Modulating Electronic Environment and Coordination Structure of Ruthenium with Ultralow Loading Atomic Nickel toward Highly Reversible Li–O₂ Batteries

The atomic-scale catalyst has attracted growing interests with great potential for next-generation energy storage systems, owing to its extremely high atomic utilization efficiency (≈100%) and superior catalytic activity. However, due to the lack of control over coordination environments and electronic density, it remains a significant challenge to precisely construct a redox-active single-atom site in electrochemical reactions. Herein, a direct bimetallic modification strategy is reported to modulate the electronic environment and coordination structure of ruthenium with ultra-low loading atomic nickel (NiRu─N/rGO). Through a series of characterization (e.g., HAADF-STEM and XAFS), it can be found the dispersed atomic nickel sites are immobilized on the ruthenium interface by forming the new chemical heteroatom bonds (Ni─Ru), which will further reduce the grain size, tune coordination structure and tailor the electronic state of ruthenium through the electron transfer and redistribution. Interestingly, the above elaborately designed Ni─Ru heterogeneous bimetallic catalyst can be expected to enhance the electrocatalytic reactivity at the cathode/anode sides of Li–O₂ battery (LOB) system, and the working mechanisms of above are revealed through the carefully designed in situ experiments and theoretical calculations. This work will provide a novel research paradigm for the design of high-performance LOBs towards practical applications.