Oxygen Reduction Reaction Causes Iron Leaching from Fe-N-C Electrocatalysts

Author(s):  
Yu-Ping Ku ◽  
Konrad Ehelebe ◽  
Markus Bierling ◽  
Florian Speck ◽  
Dominik Seeberger ◽  
...  

Abstract The electrochemical activity of modern Fe-N-C electrocatalysts in alkaline media is on par with that of platinum. For successful application in fuel cells, however, also high durability and longevity must be demonstrated. Currently, design and synthesis of simultaneously active and stable platinum group metal-free electrocatalysts is hindered by a limited understanding of Fe-N-C degradation, especially under operando conditions. In this work, using a gas diffusion electrode half-cell coupled with inductively coupled plasma mass spectrometry setup, Fe dissolution is studied under more realistic conditions, i.e. real catalyst layer and current densities up to 125 mA·cm-2. Varying the rate of oxygen reduction reaction, we show a remarkable correlation between Faradaic electrode charge and Fe dissolution. This finding is rationalized assuming that oxygen reduction and Fe dissolution reactions are interlinked, likely through a common intermediate formed during the Fe3+/Fe2+ redox transitions in coordinated Fe cations. Moreover, such linear correlation allows an introduction and use of a simple metric (stability number). Hence, in the current work, a powerful tool for a more applied stability screening of different electrocatalysts is introduced, which allows on the one hand fast performance investigations under more realistic conditions, and on the other hand more advanced mechanistic understanding of Fe-N-C degradation in catalyst layers.

2016 ◽  
Vol 72 ◽  
pp. 140-143 ◽  
Author(s):  
Rohan Gokhale ◽  
Yechuan Chen ◽  
Alexey Serov ◽  
Kateryna Artyushkova ◽  
Plamen Atanassov

NANO ◽  
2018 ◽  
Vol 13 (01) ◽  
pp. 1850006 ◽  
Author(s):  
Zhongliang Deng ◽  
Qingfeng Yi ◽  
Yuanyuan Zhang ◽  
Huidong Nie ◽  
Guang Li ◽  
...  

In this study, we report the findings that the C–N composites containing Ni and Co (Ni1Co1/C–N, Ni3Co1/C–N, Ni6Co1/C–N, Ni9Co1/C–N, Ni[Formula: see text]Co0/C–N and Ni0Co[Formula: see text]/C–N) can be produced by direct pyrolysis of the NiCo-doped polyaniline (PANI) precursors in N2 atmosphere at 800[Formula: see text]C and show efficient electroactivity for oxygen reduction reaction (ORR) in alkaline media. Distribution and compositions of the catalysts were characterized by SEM, TEM, EDS and XRD techniques. The catalysts were loaded on carbon paper to prepare gas diffusion electrodes, in which electrocatalytic activity for ORR in alkaline media was investigated by voltammetric techniques. The ORR current density on these carbon paper-supported NiCo/C–N catalysts exhibits a linear increase with the negative shift of ORR potential. The ORR onset potential is around [Formula: see text]0.2[Formula: see text]V (versus Ag/AgCl) in alkaline media. Among the prepared catalysts, the catalyst Ni6Co1/C–N presents the largest ORR current density, which is 68.5[Formula: see text]mA[Formula: see text]cm[Formula: see text]@[Formula: see text]0.8[Formula: see text]V (versus Ag/AgCl) in alkaline media. Moreover, Ni6Co1/C–N catalyst also presents good electrocatalytic activity stability for ORR.


2020 ◽  
Vol 9 (1) ◽  
pp. 843-852
Author(s):  
Hunan Jiang ◽  
Jinyang Li ◽  
Mengni Liang ◽  
Hanpeng Deng ◽  
Zuowan Zhou

AbstractAlthough Fe–N/C catalysts have received increasing attention in recent years for oxygen reduction reaction (ORR), it is still challenging to precisely control the active sites during the preparation. Herein, we report FexN@RGO catalysts with the size of 2–6 nm derived from the pyrolysis of graphene oxide and 1,1′-diacetylferrocene as C and Fe precursors under the NH3/Ar atmosphere as N source. The 1,1′-diacetylferrocene transforms to Fe3O4 at 600°C and transforms to Fe3N and Fe2N at 700°C and 800°C, respectively. The as-prepared FexN@RGO catalysts exhibited superior electrocatalytic activities in acidic and alkaline media compared with the commercial 10% Pt/C, in terms of electrochemical surface area, onset potential, half-wave potential, number of electrons transferred, kinetic current density, and exchange current density. In addition, the stability of FGN-8 also outperformed commercial 10% Pt/C after 10000 cycles, which demonstrates the as-prepared FexN@RGO as durable and active ORR catalysts in acidic media.


2021 ◽  
Author(s):  
Suojiang Zhang ◽  
jiayao Cui ◽  
Qingjun Chen ◽  
Xiaojin Li

The high cost and limited supply of platinum has driven intensive research into the use of non-platinum group metal (PGM-free) as cathode oxygen reduction reaction (ORR) catalysts for proton exchange...


ChemSusChem ◽  
2014 ◽  
Vol 7 (12) ◽  
pp. 3356-3361 ◽  
Author(s):  
Zhiming Cui ◽  
Minghui Yang ◽  
Hao Chen ◽  
Mengtian Zhao ◽  
Francis J. DiSalvo

2019 ◽  
Vol 71 ◽  
pp. 234-241 ◽  
Author(s):  
Yun Sik Kang ◽  
Yoonhye Heo ◽  
Jae Young Jung ◽  
Yeonsun Sohn ◽  
Soo-Hyoung Lee ◽  
...  

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