AUTHOR=Zhou Yu , Zhang Yan , Xu Xianzhen , Zhao Shenlong , Guo Ziyi , Wu Kuang-Hsu , Tan Chunhui , Wang Zonghua 

TITLE=Bimetallic Metal-Organic Framework Derived Metal-Carbon Hybrid for Efficient Reversible Oxygen Electrocatalysis

JOURNAL=Frontiers in Chemistry

VOLUME=7

YEAR=2019

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2019.00747

DOI=10.3389/fchem.2019.00747

ISSN=2296-2646

ABSTRACT=<p>Development of cost-effective electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is key to enabling advanced electrochemical energy conversion technologies. Here, a novel nitrogen-doped metal-carbon hybrid (NiCo/CN) with a unique 3D hierarchical structure, consisting of uniformly distributed bimetallic nanoparticles encapsulated by partially graphitized N-doped carbon shells, is fabricated by a one-step pyrolysis of a nanoscale metal-organic framework as precursor, which exhibits excellent activity for both ORR and OER. The surface chemical changes on the carbon hybrid probed by X-ray photoelectron spectroscopy (XPS) reveal the presence of favorable electronic interaction at the metal-nitrogen-carbon interface. Remarkably, the NiCo/CN catalyst prepared at high temperature (800°C) manifests a comparable performance to a commercial Pt/C catalyst for the ORR, but also superior stability, path selectivity and methanol tolerance. On the other hand, the <italic>E</italic><sub>onset</sub> (1.48 V vs. reversible hydrogen electrode) and <inline-formula><mml:math id="M4" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mrow><mml:msub><mml:mi>E</mml:mi><mml:mrow><mml:mtext>j</mml:mtext><mml:mo>=</mml:mo><mml:mn>10</mml:mn><mml:mtext>mA/cm</mml:mtext></mml:mrow></mml:msub></mml:mrow><mml:mn>2</mml:mn></mml:msup></mml:math></inline-formula> of NiCo/CN-800 for OER is very close to the state-of-the-art noble catalyst RuO<sub>2</sub> (E<sub>onset</sub> = 1.46 and <inline-formula><mml:math id="M6" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mrow><mml:msub><mml:mi>E</mml:mi><mml:mrow><mml:mtext>j</mml:mtext><mml:mo>=</mml:mo><mml:mn>10</mml:mn><mml:mtext>mA/cm</mml:mtext></mml:mrow></mml:msub></mml:mrow><mml:mn>2</mml:mn></mml:msup></mml:math></inline-formula>) along with superior stability over 20 h of operation. The excellent catalytic property is attributable to the unique nanostructure, high porosity and the constructive synergistic effects of the elements M, N, and C.</p>