Patiño Cárdenas Juan, Encinas Armando, Ramírez Villegas Rossana, de la Torre Medina Joaquín
Instituto de Investigaciones en Materiales - Unidad Morelia, Universidad Nacional Autónoma de México Antigua Carretera a Pátzcuaro No. 8701 Col. Ex Hacienda de San José de la Huerta C. P. 58190 Morelia Mexico
División de Materiales Avanzados, Instituto Potosino de Investigación Científica y Tecnológica A. C. Caminio a la Presa 2055 78216 San Luis Potosí, SLP Mexico.
RSC Adv. 2021 Jul 28;11(42):25892-25900. doi: 10.1039/d1ra04198c. eCollection 2021 Jul 27.
A novel electrochemical methodology for the growth of arrays of Ni and Co nanowires (NWs) with linear and non-linear varying micro-height gradient profiles (μHGPs), has been developed. The growth mechanism of these microstructures consists of a three-dimensional growth originating from the allowed electrical contact between the electrolyte and the edges of the cathode at the bottom side of porous alumina membranes. It has been shown that the morphology of these microstructures strongly depends on electrodeposition parameters like the cation material and concentration and the reduction potential. At constant reduction potentials, linear Ni μHGPs with trapezoid-like geometry are obtained, whereas deviations from this simple morphology are observed for Co μHGPs. In this regime, the μHGPs average inclination angle decreases for more negative reduction potential values, leading as a result to more laterally extended microstructures. Besides, more complex morphologies have been obtained by varying the reduction potential using a simple power function of time. Using this strategy allows us to accelerate or decelerate the reduction potential in order to change the μHGPs morphology, so to obtain convex- or concave-like profiles. This methodology is a novel and reliable strategy to synthesize μHGPs into porous alumina membranes with controlled and well-defined morphologies. Furthermore, the synthesized low dimensional asymmetrically loaded nanowired substrates with μHGPs are interesting for their application in micro-antennas for localized electromagnetic radiation, magnetic stray field gradients in microfluidic systems, non-reciprocal microwave absorption, and super-capacitive devices for which a very large surface area and controlled morphology are key requirements.
已经开发出一种新型电化学方法，用于生长具有线性和非线性变化微高度梯度轮廓（μHGPs）的镍和钴纳米线（NWs）阵列。这些微观结构的生长机制包括三维生长，其源于电解质与多孔氧化铝膜底部阴极边缘之间允许的电接触。结果表明，这些微观结构的形态强烈依赖于电沉积参数，如阳离子材料、浓度和还原电位。在恒定还原电位下，可获得具有梯形几何形状的线性镍μHGPs，而钴μHGPs则观察到偏离这种简单形态的情况。在这种情况下，对于更负的还原电位值，μHGPs的平均倾斜角减小，导致微观结构在横向更扩展。此外，通过使用简单的时间幂函数改变还原电位，可获得更复杂的形态。使用这种策略使我们能够加速或减速还原电位，以改变μHGPs的形态，从而获得凸形或凹形轮廓。这种方法是一种新颖且可靠的策略，可将具有可控且明确形态的μHGPs合成到多孔氧化铝膜中。此外，合成的具有μHGPs的低维非对称负载纳米线基底因其在用于局部电磁辐射的微天线、微流体系统中的磁杂散场梯度、非互易微波吸收以及超级电容装置中的应用而备受关注，对于这些应用而言，非常大的表面积和可控形态是关键要求。
