Metallic NiPS3@NiOOH Core–Shell Heterostructures as Highly Efficient and Stable Electrocatalyst for the Oxygen Evolution Reaction

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• 作者：Bharathi Konkena ; Justus Masa ; Alexander J. R. Botz ; Ilya Sinev ; Wei Xia ; Jörg Koßmann ; Ralf Drautz ; Martin MuhlerWolfgang Schuhmann
• 刊名：ACS Catalysis
• 出版年：2017
• 出版时间：January 6, 2017
• 年：2017
• 卷：7
• 期：1
• 页码：229-237
• 全文大小：633K
• ISSN：2155-5435

文摘

We report metallic NiPS₃@NiOOH core–shell heterostructures as an efficient and durable electrocatalyst for the oxygen evolution reaction, exhibiting a low onset potential of 1.48 V (vs RHE) and stable performance for over 160 h. The atomically thin NiPS₃ nanosheets are obtained by exfoliation of bulk NiPS₃ in the presence of an ionic surfactant. The OER mechanism was studied by a combination of SECM, in situ Raman spectroscopy, SEM, and XPS measurements, which enabled direct observation of the formation of a NiPS₃@NiOOH core–shell heterostructure at the electrode interface. Hence, the active form of the catalyst is represented as NiPS₃@NiOOH core–shell structure. Moreover, DFT calculations indicate an intrinsic metallic character of the NiPS₃ nanosheets with densities of states (DOS) similar to the bulk material. The high OER activity of the NiPS₃ nanosheets is attributed to a high density of accessible active metallic-edge and defect sites due to structural disorder, a unique NiPS₃@NiOOH core–shell heterostructure, where the presence of P and S modulates the surface electronic structure of Ni in NiPS₃, thus providing excellent conductive pathway for efficient electron-transport to the NiOOH shell. These findings suggest that good size control during liquid exfoliation may be advantageously used for the formation of electrically conductive NiPS₃@NiOOH core–shell electrode materials for the electrochemical water oxidation.