Seawater Electrolysis Research Articles

Upcycling of waste polyethylene terephthalate (PET) into CoFe@C for highly efficient PV-driven bifunctional seawater splitting via a “waste materialization” strategy

Developing green and efficient techniques to convert plastic wastes into functional materials is attractive and remains highly challenging. This study employs a hydrothermal combining with pyrolysis process for constructing a Co3Fe1@C heterostructure from the polyethylene terephthalate (PET) waste-mediated metal-organic frameworks. The as-obtained Co3Fe1@C shows a core-shell structure and possesses good performance towards water electrolysis. The Co3Fe1@C can attain the current density of 100 mA cm−2 with an overpotential of 250 mV for oxygen evolution reaction (OER). In addition, the bifunctional Co3Fe1@C can realize the overall seawater electrolysis at 50 mA cm−2 with good stability for 280 h driven by a 2.2 V commercial silicon solar cell. Overall, this study demonstrates a green chemistry approach to simultaneous plastic waste upcycling and cost-effective electrocatalyst fabrication, which may stimulate further research on the “waste materialization” approach to converting solid waste into highly efficient catalysts for various chemistry and energy industry applications.

Efficient and Ultrastable Seawater Electrolysis at Industrial Current Density with Strong Metal-Support Interaction and Dual Cl--Repelling Layers.

Direct seawater electrolysis is emerging as a promising renewable energy technology for large-scale hydrogen generation. The development of Os-Ni4Mo/MoO2 micropillar arrays with strong metal-support interaction (MSI) as a bifunctional electrocatalyst for seawater electrolysis is reported. The micropillar structure enhances electron and mass transfer, extending catalytic reaction steps and improving seawater electrolysis efficiency. Theoretical and experimental studies demonstrate that the strong MSI between Os and Ni4Mo/MoO2 optimizes the surface electronic structure of the catalyst, reducing the reaction barrier and thereby improving catalytic activity. Importantly, for the first time, a dual Cl- repelling layer is constructed by electrostatic force to safeguard active sites against Cl- attack during seawater oxidation. This includes a strong Os─Cl adsorption and an in situ-formed MoO4 2- layer. As a result, the Os-Ni4Mo/MoO2 catalyst exhibits an ultralow overpotential of 113 and 336mV to reach 500mA cm-2 for HER and OER in natural seawater from the South China Sea (without purification, with 1m KOH added). Notably, it demonstrates superior stability, degrading only 0.37 µV h-1 after 2500 h of seawater oxidation, significantly surpassing the technical target of 1.0 µV h-1 set by the United States Department of Energy.

Nanoarchitectonics of Nickel Nitride‐V2CTX Mxene: An Efficient Bifunctional Catalyst for Alkaline Water/Seawater Applications

AbstractSeawater, being the most plentiful natural water source worldwide, is a highly abundant and cost‐efficient medium for producing hydrogen by alkaline water electrolysis. However, the advancement of seawater electrolysis is hindered by notable impediments caused by chloride corrosion at the anode and the simultaneous chlorine evolution process. Only a limited number of non‐noble electrocatalysts demonstrate noteworthy bifunctional catalytic efficacy and long‐term durability. In this regard, Nickel Nitride tailored V2CTX Mxene nanostructures is reported as a bifunctional catalyst for overall water/seawater applications. The optimized sample Ni3N@3000‐V2CTx exhibits low overpotential values of 90 and 300 mV in acidic and alkaline + seawater solutions respectively at 10 mA cm−2 for hydrogen evolution reaction. Similarly, this catalyst shows 70 and 240 mV overpotential values in alkaline water and alkaline + seawater solutions respectively at the same current density for oxygen evolution reaction. Synergetic effects of Multiple Vanadium and Nickel valency along with compelling nitrogen bonds creates elevated density of exposed functional sites for electrocatalytic activity. Furthermore, the notable electrochemical active surface area and mass activity suggest an enhanced and significant presence of abundant active sites. Additionally, the high stability and significantly decreased charge transfer resistance expedited the overall water/seawater‐splitting reaction rate.

Long‐term Durability of Seawater Electrolysis for Hydrogen: From Catalysts to Systems

AbstractDirect electrochemical seawater splitting is a renewable, scalable, and potentially economic approach for green hydrogen production in environments where ultra‐pure water is not readily available. However, issues related to low durability caused by complex ions in seawater pose great challenges for its industrialization. In this review, a mechanistic analysis of durability issues of electrolytic seawater splitting is discussed. We critically analyze the development of seawater electrolysis and identify the durability challenges at both the anode and cathode. Particular emphasis is given to elucidating rational strategies for designing electrocatalysts/electrodes/interfaces with long lifetimes in realistic seawater including inducing passivating anion layers, preferential OH−adsorption, employing anti‐corrosion materials, fabricating protective layers, immobilizing Cl− on the surface of electrocatalysts, tailoring Cl− adsorption sites, inhibition of OH− binding to Mg2+ and Ca2+, inhibition of Mg and Ca hydroxide precipitation adherence, and co‐electrosynthesis of nano‐sized Mg hydroxides. Synthesis methods of electrocatalysts/electrodes and innovations in electrolyzer are also discussed. Furthermore, the prospects for developing seawater splitting technologies for clean hydrogen generation are summarized. We found that researchers have rethought the role of Cl− ions, as well as more attention to cathodic reaction and electrolyzers, which is conducive to accelerate the commercialization of seawater electrolysis.

Redox-mediated decoupled seawater direct splitting for H2 production

Seawater direct electrolysis (SDE) using renewable energy provides a sustainable pathway to harness abundant oceanic hydrogen resources. However, the side-reaction of the chlorine electro-oxidation reaction (ClOR) severely decreased direct electrolysis efficiency of seawater and gradually corrodes the anode. In this study, a redox-mediated strategy is introduced to suppress the ClOR, and a decoupled seawater direct electrolysis (DSDE) system incorporating a separate O2 evolution reactor is established. Ferricyanide/ferrocyanide ([Fe(CN)6]3−/4−) serves as an electron-mediator between the cell and the reactor, thereby enabling a more dynamically favorable half-reaction to supplant the traditional oxygen evolution reaction (OER). This alteration involves a straightforward, single-electron-transfer anodic reaction without gas precipitation and effectively eliminates the generation of chlorine-containing byproducts. By operating at low voltages (~1.37 V at 10 mA cm−2 and ~1.57 V at 100 mA cm−2) and maintaining stability even in a Cl−-saturated seawater electrolyte, this system has the potential of undergoing decoupled seawater electrolysis with zero chlorine emissions. Further improvements in the high-performance redox-mediators and catalysts can provide enhanced cost-effectiveness and sustainability of the DSDE system.

Seawater Electrolysis: Challenges, Recent Advances, and Future Perspectives

AbstractDriven by the advantages of hydrogen energy, such as environmental protection and high energy density, the market has an urgent demand for hydrogen energy. Currently, the primary methods for hydrogen production mainly include hydrogen generation from fossil fuels, industrial by‐products, and water electrolysis. Seawater electrolysis for hydrogen production, due to its advantages of cleanliness, environmental protection, and ease of integration with renewable energy sources, is considered the most promising method for hydrogen production. However, seawater electrolysis faces challenges such as the reduction of hydrogen production efficiency due to impurities in seawater, as well as high costs associated with system construction and operation. Therefore, it is particularly necessary to summarize optimization strategies for seawater electrolysis for hydrogen production to promote the development of this field. In this review, the current situation of hydrogen production by seawater electrolysis is first reviewed. Subsequently, the challenges faced by seawater electrolysis for hydrogen production are categorized and summarized, and solutions to these challenges are discussed in detail. Following this, an overview of an in situ large‐scale direct electrolysis hydrogen production system at sea is presented. Last but not least, suggestions and prospects for the development of seawater electrolysis for hydrogen production are provided.

Rational design of chromium-doped NiFe phosphide/phosphate heterostructures for inhibiting chloride ion adsorption and achieving alkaline seawater splitting at industrial-level current density

Electrocatalysts with high activity and corrosion resistance, tailored for industrial-grade current densities, played a crucial role in seawater electrolysis. Here, we synthesized a petal-like Cr-doped NiFe phosphate 'semi-coated' phosphide heterostructure electrocatalyst grown on nickel foam (Cr-NiFeP/PO3@NF). This catalyst demonstrated superior catalytic performance in natural seawater, maintaining stability and only a slight increase in cell voltage after operating continuously for 100 h at a current density of 1 A cm−2. The incorporation of Cr introduced a significant number of unpaired electrons, which enhanced the conductivity of the catalyst, facilitated the creation of electron depletion regions around Ni and Fe, and improved the interaction with adsorption intermediates. Furthermore, the high activity and corrosion resistance during the oxygen evolution reaction (OER) were due to the interaction between the in-situ formed high-valent phosphate and NiFeCrOOH during the anodization process.

Frustrated Lewis Pair Mediated f‐p‐d Orbital Coupling: Achieving Selective Seawater Oxidation and Breaking *OH and *OOH Scaling Relationship

The development of materials for hydrogen production via seawater electrolysis at high current densities plays a crucial role in producing renewable hydrogen energy. However, during the seawater electrolysis process, the anode inevitably undergoes chloride oxidation reaction (ClOR) due to Cl‐ adsorption, making the seawater electrolysis process difficult to sustain. Inspired by the selective permeability of cell membranes, we propose a biomimetic design of frustrated Lewis pairs (FLPs) layers. Combining experimental results and molecular dynamics simulations, it has been demonstrated that cerium dioxide layers with FLPs sites can decompose water molecules, capture hydroxyl anions, and repel chloride ions simultaneously. DFT theoretical analysis indicates that the FLP sites regulate the Ce 4f‐O 2p‐Ni 3d gradient orbital coupling, providing additional oxygen non‐bonding (ONB) to stabilize the Ni‐O bond and optimize the adsorption strength of intermediates, thereby breaking the *OH and *OOH scaling relationship. Assembled anion exchange membrane electrolyzers exhibit an efficiency of 95.7% at a current density of 0.1 A cm‐2 and can stably operate for 250 hours at a current density of 0.2 A cm‐2.

Ultrafast Room-Temperature Synthesis of Phosphate-Intercalated NiFe Layered Double Hydroxides for High-Performance Alkaline Seawater Oxidation.

Quick and easy synthetic methods and highly efficient catalytic performance are equally important to anodic oxygen evolution reaction (OER) electrocatalysts for alkaline seawater electrolysis. Herein, we report a facile one-step route to in situ growing PO43- intercalated NiFe layered double hydroxides (NiFe-LDH) on Ni foam (denoted as NiFe-P/NF) by a room-temperature immersion for several minutes. This ultrafast approach transforms the NF surface into a rough PO43- intercalated NiFe-LDH overlayer, which demonstrates outstanding OER performance in both alkaline simulated and natural seawaters owing to good hydrophilic interface and the electrostatic repulsion of PO43- against Cl- anions. Density functional theory calculations reveal that the intercalated PO43- can not only promote electron transfer but also prevent Cl- from entering the interlayer and simultaneously inhibit the migration of Cl- over the NiFe-LDH surface. In alkaline simulated and natural seawater electrolytes, NiFe-P/NF needs low overpotentials of 248 and 298 mV to achieve a current density of 100 mA cm-2, respectively. NiFe-P/NF can stably run over 42 h in an alkaline high-salty electrolyte (1 M KOH + 2.5 M NaCl) at 250 mA cm-2, more than 70 times that of NiFe/NF (0.6 h), emphasizing the critical role of the intercalated PO43- anions on the excellent durability. This study offers a new strategy to modify commercial NF to prepare efficient and stable OER catalysts for seawater electrolysis.

Frustrated Lewis Pair Mediated f-p-d Orbital Coupling: Achieving Selective Seawater Oxidation and Breaking *OH and *OOH Scaling Relationship.

The development of materials for hydrogen production via seawater electrolysis at high current densities plays a crucial role in producing renewable hydrogen energy. However, during the seawater electrolysis process, the anode inevitably undergoes chloride oxidation reaction (ClOR) due to Cl- adsorption, making the seawater electrolysis process difficult to sustain. Inspired by the selective permeability of cell membranes, we propose a biomimetic design of frustrated Lewis pairs (FLPs) layers. Combining experimental results and molecular dynamics simulations, it has been demonstrated that cerium dioxide layers with FLPs sites can decompose water molecules, capture hydroxyl anions, and repel chloride ions simultaneously. DFT theoretical analysis indicates that the FLP sites regulate the Ce 4f-O 2p-Ni 3d gradient orbital coupling, providing additional oxygen non-bonding (ONB) to stabilize the Ni-O bond and optimize the adsorption strength of intermediates, thereby breaking the *OH and *OOH scaling relationship. Assembled anion exchange membrane electrolyzers exhibit an efficiency of 95.7% at a current density of 0.1 A cm-2 and can stably operate for 250 hours at a current density of 0.2 A cm-2.

Superhydrophilicity and superaerophobicity Ni/Ni3S4/1T-MoS2 for hydrazine-assisted seawater splitting

The overall hydrazine splitting (OHzS) is a promising strategy to achieve the efficient hydrogen production in seawater through replacing the slow kinetic oxygen evolution reaction (OER) and toxic chlorine evolution reaction (ClOR) by hydrazine oxidation (HzOR). We report an efficient bifunctional electrocatalyst of Ni/Ni3S4/1T-MoS2 on carbon cloth (Ni/Ni3S4/1T-MoS2/CC), which was formed from large layer spacing MoS2 and Ni3S4 with metal-Ni, and was applied as for both hydrogen evolution reaction (HER) and HzOR. The MoS2 had expanded interlayer spacing and showed 1T phase, with significantly improved conductivity and hydrophilicity, which promotes transfer process of reactants. Furthermore, the introduction of Ni/Ni3S4 on the 1T-MoS2 base surface leaded to superhydrophilic and superaerophobic properties, which makes it more conducive to the adsorption of H. The improvement of electrical conductivity induced the excellent HER and HzOR electrocatalytic properties of Ni/Ni3S4/1T-MoS2/CC, which showed an ultralow overpotential of 24 mV and working potential of 0 mV at a current density of 10 mA cm−2, respectively. Inspiringly, Ni/Ni3S4/1T-MoS2/CC also showed excellent performance in hydrazine-assisted alkaline seawater electrolysis, as well as solar panel powered electrolysis of seawater OHzS, therefore, exhibiting great potential for practical applications.

Sustainability assessment of seawater splitting: Prospects, challenges, and future directions

AbstractSeawater splitting is one of the desirable techniques for producing green hydrogen from the vast natural resource. Several reports about designing and fabricating efficient electrocatalysts to boost the oxygen evolution reaction and hydrogen evolution reaction have been published. However, they mainly focus on the electrodes, electrocatalysts, cost, and system stability. This article presents an overview of seawater splitting by highlighting the most challenging issues that complicate seawater electrolysis, such as durability, to guide future research in this important area. The strategy to launch life cycle assessments is described to evaluate the short and long‐term impacts. Finally, the current challenges and prospective solutions are discussed.

Advancing the utilization of 2D materials for electrocatalytic seawater splitting

AbstractApplying catalysts for electrochemical energy conversion holds great promise for developing clean and sustainable energy sources. One of the main advantages of electrocatalysis is its ability to reduce conversion energy loss significantly. However, the wide application of electrocatalysts in these conversion processes has been hindered by poor catalytic performance and limited resources of catalyst materials. To overcome these challenges, researchers have turned to two‐dimensional (2D) materials, which possess large specific surface areas and can easily be engineered to have desirable electronic structures, making them promising candidates for high‐performance electrocatalysis in various reactions. This comprehensive review focuses on engineering novel 2D material‐based electrocatalysts and their application to seawater splitting. The review briefly introduces the mechanism of seawater splitting and the primary challenges of 2D materials. Then, we highlight the unique advantages and regulating strategies for seawater electrolysis based on recent advancements. We also review various 2D catalyst families for direct seawater splitting and delve into the physicochemical properties of these catalysts to provide valuable insights. Finally, we outline the vital future challenges and discuss the perspectives on seawater electrolysis. This review provides valuable insights for the rational design and development of cutting‐edge 2D material electrocatalysts for seawater‐electrolysis applications.image

Cr-doped tri-metallic nano prism catalyst for efficient alkaline and seawater splitting

Electrochemical water splitting is one of the most promising methods for sustainable production of green hydrogen. The oxygen evolution reaction (OER) is a crucial step in the process of water splitting. However, it exhibits sluggish kinetics and requires a significant overpotential for functioning at reasonable reactionrates. The efficiency of the reaction can be enhanced by reducing the overpotential, lowering the energy barrier, and using an effective electrocatalyst. Transition metal-basedcatalysts are well studied for this purpose. Specially, nickel–cobalt (Ni-Co) based catalysts have been regarded as the best OER electrocatalysts. Therefore, several studies have been carried out to enhance the electrocatalytic efficiency of Ni-Co catalysts. While mixing other transition metals with Ni-Co is a straightforward and reliable method to improve the OER activity of Ni-Co catalysts, there is still a need for a thorough examination of the design of Ni-Co catalysts with various additional elements. Seawater electrolysis, which utilizes abundant water resources that constitute over 97% of the world’s water, is highly appealing for sustainable energy production. To achieve commercial feasibility, scientists are striving to solve challenges, such as corrosion resistance, highoverpotential, and the need for efficient and durable electrocatalysts.In this study, we fabricated a transition metal-based trimetallic catalyst (CNF), consisting of cobalt (Co), nickel (Ni), and iron (Fe). Furthermore, CNF was doped with chromium (Cr-doped CNF) and tested for the OER in alkaline freshwater and alkaline seawater. Our Cr-doped trimetallic CNF catalyst demonstrates exceptional performance in both seawater and freshwater, with overpotential of 320 mV and 280 mV at 10 mA cm−2 current density, making it a promising candidate for large-scale, sustainable hydrogen production.

Fluorine-doped carbon dots decorated on iron-cobalt selenide nanosheets as superior electrocatalysts for oxygen evolution in seawater

Developing oxygen evolution reaction (OER) catalysts that can efficiently and stably operate at high current densities in seawater electrolysis is urgently demanded but challenging. In this study, selenium-vacancies-rich iron-cobalt selenide nanosheets (FeCoSe-VSe) decorated with fluorine-doped carbon dots (FCDs) are rationally designed and prepared on nickel foams (NF) through the successive processes of hydrothermal treatment and selenization. Benefiting from the large accessible surface area and abundant active sites provided by FCDs and selenium vacancy defects, as well as the coupled interface between FCDs and FeCoSe-VSe that optimizes the oxygen adsorption energy and accelerates the kinetic process, the FCDs/FeCoSe-VSe/NF composite exhibits excellent OER catalytic activities with a low overpotential of 258 mV at a current density of 200 mA cm−2 in 1 M KOH and a small Tafel slope of 34.7 mV dec–1. In the electrolytes of simulated and natural seawater, the overpotentials of the FCDs/FeCoSe-VSe/NF electrode are slightly higher, measured to be 264 and 297 mV, respectively. More profoundly, the introduction of FCDs enhances the corrosion resistance of the catalyst in alkaline electrolytes, ensuring the long-term stability. This work offers a guidance to improve the electrochemical performances of catalysts for high-efficiency seawater oxidation.

Modulating electronic by construction WS2/WN heterostructure coupled with N-doped carbon to boost alkaline seawater hydrogen production

The development of an efficient and durable non-precious electrocatalyst for alkaline seawater electrolysis is of great significance. Herein, two-dimensional (2D) lamellar heterostructure WS2/WN was dispersed on the carbon matrix (marked as WS2/WN@CM). The obtained WS2/WN@CM catalysts demonstrate exceptional performance in the hydrogen evolution reaction (HER) in alkaline freshwater (1.0 M KOH), alkaline simulated seawater (1.0 M KOH + 0.5 M NaCl) and alkaline natural seawater (1.0 M KOH + seawater), respectively, which achieved a low overpotential (92 mV, 95 mV and 113 mV) at 10 mA cm−2 and outstanding long-term durability at 200 mA cm−2 for 100 h. The catalyst benefits from the 3D carbon skeleton, which not only effectively prevents stacking of the 2D lamellar WS2/WN to fully utilize the active material, but also provides rapid electron transport. Moreover, stress effects at WS2/WN interfaces lead to distortions of torsion angles in the WS2 lattice, thereby increasing crystal surface defects accompanied by an enhancement of electrical conductivity. Density functional theory (DFT) calculations combined with XPS evidence confirm the electronic structure reorganization of WS2/WN at interfaces, which optimizes the adsorption energy of specific intermediates. Additionally, WN captures many electrons from WS2, so the WN region favors the reduction reaction and thus enhances the HER process.

Efficient, chlorine-free, and durable alkaline seawater electrolysis enabled by MOF-derived nanocatalysts

The development of cost-effective, scalable, and non-precious based bifunctional catalysts that can efficiently catalyze the sluggish oxygen and hydrogen evolution reactions (OER and HER) in the highly corrosive seawater medium is challenging, yet vital to realize a practical seawater electrolyzer. In this work, we demonstrate a nickel-exchanged zeolitic imidazolate framework (Ni@ZIF67)-derived nickel-cobalt-cobalt oxide nanoparticles embedded amorphous carbon (Ni–Co–CoO@C) nanocomposite as an efficient, chloride-resistant, and stable bifunctional catalyst in alkaline seawater. The OER and HER activities are meticulously characterized by comparing nanocomposites prepared at different pyrolysis temperatures. Ni@ZIF67 pyrolyzed at 700 °C (NZ700) exhibits the lowest OER overpotential (281 mV @ 10 mA cm−2) whereas that pyrolyzed at 500 °C reveals the lowest HER overpotential (196 mV @ 50 mA cm−2) in alkaline seawater. The NZ700||NZ700 cell also exhibits the lowest overall splitting voltage in alkaline seawater (1.72 V @ 20 mA cm−2). Detailed post-electrolysis studies are also carried out to explore the origin of the electrocatalytic activities. Furthermore, a zero-gap, flow-cell type alkaline seawater electrolyzer prototype has been fabricated to demonstrate the viability of our catalysts.

Controlled synthesis of the M doped (M = Fe, Cu, Zn, Mn)-Co4S3/Ni3S2 catalyst with high electrocatalytic performance for hydrogen evolution reaction in seawater and urea

Electrolysis of seawater is a promising method for producing hydrogen, but sluggish reaction kinetics and electrolyte containing corrosive ions limit its development. In this work, a series of M doped (M = Fe, Cu, Zn, Mn)-Co4S3/Ni3S2 catalyst has been prepared on Ni foam by hydrothermal method with excellent seawater and urea splitting performance. The unique 3D porous structure provides a large number of active sites for the catalyst, which has strong catalytic activity. Fe-Co4S3/Ni3S2 electrode showed excellent hydrogen evolution reaction (HER) catalytic activity in 1 M KOH + seawater and 1 M KOH + 0.5 M urea, driving a current density of 10 mA cm−2 at a low overpotential of 81 and 66 mV. In addition, Fe-Co4S3/Ni3S2 electrode also shows strong stability in 15 h stability test. The results show that although the impurity ions in seawater affect the activity of catalyst, the corrosion resistance of catalyst also improves the catalytic activity and stability. Density functional theory calculations show that this Fe-Co4S material exhibits the optimal Gibbs free energy of hydrogen, the introduction of this Ni3S2 material enhances the electrical conductivity of the material, and the synergistic catalysis of the two materials promotes the optimal hydrogen production performance of the Fe-Co4S3/Ni3S2 material. This work provides a novel understanding for the research of catalysts used in the electrolysis of seawater and urea.

Amorphous/crystalline Ni-Fe based electrodes with rich oxygen vacancies enable highly active oxygen evolution in seawater electrolysis

To realize large-scale production of hydrogen through seawater electrolysis, it is highly crucial to engineer high-activity and robustly stable catalytic materials for oxygen evolution reaction (OER). Here, a facile etching growth strategy based on Ni foam (NF) is employed to fabricate an amorphous/crystalline Ni-Fe based electrode with rich oxygen vacancies as a promising OER electrocatalyst (a/c-NiFeOxHy@NF). Of note, the introduction of Fe induces the generation of plentiful Ni(Fe)OOH species, which can contribute to the remarkable OER behavior. Profiting from the favorable geometric microstructure of ultrathin nanosheets coupled with 3D open-pore architecture and regulated electronic state by increased oxygen vacancies and abundant crystalline-amorphous boundaries, the resulting a/c-NiFeOxHy@NF displays prominent electrocatalytic OER activity in pure alkaline solution and seawater, achieving impressive overpotentials of only 219 and 233 mV to reach 100 mA cm−2, respectively. More significantly, the electrode can keep stable operation without obvious attenuation for over 1200 h at 100 mA cm−2, demonstrating its exceptional corrosion resistance. Such robustness of this electrode surpasses those of almost all reported OER electrocatalysts. Furthermore, in a self-assembled seawater electrolyzer with a/c-NiFeOxHy@NF as the anode and l-RuP@NF as the cathode, a large current density of 500 mA cm−2 is easily achieved at the voltage of 1.795 V at 65 °C. The work offers a novel paradigm for constructing low-cost, high-efficiency, and ultra-stable OER catalysts, which shows huge promise for industrial seawater electrolysis applications.

Efficient and stable hydrogen evolution and antibiotic degradation in all-pH-scale water/alkaline seawater using Fe-Co phosphide hollow nanocages fabricated from metallurgical solid waste

The utilization of seawater, a plentiful and cost-effective resource, instead of freshwater for H2 production through electrolysis has garnered significant attention. Herein, we present the synthesis of open-structured Fe-Co phosphide (FCP) nanocages for the overall seawater electrolysis, employing metallurgical solid waste (steel rolling sludge, SRS) as the precursor material. The FCP nanocages demonstrate exceptional catalytic activity for the hydrogen evolution reaction (HER) in all pH scales, achieving performance comparable to that of Pt/C catalysts at high current densities. The electrolyzer assembled with FCP||FCP requires 1.57 and 1.68 V to achieve current densities of 10 and 100 mA cm−2, respectively. Furthermore, the assembled FCP electrolyzer showcases over 100 h of cycling stability and nearly 100% Faradaic efficiency. Crucially, it can be powered by commercially available silicon solar panels, operating under an intensity of 100 mW cm−2, and by wind-driven sources, rendering it highly promising for real-world applications. The seawater hydrogen evolution system coupled with levofloxacin (LEV) degradation was constructed for the first time. The oxidation potential of LEV oxidation reaction (LEVOR) was significantly lower than that of oxygen evolution reaction (OER), indicating that the LEV degradation reaction occurred preferentially and achieved a removal efficiency of 98.57% within 60 min. This study provides effective strategies for valorizing SRS and offers insights into the fabrication of high-performance catalysts.