Introducing oxygen vacancy (Vo) has been considered as an effective and significant method to accelerate the sluggish electrocatalytic nitrogen reduction reaction (NRR). In this work, a series of bimetallic zeolitic imidazolate frameworks based on ZIF-67 and ZIF-8 with varied ratios of Co/Zn have been applied as precursors to prepare Vo-rich Zn-doped Co3O4 nanopolyhedrons (Zn-Co3O4) by a low-temperature oxidation strategy. Zn-Co3O4 presents an ammonia yield of 22.71 μg h-1 mgcat.-1 with a high faradaic efficiency of 11.9% for NRR under ambient conditions. The remarkable catalytic performances are believed to result from the plentiful Vo as the Lewis acid sites and electron-rich Co sites to promote the adsorption and dissociation of N2 molecules. Remarkably, Zn-Co3O4 also demonstrates a high electrochemical stability. This work presents a guiding method for developing a stable and efficient electrocatalyst for the NRR.
Keywords: cobalt oxide; doping; nitrogen reduction reaction; oxygen vacancy.