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Volume 08

Innovative Energy & Research

ISSN: 2576-1463

Advanced Energy Materials 2019

July 11-12, 2019

July 11-12, 2019 | Zurich, Switzerland

21

st

International Conference on

Advanced Energy Materials and Research

Discrete Zn, Co bimetallic sites supported on N doped carbon for high performance oxygen reduction

reaction catalysis

Yufeng Zhao

1

, Ziyang Lu

2

and

Hongguan Li

2

1

Shanghai University, China

2

Yanshan University, China

A

new design of discrete Zn, Co bimetallic sites supported on N-doped carbon was fabricated through a

competitive complexation strategy. Aberration corrected atomic resolution high angle annular dark field

scanning transmission electron microscopy (HAADF-STEM) measurements combined with X-ray absorption

fine structure (XAFS) reveals the existence and the structure of the Zn-Co bimetallic sites. This Zn-Co dual atom

catalysts exhibit significantly improved oxygen reduction catalytic activity compared to single atom catalysts in both

acid and alkaline conditions. Density functional theory (DFT) calculations reveal that the enhanced catalytic activity

can significantly be attributed to the elongated O-O bond length (from 1.23 Å to 1.42 Å), and thus facilitates the

cleavage of O-O bond at the ZnCoN

6

(OH) sites, showing a theoretical over potential of 0.335 V during ORR process.

In-situ XAS study demonstrates that Co serves as the active center during the catalysis. Furthermore, a highly active

sulfur (S)-modified Zn, Co-Nx-C-Sy ORR catalyst is also developed. Besides the elongated O-O band length, the S

doping can further modify the charges around Zn, Co active center and strengthen the interaction with oxygenated

species by decreasing the free energy changes of *O

2

+ e- + H

2

O→*OOH + OH- step. The prepared catalysts show

promising potential in practical applications in both fuel cell and Zn-air batteries. Particularly, the H

2

/O

2

fuel cell

tests based on the Zn-Co atomic pair presents a peak power density of 705 mW cm

-2

along with excellent stability.

yufengzhao@ysu.edu.cn

Innov Ener Res 2019, Volume 08