The efficiency of oxygen evolution reaction (OER) depends critically on the steric and electronic structures of electrocatalysts. Moreover, a high conductivity of electrocatalysts ensures a fast electron transfer and thus plays a significant role in OER. Therefore, the development of efficient electrocatalysts with synergistically engineered structure and conductivity is urgently needed. Here, we present an ingenious design of manganese-modulated cobalt selenide nanosheets with systematically engineered structure and conductivity for efficient OER. Tailored atomic disorder, tuned electronic structure, and optimized electrical conductivity could be simultaneously realized by Mn modulation, leading to effective generation of active sites and promoted OER rate. The resultant (CoMn)Se₂ catalysts exhibited remarkable electrocatalytic OER performance with a 5.8-fold and 10.8-fold higher activity relative to CoSe₂ and state-of-the-art IrO₂. This work provides a comprehensive understanding on origin of high activity of transition metal non-oxide electrocatalysts and enables the rational design of highly efficient electrocatalysts with precisely engineered structural and electrical properties.

放氧反应（OER）的效率主要取决于电催化剂的空间和电子结构。此外，电催化剂的高电导率可确保快速的电子转移，因此在OER中起着重要的作用。因此，迫切需要开发具有协同设计的结构和电导率的高效电催化剂。在这里，我们提出了锰调制的硒化钴纳米片的巧妙设计，该片具有经过系统设计的结构和电导率，可实现有效的OER。通过Mn调制可以同时实现定制的原子无序，可调节的电子结构和优化的电导率，从而有效地生成活性位点并提高OER率。生成的（CoMn）Se ₂催化剂表现出卓越的电催化OER性能，相对于CoSe ₂和最新的IrO ₂活性高5.8倍和10.8倍。这项工作提供了对过渡金属非氧化物电催化剂高活性起源的全面理解，并使合理设计具有精确设计的结构和电性能的高效电催化剂成为可能。