电沉积纳米锥镍的生长机理及其性能的研究

本文通过恒电流沉积法在柔性覆铜基板上制备了具有纳米锥阵列结构的黑色镍层,制备的纳米锥镍的底部约为200 nm, 高度约为1 μm,且大小均一,分布致密。本文探讨了镍电沉积中电流密度和主盐浓度对纳米锥镍结构形貌的影响,结果表明低电流密度和高主盐浓度有利于纳米锥镍的形成。电沉积过程中保持镍离子的供应充足是锥镍结构产生的关键因素之一, 而高电流密度会影响镍离子浓度的浓差极化,从而影响锥镍的成核过程。温度、主盐浓度以及结晶调整剂的变化会导致镍颗粒的形貌发生圆包状和针锥状结构的相互转化。温度升高具有一定的细化晶粒作用,锥镍结构需要在大于50 ^oC的条件下生成。结晶调整剂能够改变沉积过程中的晶面择优生长,且可以调控镍晶粒的形貌,使得生成的锥结构分布均匀, 颗粒细致。结果表明,在4.0 mol·L^-1 NH₄Cl和1.68 mol·L^-1 NiCl₂·6H₂O体系中沉积出分布均匀的纳米锥镍阵列结构。本文利用氯化铵作为纳米锥镍的晶体改性剂,通过分子动力学模拟理论上分析了NH₄⁺在镍表面的吸附过程。计算结果表明镍不同晶面上NH₄⁺吸附能的差异引起各晶面镍沉积速率的差异, 从而导致纳米锥镍阵列的形成。本文呢进一步结合形貌表征,提出了纳米锥镍阵列的电沉积生长的两步生长机理,包括前期的成核生长和后期的核生长过程,前期成核过程为优势生长,生成大量的晶核, 为锥镍的生长提供了生长位点,而后期的核生长过程表现为锥状镍核的择优生长, 最终形成完整均匀的锥镍阵列结构。本文制备的纳米锥镍结构还具有优异的亲水性和良好的吸光效果, 对于近紫外和可见光的吸收率大于95%, 具有较好的应用前景。

Mechanism and Application of Nickel Nano-Cone by Electrodeposition on a Flexible Substrate

Nano-array structure possesses promising prospect in power supply, optical device and electronic manufacturing. In this paper, a black nickel nano-cone array was prepared on a flexible substrate by galvanostatic deposition and the corresponding factors involved in the fabrication of nickel nano-cone array was explored. Experimental results showed that a large current density and low main salt concentration were not favored to the formation of cone nickel structure. It was also found that ammonium chloride, as the crystal modifier, was crucial to deposit the uniform nano-cone array. In addition, the growth mechanism of nickel nano-cone was further studied by molecular dynamics simulation. The excellent wettability and light absorption of nickel nano-cone array were investigated, which demonstrates potential applications of the nickel nano-cone array.