Role of boric acid in nickel nanotube electrodeposition: a surface-directed growth mechanism

Conductive carbon paint: An efficient way to electrodeposit metallic nanowires by using porous membranes

The present work demonstrates that conductive carbon paint, used for sample preparation in electron microscopy, can be a more straightforward and as-effective substitute for the metallic layer deposition usually used for the electrodeposition of metallic nanowires within porous membranes. AFM images demonstrated the good surface quality of the carbon layer. Raman spectroscopy confirmed the high crystallinity of carbon and high density of π-electrons. The electrical conductivity of the carbon layer was estimated using the linear sweep voltammetry technique. This new cathode was employed to grow continuous (Ni) and composition-modulated (Ni/Cu) nanowires within alumina templates, starting from aqueous solutions of Ni²⁺ and Cu²⁺ mixed salts. The obtention of metallic copper and nickel, and their separation can be readily observed by scanning electron microscopy and elemental mapping by EDS.

Hydrogen Bubble-Directed Tubular Structure: A Novel Mechanism to Facilely Synthesize Nanotube Arrays with Controllable Wall Thickness

Nanowire arrays can be conveniently fabricated by electrodeposition methods using porous anodized alumina oxide templates. They have found applications in numerous fields. Nanotube arrays, with their hollow structure and much enhanced surface-to-volume ratio, as well as an additional tuning parameter in tube wall thickness, promise additional functions compared with nanowire arrays. Using a similar fabrication method, we have developed a facile and general method to fabricate metallic nanotubes (NTs). Using Ni NTs as a model system, the mechanism of the hydrogen-assisted NT growth was postulated and confirmed by controlling the hydrogen formation with conductive salts in an electrodeposition solution, which improves the H₂ concentration but prevents the large H₂ bubbles from blocking the nanochannel of a template. The controlled hydrogen generation forces the growth along the wall of nanochannels in the templates, leading to the NT formation. The magnetic properties can be controlled by the NT wall thickness, making these NTs useful for various applications.

Recycled Cobalt from Spent Li-ion Batteries as a Superhydrophobic Coating for Corrosion Protection of Plain Carbon Steel

A new recycling and film formation scheme is developed for spent Li-ion batteries, which involves the combination of ascorbic-assisted sulfuric leaching and electrodeposition to fabricate a corrosion resistance superhydrophobic coating. The idea behind the simultaneous use of sulfuric and ascorbic is to benefit from the double effect of ascorbic acid, as a leaching reducing agent and as morphological modifier during electrodeposition. Quantum chemical calculations based on the density functional theory are performed to explain the cobalt-ascorbate complexation during the electrocristalization. The optimum parameters for the leaching step are directly utilized in the preparation of an electrolyte for the electrodeposition process, to fabricate a superhydrophobic film with a contact angle of >150° on plain carbon steel. The potentiodynamic polarization measurments in 3.5 wt % NaCl showed that boric-pulsed electrodeposited cobalt film has 20-times lower corrosion current density and higher corrosion potential than those on the non-coated substrate.

Synthesis of Co nanotubes by nanoporous template-assisted electrodeposition via the incorporation of vanadyl ions

We report a facile fabrication concept for nanotubes (NTs) based upon template-assisted electrodeposition, which is widely applied for metallic nanowire (NW) synthesis. Co NTs have been synthesized into nanoporous anodized aluminum oxide (AAO) templates via electrodeposition by simply adding a small amount of chemicals including vanadyl ions (VO²⁺).

Carbon and metal nanotube hybrid structures on graphene as efficient electron field emitters

We report a facile and efficient method for the fabrication of highly-flexible field emission devices by forming tubular hybrid structures based on carbon nanotubes (CNTs) and nickel nanotubes (Ni NTs) on graphene-based flexible substrates. By employing an infiltration process in anodic alumina oxide (AAO) templates followed by Ni electrodeposition, we could fabricate CNT-wrapped Ni NT/graphene hybrid structures. During the electrodeposition process, the CNTs served as Ni nucleation sites, resulting in a large-area array of high aspect-ratio field emitters composed of CNT-wrapped Ni NT hybrid structures. As a proof of concepts, we demonstrate that high-quality flexible field emission devices can be simply fabricated using our method. Remarkably, our proto-type field emission devices exhibited a current density higher by two orders of magnitude compared to other devices fabricated by previous methods, while maintaining its structural integrity in various bending deformations. This novel fabrication strategy can be utilized in various applications such as optoelectronic devices, sensors and energy storage devices.

Fast electrodeposition, influencing factors and catalytic properties of dendritic Cu–M (M = Ni, Fe, Co) microstructures

Dendritic Cu–M (M = Fe/Co/Ni) microstructures with good catalytic performances were successfully prepared through a rapid electrodeposition route.