Surface-modulated palladium-nickel icosahedra as high-performance non-platinum oxygen reduction electrocatalysts
Yonggang Feng1 *, Qi Shao1 *, Yujin Ji2 *, Xiaoneng Cui1 , Youyong Li2†（李有勇）, Xing Zhu3 , Xiaoqing Huang1††（黄小青）
1College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Jiangsu 215123, China.
2 Institute of Functional Nano and Soft Materials, Soochow University, Jiangsu 215123, China.
3 Testing and Analysis Center, Soochow University, Jiangsu 215123, China.
*These authors contributed equally to this work.
†Corresponding author.
Sci. Adv.2018，4 : eaap8817
The search for high-performance non-platinum (Pt) electrocatalysts is the most challenging issue for fuel cell technology. Creating bimetallic non-Pt nanocrystals (NCs) with core/shell structures or alloy features has widely been explored as the most effective way for enhancing their electrochemical properties but still suffered from undesirable performance due to the limited interactions between the different components. By addressing the above issue, we report on a new class of active and stable bimetallic non-Pt electrocatalysts with palladium (Pd) icosahedra as the core and nickel (Ni) decorating the surface toward cathodic oxygen reduction reaction (ORR) under alkaline conditions. The optimized Pd6Ni icosahedra with unique interaction between an icosahedral Pd core and surface Ni yield the highest ORR activity with a mass activity of 0.22 A mgPd−1, which is better than those of the conventional Pd6Ni icosahedra with alloy surfaces or Pd-rich surfaces, and even two times higher than that of the commercial Pt/C (0.11 A mgPt−1), representing one of the best non-Pt electrocatalysts. Simulations reveal that the Pd icosahedra decorated with Ni atoms emerged in the subsurface can weaken the interaction between the adsorbed oxygen and Pd (111) facet and enhance the ORR activities due to an obvious shift of d-band center. More significantly, under electrochemical accelerated durability test, the Pd6Ni icosahedra can endure at least 10,000 cycles with negligible activity decay and structural change. The present work demonstrates an important advance in surface tuning of bimetallic NCs as high-performance non-Pt catalysts for catalysis, energy conversion, and beyond.
链接：http://advances.sciencemag.org/content/4/7/eaap8817
