Oxygen reduction reaction on platinum single-crystal electrodes modified with protonic ionic liquid

Abstract

The oxygen reduction reaction (ORR) on the low- and high-index planes of Pt modified with a protonic ionic liquid ([7-methyl-1,5,7-triazabicyclo(4.4.0)dec-5-ene][bis(pentafluoroethylsulfonyl)imide], referred to here as [MTBD][beti]) was studied in 0.1 M perchloric acid solution. The specific activity of the ORR on Pt(111) modified with [MTBD][beti] was 3.1 times higher than that on unmodified Pt(111), while the ORR was deactivated on modified Pt(100). [MTBD][beti] slightly enhanced the ORR activity of the Pt n(111)–(111) planes (where n = 2–9). These results show that a larger (111) terrace is essential for a marked increase in the ORR activity on Pt electrodes modified with [MTBD][beti]. Although the ratio of the increase in the activity of n(111)–(111) was lower than that of Pt(111), Pt(331) = 3(111)–(111) showed the highest ORR activity after [MTBD][beti] modification. The effects of MTBD and beti were also studied separately. MTBD provided the main contribution to the increase in ORR activity, giving the highest activity at a concentration of 2.0–3.5 × 10–5 M, whereas beti affected the ORR activity only slightly.

Keywords

• Pt single crystal electrodes
• High-index planes
• Protonic ionic liquids
• [MTBD][beti]
• Oxygen reduction reaction
• Electrocatalysis