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.

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。