α-Al_2O_3纳米粒子对Co-Ni合金异常共沉积电化学行为的影响

Influence of α-Al_2O_3 Nanoparticles on the Anomalous Electrodeposition of Co-Ni Alloys

为了研究在电化学复合共沉积过程中,惰性纳米粒子和金属离子、电极表面的相互作用,以及由此产生的对合金电化学共沉积行为的影响.本文从两个吸附过程出发:电解液中的金属离子和H+在纳米粒子表面的吸附;纳米粒子迁移到阴极表面,在电极表面的吸附.采用Zeta电势和稳态极化以及电化学交流阻抗(EIS)研究了纳米Al2O3粒子和电解液中的金属离子,和电极表面的相互作用,进而分析了纳米粒子对Co2+和Ni2+还原沉积的影响规律.通过对阻抗数据的拟合,讨论了Al2O3纳米粒子对等效电路中各物理参数的影响.在H+和不同金属离子在纳米粒子上发生竞争吸附的基础上,提出了纳米粒子和合金共沉积的可能反应历程.

The interactions between α Al2O3 nanoparticles and metal ions or electrode surface during composite electrodeposition process were investigated by Zeta potential and electrochemical methods.Zeta potential measurements reveal that Al2O3 nanoparticles have a stronger tendency to adsorb Co2+ on their surface than Ni2+ in sulfamate electrolytes.Steady state polarization and electrochemical impedance spectroscopy (EIS) indicate that the effect of Al2O3 nanoparticles on the Co Ni electrochemical codeposition in different electrolytes (/=1/5 and 5/1) is quite contrary.In nickel rich electrolytes (/=1/5),the Al2O3 particles have an inhibitory action on the reduction of Ni2+,while in cobalt rich electrolytes (/=5/1),Al2O3 particles activate the reduction of Co2+.That nanoparticles exhibit different influence on the reduction of Co2+ and Ni2+ were explained by considering the adsorption of metal ions on nanoparticle surface.Moreover,it can be seen from EIS that besides one capacitive loop at high frequency and one inductive loop at low frequency,the introduction of Al2O3 particles leads to exhibit a further inductive loop at low frequency.According to the simulated results,the electrochemical codeposition mechanism and simulated impedance parameters were analyzed and in good agreement with the experimental results.