Abstract: Ga is usually extracted from alkaline solution with low Ga concentration by electrodeposition method in industry, where the hydrogen evolution side reaction and low mass transfer rate are the main reasons for the low current efficiency. In this work, three-dimensional porous electrodes were applied for Ga electrodeposition on account of their high surface area. The hydrogen evolution characteristics of the different electrode materials (foam metal and porous carbon) were studied. And on this basis, Ga electrodeposition behavior of each material under different electrolysis temperatures and current density was researched. The results showed that Cu foam and graphite felt (GF) had low hydrogen evolution activity, but the electrodeposition performance of Ga on the two electrodes was very different. The current efficiency (QE) of Cu foam at 40℃ and 0.1 A/cm2 was 22.5%, which was much higher than that of Cu plate (10.7%). Under the same conditions, the QE value of GF electrode was only 9.6%, which was lower than that of Cu plate and would be related to the hydrophobicity of the electrode surface. The electrodeposition behavior of Ga on electrodes with high hydrogen evolution activity (Fe foam, Ni foam, and reticulated vitreous carbon) was greatly affected by electrolysis temperature and current density. At high current density, the Fe foam electrode showed a QE value only second to that of Cu foam, and Ga electrodeposition was difficult to occur at low current density. The electrodeposition of Ga occurred only below the melting point of Ga (20℃) at Ni foam and reticulated vitreous carbon (RVC) electrodes, but it was difficult to occur at 40℃ above the melting point of Ga due to the high activity of the electrodeposited liquid Ga. Therefore, the hydrogen evolution activity of the electrode materials had a great influence on Ga electrodeposition. The key factors affecting the current efficiency of Ga electrodeposition included electrolysis temperature, current density, and hydrophilicity of the electrode surface.

Key words: Metal Ga, Electrodeposition, Foam metal, Porous Carbon, Current efficiency

摘要： 在工业上，稀散金属镓通常是从碱性溶液中电解提取得到的。在镓电解过程中，由于析氢副反应和传质速率低的原因导致镓电沉积的电流效率很低。本工作采用三维多孔电极电沉积镓，利用三维多孔电极发达的表面积促进镓电沉积过程，研究了不同电极材料(泡沫金属和多孔碳)的析氢特性，结合不同电解温度和电流密度下各材料的镓电沉积行为，揭示三维多孔电极上镓电沉积的特性规律。结果表明，泡沫铜和石墨毡(GF)具有较低的析氢活性，但两种电极的镓电沉积性能差别很大。其中泡沫铜表现出最佳的镓电沉积性能，在温度为40℃、电流密度为0.1 A/cm2条件下镓电沉积的电流效率(QE)达到22.5%，远高于铜片电极(10.7%)；而相同条件下，GF电极的QE值仅为9.6%，低于铜片，这与电极表面的疏水性有关。具有较高析氢活性的泡沫铁、泡沫镍和网状玻璃碳(RVC)电极的镓电沉积过程受电解温度和电流密度的影响较大。在高电流密度下，泡沫铁电极表现出仅次于泡沫铜的QE值，在低电流密度下难以发生镓的电沉积；泡沫镍和RVC电极仅在低于镓熔点(20℃)的条件下发生镓的电沉积，在高于镓熔点(40℃)的条件下，由于电沉积的液态镓的活性较高，容易返溶，难以实现镓的析出。因此，电极材料的析氢活性对镓电沉积性能有较大影响，影响镓电沉积电流效率的关键因素还有电解温度、电流密度及电极表面的亲疏水性。

关键词: 金属镓, 电沉积, 泡沫金属, 多孔碳, 电流效率