Page 71
conferenceseries
.com
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.cnInnov Ener Res 2019, Volume 08