Sign inversion of surface stress-charge response of bulk nanoporous nickel actuators with different surface states
Sign inversion of surface stress-charge response of bulk nanoporous nickel actuators with different surface states
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不同表面状态的块体纳米多孔镍执行器的表面应力-电荷响应的符号反演
DOI：
10.1039/c6cp02535h
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发表时间：
2016
影响因子：
3.3
通讯作者：
Zhang Zhonghua
中科院分区：
文献类型：
--
作者：
Bai Qingguo;Si Conghui;Zhang Jie;Zhang Zhonghua
表面应力电荷系数ζ是一个基本的材料参数，它反映了表面应力对表面电荷变化的响应。ζ的符号和数量在纳米结构金属的电化学诱导激活中起着至关重要的作用。在这里，我们首次研究了块体纳米多孔镍(NP-Ni)在强(NaOH)和弱(NaF)吸附电解液中的电化学驱动和相关的应力-电荷系数。结果表明，对于表面清洁的NP-Ni，ζ为正常的负值，而对于氧化物覆盖的表面，ζ为异常的正值。有趣的是，被氧化的Np-Ni即使在阴极电位窗口也不能恢复传统的ζ负值。此外，在不同的电势窗口(相同的电解液)或不同的电解液(强吸附或弱吸附)中，可逆应变幅度和所涉及的电荷也有很大的不同。此外，还用密度泛函理论(DFT)计算了不同表面态的Np-Ni的电化学驱动行为。在某些方面，NP-Ni的情况确实不同于金或铂等纳米多孔贵金属的情况。我们的发现为理解纳米结构金属的电化学驱动提供了有用的信息，并且可以基于富含地球的金属如镍、钴等来开发新型的致动器或传感器。
The surface stress–charge coefficient, ζ, is a fundamental material parameter and reflects the response of surface stress to the change of superficial charge. The sign and the quantity of ζ play a crucial role in electrochemically induced actuation of nanostructured metals. Here, for the first time, we address the electrochemical actuation and the associated stress–charge coefficients of bulk nanoporous nickel (np-Ni) in both strongly (NaOH) and weakly (NaF) adsorbed electrolytes. The results reveal a normal negative value of ζ for the np-Ni with the clean surface, and unusual positive values of ζ for the oxide-covered surface. Interestingly, the oxidized np-Ni cannot recover the conventional negative value of ζ even in the cathodic potential window. Moreover, the reversible strain amplitude and the involved charge are quite different in distinct potential windows (the same electrolyte) or in different electrolytes (strongly or weakly adsorbed). In addition, density functional theory (DFT) calculations have been performed to understand the electrochemical actuation behaviors of the np-Ni with different surface states. In some aspects, the scenario of the np-Ni indeed differs from that of nanoporous noble metals like Au or Pt. Our findings provide useful information on understanding the electrochemical actuation of nanostructured metals, and novel actuators or sensors could be developed based upon earth-abundant metals like Ni, Co, and so forth.