Department of Applied Chemistry and Biotechnology, Graduate School of Engineering, Chiba University, Yayoi-cho 1-33, Inage-ku, Chiba, 263-8522, Japan.
Research and Utilization Division, Japan Synchrotron Radiation Research Institute/SPring‒8, Kouto 1-1-1, Sayo-gun, Hyogo, 679-5148, Japan.
Nat Commun. 2018 Nov 5;9(1):4378. doi: 10.1038/s41467-018-06917-4.
Highly active catalysts for the oxygen reduction reaction are essential for the widespread and economically viable use of polymer electrolyte fuel cells. Here we report the oxygen reduction reaction activities of single‒crystal platinum electrodes in acidic solutions containing tetraalkylammonium cations with different alkyl chain lengths. The high hydrophobicity of a tetraalkylammonium cation with a longer alkyl chain enhances the oxygen reduction reaction activity. The activity on Pt(111) in the presence of tetra‒n‒hexylammonium cation is eight times as high as that without this cation, which is comparable to the activities on PtCo(111) and PtNi(111) electrodes. Hydrophobic cations and their hydration shells destabilize the adsorbed hydroxide and adsorbed water. The hydrophobic characteristics of non‒specifically adsorbed cations can prevent the adsorption of poisoning species on the platinum electrode and form a highly efficient interface for the oxygen reduction reaction.
对于聚合物电解质燃料电池的广泛应用和经济可行性而言，高效的氧还原反应催化剂是必不可少的。在此，我们报告了在含有不同链长的四烷基铵阳离子的酸性溶液中单晶铂电极的氧还原反应活性。具有较长烷基链的四烷基铵阳离子的高疏水性增强了氧还原反应活性。在存在四正己基铵阳离子的情况下，Pt(111)的活性是没有这种阳离子时的八倍，与 PtCo(111)和 PtNi(111)电极的活性相当。疏水性阳离子及其水合壳会破坏吸附的氢氧化物和吸附水的稳定性。非特异性吸附阳离子的疏水性特征可以防止毒化物质在铂电极上的吸附，并形成高效的氧还原反应界面。
