过电位
化学
无定形固体
析氧
电催化剂
X射线光电子能谱
化学工程
异质结
高分辨率透射电子显微镜
电化学
透射电子显微镜
材料科学
结晶学
物理化学
电极
工程类
光电子学
作者
Yilin Deng,Wei Lai,Lihong Ge,Hua Yang,Jian Bao,Bo Ouyang,Mengxia Ji
出处
期刊:Inorganic Chemistry
[American Chemical Society]
日期:2023-02-24
卷期号:62 (9): 3976-3985
被引量:15
标识
DOI:10.1021/acs.inorgchem.2c04437
摘要
The development of an efficient and low-cost electrocatalyst for oxygen evolution reaction (OER) is the key to improving the overall efficiency of water electrolysis. Here, we report the design of a three-dimensional (3-D) heterostructured Ni9S8/Ni3S2 precatalyst composed of unstable Ni9S8 and inert Ni3S2 components, which undergoes in situ electrochemical activation to generate an amorphous-NiOOH/Ni3S2 heterostructured catalyst. In situ Raman spectroscopy combined with ex situ characterizations, such as X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy, reveals that during the activation, Ni9S8 loses the sulfur element to form nickel oxides and eventually transforms to amorphous NiOOH at O2-evolving potentials, while the Ni3S2 component is rather inert that its majority in the bulk remains, thus forming a 3-D congee-like NiOOH/Ni3S2 heterostructure with the Ni3S2 crystalline particles randomly dispersed among amorphous NiOOH species. Unlike the sparse heterostructure that consists of a layer of NiOOH on top of Ni3S2, our unique congee-like NiOOH/Ni3S2 heterostructure provides plentiful reactive amorphous-crystalline interfacial sites. Moreover, the partial electron transfer between the NiOOH and remaining Ni3S2, benefiting from their dense interfacial sites, contributes to a higher valence state of the Ni3+ active centers in NiOOH, hence optimizing the adsorption of OER intermediates. Density functional theory calculations further disclose that the electronic structure regulation not only optimizes the Gibbs free energy of intermediate adsorption but also tunes the OH* absorption behavior to be exothermic, elucidating the spontaneous occurrence of OH* absorption and hence improves the OER. Therefore, a low overpotential of only 197 mV at an O2-evolving current density of 10 mA/cm2, a small Tafel slope of 38.8 mV/dec, and good stability are achieved on the amorphous-NiOOH/crystalline-Ni3S2 heterostructured catalyst.
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