Double Gyroid Nanostructured Platinum As Highly Durable Oxygen Reduction Reaction Electrocatalyst

Improving the stability of platinum-based polymer electrolyte fuel cells is a key to facilitate their aspired commercialization [1]. The current industry standard Pt nanoparticles are subject to dissolution, agglomeration and detachment of whole particles which lead to a loss of active catalytic surface area [2, 3]. Here we present on an extended 3D nanoporous double gyroid (DG) Pt network structure that displays a superior durability over commercial Pt nanoparticles. The DG Pt catalyst was synthesized on a glassy carbon rotating disk electrode by means of a silica template created by evaporation induced self-assembly using the commercially available Pluronic P84 surfactant. The high surface area DG Pt shows improved catalytic activity for the oxygen reduction reaction (ORR) as measured by the intrinsic kinetic current density compared to commercial Pt nanoparticles. Accelerated stability test was performed by potential cycling up to 10000 cycles and DG Pt displays a greatly enhanced stability compared to commercial Pt nanoparticles. Whereas Pt nanoparticles loose over half of their electrochemical surface area (ECSA) after 10000 cycles, DG Pt maintains over 80% of the initial ECSA. We attribute the superior durability of the DG structure to a very high mechanical stability. The interlocked continuous DG network structure renders the catalyst sinter-proof and not prone to detach from the carbon support as has recently been demonstrated to be major loss mechanisms [3]. The high stability together with a high catalytic activity ensured by the nanometer scale of the DG network structure and good mass-transport properties render DG Pt an excellent and durable ORR catalyst.

References:

[1] Handbook of Fuel Cells: Fundamentals, Technology, and Applications. W. Vielstich, H. A. Gasteiger, A. Lamm, H. Yokokawa, Eds., John Wiley & Sons Ltd, Chichester, (2009).

[2] Y. Shao-Horn, W. Sheng, S. Chen, P. Ferreira, E. Holby, D. Morgan: Topics in Catalysis, Vol. 46 (2007),

p. 285-305.

[3] K. Hartl, M. Nesselberger, K. J. J. Mayrhofer, S. Kunz, F. F. Schweinberger, G. Kwon, M. Hanzlik, U. Heiz, M. Arenz: Electrochimica Acta, Vol. 56, (2010), p. 810-816.