CuNi alloy anchored on dual-substrate TiOx/N-doped carbon nanofibers as a bifunctional electrocatalyst for rechargeable zinc-air batteries

Development of non-noble metal-based electrocatalysts to enhance the performance of zinc-air batteries (ZABs) is of great significance, but it remains a formidable challenge due to their poor stability and activity. Herein, a bifunctional CuNi-TiO x /NCNFS electrocatalyst, featuring with electron-rich copper-nickel (CuNi) alloy nanoparticles anchored on titanium oxide/ N-doped carbon nanofibers (TiO x /NCNFS), is constructed by a dualsubstrate loading strategy. The introduction of TiO x has led to a significant increase in the stability of the dual-substrate. The strong electronic interaction between CuNi and TiO x strengthens the anchoring of active metal sites, thus accelerating the electron transfer. Theoretical calculations unclose that NCNFS can regulate the charge distribution of TiO x , inducing the charge transfer from NCNFS -> TiO x -> CuNi, thereby reducing the dband center of Cu and Ni, which is beneficial to the desorption of intermediate oxide species of the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). Therefore, CuNi-TiO x /NCNFS delivers a remarkable bifunctional performance with a low OER overpotential of 258 mV at 10 mA cm-2 and an ORR half wave potential of 0.85 V. When assembled into ZABs, CuNi-TiO x /NCNFS shows a low potential gap of 0.64 V, a higher power density of 149.6 mW cm-2 at 330 mA cm-2 , and an outstanding stability for 250 h at 5mA cm-2 . This study provides a novel approach by constructing dual-substrate to tune the electronic structure of active metal sites for efficient rechargeable ZABs.