金属氢氧化物电沉积过程电极/溶液界面pH变化的原位研究

采用自制的界面pH测量复合装置,原位研究了不同沉积电位下Ni（OH）2电沉积过程中电极/溶液界面pH的动态变化.实验结果表明,阴极过电位对电极表面pH变化起着至关重要的作用,同时电极表面沉积物使得界面微化学环境更加复杂.当阴极表面施加一定电位后,电极/溶液界面pH值快速上升后达到平衡,且阴极过电位越大,达到平衡pH值的时间越短,界面pH值越高.并结合界面pH值变化和Ni（OH）2相关热力学数据,讨论了阴极表面金属氢氧化物电化学沉积机理.

In-situ Study on pH Changes at the Electrode/Solution Interface During the Electrodeposition Process of Metal Hydroxides

The pH changes at the substrate/solution interface were in-situ measured with a self-designed pH composite equipment during the Ni （OH）2 electrodeposition process at different potentials. The ex- perimental results showed that the cathode overpotential was crucial for the pH change at the electrode/ solution interface, and at the same time, the complexity of the interracial microchemical environment would further increase owing to the electrochemical precipitation at the electrode surface. While a poten- tial was applied at the cathode, the interfacial pH fast increased at the electrodeposition initial stage, then achieved a balance value. The results indicated that the larger the electrodeposition overpotential was, the less it took to achieve the pH balance as well as the higher the pH balance value was. Both the inter- facial pH changes and the thermodynamic constants of nickel hydroxide were used to discuss the reaction mechanism for the metal hydroxide electrodeposition at the cathode surface.