Electrochemical Deposition of Cr from Cr3+ in the Mixed Electrolyte of [BMIM]OAc/H2O
- 2017年第23卷 
本文在[BMIM]OAc-H2O电解液中研究了Cr3+的电沉积反应. 经循环伏安研究表明, Cr3+的还原属于受扩散控制的分步还原过程, 即Cr3+ + e → Cr2+和Cr2+ + 2e → Cr0. 在40℃下通过Rendle-Sevcik方程计算得到Cr3+的扩散系数为1.2×10-8 cm2/s. 采用计时电流法探讨了Cr的三维瞬时成核机理. 对沉积的铬镀层进行了XRD、SEM表征, 结果表明经600℃氩气保护下煅烧后的镀层由Cr和Cr2O3纳米球状颗粒聚集而成, 其平均粒径为0.48μm. 对40℃，-3.0V条件下所得镀层进行EDX检测，发现Cr与O的能级峰十分明显，其中Cr的质量分数为83.8%. 通过在[BMIM]OAc、[BMIM]BF4和[BMIM]PF6三种离子液体体系中电镀得到的Cr镀层质量的比较, 表明OAc-的确有利于Cr的电沉积.The electrochemical reduction of trivalent chromium ion (Cr3+) to Cr in 1-butyl-3-methylimidazolium acetate ([BMIM]OAc)-H2O mixed electrolyte was investigated. The cyclic voltammograms showed that the electroreduction of Cr3+ in the mixed electrolyte occurred in a two-step process, namely, Cr3+ + e → Cr2+ and Cr2+ + 2e→ Cr0, controlled by the diffusion of Cr3+ to the electrode. The diffusion coefficient of Cr3+ was 1.2×10-8 cm2/s at 40 ℃ obtained by Rendle-Sevcik equation. The chronoamperomograms of the Cr3+ electrodeposition confirmed the three-dimensional instantaneous nucleation mechanism of Cr. The XRD and SEM characterizations on the Cr coating after calcining in argon atmosphere at 600℃ revealed that the coating was composed of Cr and chromium oxide (Cr2O3) nanoparticles with an average particle size of 0.48 μm. The elements of Cr and O were obviously detected from the coating obtained at 40℃ and -3.0V by EDX and the mass fraction of Cr reached 83.8%. Comparison in the qualities of coating layers prepared by Cr electrodepositions in [BMIM]OAc, [BMIM]BF4 and [BMIM]PF6 electrolytes indicated that the OAc- was presented in favor of Cr3+ reduction.