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  1. Solar-powered self-descaling seesaw extractor for lithium production from seawater

    Chen, Yi-Zhou 陈奕舟 ; Li, Hao-Nan 李浩南 ; Xin, Jia-Hui 忻嘉辉 ; ... - Device
    The low Li+ concentration and the abundance of competing ions limit the efficiency of lithium extraction from seawater. Here, in this work, we report a solar-powered seesaw extractor (SPSE) to boost Li+ adsorption while minimizing scaling caused by competing ions during photothermal evaporation. The SPSE features a sandwich architecture, with a hydrophilic adsorbent layer placed between two hydrophobic photothermal layers. The seesaw configuration enables Li+ to be elevated and concentrated through evaporation to overcome sluggish adsorption kinetics, while the associated salt scaling is removed by the seesawing motion. As a demonstration, we assembled 60 SPSEs into a 3 × 20more » array that achieved a 15.5-fold increase in local Li+ concentration and a 69.1% improvement in Li+ uptake over 120 h, with a Li+/Na+ separation factor exceeding 370,000.« less

  2. 3D Printing of Cement-Based Materials Using Seawater for Simulated Marine Environments

    Rodriguez, Fabian B. ; Vugteveen, Caiden ; Fross, Xavier ; ... - Materials
    Global demand for adaptable and rapidly deployable construction solutions in offshore, coastal, and fluvial environments continues to rise, driven by pressing needs to develop energy platforms, improve coastal resilience, and support emergency response in the face of natural disasters. Increased investment in human-made coastal infrastructure, such as piers, support structures for power lines, offshore wind farms, and seawall protection systems, further underscores this trend. This study investigates the development of printable concrete mixtures for underwater environments using seawater as a replacement for freshwater, using a 3D printing syringe-based extrusion system. The effect of seawater addition and the printing medium (inmore » air vs. underwater) was assessed via rheological and mechanical performance characterization. The results indicate rheological properties are favorable for seawater adoption by producing mixtures with higher yield stress and viscosity with the same levels of admixtures used for freshwater. Seawater-based mixtures demonstrated superior dimensional stability compared to freshwater counterparts, maintaining cross-sectional geometry, while compressive strength results showed no statistical differences between in-air and underwater samples. However, flexural strength was significantly influenced by geometry and printing medium. These findings establish critical rheological parameters for printable underwater mixtures and highlight the need for optimized curing strategies and layer bonding techniques to improve interfacial strength in underwater 3D printing applications.« less

  3. From Pure to Seawater Electrolysis: Unveiling the Impact of Ionic Species and Contaminants on Electrocatalysis

    Parvin, Sahanaz ; Aransiola, Emmanuel ; Saini, Sonakshi ; ... - ACS Electrochemistry
    Water electrolysis, including seawater splitting to produce hydrogen and oxygen, stands as a promising approach for the efficient storage of intermittent energy. However, the half-reactions of water splitting, the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), are known to be very sensitive toward the quality of water employed and are susceptible to contaminants originating from various sources, including the electrolyte or the electrodes. Those contaminants have a profound impact on the activity of these reactions of water splitting by modifying the electronic and physical structures of electrocatalysts as well as electrode–electrolyte interfaces. For seawater electrolysis, the unintentional presencemore » of impurities, such as anions, cations, and organic compounds, affects the catalyst stability, selectivity, and activity. Despite the existence of numerous comprehensive reviews that delve into various aspects of catalysts and their structure–property relationships for several electrocatalytic reactions, the impact of contaminants has often been ignored. This critical review endeavors to address this issue by providing an overview of the diverse sources of contaminants influencing electrocatalytic water splitting and seawater splitting reactions, delineating the trends in electrochemical parameters and detailing different characterization methods for elucidating the physical and electronic changes of the electrode and electrolyte.« less

  4. Pulse Electrodeposition for Carbonate-Rich Deposits from Seawater

    Robinson, Alexander J. ; Ryan, Elisabeth A. ; Wang, Qingpu ; ... - Sustainability (Basel)
    Seawater electrodeposition is gaining renewed interest in the context of sustainable development, both to build climate-resilient coastal infrastructure and for ocean-based decarbonization applications. Most of the applications benefit from CaCO3-rich deposits, but constant-voltage electrodeposition results in a mixture of CaCO3 and Mg(OH)2, especially at higher voltages where precipitation rates are more desirable. The use of pulse voltages can help control interfacial pH that dictates the precipitation reactions. Here, we explore the use of pulse electrodeposition as a function of pulse frequency and duty cycle to control deposit composition. The most CaCO3-rich deposits were obtained under 10 Hz frequency and 10%more » duty cycle conditions for the voltage window investigated (-0.8 V to -1.2 V vs. SCE). While pulsing the voltage increases the amount of CaCO3 deposited, the energy required per gram of CaCO3 is significantly higher (14.5×) when compared to the base case of applying a constant voltage of -0.8 V vs. SCE. Further optimization of pulse conditions, electrode materials, and system configuration could lead to finding parameters that result in exclusively carbonate deposits without compromising precipitation rates, which may prove to be more useful for corrosion protection, coastal infrastructure, and other applications in sustainable development.« less

  5. ZeroCAL: Eliminating Carbon Dioxide Emissions from Limestone’s Decomposition to Decarbonize Cement Production

    Leão, Adriano ; Collin, Marie ; Ghodkhande, Swarali ; ... - ACS Sustainable Chemistry & Engineering
    Limestone (calcite, CaCO3) is an abundant and cost-effective source of calcium oxide (CaO) for cement and lime production. However, the thermochemical decomposition of limestone (~800 °C, 1 bar) to produce lime (CaO) results in substantial carbon dioxide (CO2(g)) emissions and energy use, i.e., ~1 tonne [t] of CO2 and ~1.4 MWh per t of CaO produced. Here, we describe a new pathway to use CaCO3 as a Ca source to make hydrated lime (portlandite, Ca(OH)2) at ambient conditions (p, T) while nearly eliminating process CO2(g) emissions (as low as 1.5 mol. % of the CO2 in the precursor CaCO3, equivalentmore » to 9 kg of CO2(g) per t of Ca(OH)2) within an aqueous flowelectrolysis/ pH-swing process that coproduces hydrogen (H2(g)) and oxygen (O2(g)). Because Ca(OH)2 is a zero-carbon precursor for cement and lime production, this approach represents a significant advancement in the production of zero-carbon cement. The Zero CArbon Lime (ZeroCAL) process includes dissolution, separation/recovery, and electrolysis stages according to the following steps: (Step 1) chelator (e.g., ethylenediaminetetraacetic acid, EDTA)-promoted dissolution of CaCO3 and complexation of Ca2+ under basic (>pH 9) conditions, (Step 2a) Ca enrichment and separation using nanofiltration (NF), which allows separation of the Ca-EDTA complex from the accompanying bicarbonate (HCO3–) species, (Step 2b) acidity-promoted decomplexation of Ca from EDTA, which allows near-complete chelator recovery and the formation of a Ca-enriched stream, and (Step 3) rapid precipitation of Ca(OH)2 from the Ca-enriched stream using electrolytically produced alkalinity. These reactions can be conducted in a seawater matrix yielding coproducts including hydrochloric acid (HCl) and sodium bicarbonate (NaHCO3), resulting from electrolysis and limestone dissolution, respectively. Careful analysis of the reaction stoichiometries and energy balances indicates that approximately 1.35 t of CaCO3, 1.09 t of water, 0.79 t of sodium chloride (NaCl), and ~2 MWh of electrical energy are required to produce 1 t of Ca(OH)2, with significant opportunity for process intensification. This approach has major implications for decarbonizing cement production within a paradigm that emphasizes the use of existing cement plants and electrification of industrial operations, while also creating approaches for alkalinity production that enable cost-effective and scalable CO2 mineralization via Ca(OH)2 carbonation.« less

  6. Observations of Atmospheric Corrosion Testing on Heated Austenitic Stainless Steel Surfaces: Exploring the Role of Inert Dust Particulates and Seawater

    Schaller, R. F. ; Snow, J. ; Maguire, M. ; ... - Nuclear Technology
    Relevant atmospheric corrosion laboratory testing environments were developed to explore the influence of inert dust and seawater on the corrosion susceptibility of stainless steel in spent nuclear fuel dry storage conditions. Measurements from dust collected on in-service dry storage canisters were applied to develop exposure conditions. Three atmospheric exposure conditions, two static and one cyclic, were examined with three different surface coverages: co-deposited large dust and seawater, co-deposited small dust and seawater, and solely seawater. Stainless steel coupons representative of spent nuclear fuel dry storage canister material were subjected to the various corrosion environments, with the results from exposures upmore » to 1 year presented here. Post exposure, corrosion damage was analyzed using optical microscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy. Initial observations are presented herein, and potential implications with respect to the influence of inert dust particles on corrosion susceptibility are summarized. In general, the co-deposition of dust and salt resulted in larger pits and exhibited mixed modes of corrosion that were not observed in the no-dust conditions (i.e., crevicing, filiform, and pits within pits). The presence of the inert dust may influence brine spreading and/or act as crevice formers, leading to enhanced corrosion. This study highlights the significance of incorporating dust particulate(s) beyond the deliquescent chemistries to fully evaluate atmospheric corrosion severity.« less

  7. Electrolytic Seawater Mineralization and the Mass Balances That Demonstrate Carbon Dioxide Removal

    La Plante, Erika Callagon ; Chen, Xin ; Bustillos, Steven ; ... - ACS ES&T Engineering

  8. Hydrogen production with seawater-resilient bipolar membrane electrolyzers

    Marin, Daniela H. ; Perryman, Joseph T. ; Hubert, McKenzie A. ; ... - Joule
    Generation of H2 and O2 from untreated water sources represents a promising alternative to ultrapure water required in contemporary proton exchange membrane-based electrolysis. Bipolar membrane-based devices, often used in electrodialysis and CO2 electrolysis, facilitate impure water electrolysis via the simultaneous mediation of ion transport and enforcement of advantageous microenvironments. Herein, we report their application in direct seawater electrolysis; we show that upon introduction of ionic species such as Na+ and Cl- from seawater, bipolar membrane electrolyzers limit the oxidation of Cl- to corrosive OCl- at the anode to a Faradaic efficiency (FE) of 0.005%, while proton exchange membrane electrolyzers undermore » comparable operating conditions exhibit up to 10% FE to Cl oxidation. In conclusion, the effective mitigation of Cl- oxidation by bipolar membrane electrolyzers underpins their ability to enable longer-term seawater electrolysis than proton exchange membrane assemblies by a factor of 140, suggesting a path to durable seawater electrolysis.« less

  9. Oxygen–Chlorine Chemisorption Scaling for Seawater Electrolysis on Transition Metals: The Role of Redox

    Wexler, Robert B. ; Carter, Emily A. - Advanced Theory and Simulations
    To clarify what controls species oxidation selectivity in seawater electrolysis, density functional theory (DFT) is used to identify chemisorption enthalpy trends and scaling relations for the simplest relevant adsorbates (O, Cl, and H) on relevant surfaces of 3d transition metals, as well as Pd and Pt, in face-centered-cubic and, if different, their ground-state crystal structures. Approximations are tested for electron exchange-correlation (XC) and van der Waals interactions to assess their ability to reproduce experimental adsorption enthalpies of H and O on Pt(111). The vdW-uncorrected generalized gradient approximation to XC of Perdew, Burke, and Ernzerhof (PBE) agrees most closely with experiments.more » Using DFT-PBE thereafter, it is determined that the O chemisorption enthalpy on this wide range of transition-metal surfaces is proportional to the sum of first and second atomic ionization energies, akin to a Born–Haber cycle for a redox reaction, indicating that metal redox activity controls O chemisorption strength. Then it is shown that the O and Cl chemisorption enthalpies are strongly correlated, suggesting that the transition metals considered will oxidize unselectively water and Cl–. This strong correlation appears also for crystal reduction potentials of binary oxides and chlorides, indicating a fundamental challenge for future seawater electrode materials design.« less

  10. The Influence of Transitional Metal Dopants on Reducing Chlorine Evolution during the Electrolysis of Raw Seawater

    Adiga, Prajwal ; Doi, Nathan ; Wong, Cindy ; ... - Applied Sciences
    Electrocatalytic water splitting is a possible route to the expanded generation of green hydrogen; however, a long-term challenge is the requirement of fresh water as an electrolyzer feed. The use of seawater as a direct feed for electrolytic hydrogen production would alleviate fresh water needs and potentially open an avenue for locally generated hydrogen from marine hydrokinetic or off-shore power sources. One environmental limitation to seawater electrolysis is the generation of chlorine as a competitive anodic reaction. This work evaluates transition metal (W, Co, Fe, Sn, and Ru) doping of Mn-Mo-based catalysts as a strategy to suppress chlorine evolution whilemore » sustaining catalytic efficiency. Electrochemical evaluations in neutral chloride solution and raw seawater showed the promise of a novel Mn-Mo-Ru electrode system for oxygen evolution efficiency and enhanced catalytic activity. Subsequent stability testing in a flowing raw seawater flume highlighted the need for improved catalyst stability for long-term applications of Mn-Mo-Ru catalysts. This work highlights that elements known to be selective toward chlorine evolution in simple oxide form (e.g., RuO2) may display different trends in selectivity when used as isolated dopants, where Ru suppressed chlorine evolution in Mn-based catalysts.« less
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