催化作用
材料科学
无机化学
可逆氢电极
异质结
氢
氢溢流
化学
化学工程
物理化学
电解质
电极
有机化学
参比电极
光电子学
工程类
作者
Yang Yang,Wei Zheng,Peichen Wang,Zhiyu Cheng,Pengcheng Wang,Jiahe Yang,Changlai Wang,Jitang Chen,Yafei Qu,Dongdong Wang,Qianwang Chen
出处
期刊:ACS Nano
[American Chemical Society]
日期:2024-08-22
标识
DOI:10.1021/acsnano.4c07738
摘要
Improving the catalytic efficiency of platinum group metal-free (PGM-free) catalysts for the sluggish alkaline hydrogen oxidation reaction (HOR) is crucial to the anion exchange membrane fuel cell. Recently, numerous Ni-based heterostructures have been designed based on bifunctional theory to enhance HOR activity by optimizing the binding energy of both H* and OH*; however, their activities are still far inferior to those of PGM catalysts. Indeed, the long transfer pathway for intermediates between different active sites in such heterostructures has rarely been investigated, which could be the reason for the bottleneck. Here, we design a Ni/MoOxHy heterostructure catalyst to promote H* migration from the Ni side to the interface for alkaline HOR via the hydrogen spillover effect. In situ X-ray absorption fine structure, Raman characterizations, H/D kinetic isotope effects, and theoretical calculations have proven facile H* migration from the Ni side to the interface, which further reacts with OH* on the MoOxHy surface. Besides, the hydrogen spillover effect is also beneficial for the preservation of the metallic phase of Ni during the reaction. The catalyst exhibits a high activity with Jk,m of 58.5 mA mgNi–1 and j0,s of 42 μA cmNi–2, which is among the best PGM-free catalysts and is even comparable to some PGM catalysts. It also shows the highest power density (511 mW cm–2) as a PGM-free anode when assembled into fuel cells under moderate back pressure. These findings prove that in addition to optimizing electrophilicity and oxophilicity for active sites, we could also improve the HOR activity from the transfer pathway for intermediates, which provides insight into the design of other efficient HOR catalysts.
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