To enable future large-scale generation of hydrogen via proton exchange membrane (PEM) electrolysis, utilization of scarce iridium-based catalysts required for the oxygen evolution reaction (OER) has to be significantly lowered. To address this question, the facile synthesis of a highly active TiO₂ supported iridium oxide based OER catalyst with reduced noble metal content and an Ir-density of the catalyst powder as low as 0.05–0.08 g_Ir cm^-3 is described in this work. A high surface area corrosion-resistant titania catalyst support homogeneously coated with a 1-2 nm thin layer of amorphous IrOOH_x is oxidized in molten NaNO₃ between 350-375°C. This procedure allows for a controllable phase transformation and crystallization to form a layer of interconnected IrO₂ nanoparticles of ≈2 nm on the surface of the TiO₂ support. The increase in crystallinity is thereby accompanied by a significant increase in conductivity of up to 11 S cm^-1 for a 30 wt% Ir loaded catalyst. Oxidized samples further display a significantly increased stability with less detectable Ir dissolution under OER conditions. With a mass-based activity of 59 A g^-1 at an overpotential of 300 mV, the electrocatalytic activity is maintained at the level of the highly active amorphous IrOOH_x phase used as precursor and outperforms it at higher current densities through the increased conductivity. MEA measurements with catalyst loadings of 0.2-0.3 mg cm^-2 further confirm the high catalytic activity and initial stability at industrially relevant current densities. The introduced synthesis approach therefore shows a path for the fabrication of novel highly active and atom-efficient oxide supported catalysts with complex nanostructures and thin homogenous nanoparticle coatings that allows a future large-scale application of PEM electrolysis technology without restrictions by the natural abundance of iridium.

为了实现未来通过质子交换膜（PEM）电解大规模生产氢气，必须显着降低析氧反应（OER）所需的稀有铱基催化剂的利用率。为了解决这个问题，一种高活性TiO 2的简便合成₂基于支持氧化铱具有降低的贵金属含量与催化剂粉末为低的作为0.05-0.08克的Ir-密度OER催化剂_铱厘米^-3在这项工作中描述. 均匀涂覆有 1-2 nm 薄层无定形 IrOOH _x的高表面积耐腐蚀二氧化钛催化剂载体在熔融 NaNO _{3 中}被氧化在 350-375°C 之间。该过程允许可控的相变和结晶以在TiO ₂载体的表面上形成≈2nm的互连IrO ₂纳米颗粒层。因此，对于负载为 30wt% Ir 的催化剂，结晶度的增加伴随着电导率的显着增加，最高可达 11 S cm ^-1。氧化的样品在 OER 条件下进一步显示出显着增加的稳定性和更少的可检测的 Ir 溶解。在300 mV 的过电位下，基于质量的活性为 59 A g ^-1，电催化活性保持在高活性无定形 IrOOH _{x 的水平}相用作前体并通过增加的电导率在更高的电流密度下优于它。催化剂负载量为 0.2-0.3 mg cm ^{-2 的}MEA 测量进一步证实了在工业相关电流密度下的高催化活性和初始稳定性。因此，引入的合成方法展示了一种制备具有复杂纳米结构和薄均匀纳米颗粒涂层的新型高活性和原子效率氧化物负载催化剂的途径，该催化剂允许未来大规模应用 PEM 电解技术，而不受铱的天然丰度的限制.