Three-dimensional hierarchical conductive metal-organic frameworks/NiFe layered double hydroxide/carbon nanofibers: an efficient oxygen evolution reaction catalyst for Zn-air batteries

The structural and compositional modulation of inexpensive hydroxides is not only important, but also an ongoing challenge for the preparation of efficient oxygen evolution reaction (OER) electrocatalysts. Herein, a three-dimensional (3D) structural catalyst (Co-CAT/NiFe-LDH/CNFs) is successfully synthesized by the in situ growth of a conductive metal-organic framework on NiFe layered double hydroxide nanosheets. Density functional theory (DFT) calculations demonstrated that the sluggish kinetics of the OER can be improved by increasing the conductivity and changing the hydrophilicity of the catalyst. Accordingly, the synergistic effect between Co-CAT and NiFe LDH leads to a superior catalytic performance compared to that of Pt/C. In addition, the as-assembled Zn-air battery exhibits excellent stability and a high power density of 327.09 mW cm(-2) for 56 h and 112.04 mW cm(-2) for 11.5 h in both liquid and solid electrolytes, respectively.