Molten NaCl assisted pyrolysis of ZIF-8/PAN electrospun fibers to synthesis 1D cross-linked mesoporous N-rich carbon as oxygen reduction electrocatalysts

Controllable preparation of cross-linked mesoporous carbon materials on a large scale remains challenging. In the present work, a simple NaCl-assisted pyrolysis strategy is proposed here to efficiently convert closed pores into open pores in the pyrolysis products of 2-methylimidazole zinc salt nanoparticles/polyacrylonitrile (ZIF-8/PAN) electrospun fibers to prepare 1D cross-linked mesoporous N-rich carbon-based oxygen reduction reaction (ORR) electrocatalyst. The total specific surface area of micropores and mesopores was significantly increased from 162 m 2 /g to 1069 m 2 /g (mesopores: 704 m 2 /g). The ORR catalytic activity of open pore was superior to that of closed pore with more positive onset potential (0.96 vs . 0.85 V) and half-wave potential (0.79 vs . 0.72 V), larger limiting current density (5.23 vs . 3.62 mA cm −2 ) and electron transfer number (3.89 vs . 3.15). Such enhanced performance was attributed to the transformation from closed to open pores which greatly improved the mass transfer performance and the number of active sites.