Water electrolysis (WE) powered by renewable energy represents a pivotal pathway for large-scale hydrogen production. However, its heavy reliance on scarce, high-purity freshwater increasingly conflicts with global water-stress realities. Thus, the direct use of abundant nonpure water sources, such as seawater and salt-lake water, has emerged as a critical research frontier. This perspective provides a comprehensive, cross-technology analysis of the underlying principles, technical challenges, and recent advances in this field. First, alkaline, proton exchange membrane (PEM), anion exchange membrane (AEM), and solid oxide electrolysis pathways were compared, considering water-quality tolerance, energy efficiency, and durability. Subsequently, the specific chemistry of seawater and salt-lake electrolytes was examined, highlighting chloride-induced anode corrosion, competitive chlorine evolution, and cathodic mineral deposition as dominant failure modes. The state-of-the-art mitigation strategies were systematically summarized: (i) protective layers (MnO x , and Lewis-acidic oxides) that selectively block Cl – while preserving oxygen evolution reaction (OER) kinetics; (ii) oxygen-containing anion (PO 4 3– and SO 4 2– ) modification of layered double hydroxides to repel chloride via electrostatic and intercalation effects; (iii) chloride-induced surface reconstruction that unexpectedly activates lattice-oxygen–mediated oxygen evolution reaction pathways; and (iv) system-level designs including highly alkaline electrolytes, permselective chloride-blocking anodes, pH-asymmetric cells, and decoupled redox cycles. Finally, we outline key remaining gaps and future research directions, offering guidance for advancing sustainable hydrogen production from nonpure water sources.
Zhang et al. (Tue,) studied this question.