated on the deposited TEC10E50E powder using a FIB milling apparatus (FIB-SEM, Hitachi NB5000, Japan). The W-coated TEC10E50E powder was then milled to a thickness of less than 100 nm with a Ga ion beam of 40 keV. The particle diameter and monoclinic lattice parameters of Pt NPs were measured using the same methods of ref. [3]. The magnification of the TEM (JEOL JEM-2800, 200 kV, Tokyo) images was calibrated using high-purity silicon crystals (Optostar Ltd, Japan).
3. Results and discussion Fig. 1(a) shows a TEM image of the CB particles milled by FIB and the arrow indicates a layer of Pt NPs loaded on the CB particle surface. Fig. 1(b) shows a side view HRTEM image of the Pt NPs adhered to the CB particle surface. A Pt NP-CB adhesion interface is indicated by the white line. The side view images make it
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Fig. 1. (a) TEM image of the CB particles milled by FIB. (b) Side view HRTEM image of the Pt NPs adhered to the CB particle. (c) Side view HRTEM image of a Pt NP adhered to a CB particle. The (1 1 1) planar faults are indicated by the arrows. (d) FFT image of the circled area of the Pt NP in (c). (e) Plan view HRTEM image of a Pt NP adhered to the CB particle surface. (f) FFT image of the Pt NP in (e).
possible to measure the height H of the Pt NPs from the Pt NP-CB particle adhesion interfaces. Fig. 1(c) shows a side view HRTEM image of a Pt NP adhered to the CB particle surface via the (1 1 1) facet. The surface facets of 1), (1 1 0), (1 1 1), and (0 0 1) are also indicated. The fast Fourier (1 1 transform (FFT) image of the circled area of the Pt NP in Fig. 1(c) is 1) planar faults generated in the shown in Fig. 1(d). Due to the (1 1 Pt NP, many satellite spots are generated as indicated by the smaller arrows in Fig. 1(d). The observed interplanar angle between the 1) and (1 1 1) planes is 73.0°, and that between the (1 1 1) and (1 1 (0 0 2) planes is 52.5°. However, in the FCC lattice, the interplanar 1) and (1 1 1) planes is 70.5° and that angle between the (1 1 1) and (0 0 2) planes is 54.7°, indicating that the between the (1 1 Pt NP is anisotropically strained from the correct FCC structure.
Fig. 1(e) shows a plan view image of a Pt NP with an overlapped image of the CB matrix. The plan view images allow for the measurement of the area of the Pt NP-CB particle adhesion interface. The FFT image of Pt NP in Fig. 1(e) is shown in Fig. 1(f). The and (1 1 1) planes observed interplanar angle between the (0 0 2) and that between the (0 0 2) and (1 1 1) planes are 63.5° and 56.4°, respectively, indicating that the Pt NP is anisotropically strained from the correct FCC structure. Side view HRTEM images of the 69 Pt NPs with crossed lattice fringes and plan view HRTEM images of the 105 Pt NPs with crossed lattice fringes were analyzed, approximating their crystal structures as monoclinic lattices. Table 1 summarizes the lattice parameter measurements from the plan and side view Pt NPs. The values of the cube-root of the unit cell volume (V1/3) are also
98
K. Miyazawa et al. / Materials Letters 237 (2019) 96–100
Table 1 Monoclinic lattice parameters (a, b, c, b) and cube-root of unit cell volume (V1/3) of the 69 side view Pt NPs and 105 plan view Pt NPs in TEC10E50E. Group
a (nm)
b (nm)
c (nm)
b (°)
V1/3 (nm)
Side view images Plan view images
0.377 ± 0.026 0.369 ± 0.021
0.382 ± 0.027 0.376 ± 0.019
0.415 ± 0.042 0.412 ± 0.036
94.4 ± 3.6 94.7 ± 3.9
0.389 ± 0.019 0.384 ± 0.011
Fig. 2. Histogram showing the diameter (D (nm)) distribution of the 174 Pt NPs in TEC10E50E.
included in Table 1. No significant difference was observed in the lattice parameters or V1/3 values between the two groups. The mean diameter of the 69 Pt NPs in the side view images was 3.7 ± 1.1 nm (mean ± sd), and that of the 105 Pt NPs in the plan view images was be 3.6 ± 1.1 nm. No significant difference was observed between the two mean diameters, indicating that the Pt NPs are randomly oriented on the surface of the CB particles. Considering that the structural analyses yielded similar results for both the plan and side view Pt NPs, the two analytical data sets were merged and the relationship between the monoclinic lattice parameters and particle diameter was investigated. The size distribution of the merged 174 Pt NPs is shown in Fig. 2. The mean diameter of the 174 Pt NPs was 3.6 ± 1.1 nm, which is close to the 3.3 nm diameter of the Pt NPs in TEC10E50E as measured by XRD [6]. The monoclinic lattice parameters (a, b, c, b) of the 174 Pt NPs are plotted in Fig. 3 as a function of particle diameter. Similar to Pt NPs deposited on graphite particles [3], no relationship was observed between the monoclinic lattice parameters and Pt NP diameter.
Fig. 3. Monoclinic lattice parameters a (nm), b (nm), c (nm), and b (°) of the 174 Pt NPs plotted as a function of diameter D (nm).
99
28.7 71.3 3.2 ± 2.7 3.5 ± 2.2 1.6 ± 3.8 0.386 ± 0.015 0.0579 ± 0.0069 94.5 ± 3.8 0.413 ± 0.039
b (°) c (nm)
0.372 ± 0.023 3.6 ± 1.1
b (nm) a (nm) Diameter (nm)
Table 2 Parameters measured for the 174 Pt NPs in the FIB-processed TEC10E50E.
In Fig. 4(a), the cube root of the monoclinic unit cell volume, V1/3 (nm), of the 174 Pt NPs also showed widely scattered data with no correlation with the diameter, D, of the Pt NPs. The mean value of V1/3 was 0.386 ± 0.015 nm, 1.6% smaller than the FCC lattice parameter a0 = 0.39231 nm of bulk Pt (JCPDS 00-004-0802). In the Pt NPs deposited on the graphite particles by CAPD [3], the mean value of V1/3 was 0.386 ± 0.008 nm, which coincides with the above result. The lattice strain of the Pt NPs was defined as 100(V1/3 a0)/a0 (%). Fig. 4(b) shows a wide distribution of lattice strain between 10% and 10%. Table 2 summarizes the above results. The compressive and expansive lattice strains of the Pt NPs were 3.5 ± 2.2% and 3.2 ± 2.7%, respectively. The compressed Pt NPs constituted 71.3% of the total NPs with expanded Pt NPs, comprising the rest at 28.7%. For the Pt NPs deposited on the graphite particles [3], 73% were compressed and 27% were expanded. This is similar to the results obtained in the current study. Since the lattice parameters of each Pt NP were calculated using a single FFT image of crossed lattice fringes of the Pt NPs that were randomly oriented on the CB particles, approximately 70% of the surface area of a single Pt NP was compressed and 30% of the same Pt NP was expanded on average. Furthermore, the mean unit cell volume of the Pt NPs was 0.0579 ± 0.0069 nm3, 4.2% smaller than that of bulk Pt (0.0604 nm3). Thus, it is considered that a single Pt NP on TEC10E50E, on average, has a unit cell volume approximately 4% smaller than that of bulk Pt.
V (nm3)
Fig. 4. (a) Cube root of the monoclinic unit cell volume, V1/3 (nm), of the 174 Pt NPs plotted as a function of diameter D (nm). (b) Lattice strain distribution of the Pt NPs deposited on the CB particles.
0.378 ± 0.023
V1/3 (nm)
Lattice strain (%)
Compressed lattice strains (%)
Expansive lattice strain (%)
Compressed Pt NPs (%)
Expanded Pt NPs (%)
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4. Conclusion (1) The Pt NPs loaded on CB particles of TEC10E50E were inhomogeneously strained and approximated as monoclinic structures. The monoclinic lattice parameters showed similar values for both the side and plan view lattice images. (2) The adhered Pt NPs were randomly oriented on the surface of the CB particles. (3) No correlation was observed between the monoclinic lattice parameters and diameter of the Pt NPs. (4) The mean unit cell volume of the Pt NPs was 4.2% smaller than that of bulk Pt. It was suggested that a single Pt NP had ca. 70% compressive facets and ca. 30% expansive facets on average.
Acknowledgements Part of this study was conducted at Advanced Characterization Nanotechnology Platform of the University of Tokyo and NIMS. This study is based on the results obtained from a project commissioned by the New Energy and Industrial Technology Development Organization.
References [1] S. Sepp, K. Vaarmets, J. Nerut, et al., Performance of polymer electrolyte membrane fuel cell single cells prepared using hierarchical microporousmesoporous carbon supported Pt nanoparticles activated catalysts, Electrochim. Acta 203 (2016) 221–229. [2] K.N. Leontyev, A.B. Kuriganova, N.G. Leontyev, et al., Size dependence of the lattice parameters of carbon supported platinum nanoparticles: X-ray diffraction analysis and theoretical considerations, RSC Adv. 4 (2014) 35959– 35965. [3] K. Miyazawa, M. Yoshitake, Y. Tanaka, HRTEM analyses of the platinum nanoparticles prepared on graphite particles using coaxial arc plasma deposition, J. Nanopart. Res. 19 (2017) 191 1–191 9. [4] T. Daio, A. Staykov, L. Guo, et al., Lattice strain mapping of platinum nanoparticles on carbon and SnO2 supports, Sci. Rep. 5 (2015) 13126. [5] K. Miyazawa, M. Yoshitake, Y. Tanaka, HRTEM Characterization of platinum nanoparticles deposited on various novel nanocarbons using coaxial arc plasma deposition and nanocarbon supports, Proceedings of 2017 Sustainable Industrial Processing Summit & Exhibition (SIPS 2017), Mexico, Paper Id 160. [6] V.A. Sethuraman, J.W. Weidner, A.T. Haug, et al., Importance of catalyst stability vis-à-vis hydrogen peroxide formation rates in PEM fuel cell electrodes, Electrochim. Acta 54 (2009) 5571–5582.