RuO2 Nanosheet Modified Pt-Based Catalysts as CO Tolerant PEFC Anode

PtRu/C are presently used as the anode catalyst for residential polymer electrolyte fuel cells. Anode catalysts with increased CO tolerance is desired since trace amounts of CO residing in reformates poisons the catalysts. In addition, catalyst degradation due to gradual loss of Ru is known to occur due to start/stop cycles. Thus efforts have been made to develop CO-tolerant electrocatalysts with high durability. The addition of nanostructured oxides has shown some promising results. In an earlier study, the authors showed that the addition of oxide nanosheets to carbon supported Pt-based catalysts can act as co-catalysts for the oxidation of adsorbed CO and enhance the durability [1-3]. Here we have studied catalyst activity and durability of Pt_xRu_y/C catalysts modified with RuO_2.1 nanosheets (RuO_2.1ns) towards the hydrogen oxidation reaction in the presence of CO.

 RuO_2.1ns were derived from layered K_0.2RuO_2.1.nH₂O [4]. Commercially available Pt_xRu_y/C were modified with RuO_2.1ns following previously described methods [5,6]. Catalytic activity was measured using rotating disk electrodes in 0.1 M HClO₄ (25^oC) in pure H₂ (j(H₂)) or 300 ppm CO/H₂ (j(CO/H₂)). Chronoamperometry was conducted at 20 mV vs RHE at 400 rpm.

 The composite catalyst RuO_2.1ns-Pt/C had the same ECSA and j(H₂) value as Pt/C, indicating that RuO_2.1ns does not impede H₂ diffusion to the Pt surface. The j(CO/H₂) value of RuO_2.1ns-Pt/C was 18% higher than Pt/C.

The j(CO/H₂) value of RuO_2.1ns-PtRu/C after 1000 consecutive cycles between 0.05 and 0.4 V vs. RHE (v = 100 mV/s) was compared with Pt₂Ru₃/C. The initial j(CO/H₂) of RuO_2.1ns-PtRu/C was similar to PtRu/C and Pt₂Ru₃/C. After cycling, the j(CO/H₂) of RuO_2.1ns-PtRu/C was 20% higher than commercial catalysts.

 This work was supported in part by the “Polymer Electrolyte Fuel Cell Program” from the New Energy and Industrial Technology Development Organization (NEDO), Japan.

[1] W. Sugimoto, T. Saida, Y. Takasu, Electrochem. Commun., 8, 411 (2006).

[2] T. Saida, W. Sugimoto, Electrochim. Acta, 55, 857 (2010).

[3] T. Saida, N. Ogiwara, Y. Takasu, W. Sugimoto, J. Phys. Chem. C, 114, 13390 (2010).

[4] W. Sugimoto, H. Iwata, Y. Yasunaga, Y. Murakami, Y. Takasu, Angew. Chem. Int. Ed.,42, 4092 (2003).

[5] D. Takimoto, C. Chauvin, W. Sugimoto, Electrochem. Commun, 33, 123 (2013).

[6] C. Chauvin, T. Saida W. Sugimoto, J. Electrochem. Soc., 161, F318 (2014).