Active Pt3Ni (111) Surface of Pt3Ni Icosahedron for Oxygen Reduction

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Active Pt3Ni (111) Surface of Pt3Ni Icosahedron for Oxygen Reduction Jianbing Zhu, Meiling Xiao, Kui Li, Changpeng Liu, Xiao Zhao, and Wei Xing ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.6b04237 • Publication Date (Web): 13 Oct 2016 Downloaded from http://pubs.acs.org on October 17, 2016

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ACS Applied Materials & Interfaces

Active Pt3Ni (111) Surface of Pt3Ni Icosahedron for Oxygen Reduction Jianbing Zhu†,‡, Meiling Xiao†,‡, Kui Li†,‡, Changpeng Liu§, Xiao Zhao*,& and Wei Xing*,†,‡ †

State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied

Chemistry, Chinese Academy of Sciences, Changchun, Jilin, 130022, China. ‡

University of Chinese Academy of Sciences, Beijing, 100039, China

§

Laboratory of Advanced Power Sources, Changchun Institute of Applied Chemistry,

Changchun, Jilin, 130022, China &

Department

of

applied

physics

and

chemistry, The

University

of

Electro-

Communications, Chofugaoka Chofu, Tokyo, 182-8585, Japan

ACS Paragon Plus Environment

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ABSTRACT: Highly active, durable oxygen reduction reaction (ORR) electrocatalysts are extremely important for fuel cell applications. Herein, we provide an efficient way to synthesis of activity Pt3M icosahedra by the one-pot hydrothermal method in the presence of glucosamine which can well adjust the reduction rate of Pt4+ and efficiency control the morphology of final catalysts. Compare to Pt/C, the Pt3Ni icosahedra show 32-fold and 12-fold enhancement in specific and mass activity. Furthermore, robust durability was also observed in the accelerated durability test. Thus, this Pt3Ni icosahedron is found among the best Pt-based ORR catalysts, moreover, the finding also demonstrate how to mimic active extended surfaces in nano-scale. KEYWORDS: icosahedrons; hydrothermal method; core-shell; oxygen reduction reaction; Pt3M


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1. INTRODUCTION Electrocatalytic oxygen reaction is a cornerstone for clean energy applications, e.g. fuel cells, metal-air batteries1-3. However the ORR kinetics are sluggish intrinsically and require precious metal catalysts containing Pt to reduce the over-potential4-6. The use of Pt unfortunately generates numerous obstacles, such as expensive, scarcity, ready poisoning by impurities2, 7. Thus, increasing research efforts have been devoted to design and synthesize active, durable and economic Pt-based catalysts. According to previous researches, the most efficient ORR electrocatalysts are Pt-based bi-/ multi-metallic catalysts with optimized morphology and composition at the atomic scale. Intensively exploiting the shaped NCs, for example the octahedral PtxNi1−x alloy NCs8, 9, intermetallic PtCo core–shell nanoparticles10 and Pt3Ni nanoframes11,

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, has brought out

substantial enhancements in both activity and durability. Especially, a fundamental study demonstrated that the single crystal Pt3Ni( 111) surface was the most active surface ever reported for ORR, with a 90-fold enhancement over state-of-the-art Pt/C1. This intriguing performance thus inspired widespread efforts to mimic this active Pt3Ni (111) surface while keeping materials in the nano-scale. As a response, octahedral Pt3Ni NCs have been well investigated and have shown remarkable ORR performance8, 14, 15. However, another (111) exclusively enclosed NC shape with a polycrystalline or twinned structure, i.e. icosahedral Pt3M (M represents Fe, Co, Ni and Cu) NCs, which features twenty active (111) facets, has been explored very little to date. This is partly due to the challenge in the synthesis of icosahedral Pt3M alloy which requires careful and accurate regulation of the co-reduction of two metals with different nucleation and growth behaviors relative to the synthesis of icosahedral Pt NCs16, 17. Furthermore, a strongly reductive environment in synthesizing Pt-based metallic materials, such as carbon monoxide at high temperature, is required due to the fact that in icosahedral nanoparticles the strain energy for


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Pt twin boundary is too high15, 18. Thus synthetic methods for Pt-based icosahedra with mild conditions are urgently desirable and still challenging. In this work, we have provided a new and general synthetic tactic for one-step fabrication of icosahedral Pt3M NCs exclusively bound by twenty (111) facets. Benefitting from easily obtained and non-toxic reductant, Pt3M NCs are suitable for large-scale synthesis. Taking Pt3Ni icosahedra as an example, the synthesis involved the hydrothermal reaction of glucosamine, NiCl2, and H2PtCl6. The fine structure characterization revealed the formation of nanosegregated Pt skin on PtxNi alloy core. Electrochemical studies showed that these Pt3Ni icosahedra exhibited superb activity towards ORR with 6.38 mAcm-2Pt and 1.781 Amg-1Pt at 0.9 V for specific and mass activity, respectively, while those for commercial Pt/C are 0.2 mAcm-2Pt and 0.146 Amg-1Pt. 2. EXPERIMENTAL SECTION 2.1 Chemical Glucosamine, nickel chloride, cobalt chloride, iron chloride and copper chloride were obtained from Aladdin Company. 5 wt% Nafion ionomer (Sigma-Aldrich), Perchloric acid (Alfa Aesar). The contrast Pt/C catalyst was purchased from Johnson Matthey Company with the Pt loading of 20 wt% (HiSPEC™ 3000). In all experiments hyperpure water (Millipore, 18.2 MΩ cm) was used. 2.2 Synthesis of Pt3M icosahedra Pt3M icosahedra nanocrystals were generated by hydrothermal reaction using glucosamine as reductant in a sealed, PTFE-lined vessel. Chloroplatinic acid, nickel chloride, cobalt chloride, iron chloride and copper chloride were used as metal precursors. In a typical synthesis, 1.2 mmol glucosamine, 0.03 mmol chloroplatinic acid and 0.01 mmol nickel chloride were dissolved in 15 mL H2O with vigorous stirring. After 30 min, the precursor solution was subjected to hydrothermal reaction in an autoclave (20 mL) at


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180 °C (6 h). Then, centrifuging and washing with water and ethanol, obtain the Pt3Ni icosahedra catalyst. Finally, the Pt3Ni icosahedra nanoparticles were re-dispersed in 10 mL ethanol for further use. For comparison, Pt icosahedral nanocrastal was also synthesized using the hydrothermal method but without adding of the transition element and the obtained sample was denoted as Pt NI. 2.3 Synthesis of carbon supported Pt3M catalysts To minimize nanoparticle aggregation and facilitate electrochemical characterization, the alloy nanoparticles were supported on carbon (Vulcan XC-72). In a typical process, 20 mg Vulcan XC-72 were dispersed in an ethanol-water mixture (v/v=1/9) by ultrasonic treatment (1 h). After adding 5 mg platinum nickel nanoparticles, the suspension was sonicated for another 0.5 h, followed by stirred for several hours. The final products were collected and dried under argon protection. 2.4 Material characterization Fourier transform infrared (FTIR) spectra were performed on a Vertex 70 FTIR spectrometer (Bruker). Transmission electron microscopy (TEM, Tecnai G2 F20 S-TWIN, 200 kV) was used to discern the morphology, element distributions and component of the synthesized Pt3M catalysts. The metal contents in the catalysts were determined by inductively coupled plasma optical emission spectrometry (ICP-OES, iCAP6300, Thermo Scientific USA). Power X-ray diffraction (XRD, PW1700, Philips Co. 40 kV and 30 Ma with a Cu Kα (λ = 0.15405 nm) radiation) was employed to examine the bulk composition and crystallinity of the catalysts. X-ray photoelectron spectroscopy (XPS) data were collected by a VG Thermo ESCALAB 250 spectrometer (VG Scientific, 120 W, Mg Ka radiation) and C 1s line was used to correct the binding energy.


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2.5 Electrochemical Measurements The ORR performances of Pt3M/C icosahedral nanocrystal electrocatalysts were measured by rotating disk electrode (RDE) technique (details were shown in Supporting Information). The electrochemical workstation was 760EBi potentiostat (CH Instruments). A four-electrode cell equipped with a SCE reference electrode (Hg/Hg2Cl2/ (KCl, saturated)), a Pt counter electrode, a working electrode (catalysts film coated glassy carbon electrodes) and Pt ring electrode was used. The ORR currents presented are capacitive current corrected, and all present potentials were convert to reversible hydrogen electrode (RHE) achieved by gauging potential ∆E between SCE and Pt reference electrode (Pt-black deposited on a Pt wire) in H2-saturated 0.1M HClO4 electrolyte. The measured ∆E was 0.304 V. All the measurements were conducted at ambient temperature. 3. RESULTS AND DISCUSSION The representative TEM (Figure 1a) and high resolution TEM (HRTEM, Figure 1b, c) images show these NCs with icosahedral shape and well-faceted crystals with the size of ca. 20 ± 1 nm. The characteristic 5-fold symmetry and the (111) and (200) faces in the tetrahedral subunits can also be clearly detected (Figure 1b, c) 19, 20. The combination of high-angle annular dark-field scanning TEM (HAADF-STEM) image and the corresponding linear scan spectrum (Figure 1c) reveal the existence of nano-segregated Pt shell on PtNi core. Nanoscale elemental mapping (Figure 1d-f) further confirms that there is a Pt shell and an alloyed PtNi core for this Pt3Ni icosahedron. The Pt shell displays a thickness of 1.0 nm consisting of 4-5 Pt atomic layers assuming the spacing of Pt layers is 0.22 nm. Crystal structures were obtained from the XRD analysis (Figure S1a), from which characteristic peaks for the face-centered-cubic (fcc) Pt can be clearly distinguished. The crystalline domain size was ∼11.3 nm, calculated from the Debye−Scherrer formulation, which is smaller than the icosahedral size measured from TEM


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Figure 1 (a) Bright-field TEM image of Pt3Ni icosahedra, (b) twin boundaries of five-fold symmetry obtained by HRTEM, (c) (111) and (200) crystal faces of icosahedral Pt3Ni, (d) EDS line scan and (e, f) corresponding elements mapping of Pt3Ni obtained from a 6 h hydrothermal reaction, (e) Pt, (f) Ni. images and near to that of the tetrahedral crystal domains20. This result was in accordance with the TEM analysis, from which the average particles size of Pt3Ni icosahedron was estimated to be 20 nm. ICP-OES analysis indicated that the Pt/Ni ratio was 75.5/24.5 (Table S1), similar to the initial Pt/Ni composition. Element contents on the surface of Pt3Ni icosahedra was examined by XPS, which clearly showed a higher Pt/Ni atomic ratio than that in the bulk composition further revealing a Pt-rich surface (Table S1 and Figure S1b). We found the reaction temperature was a key parameter for the synthesis of high-quality Pt3Ni icosahedra. The temperature-dependent UV-vis absorption spectra and TEM images both


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Figure 2 Bright-field TEM imagess of Pt3Ni nanoparticles obtained from hydrothermal synthesis with different reaction time at 180 oC, (a) 1h, (b) 2h, (c) 3h, (d) 6h. uncovered that the critical temperature was ca. 180℃ for obtaining the high-quality Pt3Ni icosahedra (Figure S2, S3). To track the evolution-process of Pt3Ni icosahedra, we conducted time-dependent TEM experiments (Figure 2). As shown in Figure 2a, after reacting for 1h, nanoparticles with ultrafine size were formed (∼2 nm). When the reaction proceeded to 2 h, the near spherical morphology was still preserved however with a larger size of 4 nm (Figure 2b), at this stage, sphere and icosahedra were co-existing. At 3 h (Figure 2c), the nanoparticles grow larger and well-defined Pt3Ni icosahedra with ∼10 nm size can be seen and the NCs were almost completely transformed into Pt3Ni icosahedra (Figure 2d) after reacting for 6h. The above results suggest that the reduced metal ions nucleated, formed PtNi nanoparticles in the initial stage and


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these nanoparticles slowly evolved into icosahedral structure during the growth stage in the presence of amine groups. Due to the strong coordinate bond between Pt4+ and the amine groups from glucosamine, the reduction rate of Pt4+ was largely slowed down and was thus beneficial to the control of nucleation, growth rates of the PtNi nanoparticles. FT-IR measurements revealed that there was stronger coordination effect for the Pt4+/glucosamine than Ni2+/glucosamine as revealed by the larger red-shift for N-H peak (Figure 3). This result indicates that the glucosamine can delay the reduction of Pt4+ accounting for the growth of PtNi core/Pt shell structure. Interestingly, the presented approach is versatile and general. The synthesis of Pt and other bimetallic icosahedra Pt3Fe, Pt3Co, and Pt3Cu can be easily achieved through simply changing the corresponding precursors (Figure S4 to S12). Inspired by the unique structure of twenty Pt3Ni (111) facets with nano-segregated Pt skin, we examined the electro-catalytic ORR performance. Figure 4a displays the typical cyclic

Figure 3 (a) FT-IR and (b) corresponding second derivative spectra of the precursor solution: gluNH2 + H2O; Ni2+ + gluNH2 + H2O; Pt 4+ + gluNH2 + H2O; Ni2+ + Pt 4+ + gluNH2 + H2O.


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Figure 4 (a) CVs for Pt/C and the synthesized Pt NI/C, Pt3Ni/C, (b) LSV of Pt/C and the synthesized Pt NI/C, Pt3Ni/C in 0.1M HClO4 at room temperature (O2-saturated, 1,600 rpm, 5 mVs-1), (c) mass and (d) specific activities (Ik) for the tested catalysts. voltammetry (CV) in N2-saturated 0.1M HClO4, from which it is clear that all catalysts exhibited distinct hydrogen adsorption/desorption regions from 0.05 to 0.4 V and Pt oxidation/reduction peaks within potentials between 0.6 and 1.0 V. Notably, relative to Pt/C catalyst, the redox potential of Pt (OHad)2/Pt for Pt3Ni/C catalyst is significantly positively shifted. The adsorbed OHad generally acts as a site blocker for the ORR reaction, thus reducing the Pt activity by decreasing the available active sites. The positive shift of redox potential for Pt3Ni/C catalyst indicates a weaker adsorption of OHad species and hence improved ORR kinetics. The electro-catalytic properties of Pt3Ni icosahedra were evaluated and compared with Pt icosahedra (Pt NI/C) and Pt/C (Figure 4b-d and Table S2). The LSV results indicate the best ORR performance for Pt3Ni icosahedra on the part of onset (Eonset) and half-wave (E1/2) potentials (Figure 4b, Table S2). For example, the E1/2 for Pt3Ni/C is 0. 942V, a conspicuous


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positive shift of ~64 and ~51 mV relative to Pt/C and Pt NI/C catalysts, respectively. The mass activity of Pt3Ni/C is 1.761 A mg−1Pt at 0.9 V, 4-times larger than the U.S. Department of Energy’s 2017 target (0.44 Amg−1Pt) and a 12-time improvement over Pt/C. Specific activity for Pt3Ni/C is 4.41 mAcm-2Pt (Figure 4d, S13-15), possessing a 23-fold enhancement vs. standard Pt/C catalyst (0.19 mAcm-2Pt,) and a 3-fold enhancement vs. extended polycrystalline Pt electrodes13 (∼1.2 mAcm-2Pt). Interestingly, the ORR activity of other Pt3M icosahedra NCs (M=Fe, Co, Cu) are also superb than the Pt/C catalyst, demonstrating the

Figure 5 CVs for Pt/C (a) and Pt3Ni/C (b) catalysts in N2-saturated 0.1M HClO4 solution after different cycling numbers (50 mVs-1), (c) evolution of ECSA with the CV cycles, (d) comparation of ORR performances before and after ADT test; from 0.6 to 1.2 V for 20,000 cycles in 0.1M HClO4 solution at 50 mVs-1.


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significant structure advantage for Pt skin-icosahedra (Figure S14). To explore the ORR selectivity and mechanism, we implemented the ring-disk electrode (RRDE) technique to monitor peroxide (H2O2) yields during ORR (Figure S16). The measured H2O2 percentage for Pt3Ni/C is very low, about 0.5 % at 0.90 V, lower than commercial Pt/C (ca. 2.0 %), approaching an ideal 4-electron pathway. Besides the high mass and intrinsic activities, the Pt3Ni icosahedra exhibited intriguing durability during the accelerated durability test (ADT) process. After 20,000 potential cycles, Pt/C suffered a substantial ECSA loss (~40%, 24.2 m2g-1) because of the dissolution, coalescence of Pt particles (Figure 5a, c). In contrast, after 20,000 cycles, the ECSA of Pt3Ni/C catalyst only decreased by ca.10.4% (~2.9 m2g-1) and then stabilized gradually to 20,000 cycles (Figure 5b, c). Regarding activity loss, Pt/C showed ~19 mV negative shift in E1/2, while that for Pt3Ni/C was less than 6 mV (Figure 5d). TEM images and nano-scale element mapping confirm that both icosahedral and micro-core/shell structures were maintained after ADT (Figure 6 and Figure S17). The Pt/Ni ratio after ADT test is 77.8/22.2 (Figure S18, Table S1), close to the initial value, indicating that the Ni was well protected by the Pt skin. The durability of Pt3Fe/C, Pt3Co/C and Pt3Cu/C catalysts was significantly enhanced due to the protection of Pt skin (Figure S19-21), and this result further confirmed the superiority of this Pt skin-icosahedra structure. All these results nicely emphasize the wonderful stability of Pt3Ni/C icosahedral-Pt skin catalyst as compared to Pt/C catalyst.


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Figure 6 EDX and elements mapping of Pt3Ni/C catalyst after 20,000 cycles. 4. CONCLUSIONS In conclusion, we have presented a general one-pot wet-chemistry protocol to efficiently synthesize Pt3M (M= Ni, Fe, Co, Cu) bimetallic icosahedral NCs with nano-segregated Pt skin structure for the first time. The selected reductant and structure-directing agent (glucosamine) for the synthesis of icosahedra was both economical and eco-friendly. The Pt3Ni icosahedra nicely mimic the ideally active extended (111) surface and exclusively expose Pt3Ni (111) faces with segregated Pt skin. Significantly, Pt3Ni icosahedra showed an extremely high ORR mass activity (1.761 A mg−1Pt) and specific activity 6.38mAcm−2Pt), which is among the most efficient ORR catalysts ever reported. ASSOCIATED CONTENT Supporting Information


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TEM photographs, elements mapping, EDX, XRD, XPS spectra and other electrochemical characterization. This material is available free of charge via the Internet at http://pubs.acs.org. AUTHOR INFORMATION Corresponding Author [email protected] [email protected] Corresponding Author Notes The authors declare no competing financial interests. ACKNOWLEDGMENT We are appreciative to Prof. Iwasawa, at University of Electro-Communications, Chofugaoka Chofu, Tokyo, Japan, for his contribution in manuscript review. This work was supported by 973 Program (2012CB215500), NFSC (21373199, 21433003) and Strategic Priority Research Program of the Chinese Academy of Sciences (XDA09030104).


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REFERENCES (1).

Stamenkovic, V. R.; Fowler, B.; Mun, B. S.; Wang, G.; Ross, P. N.; Lucas, C. A.; Marković, N. M. Improved Oxygen Reduction Activity on Pt3Ni (111) via Increased Surface Site Availability. Science 2007, 315 (5811), 493-497.

(2).

Gasteiger, H. A.; Kocha, S. S.; Sompalli, B.; Wagner, F. T. Activity Benchmarks and Requirements for Pt, Pt-alloy, and Non-Pt Oxygen Reduction Catalysts for PEMFCs. Appl. Catal., B, 2005, 56, 9-35.

(3).

Wang, C.; Markovic, N. M.; Stamenkovic, V. R. Advanced Platinum Alloy Electrocatalysts for the Oxygen Reduction Reaction. ACS Catal., 2012, 2, 891-898.

(4).

Shao, Y.; Yin, G.; Gao, Y. Understanding and Approaches for the Durability Issues of Ptbased Catalysts for PEM fuel cell. J. Power Sources, 2007, 171, 558-566.

(5).

Lim, B.; Jiang, M.; Camargo, P. H.; Cho, E. C.; Tao, J.; Lu, X.; Zhu, Y.; Xia, Y. Pd-Pt Bimetallic Nanodendrites with High Activity for Oxygen Reduction. Science, 2009, 324, 1302-1305.

(6).

Zhang, H.; Jin, M.; Xia, Y. Enhancing the Catalytic and Electrocatalytic Properties of Ptbased Catalysts by Forming Bimetallic Nanocrystals with Pd. Chem. Soc. Rev., 2012, 41, 8035-8049.

(7).

Mukerjee, S.; Srinivasan, S. Enhanced Electrocatalysis of Oxygen Reduction on Platinum Alloys in Proton Exchange Membrane Fuel Cells. J. Electroanal. Chem., 1993, 357, 201224.

(8).

Cui, C.; Gan, L.; Heggen, M.; Rudi, S.; Strasser, P. Compositional Segregation in Shaped Pt Alloy Nanoparticles and Their Structural Behaviour During Electrocatalysis. Nat. Mater. , 2013, 12, 765-771.


15


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

(9).

Page 16 of 18

Zhang, C.; Hwang, S. Y.; Trout, A.; Peng, Z. Solid-state Chemistry-enabled Scalable Production of Octahedral Pt–Ni Alloy Electrocatalyst for Oxygen Reduction Reaction. J. Am. Chem. Soc., 2014, 136, 7805-7808.

(10).

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. (11).

Chen, C.; Kang, Y.; Huo, Z.; Zhu, Z.; Huang, W.; Xin, H. L.; Snyder, J. D.; Li, D.; Herron, J. A.; Mavrikakis, M.; Chi, M.; More, K. L.; Li, Y.; Markovic, N. M.; Somorjai, G. A.; Yang, P.; Stamenkovic, V. R. Highly Crystalline Multimetallic Nanoframes with Three-Dimensional Electrocatalytic Surfaces. Science, 2014, 343, 1339-1343.

(12).

Oh, A.; Baik, H.; Choi, D. S.; Cheon, J. Y.; Kim, B.; Kim, H.; Kwon, S. J.; Joo, S. H.; Jung, Y.; Lee, K. Skeletal Octahedral Nanoframe with Cartesian Coordinates via Geometrically Precise Nanoscale Phase Segregation in a Pt@ Ni Core-Shell Nanocrystal. ACS Nano, 2015, 9, 2856-2867.

(13). Cui, C. H.; Gan, L.; Li, H. H.; Yu, S. H.; Heggen, M.; Strasser, P. Octahedral PtNi Nanoparticle Catalysts: Exceptional Oxygen Reduction Activity by Tuning the Alloy Particle Surface Composition. Nano Lett., 2012, 12, 5885-5889. (14).

Wu, J.; Yang, H. Synthesis and Electrocatalytic Oxygen Reduction Properties of Truncated Octahedral Pt3Ni Nanoparticles. Nano Res., 2011, 4, 72-82.

(15).

Zhou, W.; Wu, J.; Yang, H. Highly Uniform Platinum Icosahedra Made by Hot InjectionAssisted GRAILS Method. Nano Lett., 2013, 13, 2870-2874.


16

Page 17 of 18

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


(16).

Carpenter, M. K.; Moylan, T. E.; Kukreja, R. S.; Atwan, M. H.; Tessema, M. M. Solvothermal Synthesis of Platinum Alloy Nanoparticles for Oxygen Reduction Electrocatalysis. J. Am. Chem. Soc., 2012, 134, 8535-8542.

(17).

Chou, S.-W.; Shyue, J.-J.; Chien, C.-H.; Chen, C.-C.; Chen, Y.-Y.; Chou, P.-T. Surfactant-directed Synthesis of Ternary Nanostructures: Nanocubes, Polyhedrons, Pctahedrons, and Nanowires of PtNiFe. Their Shape-dependent Oxygen Reduction Activity. Chem. Mater., 2012, 24, 2527-2533.

(18).

Schmidt, T.; Gasteiger, H.; Stäb, G.; Urban, P.; Kolb, D.; Behm, R. Characterization of High‐surface‐area Electrocatalysts Using a Rotating Disk Electrode Configuration. J. Electrochem. Soc. 1998, 145 (7), 2354-2358.

(19). Wittkopf, J. A.; Zheng, J.; Yan, Y. High-Performance Dealloyed PtCu/CuNW Oxygen Reduction Reaction Catalyst for Proton Exchange Membrane Fuel Cells. ACS Catal. 2014, 4 (9), 3145-3151. (20).

Wu, J.; Qi, L.; You, H.; Gross, A.; Li, J.; Yang, H. Icosahedral Platinum Alloy Nanocrystals with Enhanced Electrocatalytic Activities. J. Am. Chem. Soc., 2012, 134, 11880-11883.


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Table of Contents


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Active Pt3Ni (111) Surface of Pt3Ni Icosahedron for Oxygen Reduction

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