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在铬镀液(CrO_3/H_2SO_4=250/2.5Wt.)中,电流扫描实验结果表明,铬在玻璃碳电极上沉积需要成核过电位;而在铜电极上不需要成核过电位,其晶核由电极表面氧化膜(CuO CrOH)还原生成的金属Cr提供。铬电沉积前后,CrO_3还原机理不同,H_2SO_4 的作用也不同,沉积前,H_2SO_4的作用主要是活化电极表面,促使CrO_3还原,同时还使表面氧化膜溶解。沉积后,H_2SO_4 则起着保持电极表面附近阴极膜相对稳定的作用,还可能与 Cr(Ⅳ)形成易还原的配合物。
In the Cr plating solution (CrO_3 / H_2SO_4 = 250 / 2.5Wt.), The results of current scanning experiments show that the deposition of chromium on the glassy carbon electrode requires nucleation overpotential, while the nucleation overpotential is not required on the copper electrode. The nucleus is provided by the metal Cr produced by reduction of the electrode surface oxide film (CuO CrOH). Before and after Cr electrodeposition, the mechanism of CrO_3 reduction is different, and the effect of H_2SO_4 is also different. Before the deposition, the effect of H_2SO_4 is mainly to activate the electrode surface and promote the reduction of CrO_3, meanwhile dissolving the surface oxide film. After deposition, H_2SO_4 plays a role of keeping the cathode film near the surface of the electrode relatively stable and may also form an easily reducible complex with Cr (Ⅳ).