Mimicking Hydrazine Dehydrogenase for Efficient Electrocatalytic Oxidation of N<sub>2</sub>H<sub>4</sub> by Fe–NC
Yan Zheng, Fei He, Mingxu Chen, Jin Zhang, Guangzhi Hu, Delong Ma, Jinghua Guo, Huailin Fan, Wei Li, Xun Hu
Abstract
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.