Promoting Atomically Dispersed MnN4 Sites via Sulfur Doping for Oxygen Reduction: Unveiling Intrinsic Activity and Degradation in Fuel Cells | Zendy

Lin Guo | Zendy; Sooyeon Hwang | Zendy; Boyang Li | Zendy; Fan Yang | Zendy; Maoyu Wang | Zendy; Mengjie Chen | Zendy; Xiaoxuan Yang | Zendy; S. Karakalos | Zendy; David A. Cullen | Zendy; Zhenxing Feng | Zendy; Guofeng Wang | Zendy; Gang Wu | Zendy; Hui Xu | Zendy

Open Access

Promoting Atomically Dispersed MnN₄ Sites via Sulfur Doping for Oxygen Reduction: Unveiling Intrinsic Activity and Degradation in Fuel Cells

Author(s) -

Lin Guo,

Sooyeon Hwang,

Boyang Li,

Fan Yang,

Maoyu Wang,

Mengjie Chen,

Xiaoxuan Yang,

S. Karakalos,

David A. Cullen,

Zhenxing Feng,

Guofeng Wang,

Gang Wu,

Hui Xu

Publication year - 2021

Publication title -

acs nano

Language(s) - English

Resource type - Journals

SCImago Journal Rank - 5.554

H-Index - 382

eISSN - 1936-086X

pISSN - 1936-0851

DOI - 10.1021/acsnano.0c10637

Subject(s) - catalysis , overpotential , proton exchange membrane fuel cell , inorganic chemistry , x ray absorption spectroscopy , chemistry , materials science , electrochemistry , absorption spectroscopy , electrode , biochemistry , physics , quantum mechanics

Carbon supported and nitrogen coordinated single Mn site (Mn-N-C) catalysts are the most desirable platinum group metal (PGM)-free cathode catalysts for proton-exchange membrane fuel cells (PEMFCs) due to their insignificant Fenton reactions ( vs. Fe), earth abundances ( vs. Co), and encouraging activity and stability. However, current Mn-N-C catalysts suffer from high overpotential due to low intrinsic activity and less dense MnN 4 sites. Herein, we present a sulfur-doped Mn-N-C catalyst (Mn-N-C-S) synthesized through an effective adsorption-pyrolysis process. Using electron microscopy and X-ray absorption spectroscopy (XAS) techniques, we verify the uniform dispersion of MnN 4 sites and confirm the effect of S doping on the Mn-N coordination. The Mn-N-C-S catalyst exhibits a favorable oxygen reduction reaction (ORR) activity in acidic media relative to the S-free Mn-N-C catalyst. The corresponding membrane electrode assembly (MEA) generates enhanced performance with a peak power density of 500 mW cm -2 under a realistic H 2 /air environment. The constant voltage tests of fuel cells confirm the much-enhanced stability of the Mn-N-C-S catalyst compared to the Fe-N-C and Fe-N-C-S catalysts. The electron microscopy and Fourier transform XAS analyses provide insights into catalyst degradation associated with Mn oxidation and agglomeration. The theoretical calculation elucidates that the promoted ORR activity is mainly attributed to the spatial effect stemmed from the repulsive interaction between the ORR intermediates and adjacent S dopants.

The content you want is available to Zendy users.

Already have an account? Click here to sign in.

Having issues? You can contact us here

Accelerating Research