Rational design of single atom catalyst is critical for efficient sustainable energy conversion. However, the atomic-level control of active sites is essential for electrocatalytic materials in alkaline electrolyte. Moreover, well-defined surface structures lead to in-depth understanding of catalytic mechanisms. Herein, we report a single-atomic-site ruthenium stabilized on defective nickel-iron layered double hydroxide nanosheets (Ru₁/D-NiFe LDH). Under precise regulation of local coordination environments of catalytically active sites and the existence of the defects, Ru₁/D-NiFe LDH delivers an ultralow overpotential of 18 mV at 10 mA cm⁻² for hydrogen evolution reaction, surpassing the commercial Pt/C catalyst. Density functional theory calculations reveal that Ru₁/D-NiFe LDH optimizes the adsorption energies of intermediates for hydrogen evolution reaction and promotes the O–O coupling at a Ru–O active site for oxygen evolution reaction. The Ru₁/D-NiFe LDH as an ideal model reveals superior water splitting performance with potential for the development of promising water-alkali electrocatalysts.

单原子催化剂的合理设计对于高效的可持续能源转换至关重要。然而，活性位点的原子级控制对于碱性电解质中的电催化材料至关重要。此外，明确定义的表面结构有助于深入了解催化机制。在此，我们报告了一种稳定在有缺陷的镍铁层状双氢氧化物纳米片（Ru ₁ /D-NiFe LDH）上的单原子位钌。在催化活性位点的局部配位环境和缺陷的存在的精确调节下，Ru ₁ /D-NiFe LDH 在 10 mA cm ^{-2 下}提供了 18 mV 的超低过电位用于析氢反应，超过商业 Pt/C 催化剂。密度泛函理论计算表明，Ru ₁ /D-NiFe LDH 优化了析氢反应中间体的吸附能，并促进了析氧反应的 Ru-O 活性位点处的 O-O 偶联。作为理想模型的 Ru ₁ /D-NiFe LDH 显示出优异的水分解性能，具有开发有前景的水-碱电催化剂的潜力。