Effect of water on the electrodeposition of copper on nickel in deep eutectic solvents

ABSTRACT

Most studies of metal electrodeposition in ionic liquids dry the electrolyte thoroughly, as water is thought to be detrimental. In some cases, water has a beneficial effect on deposit morphology. The electrodeposition of copper has been studied in 1ChCl: 2EG-water mixtures. It is shown here that the presence of water increases the apparent brightness of the deposit due to changes in the electrodeposit surface feature size, up to a water content of approximately 20 wt-%. This study characterises speciation and mass transport in solution, and shows that diffusion can be controlled independently of speciation. It is shown that there is an optimal water content, which is thought to originate from formation of a bi-continuous micro-emulsion phase in DES-water mixtures. Additionally, the copper species remains in a predominantly ionic medium at low water content but moves to an aqueous environment when water is the main component.     

The morphology and corrosion resistance of electrodeposited Co‐TiO2 nanocomposite coatings

Co‐TiO₂ nanocomposite coatings with various contents of TiO₂ nanoparticles were prepared by electrodeposition in Co sulfate plating bath containing TiO₂ nanoparticles. The influence of the TiO₂ nanoparticles concentration in the bath, of the current density and of sodium dodecyle sulfate (SDS) as anionic surfactant on the morphology, composition, texture, roughness, and microhardness of the coatings was investigated. The morphology and composition of coatings were studied by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The phase structure of coatings was analyzed by X‐ray diffraction (XRD). The results showed that the maximum codeposition of TiO₂ nanoparticles in Co matrix was around 4.5 vol% obtained in 60 g/L TiO₂ in the bath, 30 mA/cm² and 0.15 g/L SDS. The microhardness of coatings was increased up to 504 Hv by increasing TiO₂ concentration in the bath to 60 g/L TiO₂. The electrochemistry tests including potentiodynamic polarization and impedance spectroscopy revealed that by addition of TiO₂ into Co matrix, the corrosion current density, polarization resistance, and charge transfer resistance of Co‐TiO₂ coating were increased compared with Co coating.     

One-step fabrication of heterostructured CoNi-LDH@NiCo alloy for effective alkaline hydrogen evolution

Construction of heterostructured electrocatalyst with interface effect is an effective strategy for enhancing the alkaline hydrogen evolution efficiency, whereas this process often requires complex treatments. Herein, we proposed a one-step electrodeposition method to obtain heterostructured CoNi-LDH@NiCo alloy on Ni foam (NF) through a competition reduction between NO₃^? group and metal cations in the electrolyte. The HER performance for the CoNi-LDH@NiCo alloy achieved the current density of 10 mA cm^?2 at overpotential of 69 mV in 1 M KOH solution, improved 60% for η₁₀ by comparing with the pristine NiCo alloy. Utilizing the specialized adsorption of CoNi-LDH for H₂O and the featured attractiveness of NiCo alloy for H atom, the interface effect of the heterostructure electrocatalyst accelerated the dissociation of water molecules and elevated the catalytic kinetics dramatically. This work points out a potential approach towards the easy construction of inexpensive heterostructured electrocatalysts for HER activity in alkaline medium.     

Structural and optical behavior of electrodeposited black chrome‐graphite encapsulated FeCo nanoparticles composite coatings

Black chrome‐graphite encapsulated FeCo nanoparticles (BC‐GEFeCo NPs) composite coatings were electrodeposited on substrates such as stainless steel, Cu, and Ni‐coated Cu. The major content of the deposited film is contributed by Cr, Fe‐Cr, Fe₂AlCr, and FeCr_0.29Ni_0.16C_0.06 as deduced from X‐ray diffraction. The root‐mean‐square roughness value of black chrome on Ni‐coated Cu employing PbSb anode is measured by atomic force microscopy (nanoindentation) studies as 57.176 nm, which is in satisfactory agreement with the literature value of 53.83 nm. With the addition of GEFeCo Nps, the root‐mean‐square roughness value for BC‐GEFeCo composite coatings on Ni‐coated Cu increases approximately 6.1 times that of black chrome surface. Copyright © 2016 John Wiley & Sons, Ltd.     

脉冲频率对纳米晶镍镀层结构及性能的影响

采用脉冲电沉积方法在黄铜基体上制备纳米晶镍镀层。研究了脉冲频率对镀镍层的微观结构、硬度及耐蚀性的影响。结果表明:直流电沉积制备的镀镍层表现为(111)晶面和(200)晶面的双择优取向,而脉冲电沉积制备的镀镍层仅在(111)晶面表现出择优取向;脉冲电沉积制备的镀镍层的硬度和耐蚀性均高于直流电沉积制备的镀镍层的;不同脉冲频率下制备的镀镍层的硬度没有显著差别,约为5 500 MPa;但不同脉冲频率下制备的镀镍层的耐蚀性存在差别,脉冲频率为0.1kHz时制备的镀镍层在3.5%的NaCl溶液中的耐蚀性最好。     

Modelling of through-hole electrodeposition Part II: Experimental study

Current distribution measurements in through-hole electrodeposition were made on sectioned copper electrodes in a cylindrical flow channel. Two copper plating solutions with the same copper sulfate concentration but with different sulfuric acid concentrations were used. Experiments were conducted potentiostatically and under steady-state conditions. Results were compared with those from the theoretical model.     

脉冲电沉积SiC/TiN颗粒增强Ni-Mo纳米复合镀层研究

采用脉冲电沉积技术在6061铝合金表面制备SiC/TiN颗粒增强Ni-Mo纳米复合镀层。通过在镀层中引入SiC、TiN纳米颗粒并改变电沉积的平均电流密度和占空比,调控复合镀层的微结构,探讨纳米颗粒增强涂层的成膜过程与晶粒细化机理,研究复合镀层的组织结构与耐蚀性、耐磨性的关系。结果表明:双纳米颗粒的加入使镀层结构由锥状向胞状转变,晶粒尺寸由29.86 nm减小至22.79 nm。其中在电流密度为8 A·dm~(-2),占空比为20%时制备的镀层最为均匀致密且Si C/Ti N颗粒复合量最高,分别为1.3%和3.1%(质量分数)。镀层具有典型的fcc结构且呈现出(111)择优取向,纳米颗粒均匀分散在Ni-Mo基体中。Tafel极化和浸泡试验研究表明Ni-Mo复合镀层的腐蚀电流密度为7.08μA/cm~2,相比之下在电流密度为4、8和12 A·dm~(-2)和占空比为40%、60%下制备的Ni-Mo/Si C-Ti N纳米复合镀层腐蚀电流密度分别为4.68、4.12、5.75、4.37和5.53μA/cm~2,分别降低了34%、42%、19%、38%和21%。研究发现在电流密度为8 A·dm~(-2),占空比为20%下制备的纳米复合镀层表现出最好的耐蚀性。与Ni-Mo镀层相比,SiC/TiN颗粒的引入显著地提升了镀层耐磨性。此外,还对脉冲共沉积机理进行了讨论。     

离子液体电沉积铝添加剂的研究进展

离子液体作为一种新型绿色室温电解质,具有蒸气压低、挥发性小、电化学窗口宽等优点,是电沉积Al的理想选择.但是采用离子液体电沉积Al,当沉积时间较长、电流密度较大时,沉积层的晶粒粗大,表面较为粗糙,甚至会出现树枝状沉积,容易剥落,严重影响到Al沉积层的质量与性能.离子液体添加剂可显著改善Al沉积层光亮度、平整度、致密度以及耐腐蚀性能.综述了添加剂对离子液体电沉积Al的影响,重点介绍了添加剂对Al沉积层微观结构、离子液体物理性质、Al沉积层耐腐蚀性能的影响,以及添加剂在离子液体电沉积Al中的作用机理.添加剂通过优化离子液体电导率、黏度等电化学性能与离子放电条件,来控制Al晶粒的形核与生长,从而调整晶粒的形核位置、细化晶粒尺寸、择优晶粒取向,甚至一些无机氯化物添加剂可与Al形成合金,最终获得光亮、平整、致密且耐蚀性能优异的Al沉积层.添加剂在离子液体电沉积Al中主要起整平剂与光亮剂的作用.最后,分析展望了添加剂在离子液体电沉积Al中的应用前景及未来的研究重点.     

温度对电沉积制备Pt-Ni阴极催化剂性能的影响

采用电化学还原法在碳布上电沉积Pt-Ni合金催化剂作为质子交换膜燃料电池阴极。通过循环伏安线性扫描法确定Pt-Ni合金的沉积电位,并在该电位下考察了不同电解液温度下所得催化剂的物理、化学性质及电催化性能。研究表明:在-0.35 V电位下可得到Pt-Ni合金,不同的电解液温度会影响Pt-Ni合金催化剂结构、形貌及组分比,进而影响其催化性能。当电解液温度为50℃时,Pt-Ni合金催化剂具有最佳的催化活性,此时催化剂为较小的球状颗粒,Pt与Ni的原子比接近3∶1,其电化学活性表面积为44.19 m2/g,是电解液温度为70℃下制备的催化剂的1.8倍。适当的温度下电沉积制得的Pt-Ni合金催化剂明显提高了铂对氧还原的催化活性。