Thermal annealing synthesis of double-shell truncated octahedral Pt-Ni alloys for oxygen reduction reaction of polymer electrolyte membrane fuel cells

Abstract

Shape-controlled Pt-Ni alloys usually offer an exceptional electrocatalytic activity toward the oxygen reduction reaction (ORR) of polymer electrolyte membrane fuel cells (PEMFCs), whose tricks lie in well-designed structures and surface morphologies. In this paper, a novel synthesis of truncated octahedral PtNi_3.5 alloy catalysts that consist of homogeneous Pt-Ni alloy cores enclosed by NiO-Pt double shells through thermally annealing defective heterogeneous PtNi_3.5 alloys is reported. By tracking the evolution of both compositions and morphologies, the outward segregation of both PtO_x and NiO are first observed in Pt-Ni alloys. It is speculated that the diffusion of low-coordination atoms results in the formation of an energetically favorable truncated octahedron while the outward segregation of oxides leads to the formation of NiO-Pt double shells. It is very attractive that after gently removing the NiO outer shell, the dealloyed truncated octahedral core-shell structure demonstrates a greatly enhanced ORR activity. The as-obtained truncated octahedral Pt_2.1Ni core-shell alloy presents a 3.4-folds mass-specific activity of that for unannealed sample, and its activity preserves 45.4% after 30000 potential cycles of accelerated degradation test (ADT). The peak power density of the dealloyed truncated octahedral Pt_2.1Ni core-shell alloy catalyst based membrane electrolyte assembly (MEA) reaches 679.8 mW/cm², increased by 138.4 mW/cm² relative to that based on commercial Pt/C.

Keywords

dealloyed Pt-Ni alloys / truncated octahedron / double-shell / thermal annealing / oxygen reduction reaction (ORR)

References

[1] 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. Applied Catalysis B: Environmental, 2005, 56(1–2): 9–35

[2] Papageorgopoulos D. Fuel cells R&D overview. 2018–06–13, available at the website of hydrogen.energy.gov

[3] Shao M, Chang Q, Dodelet J P, Chenitz R. Recent advances in electrocatalysts for oxygen reduction reaction. Chemical Reviews, 2016, 116(6): 3594–3657

[4] Wang Y J, Zhao N, Fang B, Li H, Bi X T, Wang H. Carbon-supported Pt-based alloy electrocatalysts for the oxygen reduction reaction in polymer electrolyte membrane fuel cells: particle size, shape, and composition manipulation and their impact to activity. Chemical Reviews, 2015, 115(9): 3433–3467

[5] Chaudhari N K, Joo J, Kim B, Ruqia B, Choi S I, Lee K. Recent advances in electrocatalysts toward the oxygen reduction reaction: the case of PtNi octahedra. Nanoscale, 2018, 10(43): 20073–20088

[6] Arán-Ais R M, Dionigi F, Merzdorf T, Gocyla M, Heggen M, Dunin-Borkowski R E, Gliech M, Solla-Gullón J, Herrero E, Feliu J M, Strasser P. Elemental anisotropic growth and atomic-scale structure of shape-controlled octahedral Pt-Ni-Co alloy nanocatalysts. Nano Letters, 2015, 15(11): 7473–7480

[7] Salgado J R C, Antolini E, Gonzalez E R. Structure and activity of carbon-supported Pt-Co electrocatalysts for oxygen reduction. Journal of Physical Chemistry B, 2004, 108(46): 17767–17774

[8] Stamenkovic V, Mun B S, Mayrhofer K J J, Ross P N, Markovic N M, Rossmeisl J, Greeley J, Nørskov J K. Changing the activity of electrocatalysts for oxygen reduction by tuning the surface electronic structure. Angewandte Chemie International Edition, 2006, 45(18): 2897–2901

[9] Zhang J, Fang J. A general strategy for preparation of Pt 3d-transition metal (Co, Fe, Ni) nanocubes. Journal of the American Chemical Society, 2009, 131(51): 18543–18547

[10] Zhu Z, Zhai Y, Dong S. Facial synthesis of PtM (M= Fe, Co, Cu, Ni) bimetallic alloy nanosponges and their enhanced catalysis for oxygen reduction reaction. ACS Applied Materials & Interfaces, 2014, 6(19): 16721–16726

[11] Choi S I, Xie S, Shao M, Odell J H, Lu N, Peng H C, Protsailo L, Guerrero S, Park J, Xia X, Wang J, Kim M J, Xia Y. Synthesis and characterization of 9 nm Pt-Ni octahedra with a record high activity of 3.3 A/mg_Pt for the oxygen reduction reaction. Nano Letters, 2013, 13(7): 3420–3425

[12] Chou S W, Lai Y R, Yang Y Y, Tang C Y, Hayashi M, Chen H C, Chen H L, Chou P T. Uniform size and composition tuning of PtNi octahedra for systematic studies of oxygen reduction reactions. Journal of Catalysis, 2014, 309: 343–350

[13] Cui C, 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 Letters, 2012, 12(11): 5885–5889

[14] Gan L, Heggen M, Rudi S, Strasser P. Core-shell compositional fine structures of dealloyed Pt_xNi_1−x nanoparticles and their impact on oxygen reduction catalysis. Nano Letters, 2012, 12(10): 5423–5430

[15] Park J, Liu J, Peng H, Figueroa-Cosme L, Miao S, Choi S I, Bao S, Yang X, Xia Y. Coating Pt-Ni octahedra with ultrathin Pt shells to enhance the durability without compromising the activity toward oxygen reduction. ChemSusChem, 2016, 9(16): 2209–2215

[16] Wu J, Yang H. Synthesis and electrocatalytic oxygen reduction properties of truncated octahedral Pt₃Ni nanoparticles. Nano Research, 2011, 4(1): 72–82

[17] Wu J, Zhang J, Peng Z, Yang S, Wagner F T, Yang H. Truncated octahedral Pt₃Ni oxygen reduction reaction electrocatalysts. Journal of the American Chemical Society, 2010, 132(14): 4984–4985

[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. Journal of the American Chemical Society, 2014, 136(22): 7805–7808

[19] Zhang J, Yang H, Fang J, Zou S. Synthesis and oxygen reduction activity of shape-controlled Pt₃Ni nanopolyhedra. Nano Letters, 2010, 10(2): 638–644

[20] Wu J, Qi L, You H, Gross A, Li J, Yang H. Icosahedral platinum alloy nanocrystals with enhanced electrocatalytic activities. Journal of the American Chemical Society, 2012, 134(29): 11880–11883

[21] Beermann V, Gocyla M, Kühl S, Padgett E, Schmies H, Goerlin M, Erini N, Shviro M, Heggen M, Dunin-Borkowski R E, Muller D A, Strasser P. Tuning the electrocatalytic oxygen reduction reaction activity and stability of shape-controlled Pt-Ni nanoparticles by thermal annealing-elucidating the surface atomic structural and compositional changes. Journal of the American Chemical Society, 2017, 139(46): 16536–16547

[22] 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(6177): 1339–1343

[23] 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. Nature Materials, 2013, 12(1): 81–87

[24] Gocyla M, Kuehl S, Shviro M, Heyen H, Selve S, Dunin-Borkowski R E, Heggen M, Strasser P. Shape stability of octahedral PtNi nanocatalysts for electrochemical oxygen reduction reaction studied by in situ transmission electron microscopy. ACS Nano, 2018, 12(6): 5306–5311

[25] Gan L, Heggen M, Cui C, Strasser P. Thermal facet healing of concave octahedral Pt-Ni nanoparticles imaged in situ at the atomic scale: implications for the rational synthesis of durable high-performance ORR electrocatalysts. ACS Catalysis, 2016, 6(2): 692–695

[26] Wang G, Van Hove M A, Ross P N, Baskes M I. Monte Carlo simulations of segregation in Pt-Ni catalyst nanoparticles. Journal of Chemical Physics, 2005, 122(2): 024706

[27] Calle-Vallejo F, Pohl M D, Reinisch D, Loffreda D, Sautet P, Bandarenka A S. Why conclusions from platinum model surfaces do not necessarily lead to enhanced nanoparticle catalysts for the oxygen reduction reaction. Chemical Science (Cambridge), 2017, 8(3): 2283–2289

[28] Patrick B, Ham H C, Shao-Horn Y, Allard L F, Hwang G S, Ferreira P J. Atomic structure and composition of “Pt₃Co” nanocatalysts in fuel cells: an aberration-corrected STEM HAADF study. Chemistry of Materials, 2013, 25(4): 530–535

[29] Martinez U, Komini Babu S, Holby E F, Zelenay P. Durability challenges and perspective in the development of PGM-free electrocatalysts for the oxygen reduction reaction. Current Opinion in Electrochemistry, 2018, 9: 224–232

[30] Hartl K, Nesselberger M, Mayrhofer K J J, Kunz S, Schweinberger F F, Kwon G H, Hanzlik M, Heiz U, Arenz M. Electrochemically induced nanocluster migration. Electrochimica Acta, 2010, 56(2): 810–816

[31] Liu C, Wu X, Klemmer T, Shukla N, Weller D, Roy A G, Tanase M, Laughlin D. Reduction of sintering during annealing of FePt nanoparticles coated with iron oxide. Chemistry of Materials, 2005, 17(3): 620–625

[32] Gao M Y, Li A D, Zhang J L, Kong J Z, Liu X J, Li X F, Wu D. Fabrication and magnetic properties of FePt nanoparticle assemblies embedded in MgO-matrix systems. Journal of Sol-Gel Science and Technology, 2014, 71(2): 283–290

[33] Zeynali H, Sebt S A, Arabi H, Akbari H, Hosseinpour-Mashkani S M, Rao K V. Synthesis and characterization of FePt/NiO core-shell nanoparticles. Journal of Inorganic and Organometallic Polymers and Materials, 2012, 22(6): 1314–1319

[34] Beard B C, Ross P N. Platinum-titanium alloy formation from high-temperature reduction of a titania-impregnated platinum catalyst: implications for strong metal-support interaction. Journal of Physical Chemistry, 1986, 90(26): 6811–6817

[35] Choi S I, Lee S U, Kim W Y, Choi R, Hong K, Nam K M, Han S W, Park J T. Composition-controlled PtCo alloy nanocubes with tuned electrocatalytic activity for oxygen reduction. ACS Applied Materials & Interfaces, 2012, 4(11): 6228–6234

[36] Tan X, Prabhudev S, Kohandehghan A, Karpuzov D, Botton G A, Mitlin D. Pt-Au-Co alloy electrocatalysts demonstrating enhanced activity and durability toward the oxygen reduction reaction. ACS Catalysis, 2015, 5(3): 1513–1524

[37] 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. Journal of Physical Chemistry B, 2006, 110(46): 23489–23496

[38] Kitchin J R, Nørskov J K, Barteau M A, Chen J G. Modification of the surface electronic and chemical properties of Pt(111) by subsurface 3d transition metals. Journal of Chemical Physics, 2004, 120(21): 10240–10246

[39] Zhang J, Vukmirovic M B, Xu Y, Mavrikakis M, Adzic R R. Controlling the catalytic activity of platinum-monolayer electrocatalysts for oxygen reduction with different substrates. Angewandte Chemie International Edition, 2005, 44(14): 2132–2135

[40] Li W X, Österlund L, Vestergaard E K, Vang R T, Matthiesen J, Pedersen T M, Lægsgaard E, Hammer B, Besenbacher F. Oxidation of Pt(110). Physical Review Letters, 2004, 93(14): 146104

[41] Ahmadi M, Behafarid F, Cui C, Strasser P, Cuenya B R. Long-range segregation phenomena in shape-selected bimetallic nanoparticles: chemical state effects. ACS Nano, 2013, 7(10): 9195–9204

[42] Menning C A, Chen J G. Regenerating Pt-3d-Pt model electrocatalysts through oxidation-reduction cycles monitored at atmospheric pressure. Journal of Power Sources, 2010, 195(10): 3140–3144

RIGHTS & PERMISSIONS

Higher Education Press