The atomic-level interfacial regulation of single metal sites through heteroatom doping can significantly improve the characteristics of the catalyst and obtain surprising activity. Herein, nickel single-site catalysts (SSCs) with dual-coordinated phosphorus and nitrogen atoms were developed and confirmed (denoted as Ni-P_xN_y, x = 1, 2 and y = 3, 2). In CO₂ reduction reaction (CO₂RR), the CO current density on Ni-P_xN_y was significantly higher than that of Ni-N₄ catalyst without phosphorus modification. Besides, Ni-P₁N₃ performed the highest CO Faradaic efficiency (FE_CO) of 85.0%–98.0% over a wide potential range of −0.65 to −0.95 V (vs. the reversible hydrogen electrode (RHE)). Experimental and theoretical results revealed that the asymmetric Ni-P₁N₃ site was beneficial to CO₂ intermediate adsorption/desorption, thereby accelerating the reaction kinetics and boosting CO₂RR activity. This work provides an effective method for preparing well-defined dual-coordinated SSCs to improve catalytic performance, targetting to CO₂RR applications.

Electrocatalytic ammonia oxidation reaction (EAOR) provides an ideal solution for on-board hydrogen supply for fuel cells, while the lack of efficient and durable EAOR catalysts has been a long-standing obstacle for its practical application. Herein, we reported that the defect engineering via in-situ electrochemically introducing oxygen vacancies (Vo) not only turns the inactive CuO into efficient EAOR catalyst but also achieves a high stability of over 400 h at a high current density of ~ 200 mA·cm⁻². Theoretical simulation reveals that the presence of Vo on the CuO surface induces a remarkable upshift of the d-band center of active Cu site closer to the Fermi level, which significantly stabilizes the reaction intermediates (*NH_x) and efficiently oxidizes NH₃ into N₂. This Vo-modulated CuO shows a different catalytic mechanism from that on the conventional Pt-based catalysts, paving a new avenue to develop inexpensive, efficient, and robust catalysts, not limited to EAOR.