Green hydrogen production from abundant water sources is an important component of renewable energy storage. Water oxidation catalysts are typically considered bound by adsorbate scaling relations, limiting their activity for the oxygen evolution reaction (OER) as well as selectivity between OER and the chlorine evolution reaction (CER) that compete in saline water streams. RuO₂ is highly active for both reactions, and recent measurements have shown the OER activity is greater on undercoordinated, high index facets compared to the lowest-energy (110) facet often studied. The growth of such orientations as epitaxial films, however, can result in appreciable strain and potential surface faceting via its relaxation. We find the activity and selectivity towards OER and CER vary with thickness in epitaxial (101) RuO₂ thin films: OER activity decreases 4x as film thickness increases from 8 nm to 48 nm, while CER activity is comparable. Thus, strain and its relaxation can be used to break scaling relationships between OER and CER, highlighting the important role that defects play in selective oxidation processes on RuO₂ in chloride-containing media.

从丰富的水源中生产绿色氢气是可再生能源储存的重要组成部分。水氧化催化剂通常被认为受吸附质结垢关系的约束，限制了它们对析氧反应 (OER) 的活性以及 OER 和析氯反应 (CER) 在盐水流中竞争的选择性。氧化钌₂对这两种反应都具有很高的活性，最近的测量表明，与经常研究的最低能量 (110) 晶面相比，在欠协调、高指数晶面上的 OER 活性更大。然而，像外延膜这样的取向的生长会通过其弛豫导致明显的应变和潜在的表面刻面。我们发现对 OER 和 CER 的活性和选择性随外延 (101) RuO ₂薄膜的厚度而变化：随着薄膜厚度从 8 nm 增加到 48 nm，OER 活性降低 4 倍，而 CER 活性相当。因此，应变及其弛豫可用于打破 OER 和 CER 之间的比例关系，突出了缺陷在含氯化物介质中RuO _{2选择性氧化过程中的重要作用。}