Ten thousand hour stable zinc air batteries via Fe and W dual atom sites

Durable and highly active oxygen electrocatalysts are crucial to the large-scale application of rechargeable zinc-air batteries.Here we utilize the N 4 unit in phthalocyanine molecule to trap the tungsten atoms scratched off from the tungsten carbide milling balls and place the obtained W-N 4 unit adjacent to the Fe-N 4 units from iron () phthalocyanine, resulting in highly active Fe-N 4 /W-N 4 diatomic sites with well-pronounced 3d-5d hybrid for efficient and durable oxygen electrocatalysis.The electron distribution of the Fe-N 4 site is optimized by the neighboring W-N 4 site, which facilitates the O 2 activation and the desorption of *OH and enhances the catalytic activity of the Fe-N 4 site.Meanwhile, the unsaturated 5 d orbitals and tunable valence of the W atoms could modulate the electronic state of the Fe species, prevent leaching, and further enhance the catalytic stability.The resulting zinc-air battery with Fe,W-N-C air cathode exhibits notable cycling stability and repeatability for over 10,000 h.This enhanced stability highlights the possibility of developing 5 d metalboosted 3 d metal active sites for the fabrication of efficient oxygen electrocatalysts and stable zinc-air batteries.The oxygen reduction reaction (ORR) is an important cathodic reaction in emerging energy technologies such as metal-air batteries and fuel cells, which involves multi-electron and proton-coupling processes 1,2 .Its sluggish kinetics and the high cost of commercial Ptbased electrocatalysts severely limit the widespread commercial applications 3,4 .Among the atomically dispersed metal catalysts, the Fe-N 4 sites with a porphyrin-like structure are widely recognized as one of the most promising sites for ORR [5][6][7][8] .However, the symmetric electron distribution of the Fe-N 4 site and the limited orbital overlap between Fe 3 d and O 2p orbitals increase the energy requirements to activate the O 2 (*O 2 *OOH) [9][10][11] .The strong affinity of OH -on the Fe-N 4 sites hinders the desorption of *OH, resulting in large overpotentials due to the accumulation of OH -12-17 .Moreover, at high potentials, the FeNC/Fe 2+ thermodynamic equilibrium will shift toward the formation of Fe 2+ , and the leaching and dissolution of the Fe sites during the ORR process will cause decrements of the catalytic stability and further limit the commercial applications of the Fe-based catalysts [18][19][20] .Inspired by the Cu-Fe bimetallic atomic structure of cytochrome c oxidase, a natural oxidoreductase often found in animals and plants, researchers realized that they might need another atom with different radii and electronegativities forming bimetallic configuration with Fe to break the electronic density plane symmetry of the Fe-N 4 sites 21 .The interaction between two different atoms may mitigate the dissolution of the Fe center and enhance the catalytic stability 22 .Recently, numerous efforts have been devoted to designing dual-atom catalysts with bimetallic active sites, such as Fe-Co, Fe-Cu, and Fe-Ni [23][24][25][26] .Although these diatomic catalysts exhibit improved ORR catalytic activity relative to single-atom catalysts due to the synergistic effect of the bimetallic sites, the electronic structure of these second metals (3 d) is quite close to Fe, making them less efficient in breaking the symmetrical charge distribution 27 .Therefore, introducing metal atoms that cause more asymmetric electron distribution seems to be a straightforward solution.Wang et al. found that the Ir possesses increased 5 d electronic wave function spatial extent, and can