Synergistic Cu and Fe-N-C sites on porous carbon fibers for boosting bifunctional oxygen electrocatalysis in rechargeable liquid and flexible Zn-air batteries

The Cu/Fe-N@PCFs catalyst is prepared by electrospinning and pyrolysis. • Cu active species synergize with Fe-N@PCFs to boost the catalytic performance. • Cu/Fe-N@PCFs shows excellent ORR/OER activity with a low ΔE of 0.73 V. • Flexible Cu/Fe-N@PCFs achieves high peak power densities in ZAB and FZAB. The key to advancing Zn-air batteries (ZABs) and flexible Zn-air batteries (FZABs) lies in creating electrocatalysts with flexibility, porosity, high efficiency, and stability. Herein, Cu/Fe-N@PCFs is prepared by electrospinning and pyrolysis. Fe-ZIF-8 serves as a carbon and nitrogen source dispersing Fe sites, and promotes the formation of microporous structures during pyrolysis together with NaCl. Cu species are introduced onto the surface of Fe-N@PCFs to interact with Fe-N x sites and alleviate the Fenton-like effect, synergistically enhancing the bifunctional oxygen electrocatalytic performance toward oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). The fibrous structure improves the peak power density of ZAB and FZAB. The Cu/Fe-N@PCFs exhibits an ORR half-wave potential (E 1/2 ) of 0.865 V (vs. 0.838 V for Pt/C) and an OER overpotential of 370 mV (vs. 305 mV for RuO 2 ) at 10 mA cm −2 . The ZAB achieves a peak power density of 278.2 mW cm −2 (vs. 145.5 mW cm −2 for Pt/C + RuO 2 ) and durability of 190 h. The self-supporting Cu/Fe-N@PCFs is assembled as FZAB, delivering a peak power density of 82.4 mW cm −2 (vs. 16.4 mW cm −2 for Pt/C + RuO 2 ) and durability of 17 h. This study provides significant perspectives on constructing flexible catalysts, potentially advancing the development of ZABs and FZABs. Download: Download high-res image (266KB) Download: Download full-size image