Biomimetic hierarchical engineering enables stable triple-phase boundaries for long-life rechargeable Zn-Air batteries

In-situ growth strategies construct stable triple-phase boundaries. • Molecular-level insight into the enhancement of wettability and dynamics. • Hydrophilic/hydrophobic interfaces selectively promote OER and ORR kinetics. • CoFe-MOF@NCNTs exhibits excellent bifunctional activity (∆E = 0.639 V) and stability. • CoFe-MOF@NCNTs-based RZAB operates stably for over 1320 h. The development of cost-effective non-precious metal catalysts (NPMCs) with high bifunctional activity and stability is vital for advancing rechargeable zinc-air batteries (RZABs). However, simultaneous optimizing of oxygen reduction (ORR) and oxygen evolution (OER) reactions at unified active sites remains challenging. Here, we construct a biomimetic hierarchical porous catalyst featuring stable hydrophilic/hydrophobic triple-phase boundaries through the in-situ growth of nitrogen-doped carbon nanotubes (NCNTs) on hydrophobic CoFe-MOF nanoflowers (CoFe-MOF@NCNTs). The NCNTs network introduces abundant carbon defects and polar nitrogen species that subsequently enrich surface -OH groups, thereby modulating interfacial H 2 O adsorption and establishing a favorable wettability gradient. As a result, CoFe-MOF@NCNTs exhibits outstanding bifunctional oxygen electrocatalysis in alkaline media with a small potential gap of 0.639 V, outperforming commercial Pt/C+RuO 2 (0.695 V). When integrated into RZABs, the devices deliver a high discharge capacity of 796.5 mAh/g Zn , a peak power density of 194.5 mW/cm 2 , and exceptional long-term cycling stability over 1320 h. Moreover, flexible RZABs and liquid Al-air batteries (LAABs) assembled with CoFe-MOF@NCNTs demonstrate excellent mechanical adaptability and promising energy output. This work elucidates the mechanistic role of wettability-engineered interfaces and offers a versatile strategy for designing high-performance bifunctional catalysts toward next-generation portable and wearable energy-storage systems. Download: Download high-res image (275KB) Download: Download full-size image The biomimetic hierarchical porous catalyst, featuring stable hydrophilic/hydrophobic triple-phase boundaries, exhibits remarkable ORR/OER bifunctional activity (ΔE = 0.639 V) and enables long-life Zn-air batteries.