Key Takeaways & Executive Findings
- •• • Seawater contains ~0.5 M Cl− ions, which at high current densities can oxidize to chlorine or hypochlorite, competing with the oxygen evolution reaction (OER) and reducing Faraday efficiency while corroding the electrolytic cell. • • The review systematically categorizes chloride suppression strategies into three areas: directional catalyst design for OER, electrolyte composition optimization, and electrolytic cell engineering, each targeting the mitigation of chlorine-induced side reactions. • • Industrial-scale SWE requires addressing both efficiency and durability; the review emphasizes that without effective chloride suppression, the lifespan of electrolytic cells is curtailed, hindering commercialization. • • The review highlights that future development must focus on integrating these strategies to achieve stable, high-efficiency seawater electrolysis, with the goal of meeting projected hydrogen demand of at least 148 million tons annually by 2050.
Abstract
Seawater electrolysis (SWE) is a reusable and convenient avenue for producing hydrogen, offering a promising solution to the energy crisis and global warming. However, poor electrolytic efficiency and irreversible corrosion caused by high concentrations of chlorine severely hinder the commercialization of SWE. To address these challenges, numerous strategies have been proposed in recent years, involving theoretical innovations, directional catalyst design, and electrolyser modification. This review provides a systematic summary of the chlorine-related challenges and solutions encountered in SWE. The chlorine-related theoretical knowledge and challenges in SWE systems are first emphasized. Subsequently, multiple anodic chloride suppression strategies are introduced from three aspects: directional regulation of oxygen evolution catalysts, optimization of electrolyte compositions, and ingenious upgrades of electrolytic cells. Finally, future challenges and development directions for large-scale application of SWE technology are explored. This review offers an in-depth analysis of the chlorine-related challenges encountered in the industrialization of SWE, aiming to accelerate the advancement of this technology toward practical applications.
1. Introduction
Global energy demand growth and the depletion of fossil fuels necessitate renewable alternatives. Hydrogen, with its high energy density (~141.6 MJ/kg), offers a clean and renewable solution. However, conventional hydrogen production relies on fossil fuels, and water electrolysis using freshwater is unsustainable given water scarcity. Seawater electrolysis (SWE) presents an attractive alternative due to the vast seawater reserves, but its commercialization is impeded by the presence of chloride ions (~0.5 M) that cause parasitic chlorine evolution and severe electrode corrosion, reducing efficiency and durability.
This review systematically addresses the chlorine-related challenges in SWE by examining recent advances in three key areas: anode electrocatalyst design to favor OER over chlorine evolution, electrolyte engineering to suppress chloride activity, and innovative electrolytic cell configurations to mitigate corrosion. By integrating these strategies, the review aims to provide a roadmap for developing robust, efficient SWE systems that can meet the projected hydrogen demand of 148 million tons annually by 2050, thereby contributing to a sustainable energy future.
Loading authentic research manuscript (Pages 1–5)...
Junnan Song, Xu Zhang, Guiqiang Pu, Zhenjie Cheng, Chenglong Qiu, Jiacheng Wang (2026). Towards Chlorine-Tolerant Seawater Electrolysis: Anode Electrocatalysts, Electrolyte, and System Design Strategies. SCIENCE CHINA Materials. https://doi.org/10.1007/s40843-025-3865-1
Research & Educational Purpose Only: The translations, structured abstracts, analytical annotations, and data reports provided by SinoGreenTechare intended exclusively for academic research, internal corporate R&D, and educational benchmarking. They do not constitute formal engineering, chemical safety, legal, or professional advice.
Copyright & Intellectual Property Notice: Original copyright of the underlying source articles and experimental data remains with the respective authors, institutions, and original publishing journals. SinoGreenTech claims intellectual property only over its proprietary translations, analytical syntheses, and AEO structured enhancements in accordance with international fair use and academic citation principles.
Frequently Asked Questions
What are the primary mechanisms by which chloride ions interfere with the oxygen evolution reaction (OER) during seawater electrolysis?
Chloride ions (~0.5 M) can be oxidized at the anode to form chlorine or hypochlorite, competing with OER. This side reaction reduces Faraday efficiency and produces corrosive species that degrade electrode materials, ultimately shortening the electrolytic cell's lifespan.
How do anode electrocatalyst design strategies specifically enhance OER selectivity over chlorine evolution in seawater?
Strategies include developing catalysts with higher intrinsic OER activity, tuning the electronic structure to favor OER intermediates, and creating surface architectures that limit chloride adsorption. These approaches aim to shift the reaction kinetics to prefer OER, thereby minimizing chlorine production.
What electrolyte modifications are effective in suppressing chloride-induced corrosion during seawater electrolysis?
Optimizing electrolyte composition, such as adjusting pH, adding specific ions to form protective layers, or using concentrated alkaline conditions, can reduce chloride ion activity and mitigate corrosion. The review discusses these approaches as part of a multi-faceted strategy.
What system-level design upgrades in electrolytic cells help mitigate chlorine-related issues?
Innovations include using membranes or separators that selectively transport ions, designing flow fields to minimize chloride accumulation, and implementing electrode configurations that reduce local chloride concentration. These system upgrades complement catalyst and electrolyte strategies to enhance overall durability.
What are the key challenges for scaling up seawater electrolysis from laboratory to industrial applications?
Challenges include achieving long-term stability at high current densities, maintaining high Faraday efficiency, and ensuring cost-effectiveness. The review emphasizes that integrating catalyst, electrolyte, and system design strategies is essential to overcome these barriers and meet the projected hydrogen demand.
Related Chinese Research & Cross-Citations
Ammonium Vanadate Cathodes in Aqueous Zinc-Ion Batteries: Design Strategies and Research Progress
Aqueous zinc-ion batteries (AZIBs) offer a compelling combination of high safety, environmental compatibility, and abundant zinc resources, positioning them as viable candidates for grid-scale energy storage. Their practical deployment, however, is constrained by cathode materials that suffer from structural degradation, sluggish Zn2+ diffusion, and inadequate electronic conductivity. Ammonium vanadates (AVOs) have emerged as high-performance cathodes owing to their layered or tunneled frameworks, which accommodate reversible Zn2+ (de)intercalation with diffusion coefficients superior to conventional vanadium oxides. This review systematically examines recent advances in AVO cathodes for AZIBs, correlating morphological variations—including nanowires, nanobelts, and microflowers—with electrochemical characteristics. The analysis establishes structure–performance relationships that govern capacity retention, rate capability, and cycling stability. Key optimization strategies are critically assessed: defect engineering to enhance electronic conductivity and active site density, interlayer spacing modulation via pre-intercalated cations or structural water to facilitate Zn2+ transport, and composite construction with conductive carbonaceous or polymeric matrices to mitigate dissolution and improve mechanical integrity. Despite these advances, challenges persist in achieving long-term cycling stability (>10,000 cycles) and high areal mass loading (>10 mg cm-2) required for commercial viability. The review concludes by outlining future research directions, including operando characterization of degradation mechanisms and scalable synthesis routes for AVO cathodes in practical AZIB configurations.
Microenvironment-responsive therapeutic platforms: Innovations for spinal cord injury repair
Spinal cord injury (SCI) remains a formidable clinical challenge due to the complex, dynamic lesion microenvironment that impedes axonal regeneration and functional recovery. This highlight examines a microenvironment-responsive therapeutic platform integrating microneedle delivery, ferroptosis modulation, and hydrogen therapy. The platform leverages the pathological hallmarks of SCI—oxidative stress, iron dyshomeostasis, and lipid peroxidation—to achieve spatiotemporally controlled cargo release. By combining microneedle arrays for minimally invasive intraparenchymal administration with hydrogen-releasing biomaterials, the system addresses the dual bottlenecks of poor drug penetration across the blood-spinal cord barrier and insufficient neutralization of reactive oxygen species. Ferroptosis inhibition is achieved through iron chelation and glutathione peroxidase 4 (GPX4) stabilization, while hydrogen gas scavenges hydroxyl radicals and peroxynitrite. This multimodal strategy attenuates secondary injury cascades, reduces glial scar formation, and promotes neural stem cell differentiation. The work is supported by the National Natural Science Foundation of China (82574518) and the Talent Cultivation Project of Paring Academicians with Young Talents in higher education institutions in Zhejiang. The authors declare no conflict of interest. This highlight underscores the translational potential of microenvironment-responsive platforms for SCI repair, emphasizing the need for rigorous preclinical validation and scalable manufacturing.
Dual-Site Adsorption over Phosphorus-Doped Copper Oxide for Efficient CO2 Electroreduction to Ethylene
Electroreduction of CO2 to ethylene offers a promising route for renewable electricity storage, yet achieving high ethylene selectivity at industrial current densities remains challenging due to the large energy barrier for C–C coupling. Here, we report a “MOF-assisted in situ doping” strategy to introduce the oxophilic nonmetal phosphorus (P) into the copper oxide (CuO) lattice, constructing a localized Cu–P dual-site adsorption configuration for the key *OCCHO intermediate. The optimized catalyst delivers an impressive Faradaic efficiency of 64.6% for ethylene with a partial current density of 646 mA cm-2. Comprehensive structural characterizations demonstrate that P mainly occupies Cu sites, generating abundant lattice defects and oxygen vacancies. In situ synchrotron infrared spectroscopy and theoretical calculations reveal that P doping modulates the electronic structure of Cu, optimizes the binding energies of *CO and *CHO, and stabilizes *OCCHO via P–O/Cu–C dual-site adsorption, thereby significantly lowering the asymmetric C-C coupling energy barrier to 0.74 eV. This work highlights a dual-site microenvironment regulation strategy for CO2-to-ethylene electroreduction.
Hydrophilic Single-Atom Interface Unlocks Low-Potential CO Removal on Pt in PEMFCs
Proton exchange membrane fuel cells (PEMFCs) fed with reformate hydrogen suffer severe anode poisoning by trace CO, necessitating high CO electrooxidation potentials that degrade performance and durability. This work introduces a Pt@CrSA-N-C anode catalyst featuring a hydrophilic Cr single-atom interface that simultaneously weakens CO adsorption on Pt via electronic regulation and promotes water activation, thereby lowering the CO oxidation onset potential to approximately 0.13 V vs. RHE. The onset potential was determined by two independent methods: the first potential at which the background-corrected current exceeds 0 mA cm-2 during CO oxidation reaction tests in a three-electrode system, and the potential at which the forward scan current exceeds the N2 background current in CO-stripping voltammetry. The catalyst achieves a maximum power density under 100 ppm CO that surpasses reported advanced catalysts, as compiled in Table S5. Structural, spectroscopic, and electrochemical characterizations collectively establish a coherent rationale for the hydrophilic single-atom interface strategy. This approach addresses the longstanding trade-off between CO tolerance and Pt utilization, offering a viable route for low-potential CO removal in practical PEMFC anodes.
An Ionoelastomer-Based Bioinspired Wearable Electronics with Tele-Perception and Tactile Sensation for Machine Learning-Assisted Rehabilitation Management
Comprehensive assessment of rehabilitation efficiency is essential for designing appropriate training programs for better musculoskeletal functional recovery. Existing contact-receptor-dependent rehabilitation assessment systems mostly focus on assessing the restoration of muscle function by evaluating grip strength or joint flexion angle; however, parameters reflecting neuromuscular synergistic function are always overlooked. Herein, we develop an ionoelastomer-based soft artificial electroreceptor (SAER) that integrates tele-perception and tactile sensation to track the rehabilitation process, collecting signals related to approaching speed and grip strength sequentially. The SAER uses polyurethane ionoelastomer incorporated with quasi-solid conductive salt as the electric field receptor, and is integrated on a rehabilitation-training ball after assembly to establish an untethered detection device; this enables the remote capture of hand approaching parameter within a 9 cm range, followed by the quantification of grip strength when contacting and grasping. Furthermore, a data-driven assessment system is established by integrating machine learning, which accurately classifies rehabilitation efficiency into six levels; it supports for rehabilitation evaluation and training programs adjustment. Overall, the SAER-based rehabilitation management system establishes a paradigm that synergistically evaluating parameters corresponding to neuromuscular functional restoration and holds strong potential for home-based active rehabilitation for minimizing dependence on frequent clinical supervision.
Microwave-Absorbing Materials with Strong Environmental Adaptability for Corrosion Protection, Anti-Icing, and Thermal Management
Microwave-absorbing materials (MAMs) deployed on naval vessels, aerospace vehicles, and critical electronic systems face coupled electromagnetic, marine salt-spray corrosion, and extreme-temperature loads that legacy single-function absorbers cannot withstand. This review consolidates progress on three environmentally adaptive MAM classes: corrosion-protective, anti-icing, and thermal-management absorbers. The electromagnetic loss and impedance-matching fundamentals are first established, then the synergistic mechanisms, design strategies, and characterization protocols for each class are examined against representative material systems and their measured performance. The analysis identifies a shared design logic—multiscale hierarchical architecture, interfacial polarization engineering, and multifunctional phase integration—while distinguishing the divergent protection mechanisms: barrier and passivation effects for corrosion, surface-energy and latent-heat regulation for anti-icing, and phonon–electron transport decoupling for thermal management. Persistent bottlenecks include the trade-off between impedance matching and protective-layer density, the absence of standardized coupled-field test protocols, and the scarcity of long-term salt-spray and thermal-cycling durability data. Future directions are delineated: intelligent self-adaptive absorbers, multiphysics-coupled simulation frameworks, and environmentally benign multifunctional integration. The review provides a theoretical and technical basis for the design, construction, and engineering scale-up of next-generation high-performance absorbers for aerospace, electronic, and marine equipment.