Multiscale Engineering of N-CoP@NC/3D-NC Bifunctional Electrocatalyst: Synergistic Interface and Doping Design for...

The development of cost-effective, high-performance bifunctional oxygen electrocatalysts is pivotal for zinc-air batteries (ZABs). Here, we report an innovative multiscale optimization strategy that synergistically integrates hierarchical structural design with atomic-level electronic engineering to fabricate an encapsulated N-doped cobalt phosphide catalyst (N-CoP@NC) embedded within a 3D porous nitrogen-doped carbon scaffold (3D-NC). The macro/mesoscopic design employs NaCl-templated 3D-NC frameworks to create optimized mass transport pathways and high surface area, while the atomic/nanoscale engineering achieves precise nitrogen doping into CoP lattices and strategic construction of metal-carbon interfaces, enabling electronic structure modulation. Mechanistic insights from theoretical calculation reveal that nitrogen incorporation fundamentally induces an electron-depletion effect in the carbon shell, precisely tuning the adsorption energy of oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) intermediates and significantly improving intrinsic activity. The resulting N-CoP@NC/3D-NC catalyst exhibits exceptional bifunctional performance with a half-wave potential of 0.80V versus RHE towards ORR and an overpotential of 380 mV at 10 mA cm^-2 for OER. When deployed in ZABs, it achieves a large peak power density of 127 mW cm^-2 and robust cycling stability (683 h with <4% efficiency decay), surpassing Pt/C+Ir/C benchmarks. This work pioneers a novel electrocatalyst design paradigm via synergistic interface engineering and heteroatom doping.