Common-Ion Effect Triggered Highly Sustained Seawater Electrolysis with Additional NaCl Production

Pengsong Li; Shiyuan Wang; Imran Ahmed Samo; Xingheng Zhang; Zhaolei Wang; Cheng Wang; Yang Li; Yiyun Du; Yang Zhong; Congtian Cheng; Wenwen Xu; Xijun Liu; Yun Kuang; Zhiyi Lu; Xiaoming Sun

doi:10.34133/2020/2872141

Common-Ion Effect Triggered Highly Sustained Seawater Electrolysis with Additional NaCl Production

Research (Wash D C). 2020 Sep 24:2020:2872141. doi: 10.34133/2020/2872141. eCollection 2020.

Authors

Pengsong Li¹, Shiyuan Wang¹, Imran Ahmed Samo¹, Xingheng Zhang¹, Zhaolei Wang¹, Cheng Wang², Yang Li¹, Yiyun Du³, Yang Zhong¹, Congtian Cheng¹, Wenwen Xu⁴, Xijun Liu⁵, Yun Kuang¹, Zhiyi Lu^{4

6}, Xiaoming Sun¹

Affiliations

¹ State Key Laboratory of Chemical Resource Engineering, Beijing Advanced Innovation Centre for Soft Matter Science and Engineering, College of Chemistry, Beijing University of Chemical Technology, Beijing 100029, China.
² Chinese Research Academy of Environmental Sciences Institution, Beijing 100012, China.
³ State Nuclear Electric Power Planning Design & Research Institute Co., Ltd., Beijing, China.
⁴ Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201 Zhejiang, China.
⁵ Center for Electron Microscopy and Tianjin Key Lab of Advanced Functional Porous Materials, Institute for New Energy Materials & Low-Carbon Technologies, School of Materials and Engineering, Tianjin University of Technology, Tianjin 300384, China.
⁶ University of Chinese Academy of Sciences, Beijing 100049, China.

Abstract

Developing efficient seawater-electrolysis system for mass production of hydrogen is highly desirable due to the abundance of seawater. However, continuous electrolysis with seawater feeding boosts the concentration of sodium chloride in the electrolyzer, leading to severe electrode corrosion and chlorine evolution. Herein, the common-ion effect was utilized into the electrolyzer to depress the solubility of NaCl. Specifically, utilization of 6 M NaOH halved the solubility of NaCl in the electrolyte, affording efficient, durable, and sustained seawater electrolysis in NaCl-saturated electrolytes with triple production of H₂, O₂, and crystalline NaCl. Ternary NiCoFe phosphide was employed as a bifunctional anode and cathode in simulative and Ca/Mg-free seawater-electrolysis systems, which could stably work under 500 mA/cm² for over 100 h. We attribute the high stability to the increased Na⁺ concentration, which reduces the concentration of dissolved Cl^- in the electrolyte according to the common-ion effect, resulting in crystallization of NaCl, eliminated anode corrosion, and chlorine oxidation during continuous supplementation of Ca/Mg-free seawater to the electrolysis system.