Quantification of the Impact of Residual H2O on Cathodic Behavior in Molten CaCl2 Electrolysis
Quantification of the Impact of Residual H2O on Cathodic Behavior in Molten CaCl2 Electrolysis
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DOI：
10.1007/s40831-022-00516-w
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发表时间：
2022-02
影响因子：
2.4
通讯作者：
S. Natsui;Ryota Shibuya;R. Suzuki;T. Kikuchi;Akihisa Ito;T. Sato;Rei Yamamoto;H. Nogami
中科院分区：
文献类型：
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作者：
S. Natsui;Ryota Shibuya;R. Suzuki;T. Kikuchi;Akihisa Ito;T. Sato;Rei Yamamoto;H. Nogami
熔融CaCl2中的H_2O在电解过程中产生的H_2抑制了金属Ca的金属热还原。用高速成像技术在Ar气氛中电解含H2O的CaCl2，观察阴极周围的H2气泡，以分析CaCl2中H2O的不完全去除，评估了残留H2O对阴极反应的影响。当H_2O含量增加时，H_2气体的生成与钙的电化学沉积同时发生。此外，我们还发现在相同的电位下，阴极电流密度增大。当从直接观察到的气泡体积计算H_2生成量与电化学反应总电量的比率时，从库仑效率估计的H_2生成量是很小的。因此，除了以气泡形式观察到的氢的生成外，由于与沉淀的钙接触而合成氢化钙的可能性很高。
The H2generated during the electrolysis of H2O present in molten CaCl2inhibits metallothermic reduction by metallic Ca. The impact of residual H2O on the cathodic reaction was estimated by electrolyzing H2O-containing CaCl2at 1173 K in Ar atmosphere using high-speed imaging, which visualized the H2bubbles occurring around the cathode, to analyze the incomplete removal of H2O in CaCl2. The H2gas generation occurred simultaneously with the electrochemical deposition of Ca when the H2O content increased. Moreover, we established that the cathodic current density increased with respect to the same potential. The H2generation estimated from the Coulombic efficiency was miniscule when the ratio of H2generation to the total amount of electricity contributing to the electrochemical reaction was calculated from the directly observed bubble volume. Therefore, synthesis of calcium hydride due to contact with precipitated Ca is highly probable, in addition to the H2generation observed in the form of bubbles.Graphical Abstract