Self-templated poly schiff base-Fe derived Fe-N co-doped porous carbon nanosheets for efficient electrocatalysis

Rational design and fabrication of two-dimensional (2D) functional materials is of important significance in tackling fundamental issues for electrocatalysis. Here, a novel synthesis strategy is developed using basic zinc carbonate (BZC) nanosheets as 2D self-template to construct Fe-N_x active sites in porous carbon nanosheets (Fe-N-PCNS). Poly schiff base (PSB) is synthesized by in-situ polymerization reaction on the surface of BZC nanosheets, then coordinates with iron ion to obtain PSB-Fe@BZC complex. During pyrolysis, PSB-Fe@BZC complex undergoes a series process of decomposition of BZC nanosheets, reduction of zinc oxide and zinc evaporation, in which BZC nanosheets plays a decisive role in fabricating hierarchically porous carbon nanosheets with uniformly dispersed Fe-N_x active sites. As a result, Fe-N-PCNS displays an excellent electrocatalytic performance for oxygen reduction reaction with positive half-wave potential (0.91 V), large kinetic limiting current density (54.3 mA cm⁻²), high stability and superior methanol resistance in alkaline media, which surpasses those of Pt/C catalyst. Moreover, Fe-N-PCNS demonstrates remarkable electrocatalytic performance in primary Zn-air batteries with the outstanding discharge durability (with 18 cycles over 100 h). This self-templated strategy provides a new way for the fabrication of unique 2D carbon-based electrocatalysts.