Pursuing nonprecious doped carbon with Pt-like electrocatalytic N2H4 oxidation activity for hydrazine fuel cells (HzFCs) remains a challenge. Herein, we present a Fe/N-doped carbon (Fe-NC) catalyst with mesopore-rich channel and highly dispersed Fe-N sites incorporated in N-doped carbon, as an analogue of hydrazine dehydrogenase (HDH), showing the structure-dependent activity for electrocatalytic oxidation of N2H4. The maximal turnover frequency of the N2H4 oxidation reaction (HzOR) over the Fe-N sites (62870 h-1) is 149-fold that over the pyridinic-N sites of N-doped carbon. The Fe mass activity of HzOR and maximal power density of HzFCs driven by Fe-NC approximately surpass those of Pt/C by 2.3 and 2.2 times, respectively. Theoretical calculation reveals that the Fe-N sites improve the dehydrogenation process of HzOR-related intermediates. One of the roles of the mesoporous structure in Fe-NC resembles that of a substrate channel in HDH for enhancing the transport of N2H4 besides exposing Fe-N sites and improving storage capacity of HzOR-related species.
Keywords: Fe/N-doped carbon; electrocatalysis; fuel cells; hydrazine dehydrogenase; hydrazine oxidation.