Dual‐Channel σ‐Donation/π‐Backdonation‐Driven ‐p‐p‐ Coupling in Calcium Dual‐Atom Catalysts Enables Accelerated ORR

ABSTRACT Main‐group metal‐based single‐atom catalysts (SACs) are promising candidates as oxygen reduction reaction (ORR) electrocatalysts due to their earth abundance, low cost, and intrinsic resistance to Fenton‐type degradation. However, their delocalized s/p electrons and the directional nature of p orbitals result in intrinsically weak binding to ORR intermediates, limiting catalytic activity. In this study, we develop main‐group dual‐atom catalysts (DACs) based on the s‐block element calcium (Ca 2 ‐N‐HCS) to address this limitation. The dual‐atom design enables a dual‐channel mechanism involving σ‐donation and π‐backdonation through p–p orbital hybridization between Ca 3p orbitals at the Ca 2 dual‐atom sites. Density functional theory (DFT) calculations demonstrate enhanced p–p orbital coupling between Ca 3p and O 2p states, leading to optimized p‐electron configurations that promote O 2 activation and facilitate the adsorption of oxygen intermediates during the ORR. Notably, Ca 2 ‐N‐HCS achieves a half‐wave potential (E 1/2 ) of 0.91 V and exhibits excellent four‐electron ORR selectivity, significantly outperforming its single‐atom analogue. Furthermore, Ca 2 ‐N‐HCS demonstrates exceptional durability and stable performance in Zn–air batteries across a wide temperature range (−40°C–60°C). This work offers mechanistic insights into p–p orbital interactions and presents a rational design strategy for main‐group DACs.