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 dual-substrate 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 d-band 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.