【摘要】 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^-8cm²·s^-1.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和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40oC、-3.0 V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.更多还原

【Abstract】 The electrochemical reduction of trivalent chromium ion(Cr³⁺) t℃r 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^-8cm²·s^-1 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 -3.0 V 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.更多还原