Abstract
Efficient and durable nonprecious metal electrocatalysts for the oxygen reduction (ORR) are highly desirable for several electrochemical devices, including anion exchange membrane fuel cells (AEMFCs). Here, a 2D planar electrocatalyst with CoOx embedded in nitrogen-doped graphitic carbon (N-C-CoOx) was created through the direct pyrolysis of a metal organic complex with a NaCl template. N-C-CoOx showed high ORR activity, with excellent half-wave (0.84 V vs. RHE) and onset (1.01 V vs. RHE) potentials. This high intrinsic activity was translated to operating AEMFCs (containing radiation-grafted polymer electrolyte materials), with the N-C-CoOx catalyst able to achieve extremely high power density (1.05 W cm-2) and mass transport limiting current (3 A cm-2) for a precious metal free electrode. The N-C-CoOx cathode also showed excellent stability over 100 hours of operation at 600 mA/cm2 under H2/air (CO2-free) reacting gas feeds. The N-C-CoOx cathode catalyst was also paired with a very low loading PtRu/C anode catalyst, to create AEMFCs with a total PGM loading of only 0.10 mgPt-Ru cm-2 capable of achieving 7.4W mg-1PGM as well as supporting a current of 0.7 A cm-2 at 0.6 V with H2/air (CO2 free) – creating a cell that was able to meet the 2019 DOE target of initial performance of 0.6 V at 0.6 A cm-2 under H2/air with a PGM loading < 0.125 mg cm-2 with AEMFCs for the first time.