ACS Applied Materials & Interfaces
·
2020
·
IF 8.758
Yanan Wang,Shuguang Zhang,Xiuxia Meng,Ting Wang,Yu Feng,Weimin Zhang,Yu-Shi He,Yucheng Huang,Naitao Yang,Zi-Feng Ma
Heterogeneous electrocatalytic reactions only occur at the interface between the electrocatalyst and reactant. Therefore, the active sites are only necessary to be distributed on the surface of the electrocatalyst. Based on this motivation, here, we demonstrate a systematic study on surface tuning for a carbon-based electrocatalyst from metal-free (with the heteroatoms N and S, NS/C) to metal-containing surfaces (with Co, N, and S, CoNS/C). The CoNS/C electrocatalyst was obtained by pyrolyzing the Co precoordinated and p-toluenesulfonate-doped polypyrrole (PPy). It was found that the coordination of Co on the PPy ring tuned the final carbon electrocatalyst into a catalyst with a CoNx moiety-rich surface. In addition, the as-synthesized CoNS/C was determined to have a very high loading of cobalt up to 2.02 wt %. The pyrolysis of the cobalt-containing precursor tends to proceed toward a characteristic of a higher sp2 carbon content, a higher surface area, and more nitrogen as well as active nitrogen sites than its metal-free counterpart. The most distinguished feature for such a catalyst is that the truly most active component is only distributed on the surface, in contrast with that of the conventional metal–N-based catalyst present throughout the bulky structure. Especially, the electrocatalytic activity toward oxygen evolution reaction (OER) has been investigated experimentally and theoretically. The results showed that the OER performance of the carbon-based electrocatalyst was remarkably boosted after the introduction of Co with an overpotential decrease from 678 to 345 mV at 10 mA cm–2. Furthermore, CoNS/C displayed an excellent durability upon a long-term measurement. The apparent activation energy measurements revealed that the metal-rich surface contributed to overcome the energy barrier for OER. In addition, density functional theory calculations have been conducted to explain the correlated OER mechanism. This study is expected to provide an effective strategy for the design and the synthesis of highly active metal–nitrogen-type electrocatalysts with a high metal loading for various electrocatalytic reactions.
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Journal of Physical Chemistry C
·
2021
·
IF 4.126
Pengfei Yao,Jing Cao,Xue Gong,Ce Han,Mingbo Ruan,Ping Song,Weilin Xu
The development of catalysts free of platinum-group metals with a high performance for the oxygen reduction reaction (ORR) in proton exchange membrane fuel cells is a grand challenge. Herein, we report zeolitic imidazolate framework-8-based Co, N, and S tridoped carbon frameworks (Co–N–S CFs) with high ORR catalytic activity and remarkable durability in an alkaline medium. Results indicate that the high ORR performance of the Co–N–S CFs could be attributed to the unique 3D structure of carbon frames, the synergistic effect among Co, N, and S, and its high electron conductivity. It is also found that the N and S doped heteroatoms can anchor Co atoms by forming CoNx and CoSx active sites for a highly efficient ORR. The results obtained here can help in the design and understanding of the cost-effective highly active Pt-free electrocatalysts.
研究领域:
材料科学
·
能源化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE ELECTROCHEMICAL SOCIETY
·
2017
·Vol. 164
·期 12
·F1110
·
IF 3.259
Shumin Wang,Yong Qin,Yang Liu,Fuqiang Chu,Yong Kong,Yongxin Tao
Co,N,S-codoped three-dimensional graphene (Co,N,S/3DG) has been fabricated using Co(SCN)2 as the precursor. It has been found that Co,N,S/3DG is a highly efficient bi-functional electrocatalyst for oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER). It exhibits the high catalytic activity comparable to the Pt/C catalyst toward ORR, and the low overpotential of 260 mV to afford the current density of 10 mA cm−2 toward HER. The doping of S can promote the electrocatalytic performance of Co,N-codoped graphene due most likely to the defects induced by sulfur atom. The results provide new clues to design multi-functional electrocatalyst in energy storage and conversion.
研究领域:
材料科学
·
电化学
·
能源转换与存储
✓ 已验证
产品关联
DOI
高影响因子
ELECTROCHIMICA ACTA
·
2019
·
IF 5.383
Jiaxiang Chen,Lei Qiu,Zheling Li,Guanhui Gao,Wenhua Zhong,Peixin Zhang,Yongji Gong,Libo Deng
Oxygen reduction reaction (ORR), oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) are the rate-controlling and/or energy-intensive reactions of numerous energy conversion and storage devices. It is a great challenge to attain a high catalytic efficiency with a single electrocatalyst towards these reactions simultaneously. Herein, a porous carbon was prepared by pyrolysis of chitin with the assistance of CoCl 2 and ZnCl 2 and a subsequent sulfurization process, which resulted in uniform loading of Co, N and S elements. The porous and modified carbon exhibited high catalytic performance towards ORR, OER and HER. Furthermore, the catalyst was used as air electrode to construct Zn-air batteries, which showed a power of 142 mW cm −2 and discharging and charging voltages of 1.3 V and 1.74 V at 1 mA cm −2 after 100 cycles, respectively. When used as both the anode and cathode for water splitting, the voltage to achieve a 10 mA cm −2 electrolysis current was 1.58 V which was stable over 75 h of operation. The performance enhancement is attributed to the etching effect which generates defects in both carbonaceous matrix and the Co 9 S 8 crystallites during the sulfurization , as well as the doping of S and N elements which creates multiple active sites.
研究领域:
材料科学
·
电化学
·
能源存储与转换
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）