Materials for ORR Electrocatalysis: Catalytic Center and Substrate Effects

Abstract

One of the most important challenges for polymer electrolyte membrane fuel cells (PEMFCs) in terms of facilitating its widespread commercial use is to improve the performance and durability of the electrocatalyst by developing novel catalysts (precious and non-precious catalytic centers) and support materials. One way to improve the oxygen reduction reaction (ORR) activity of Pt-based catalysts is to control Pt nanoparticles (Pt NPs) size, morphology and the dispersion onto substrates. Carbonyl chemical route for synthesizing Pt NPs facilitate a narrow particle size distributions (about 2-3 nm) [1], and homogeneous dispersion on different substrates [2,3]. A variety of carbon-based materials such as carbon nanotubes (CNT), graphite (HOPG), graphene, carbon nanohorns (CNH) and non-carbonaceous based materials, such as metal oxides (Titania, Yttria, Ceria, etc.,) [4,5] can be used as both catalyst and catalyst support materials. On the way to further explore the substrate effect on non-Pt electrocatalyst, CoSe2and CoO were supported on Carbon, CNH and nitrogen doped nanohorn (NCNH). The activity modulation in non-Pt catalysts was found to be strongly dependent on the morphology as well as the composition of substrate materials. The improved interaction of nitrogen species in NCNH and the metal centers modify the active reaction centers. This modified active reaction centers boost the catalytic activity with minimum overpotential for molecular oxygen reduction in alkaline medium (Figures 1a, b). Preliminary analysis indicates that this improved activity not only constrained in oxygen reduction but other catalytic reaction such as oxygen evolution reaction and hydrogen evolution reaction and further to an application on microfluidic fuel cells.AcknowledgementsAuthors acknowledge the partial support of the European Union’s Seventh Framework Programme (FP7/2007-2013) for the Fuel Cell and Hydrogen Joint Technology Initiative under grant agreement nr 303492 CathCat. SM U acknowledges the financial assistance through Raman-Charpak Fellowship, and JMMH acknowledges CONACyT fellowship. [1] N. Alonso-Vante, Fuel Cell, 2006, 6, 182-189.[2] J. Ma, A. S. Gago, W. Vogel, N. Alonso-Vante, Chemcatchem, 2013, 5, 701-705.[3] L. Timperman, Y.J. Feng, W. Vogel, N. Alonso-Vante, Electrochimica Acta, 2010, 55, 7558-7563.[4] Walter Vogel, Laure Timperman, Nicolas Alonso-Vante, Applied Catalysis A: General, 2010, 377, 167-173.[5] C.Liu , Y.Wei and K.Wang, Chem.Comm., 2010, 46, 2483-2485.