Passivation of Nickel Nanoneedles in Aqueous Solutions

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• 作者：Bowei Zhang ; Junsheng Wu ; Xiaogang Li ; Hai Liu ; Boluo Yadian ; R. V. Ramanujan ; Kun Zhou ; Renbing Wu ; Shiji Hao ; Yizhong Huang
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：May 1, 2014
• 年：2014
• 卷：118
• 期：17
• 页码：9073-9077
• 全文大小：404K
• 年卷期：v.118,no.17(May 1, 2014)
• ISSN：1932-7455

文摘

Passivation, a typical electrochemical behavior, involves the formation of a thin layer on the surface of a bulky metal component, which has been assumed to be native, dense, and highly protective to the metal from deterioration. In the present paper, nickel was chosen and prepared into a nanoneedle. A duplex layered passive film grown around the surface of Ni nanoneedle in the alkaline solution (0.1 M NaOH) was observed in TEM, which has a thickness of 4 nm and consists of NiO inner layer and Ni(OH)₂ outer layer. However, the surface of Ni nanoneedle only appears a single inner NiO layer with a thickness of 3 nm after passivation in a strong acid solution (0.1 M H₂SO₄). This could be due to the sufficient H⁺ that inhibits the formation of Ni(OH)₂ outer layer. There may be still a mono- or bimolecular Ni(OH)₂ layer beyond the resolution of TEM. The ultrathin NiO inner layer covers the entire nickel nanoneedle and was determined to be crystalline and coherently oriented with Ni substrate.