Unraveling the Tandem Effect of Nitrogen Configuration Promoting Oxygen Reduction Reaction in Alkaline Seawater

Abstract Developing seawater‐based high‐performance oxygen reduction reaction (ORR) electrocatalysts is meaningful to renewable energy storage and conversion, and the Fe‐based derivatives encapsulated by nitrogen (N) doped carbon are the typical representative. Nevertheless, unrevealing the mechanism of N configuration to ORR activity and chlorine resistance is still a great challenge. In this work, a feasible strategy is developed to prepare controllable pyridinic/pyrrolic‐N doped carbon‐coated Fe‐based electrocatalysts (Fe x N‐NC). Drawing support from the H 3 PO 4 blocking based in situ Fourier transform infrared spectroscopy (FTIR) test and density‐functional theory (DFT) calculation, the tandem effect of pyridinic‐N and pyrrolic‐N on ORR is proved. Additionally, the low hydrogen peroxide (H 2 O 2 ) yield and 4e − pathway of Fe x N‐NC demonstrate that N doping effectively reduces the adsorption of Cl − , which is consistent with the low Cl − adsorption energy of DFT. The half‐wave potential (E 1/2 ) of Fe x N‐NC for ORR reaches 0.874 V in alkaline seawater, and ZABs assembled with Fe x N‐NC as the air cathode deliver a remarkable power density (162 mW cm −2 ), along with excellent long‐term durability (>400 h).