Improving oxygen reduction reaction activity and durability of 1.5nm Pt by addition of ruthenium oxide nanosheets

Abstract

The durability of commercial carbon supported Pt nanoparticles with average particle size of 1.5 nm (20 mass% Pt/C) has been improved by the addition of ruthenium oxide nanosheets (RuO2ns) without sacrificing the initial activity towards oxygen reduction reaction.The initial oxygen reduction reaction activity of the composite catalyst was slightly higher than as-received Pt/C. The electrocatalytic activity after consecutive potential cycling tests of the composite catalyst was c.a. 1.3 times higher than non-modified Pt/C. The increased durability of the composite catalyst is attributed to the improved preservation of the electrochemically active Pt surface area with the addition of ruthenium oxide.

Model Electrode Studies of the Electrostatic Interaction between Electrochemically Dissolved Pt Ions and RuO2Nanosheets

“…We consider that the ORR activity shown by the reduced Pt nanoparticles on nanosheet contributes to the higher ORR activity retention rate in practical catalyst. As discussed in our previous papers, [10][11][12] RuO 2 nanosheet modified Pt/C electrocatalyst shows enhanced durability compared to non-modified Pt/C. Certainly, the degradation rate of carbon blacks used in practical catalysts and HOPG used in this model electrode study should be quite different due to the difference in degree of graphitization.…”

“…9 We have reported that the ORR activity and durability of commercial Pt/C are improved by the modification with RuO 2 nanosheets. [10][11][12] Because of the complex structure of the porous carbon support in commercial catalyst coupled with the ultimate thickness of the nanosheet of 1 nm, it was difficult to obtain conclusive evidence to explain the mechanism of the improvement on the catalyst durability. Therefore, studies of a simple model electrode system are desired to understand the enhanced durability of Pt/C electrocatalyst modified with RuO 2 nanosheets.…”

Evidence of Strong Metal-Support Interaction between Pt and Crystalline RuO2Nanosheets by In-Situ AFM

“…We have recently shown that the durability of commercial Pt supported on carbon black can be enhanced with the addition of RuO 2 nanosheet. 17,18 Model electrode studies have elucidated that there is a strong electrostatic interaction between RuO 2 nanosheets and dissolved Pt ions derived electrochemically.19 This strong electrostatic interaction between ionic Pt species in solution and the nanosheets is considered to decrease the loss of dissolved Pt species into electrolyte due to migration.In this study, we present experimental evidence of a strong metalsupport interaction between RuO 2 nanosheet and metallic Pt, which may be another reason for the enhanced durability of RuO 2 nanosheet modified Pt/C. A model electrode system was employed to evaluate the difference in the adsorption strength of metallic Pt on RuO 2 nanosheet and carbon surfaces.…”

“…We have recently shown that the durability of commercial Pt supported on carbon black can be enhanced with the addition of RuO 2 nanosheet. 17,18 Model electrode studies have elucidated that there is a strong electrostatic interaction between RuO 2 nanosheets and dissolved Pt ions derived electrochemically.…”

“…12 We have suggested the use of a highly crystalline RuO 2 nanomaterial, namely RuO 2 nanosheet 13 as an additive to enhance the properties of Pt-based electrocatalyts. [14][15][16][17][18][19] RuO 2 nanosheet is a 2-dimensional RuO 2 nanocrystal which is synthesized by chemical exfoliation of a layered ruthenic acid (H 0.2 RuO 2.1 · 0.9H 2 O). 13 The 2-dimensional nanosheet has high surface/bulk ratio due to the ultimately thin thickness of ∼1 nm and retains the original properties of the bulk oxide such as excellent electronic/protonic conductivity and electrochemical stability.…”