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Metal coordination determines the catalytic activity of IrO2 nanoparticles for the oxygen evolution reaction
Journal of Catalysis ( IF 6.5 ) Pub Date : 2022-06-04 , DOI: 10.1016/j.jcat.2022.05.023
Danilo González , Mariona Sodupe , Luis Rodríguez-Santiago , Xavier Solans-Monfort

H2 production through water electrolysis is a promising strategy for storing sunlight energy. For the oxygen evolution reaction, iridium oxide containing materials are state-of-the-art due to their stability in acidic conditions. Moreover, precious metal content can be reduced by using small nanoparticles that show high catalytic activities. We performed DFT calculations on a 1.2 nm large IrO2 Wulff-like stoichiometric nanoparticle model (IrO2) with the aim of determining the factors controlling the catalytic activity of IrO2 nanoparticles. Results show that at reaction conditions tetra- and tricoordinated iridium centers are not fully oxidized, the major species being IrO(OH) and IrO(OH)2, respectively. Although the computed overpotential show that all centers present relatively similar reactivities, low coordinated iridium centers tend to be more active than the pentacoordinates sites of the well-defined facets. These low coordination sites are likely more abundant on amorphous nanoparticles, which could be one of the factors explaining the higher catalytic activity observed for non-crystalline materials.



中文翻译:

金属配位决定了 IrO2 纳米粒子对析氧反应的催化活性

通过水电解生产H 2是一种很有前途的太阳能储存策略。对于析氧反应,含氧化铱的材料由于其在酸性条件下的稳定性而成为最先进的材料。此外,可以通过使用具有高催化活性的小纳米粒子来降低贵金属含量。我们对 1.2 nm 大的 IrO 2 Wulff 样化学计量纳米粒子模型 (IrO 2 )进行了 DFT 计算,目的是确定控制 IrO 2纳米粒子催化活性的因素。结果表明,在反应条件下,四配位和三配位的铱中心没有被完全氧化,主要物质是 IrO(OH) 和 IrO(OH) 2, 分别。尽管计算的过电位显示所有中心都呈现出相对相似的反应性,但低配位铱中心往往比明确定义的刻面的五坐标位点更活跃。这些低配位点在无定形纳米颗粒上可能更丰富,这可能是解释非晶材料观察到的较高催化活性的因素之一。

更新日期:2022-06-04
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