双金属片
过电位
材料科学
双功能
电催化剂
石墨氮化碳
催化作用
碳纳米管
析氧
电化学
法拉第效率
化学工程
金属
纳米技术
电极
化学
物理化学
有机化学
光催化
工程类
冶金
作者
Xiaopeng Han,Wei Zhang,Xiaoya Ma,Cheng Zhong,Naiqin Zhao,Wenbin Hu,Yida Deng
标识
DOI:10.1002/adma.201808281
摘要
Hybrid materials composed of transition-metal compounds and nitrogen-doped carbonaceous supports are promising electrocatalysts for various electrochemical energy conversion devices, whose activity enhancements can be attributed to the synergistic effect between metallic sites and N dopants. While the functionality of single-metal catalysts is relatively well-understood, the mechanism and synergy of bimetallic systems are less explored. Herein, the design and fabrication of an integrated flexible electrode based on NiCo2 S4 /graphitic carbon nitride/carbon nanotube (NiCo2 S4 @g-C3 N4 -CNT) are reported. Comparative studies evidence the electronic transfer from bimetallic Ni/Co active sites to abundant pyridinic-N in underlying g-C3 N4 and the synergistic effect with coupled conductive CNTs for promoting reversible oxygen electrocatalysis. Theoretical calculations demonstrate the unique coactivation of bimetallic Ni/Co atoms by pyridinic-N species (a Ni, Co-N2 moiety), which simultaneously downshifts their d-band center positions and benefits the adsorption/desorption features of oxygen intermediates, accelerating the reaction kinetics. The optimized NiCo2 S4 @g-C3 N4 -CNT hybrid manifests outstanding bifunctional performance for catalyzing oxygen reduction/evolution reactions, highly efficient for realistic zinc-air batteries featuring low overpotential, high efficiency, and long durability, superior to those of physical mixed counterparts and state-of-the-art noble metal catalysts. The identified bimetallic coactivation mechanism will shed light on the rational design and interfacial engineering of hybrid nanomaterials for diverse applications.
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