Efficiency of Oxygen Evolution on Iridium Oxide Determined from the pH Dependence of Charge Accumulation
Efficiency of Oxygen Evolution on Iridium Oxide Determined from the pH Dependence of Charge Accumulation
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DOI：
10.1021/acs.jpcc.7b03749
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发表时间：
2017-08
影响因子：
3.7
通讯作者：
Hideshi Ooka;A. Yamaguchi;T. Takashima;K. Hashimoto;Ryuhei Nakamura
中科院分区：
文献类型：
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作者：
Hideshi Ooka;A. Yamaguchi;T. Takashima;K. Hashimoto;Ryuhei Nakamura
人们正在深入研究析氧反应（OER; 2H2O→O2 + 4H+ + 4e -），以产生不依赖化石燃料的能源载体。由于无定形氧化铱（IrOx）等4d/5d稀有金属催化剂比3d金属催化剂表现出更高的活性，阐明这些材料之间的关键机理差异对于合成具有成本效益的OER催化剂具有重要意义。尽管大多数关于OER催化剂的研究都集中在O-O键形成的能量学上，但在这里，我们研究了基于电荷积累的IrOx的OER机制，该机制最近被证明可以确定Mn和Fe氧化物的OER活性。利用Tafel图和小号图进行动力学分析，以及OER起始电位与铱价态变化的pH依赖性的差异表明，铱价态的变化比O-O键的形成更有利。原位倏逝波谱分析表明，与氧配体相反自旋的Ir5+可分配的中间体是该结构的主要组成部分。
The oxygen evolution reaction (OER; 2H2O → O2 + 4H+ + 4e–) is being intensively studied to generate fossil fuel-independent energy carriers. As 4d/5d rare metal catalysts, such as amorphous iridium oxide (IrOx), display higher activity than 3d metal catalysts, elucidating the critical mechanistic differences between these materials is important for the synthesis of cost-effective OER catalysts. Although most studies of OER catalysts have focused on O–O bond formation energetics, here, we examined the OER mechanism of IrOx based on charge accumulation, which was recently shown to determine the OER activity for Mn and Fe oxides. Kinetic analysis using Tafel and trumpet plots, along with the difference in the pH dependence between the OER onset potential and that of iridium valence change, showed that the valence change of iridium is more favorable than O–O bond formation. In situ evanescent wave spectroscopy revealed that an intermediate assignable to Ir5+ with oxygen ligands in opposite spin serves as the ...