Nitrogen‐doped Carbon–CoO_x Nanohybrids: A Precious Metal Free Cathode that Exceeds 1.0 W cm⁻² Peak Power and 100 h Life in Anion‐Exchange Membrane Fuel Cells

Abstract

Efficient and durable nonprecious metal electrocatalysts for the oxygen reduction (ORR) are highly desirable for several electrochemical devices,i ncluding anion exchange membrane fuel cells (AEMFCs). Here,a2D planar electrocatalyst with CoO x embedded in nitrogen-doped graphitic carbon (N-C-CoO x )was created through the direct pyrolysis of am etal-organic complex with aN aCl template.T he N-C-CoO x catalyst showed high ORR activity,indicated by excellent half-wave (0.84 Vv s. RHE) and onset (1.01 Vv s. RHE) potentials.T his high intrinsic activity was also observed in operating AEMFCs where the kinetic current was 100 mA cm À2 at 0.85 V. When paired with ar adiation-grafted ETFE powder ionomer,t he N-C-CoO x AEMFC cathode was able to achieve extremely high peak power density (1.05 Wcm À2 )a nd mass transport limited current (3 Acm À2 ) for ap recious metal free electrode.T he N-C-CoO x cathode also showed good stability over 100 hours of operation with av oltage decayo fo nly 15 %a t6 00 mA cm À2 under H 2 /air (CO 2 -free) reacting gas feeds.The N-C-CoO x cathode catalyst was also paired with avery low loading PtRu/C anode catalyst, to create AEMFCs with atotal PGM loading of only 0.10 mg Pt-Ru cm À2 capable of achieving 7.4 Wmg À1 PGM as well as supporting ac urrent of 0.7 Acm À2 at 0.6 Vw ith H 2 /air (CO 2 free)creating acell that was able to meet the 2019 U.S. Department of Energy initial performance target of 0.6 Va t0 .6 Acm À2 under H 2 /air with aP GM loading < 0.125 mg cm À2 with AEMFCs for the first time.

Poly(fluorenyl aryl piperidinium) membranes and ionomers for anion exchange membrane fuel cells

“…On the other hand, compared to the state-of-the-art polyaromatics-based AEMFCs (<2.08 W cm −2 in H 2 –O 2 with 2.0/2.0 bar back pressure) 17 , 32 , 34 , our present AEMFCs showed higher PPDs. Note that GT- x series and BTMA-HDPE-based AEMFCs employed a high Pt–Ru/C loading of 0.7 mg cm −2 , while the present PFAP-based cells exhibited high performance with a low PGM loading of 0.33–0.42 mg cm −2 44 , 45 .…”

Defect and Doping Co-Engineered Non-Metal Nanocarbon ORR Electrocatalyst

“…Similarly, Hou et al [143] reported N-, B-codoped graphitic carbon nanocage (NB-CN) with defect-rich property, which is a promising trifunctional electrocatalyst for ORR, OER, and HER. Furthermore, the P/N [73,82,125], O/N [114]-codoped, P/S/N [150,151]-tridoped porous nanocarbons with abundant edges or defects have been widely employed as the bi-or trifunctional nanocarbon electrocatalysts for ORR, OER, and HER. These results demonstrated that the co-engineering of heteroatom doping and defect inducing is a general strategy for the enhancement of the electrocatalytic activities for nanocarbon.…”

Mechanisms of Manganese Oxide Electrocatalysts Degradation during Oxygen Reduction and Oxygen Evolution Reactions

“…[13][14] Several recent research papers have also reported promising replacement of PGM-by PGM-free cathodes reaching peak powers > 1 W cm −2 . [15][16] Furthermore, continuous progress in membrane development has drastically increased the initial power performance of AEM-FC, now at par or even higher than that reached with PEM-FCs, at a comparable total PGM loading in the entire membrane-electrode-assemblies. [17][18] This advantage could lead to a significant reduction in the cost of FC technology if PGM loading at the anode of AEM-FC can be significantly reduced or zeroed in the future.…”