Interfacial coupling porous cobalt nitride nanosheets array with N-doped carbon as robust trifunctional electrocatalysts for water splitting and Zn-air battery

Compositional and structural engineering of high-performance catalysts is vital for electrochemical catalysis, but challenges remain in their facile synthesis and efficient controls. Herein, a novel vaporization-nitridation synthesis strategy with simple operation is developed to prepare hierarchically porous cobalt nitride hybrid nano sheets grown on Ni foam by coupling cobalt nitride with N-doped carbon (CoN@NC). Benefitting from the highly open 3D hierarchical porous architecture and strong coupling effect between CoN and NC, the obtained CoN@NC electrode possesses accelerated ion and electron transfer. Moreover, the transform from CoN to CoOOH during water oxidation is confirmed by in-situ Raman characterizations, which together with NC and CoN species afford multiple active sites. The optimized CoN@NC-300 exhibits remarkable trifunctional catalytic activity towards OER, HER and ORR. Consequently, a two-electrode electrolyzer based on CoN@NC-300 needs only a voltage of 1.53 V to achieve the current density of 10 mA cm(-2). Moreover, the flexible Zn-air battery assembled with CoN@NC exhibits high performance and superior durability. This work offers a novel method for designing metal nitride hybrids as highly efficient multifunctional electrocatalysts towards electrocatalysis and energy storage.