Search

Seawater corrosion poses significant challenges to marine industrial equipment, leading to a reduced lifespan and potential safety hazards. To enhance the corrosion resistance and reliability of titanium alloys in marine environments, a superhydrophobic TiO₂ nanotube-carbon fiber composite coating (SCF-TAD20) was developed through anodic oxidation, spraying, and chemical modification. SCF-TAD20 achieves a contact angle of 153°, which facilitates excellent corrosion protection due to its unique micro-nano structure, gas barrier properties, and chemical resistance. Electrochemical tests demonstrate that SCF-TAD20 increases the corrosion potential from −0.482 V to 0.0612 V and reduces the corrosion current density from 377.8 × 10−8 A/cm2 to 0.615 × 10−8 A/cm2, a four-order decrease. Its charge transfer resistance (∼8.81E6 Ω·cm2) is significantly higher than that of the substrate (∼3.03E5 Ω·cm2). The coating also performs well in seawater with varying pH levels, showing the lowest corrosion current density and a significant increase in resistive arc radius. This research presents a novel approach to enhancing TC4 titanium alloys for marine applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Tuning ammonium retention in membrane separation using the acid-base equilibrium. • Selectivity increase of nitrogen/potassium by selective permeation of neutral ammonia. • Dynamic digestate separation producing nitrogen and potassium enriched streams. Extensive nitrogen emissions with negative impact on nature and the environment urge effective valorization of manure and fractionation of nutrients to enable precision fertilization. Typically, manure is fed to a digester to produce biogas. The remaining digestate is then mechanically separated into a solid phosphorous-rich fraction and a liquid fraction containing both NH 4 + and K. These ions are difficult to separate due to their very identical size and charge. We show that with smart tuning of the pH to control the NH 3 /NH 4 + equilibrium, membranes can produce dedicated N and K-rich streams. The increased pH switches the equilibrium towards the neutrally charged solute NH 3 that permeates more easily through the membrane than charged NH 4 + and K+ ions. Experiments with both artificial NH 4 Cl/KCl mixtures as well as real liquid digestate and four different membrane types, ranging from open nanofiltration (NF) to sea water reverse osmosis (RO) membranes were performed. At neutral pH, no N/K selectivity was observed, not for single components nor for mixtures. When the pH was increased towards alkaline environment, distinct selectivity for N/K was obtained both with model solutions and real liquid digestate. At a suitable pH of 10, with >80 % of the total ammonia present as NH 3 , the RO BW membrane showed a large N/K selectivity of 35 in the crossflow system. Additional RO steps at low pH allows subsequent concentration of the formed NH 4 + and K+ fractions. The presented dynamic pH approach proofs that in a two-step RO system both N, and K-enriched fertilizers can be produced from real liquid digestate. [ABSTRACT FROM AUTHOR]

The traditional atmospheric correction models employed with the near-infrared iterative schemes inaccurately estimate aerosol radiance at high solar zenith angles (SZAs), leading to a substantial loss of valid products for dawn or dusk observations by the geostationary satellite ocean color sensor. To overcome this issue, we previously developed an atmospheric correction model suitable for open ocean waters observed by the first geostationary satellite ocean color imager (GOCI) under high SZAs. This model was constructed based on a dataset from stable open ocean waters, which makes it less suitable for coastal waters. In this study, we developed a specialized atmospheric correction model (GOCI-II-NN) capable of accurately retrieving the water-leaving radiance from GOCI-II observations in coastal oceans under high SZAs. We utilized multiple observations from GOCI-II throughout the day to develop the selection criteria for extracting the stable coastal water pixels and created a new training dataset for the proposed model. The performance of the GOCI-II-NN model was validated by in-situ data collected from coastal/shelf waters. The results showed an Average Percentage Difference (APD) of less than 23% across the entire visible spectrum. In terms of the valid data and retrieval accuracy, the GOCI-II-NN model was superior to the traditional near-infrared and ultraviolet atmospheric correction models in terms of accurately retrieving the ocean color products for various applications, such as tracking/monitoring of algal blooms, sediment dynamics, and water quality among other applications. [ABSTRACT FROM AUTHOR]

It is estimated that at least 25 % of the anthropogenic carbon dioxide (CO 2) emitted to the atmosphere since the start of the industrial revolution has been absorbed and dissolved by the oceans. The uptake of CO 2 by the oceans leads to an increase in the seawater proton concentration ([H+]), and decreases in seawater pH, carbonate ion concentration ([CO 3 2–]), and saturation state (Ω) with respect to calcium carbonate (CaCO 3) minerals; a process commonly referred to as "ocean acidification". Shallow-water (<200 m), high-magnesium, biogenic calcites are expected to be amongst the first to respond to ocean acidification, and it has been proposed that they will dissolve selectively and sequentially according to their solubility in seawater. In this study, we test this competitive dissolution hypothesis by reacting a mixture of biogenic and synthetic carbonates of varying Mg content with acidified, natural seawater to simulate the progressive acidification of surface-ocean waters by anthropogenic CO 2. The results of this study confirm the hypothesis that carbonates will dissolve sequentially according to their respective solubility. They also reveal that the dissolution of high Mg-calcites will proceed incongruently. The originality of this contribution rests with the demonstration that the presence of a single high Mg-calcite will generate, like in a sediment of mixed mineralogy, a continuum of transient states as lower Mg-calcites of greater stability are precipitated and dissolved. Consequently, in a semi-closed or closed system, the pH buffering of the acidified seawater solution will be progressive rather than occur in steps according to changes in the solubility of the individual carbonate phases that compose a sediment. Hence, we expect that, as the oceans take up more anthropogenic CO 2 and further acidify, the average mineralogy and composition (Mg content) of shallow-water carbonate sediments and reef structures will change over the next few centuries as the most soluble carbonate phases (high-Mg calcites) are dissolved and no longer precipitated. [ABSTRACT FROM AUTHOR]

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. An easy-to-prepare, scalable, and cost-effective bifunctional catalyst that can split alkaline seawater to produce hydrogen is reported. It exhibits low overall splitting voltage and overpotentials, high stability, and excellent chlorine resistance. [Display omitted] • An efficient bifunctional catalyst for alkaline seawater splitting is reported. • Synthesized by a simple, one-step pyrolysis of Ni-exchanged ZIF67. • Exhibits low OER/HER overpotentials and excellent chlorine-resistance in seawater. • Exhibits low overall seawater splitting voltage (1.72 V at 20 mA cm−2). • The catalyst performance is validated in a zero-gap seawater electrolyzer. [ABSTRACT FROM AUTHOR]

Interface engineering can expose sufficient active sites and facilitate the hydrogen evolution reaction kinetics. Herein, we developed a strategy with the designed deep eutectic solvents dissolved CoO as precursors to prepare Co 3 S 4 and NiS nanodots and carbon hybridized microspheres on the surface of nickel foam (Co 3 S 4 /NiS/C/NF) via a one-step sulfidation-pyrolysis method. The composite catalysts have abundant tightly coupled heterogeneous interfaces between Co 3 S 4 and NiS nanodots, the hybridized carbon layers and NF, which not only improve the electron transfer efficiency but also increase the number of active sites. The optimized Co 3 S 4 /NiS/C/NF electrodes exhibit excellent electrocatalytic HER activity in all-pH water and natural seawater, and were even superior to the Pt/C electrode at high current densities. In 0.5 M H 2 SO 4 , 1.0 M KOH, 1.0 M PBS, and natural seawater electrolytes, current densities as high as 10 mA cm−2 were obtained at remarkably low overpotentials of only 49, 72, 93, and 261 mV respectively. This work provides new insights for the development of excellent electrocatalysts in all-pH water and natural seawater applications. [Display omitted] • Carbon hybridized Co 3 S 4 /NiS nanodot microspheres were constructed via one-step sulfidation-pyrolysis. • Abundant heterogeneous interfaces improve electron transfer efficiency and increase active sites. • Co 3 S 4 /NiS/C/NF electrode exhibits enhanced HER activity in all pH water and seawater. [ABSTRACT FROM AUTHOR]

Suffering from their low conductivity, Mn-base oxides are commonly inactive in H–OH activation. Generally, tailoring the coordinate environment of materials could induce variation in the atomic arrangement and further influence their chemical activity. Herein, we propose a feasible strategy to mediate the electronic structure of Mn-based oxides by facile hydrothermal method and thermal reduction route. Compared with MnO 2 sheets, the as-synthesized Ru/MnO–Mn 7 C 3 /N-doped carbon sheets (Ru/MnO–Mn 7 C 3 /NC) exhibit the higher activity for both acidic (73 mV) and alkaline water reduction reaction (44 mV@10 mA/cm2). Benefitting from unique structures, Ru/MnO–Mn 7 C 3 /NC sheets show the better freshwater/seawater oxidation reactivity, exceeding RuO 2. The strong interaction of MnO–Mn 7 C 3 heterostructures, Ru, and N-doped carbon endows Ru/MnO–Mn 7 C 3 /NC with the good freshwater and seawater dissociation performance, outperforming most of the reported Mn-based oxides. Ru/MnO–Mn 7 C 3 /N-doped carbon sheets could considerably catalyze dissociation of freshwater/seawater into H 2 with 1.52/1.65V at 10 mA/cm2. [Display omitted] • Ru/MnO–Mn 7 C 3 /N-doped carbon sheets are rationally fabricated. • Ru, MnO–Mn 7 C 3 heterojunction, and N-doped carbon are observed. • It achieves high acidic and alkaline hydrogen generation efficiency. • It possesses the pronounced freshwater/seawater electrolysis reactivity. [ABSTRACT FROM AUTHOR]

Organic carbon burial in ancient lacustrine settings is a crucial source of petroleum resources. Unlike the marine environment, the dynamics of organic carbon burial in the terrestrial realm are more complex due to the interplay of global and regional climate-tectonic factors. There appears to be a potential linkage between seawater incursion events (SWIEs) and the generation of lacustrine source rocks. However, reliable proxies to reconstruct the frequency and extent of SWIEs are currently lacking. Here, we explore the potential of rhenium-platinum group elements (Re-PGE) system as a novel proxy for determining SWIEs in the Nenjiang Formation of the lacustrine Songliao Basin in China that is noted for its high-quality source rock. By comparing marine and non-marine intervals, we validate the utility of Re-PGE fractionation patterns and osmium (Os) isotope compositions. Moreover, the Re/Ir ratios demonstrate two main episodes of quantitative seawater-lake water exchange. The comparison of variable indicators shows that the Re-PGE system is more sensitive to the changes in water sources, thus providing detailed information of frequency and exchange amount. The inverse variation between seawater contribution and total organic carbon content further implies that the massive sulfate influx from SWIEs facilitated bacterial sulfate reduction in the sediment pile, which had the effect of recycling nutrients (e.g., phosphorous) back into the water column. The SWIEs-triggered eutrophication induced a positive feedback loop between productivity and hypoxia, creating ideal conditions for the preservation of organic carbon. Our data reveals the detailed mechanism of SWIEs-triggered organic carbon burial and emphasizes the significant role of SWIEs in generating economically important hydrocarbon reservoirs. [ABSTRACT FROM AUTHOR]

The Urucum iron- and manganese formation (IF-MnF) in the Santa Cruz Formation, Brazil, was deposited in a glacially influenced, late Neoproterozoic depositional environment. It has proven to be a reliable and robust archive for the late Neoproterozoic, allowing unique insights into the composition of seawater during an interval that is characterized by dramatic changes in the Earth's litho-, hydros-, atmo-, and biosphere, including several episodes of low-latitude glaciations. Here we present highly siderophile element data of the Urucum IF-MnF to evaluate elemental sources that affected the Neoproterozoic seawater from which the Urucum IF-MnF precipitated. High uncertainties associated with current dating attempts of this formation overlapped with the Marinoan glaciation (∼650–635 Ma) as well as the Gaskiers glaciation event (∼580 Ma). A Re-Os regression line defined by iron-, manganese-, and chert-rich samples of the Urucum formation is interpreted as an isochron, yielding a refined age estimate of 577 ± 38 Ma and an initial 187Os/188Os ratio of 0.122 ± 0.003. The proposed depositional age overlaps with previous published age data of the Urucum IF-MnF, but relates the Urucum IF-MnF to the Ediacaran Gaskiers glaciation and overlaps with the age of the Shuram CIE (∼567 Ma). An initial 187Os/188Os ratio of 0.122 ± 0.003 is interpreted to represent pristine Neoproterozoic seawater and supports strong hydrothermal input, probably related to rifting, that promoted ferruginous conditions in the Urucum seawater. In an alternative scenario, Re-Os isotope data for the Urucum IF-MnF could also be interpreted in a multi-component mixing scenario, defined by hydrothermally influenced water masses that sourced most metals within the Urucum basin and a crustal component that entered the Urucum seawater either as detrital admixture or via riverine loads. Although none of the scenarios can be ruled out, we consider the isochron scenario as more plausible. [ABSTRACT FROM AUTHOR]

Long-term preservation of gametes has been identified as a tool to improve broodstock management and increase the number of juveniles produced by artificial fertilization. Paralichthys orbignyanus is an important commercial and recreational species distributed in marine and estuarine waters from Rio de Janeiro (Brazil) to the San Matías Gulf (Argentina). This work focused on studying the seminal quality of tank-reared P. orbignyanus , demonstrating that males are fluent year-round, with the highest yields at the early reproductive season. Fresh sperm exhibited good forward swimming, and samples could be refrigerated up to 48 h while retaining their motility after activation. The optimal conditions for P. orbignyanus sperm motility activation were established as 950 mOsmol/Kg and pH values between 7 and 7.9. Additionally, a well-defined protocol for semen vitrification was developed to assess the cryotolerance of this species' sperm. We successfully produced high-quality sperm samples, using two vitrification formulations containing trehalose and both z-1000 and x-1000 polymers, that can be used in a near-future in vitro embryo production program. • Captive Paralichthys orbignyanus males yield year-round semen quality. • Semen retains good motility when refrigerated up to 48 h. • Optimal conditions for sperm activation were set at 950 mOsmol and pH 7–7.9. • A novel protocol for P. orbignyanus semen vitrification is reported. • The best extender formulations showed good fertilization rates vs fresh samples. [ABSTRACT FROM AUTHOR]

Developing efficient and stable oxygen evolution reaction (OER) electrocatalysts under various alkaline conditions is crucial for commercial hydrogen (H₂) production. This study synthesized superhydrophilic NiFe LDH/NF with a nanosheet structure. The strong electronic interactions between the metals modify the electronic structures of Ni and Fe. In-situ Raman spectroscopy reveals numerous high-valent nickel intermediates with high OER activity during the reaction, significantly improving the catalyst's overall performance. At room temperature, the NiFe LDH/NF catalyst exhibits a current density of 50/100 mA cm−2 with only 217/233 mV required in 1 M KOH. Moreover, the catalyst requires only 180 mV under industrial conditions (60 °C, 6 M KOH), 243 mV in alkaline artificial seawater, and 280 mV in alkaline natural seawater to achieve 100 mA cm−2. The catalyst also exhibits long-term operational durability under these conditions, indicating a wide range of potential applications. [Display omitted] • NiFe LDH was directly grown in situ on a nickel foam surface by a hydrothermal method. • The catalyst's nanosheet structure and superhydrophilicity enhance the exposure of active sites to the electrolyte. • The two metalssynergistically alter the electronic structure,generating numerous high-valent active metals. • The catalysts demonstrate high activity and stability in alkaline media, even under harsh industrial conditions and seawater. [ABSTRACT FROM AUTHOR]

The development of efficient, stable and low-cost electrocatalysts towards the seawater oxidation is highly desirable for hydrogen-based industries. In this work, we report the efficient preparation of phosphate-decorated hierarchical porous CoNiFe medium-entropy alloys as promising electrocatalysts for the oxygen evolution reaction in seawater via the solution combustion synthesis. The hierarchical porous structure of CoNiFe medium-entropy alloys enhances exposure to catalytic sites and facilitates the efficient diffusion of gas products as well as electrolytes. Moreover, the in-situ formed PO 4 3− anions not only improve the electrocatalytic performance of CoNiFe medium-entropy alloys for oxygen evolution reaction, but also prevent Cl− from contacting the catalytic sites. Thanks to these structural benefits, the optimized CoNiFeP 0.1 @NF electrode demonstrates superior electrocatalytic performance for oxygen evolution reaction, showing an overpotential of 250 mV at 10 mA cm−2, a low Tafel slope of 47.6 mV dec−1, and satisfactory stability in the 1.0 M KOH +0.5 M NaCl electrolyte. • Phosphate-decorated CoNiFe alloys were prepared via solution combustion synthesis. • The hierarchical porous structure of CoNiFe benefits the exposure of active sites. • PO 4 3− anions enhance the performance of CoNiFe alloys for seawater oxidation. [ABSTRACT FROM AUTHOR]

Creating and building an integrated system that consists of a storage tank, an electrolysis cell with many electrolyzer types, and a green hydrogen generator that produces clean, sustainable gas using solar photovoltaic (PV) energy and renewable energy sources. Three different electrolyzer modules with six, eleven, and twenty-one plates each were created locally and meant to be utilized in the production of green hydrogen. The hydrogen storage system's design was also created. It is clear that the maximum value of hydrogen production is recorded in the following ordered: KOH (5.5 L/min) > NaOH (1.2 L/min) > NaCl (0.7 L/min) > MgSO 4 (0.4 L/min). Also, sea water was used as electrolyte solution with different dilution 5, 10, 15, and 20% using a natural sea water sample collected from the Mediterranean Sea. It is found that 15% sea water dilution reaches the maximum value of H 2 production (3.4 L/min). Using distilled water and tap water, respectively, the volume of generated H 2 gas reached its maximum value of 8 L/min and 6.5 L/min at 0.4 mols of KOH. It was observed that with increased time durations (0–90 min), enhance the rate of hydrogen production to be reaches 8.2 and 11.5 L/min when using 0.05 and 0.1 mols KOH, respectively. This approach reduces environmental effect and operational costs, providing a sustainable solution to the water and energy problems. The integrated system for using solar energy and photovoltaic (PV) for hydrogen production used the storage H 2 as a source of energy to operate the small water desalination plant. [Display omitted] • Creation of three different electrolyzer modules with six, eleven, and twenty-one plates. • Electrolysis cell and a storage tank with many electrolyzers using solar energy used for H 2 production. • KOH, NaOH, NaCl, and MgSO 4 used as an electrolyte solutions for H 2 productions. • Different dilution of a natural sea water sample used as electrolyte solution. • Numerous variables were estimated in order to influence the production of green H 2. [ABSTRACT FROM AUTHOR]

In this study, Al 2 O 3 –20TiO 2 (AT) and Cr 2 O 3 –3TiO 2 –5SiO 2 (CT) coatings were prepared by atmospheric plasma spraying (APS), The microstructure, phase compositions and corrosion behavior were studied comparatively. The results indicated that both coatings had layered structure, with an average surface roughness RA around 6 μm, an adhesive strength around 35 MPa, and a porosity around 4 %. The AT coating mainly composed of γ-Al 2 O 3 and α-Al 2 O 3 , and the CT coating composed Cr 2 O 3 respectively. Moreover, the AT coating exhibited better corrosion resistance than the CT coating. In artificial seawater, the corrosion process was strongly related to the porosity. The corrosion rate (based on the corrosion current density) of the two coatings showed a same trend which decreased first and then increased. It was thought that the blocking of early corrosion products in holes was helpful to delaying the progress of corrosion. In contrast, the later corrosion products would promote the formation and propagation of cracks, accelerating the corrosion. In the simulated environment with high pressure and hydrogen sulfide seawater, the corrosion process was strongly related to the porosity as well as the brittleness of the coatings. The corrosion rate (based on the weight loss) of the AT coatings still remained the same trend as it in the artificial seawater. However, the CT coating showed a continuously increasing corrosion rate, due to higher porosity and brittleness resulted in a large number of cracks under external stress, which offered corrosion channels. [ABSTRACT FROM AUTHOR]

In this paper, we report an inexpensive one-step synthesis of self-supported 3D nickel-manganese (NiMn) bimetallic coatings and their application for the hydrogen evolution reaction in simulated seawater (1 M KOH + 0.5 M NaCl) and alkaline natural seawater (1 M KOH + natural seawater). These binary coatings were electrodeposited on a titanium substrate using a facile electrochemical deposition method by a dynamic hydrogen bubble template technique. The as-deposited NiMn coatings with variable Mn amounts produce typical globular and unique porous architecture with abundant pores of different sizes. The activity of these fabricated catalysts towards the hydrogen evolution reaction was investigated by linear sweep voltammetry towards simulated seawater and alkaline natural seawater at different temperatures. The surface morphology and composition of the catalysts were also characterized by scanning electron microscopy and inductively coupled plasma optical emission spectroscopy. The as-prepared NiMn/Ti electrocatalyst, which was electrodeposited using a chemical bath containing Ni2+ and Mn2+ ions with a molar ratio of Ni2+:Mn2+ = 1:5, exhibits excellent hydrogen evolution activity in simulated seawater with an ultra-low overpotential of 64.2 mV to reach a current density of 10 mA cm−2. It is noteworthy that this NiMn/Ti electrocatalyst also achieves a current density of 10 mA cm−2 in alkaline natural seawater with a comparably low overpotential of 79.3 mV. The current densities increase by ca. 1.75–2.35 times with an increase in temperature from 25 °C to 75 °C for hydrogen evolution in both electrolytes. This bimetallic catalyst has shown excellent long-term stability at a constant potential of −0.23 V (vs. RHE) and a constant current density of 10 mA cm−2 for 10 h, which ensures higher durability and robustness for practical application of seawater splitting technology. [Display omitted] • 3D bimetallic NiMn/Ti electrocatalysts synthesized using a dynamic hydrogen bubble template technique. • Efficient and stable 3D bimetallic NiMn/Ti electrocatalysts for HER in simulated seawater/alkaline natural seawater. • NiMn/Ti-5 shows excellent HER activity with overpotentials of 64.2 and 79.3 mV at 10 mAcm−2 in simulated and natural seawater. • Simple, non-toxic, affordable, and time-saving synthesis procedure. [ABSTRACT FROM AUTHOR]

In situ reconstructed anti-corrosive and active surface on hierarchically porous carbonized wood for efficient overall seawater electrolysis. [Display omitted] [ABSTRACT FROM AUTHOR]

Electrocatalytic seawater splitting represents a highly promising sustainable technique for hydrogen production. There exists an urgent imperative to develop cost-effective and highly active electrocatalysts for the electrocatalytic hydrogen evolution reaction (HER) from seawater. Herein, we have designed and synthesized a novel amorphous medium-entropy oxide electrocatalyst, (Co 0·40 Ni 0·30 Mo 0.17 Re 0.13)O. The amorphous structure furnishes abundant active sites, while the distinguish electronic configuration of medium-entropy oxide bestows high electrocatalytic activity upon (Co 0·40 Ni 0·30 Mo 0.17 Re 0.13)O. Density functional theory calculations and electrochemical measurements have demonstrated the superior electrocatalytic activity of the amorphous (Co 0·40 Ni 0·30 Mo 0.17 Re 0.13)O electrocatalyst towards HER. Overpotentials of only 33 and 265 mV are required to achieve a current density of 10 mA cm−2 in 1 M KOH and natural seawater, respectively. Moreover, the (Co 0·40 Ni 0·30 Mo 0.17 Re 0.13)O electrocatalyst exhibits exceptional stability. This study presents a cost-effective and highly active electrocatalyst with great potential for seawater hydrogen production and provides insights into enhancing catalyst activity through deliberate composition and structural design. [Display omitted] • A novel amorphous medium-entropy oxide (Co 0·40 Ni 0·30 Mo 0.17 Re 0.13)O electrocatalyst. • DFT calculation reveals the strong H 2 O adsorption capacity and moderate ΔG H*. • Overpotentials of 33 and 265 mV @ 10 mA/cm2 for HER in 1 M KOH and natural seawater. [ABSTRACT FROM AUTHOR]

The investigation of cost-effective and highly efficient electrocatalysts for alkaline water and simulative seawater oxidation is essential to the conversion and storage of renewable energy. In this paper, the Ce–NiSe 2 /CoP catalyst with multihole and ultrathin nanosheet structure is generated. The unique structural characteristics of Ce–NiSe 2 /CoP heterojunction nanosheets contribute the excellent OER performance under different alkaline 1 M KOH and simulated seawater (1 M KOH + 0.5 M NaCl) electrolytes. Specifically, this catalyst exhucture is generated. The unique structural characteristics of Ce–NiSe 2 /CoP heterojunction nanosheets conibits the low overpotentials of 287 and 304 mV at the current density of 10 mA cm−2, along with the Tafel slopes of 87.1 and 78.8 mV dec−1 in two solutions, respectively. Moreover, the Ce–NiSe 2 /CoP target product also displays good stability. The present study introduces a promising strategy for the advancement of high-performance electrocatalysts in green energy field. [Display omitted] • The Ce-doped NiSe 2 /CoP heterostructure nanosheets are triumphantly generated. • The Ce–NiSe 2 /CoP product possesses multihole and ultrathin lamella architecture. • Each nanosheet with coarse surface is composed of prolifically nanosecondary units. • This catalyst presents fine OER properties in alkaline water and simulative seawater. [ABSTRACT FROM AUTHOR]

Greenhouse gas emission was effectively reduced and the energy crisis was alleviated by decomposing seawater into hydrogen energy. Producing hydrogen from seawater through electrolysis poses particular challenges, such as competition between oxygen and chlorine evolution reactions on the anode and low conductivity of seawater, and therefore, researchers are actively working towards finding innovative solutions to overcome these obstacles. An in-depth overview of the principles and progress of seawater electrolysis for hydrogen energy production was provided in this paper. Various design strategies for electrocatalysts (such as transition metal nitrides, transition metal sulfides and transition metal phosphates), electrocatalysts performance evaluation index and the electrolysis mechanism were summarized. Finally, prospects and challenges of using seawater electrolysis for hydrogen energy production in future were proposed. • A comprehensive overview for transition metal-based electrocatalysts for hydrogen production from seawater. • Various design strategies for electrocatalysts, performance evaluation index and the electrolysis mechanism were summarized. • Prospects and challenges of seawater electrolysis for hydrogen production were proposed. [ABSTRACT FROM AUTHOR]

Oxygen evolution reaction (OER) with sluggish kinetics plays a crucial role in the field of renewable energy conversion, and it is urgent but still challenging to develop highly active and stable OER electrocatalysts. Herein, heterostructured and hierarchical transition metal phosphide (CoP/CoFeP) nanosheet is prepared as a high-performance OER electrocatalyst. Strong electronic interaction is observed between CoP and CoFeP, which could regulate the electronic structure and promote the generation of high-valence cobalt. The hierarchical architecture is beneficial to enlarging the surface area. Consequently, CoP/CoFeP only needs an overpotential of 211 and 274 mV to afford a current density of 10 and 400 mA cm−2, respectively. Moreover, CoP/CoFeP could maintain superior electrocatalytic activity in alkaline seawater, which achieves 400 mA cm−2 with a potential lower than the thermodynamic potential of chloride oxidation. This work provides a deep understanding on the heterostructured transition metal phosphides for electrocatalytic OER and opens up a novel avenue to prepare highly active electrocatalysts. A facile strategy has been developed to prepare heterostructured and hierarchical CoP/CoFeP nanosheets, which demonstrate regulated electronic structure, abundant heterointerface, and large surface area. As a result, CoP/CoFeP nanosheets display superior electrocatalytic OER performance in alkaline freshwater and seawater. [Display omitted] • A facile strategy was developed to prepare heterostructured and hierarchical CoP/CoFeP. • Heterostructured CoP/CoFeP demonstrated large ECSA and regulated redox behavior. • CoP/CoFeP demonstrates superior electrocatalytic OER performance in alkaline freshwater and seawater. [ABSTRACT FROM AUTHOR]

Photocatalytic natural seawater-derived splitting to produce hydrogen is one of the most potential strategies to alleviate the shortage of freshwater resources and energy crisis. Nevertheless, the complicated composition of natural seawater poses substantial challenges to the activity and stability of photocatalysts. Here, we report on the fabrication of carbon dots (CDs) and B elements co-modified carbon nitride (i.e. CDs/BCN) via precursor-mediated supramolecular self-assembly and subsequent NaBH 4 -assisted thermal reduction as well as its implementation as seawater-derived H 2 production. The fabricated CDs/BCN exhibits the flaky porous structure capable of providing more transport channels for the generated gases (e.g. H 2) and precipitates (e.g. Mg(OH) 2 , Ca(OH) 2) during the seawater splitting process. Benefitting from cooperation of CDs and B elements i.e. the inhibited recombination of electron-hole pairs as well as the extended optical absorption range of CN, the optimal CDs/BCN-2 under visible-light irradiation exhibits the high H 2 production rate up to 10369 μmol g-1 h-1 in natural seawater. The proven satisfactory reusability and the corresponding structural stability demonstrate the excellent corrosion resistance of CDs/BCN-2 in natural seawater. Additionally, CDs/BCN-20 photocatalyst synthesized via 20-fold precursor amplification procedure still displays efficient photocatalytic performance of 9022 μmol g-1 h-1, indicating its potential for industrial applications. [Display omitted] • CDs and B co-modified flaky porous CN is fabricated by a facile calcination method. • The optimized CDs/BCN-2 displays superb H 2 production activity in natural seawater. • The satisfactory stability of CDs/BCN exhibits its excellent corrosion resistance. • After amplification procedure CDs/BCN-20 exhibits high photocatalytic performance. [ABSTRACT FROM AUTHOR]

Developing efficient and economical electrocatalysts for hydrogen evolution reaction (HER) over a broad pH range has received considerable attention. In this work, we prepared multi-dimensional MoS 2 /S-CoP heterojunction catalysts by utilizing the carbon clothes supported ZIF-67 array as templates combining with Mo-ion exchange and high-temperature phosphorization-sulfidation strategy. The introduction of MoS 2 into S-CoP results in electron redistribution and the formation of a distinctive space charge region at the two-phase contact interface, thereby effectively tuning surface properties, enhancing electron conductivity, and improving electrocatalytic activity. According to Density Functional Theory (DFT) calculations, the introduction of MoS 2 is advantageous for the adsorption and desorption of H*, resulting in the value of ΔG H* very close to zero. Furthermore, the adsorbed water molecules are more readily activated, rendering the ΔG H2O-dis decrease, thus significantly promoting HER activity. These features contribute to robust HER electrocatalytic performance in a wide pH range and even in seawater, which is also beneficial for industrial applications. In particular, MoS 2 /S-CoP exhibits superior HER performance in alkaline seawater, requiring only 197 and 228 mV to reach the current densities of 100 and 200 mA cm-2, respectively. This study offers novel perspectives on high-performance heterostructures for HER electrocatalysts in alkaline seawater environments. [ABSTRACT FROM AUTHOR]

The cocatalysts play a key role in photocatalytic technology in remarkably improving the efficiency of H 2 evolution. Herein, S vacancies-rich Cd 0.6 Zn 0.4 S nanorods (CZS NRs) were prepared via solvothermal method. Then, as-obtained CZS NRs were modified with Ni–Co PBA-derived NiS x nanoparticles (NPs) cocatalyst using grinding method. The optimized CZS/NiS x -N-1.5 hybrids (CZS/NiS x -N, where N represents nickel nitrate which was used as nickel source) exhibited outstanding stability and activity, the average rate of H 2 was up to 192.82 mmolg−1h−1 in deionized water medium, which was 201.4% higher than that of CZS. Besides, NiS x -A and NiS x -C cocatalysts with different particle sizes were obtained using nickel acetate (A) and nickel chloride (C) as nickel source, respectively. The CZS/NiS x -C-1.5 and CZS/NiS x -A-1.5 exhibited the H 2 evolution rate of 180.70 and 201.93 mmolg−1h−1 in deionized water medium, respectively. The as-prepared materials also exhibited the excellent H 2 evolution performance in natural seawater medium. Besides, the photocatalytic mechanism of H 2 evolution over CZS NRs/NiSs NPs was also discussed. This work develops a novel H 2 evolution cocatalyst and unveils the relationship between the loading amount/particle size of cocatalyst on the H 2 evolution rate. CZS NRs/NiSx NPs hybrids for photocatalytic pure water and natural seawater hydrogen production. [Display omitted] • A novel photocatalytic H 2 evolution cocatalyst was prepared. • Optimized CZS/NiS x exhibits high reusability, and structural stability. • The relationship of loading amount/particle size of cocatalyst on H 2 evolution rate were unveiled. • The evolution process of morphology from Ni–Co PBA NCs to NiS x NPs was explored. • Optimized CZS/NiS x exhibits excellent high activity in deionized water and natural seawater medium. [ABSTRACT FROM AUTHOR]

Icy moons with subsurface oceans of liquid water rank among the most promising astrobiological targets in our Solar System. In this work, we assess the feasibility of deploying laser sail technology in precursor life-detection missions. We investigate such laser sail missions to Enceladus and Europa, as these two moons emit plumes that seem accessible to in situ sampling. Our study suggests that GigaWatt laser technology could accelerate a 100 kg probe to a speed of ∼ 30 km s − 1 , thereupon reaching Europa on timescales of 1–4 years and Enceladus with flight times of 3–6 years. Although the ideal latitudes for the laser array vary, placing the requisite infrastructure close to either the Antarctic or Arctic Circles might represent technically viable options for an Enceladus mission. Crucially, we determine that the minimum encounter velocities with these moons (about 6 km s − 1 ) may be near-optimal for detecting biomolecular building blocks (e.g., amino acids) in the plumes by means of a mass spectrometer akin to the Surface Dust Analyzer onboard the Europa Clipper mission. In summary, icy moons in the Solar System are potentially well-suited for exploration via the laser sail architecture approach, especially where low encounter speeds and/or multiple missions are desirable. • Light sail astrobiology mission architecture to analyze Enceladus and Europa formulated. • GigaWatt laser technology capable of achieving flight times of ≤ 6 years. • Encounter velocities with plumes of icy moons compatible with optimal detection of biomolecules. • Potential of light sail flotillas for Solar System exploration discussed. [ABSTRACT FROM AUTHOR]

[Display omitted] [ABSTRACT FROM AUTHOR]

This work focused on the intermittent characteristics of renewable energy and studied the dynamic response characteristics of seawater/CO 2 co-electrolysis on solid oxide cell stacks to produce syngas under strong fluctuation electricity conditions. The results showed that when using a strong fluctuating current density of 58.2–658.1 mA/cm2 to simulate wind turbines, the power variation of the solid oxide cell stack was almost in line with the simulated wind turbine power variation curve. The theoretical conversion rate of solid oxide cell stack electrolysis products is linearly related to the current density. The measured H 2 O+CO 2 conversion rate is similar to the theoretical value, and the current variation hardly changes the H 2 /CO ratio in the exhaust gas. Therefore, solid oxide electrolysis cell stacks have strong adaptability to fluctuating electricity. • SOEC stacks have adaptability to strong fluctuation power electrolysis. • The impact of current changes on product proportion is relatively small. • The conversion rate of H 2 O + CO 2 is close to the theoretical conversion rate. [ABSTRACT FROM AUTHOR]

Electrolysis of water for production of hydrogen has become one of the most fascinating methods to relieve the energy crisis and environmental pollution. In this paper, a series of M-NiS/Mo 2 S 3 (M = Co, Fe, Ce and Bi) materials was in situ grown on Ni foam through a two-step hydrothermal process, and the synthesized Co–NiS/Mo 2 S 3 material present excellent hydrogen evolution reaction (HER) properties. Under an alkaline condition of 1 M KOH, Co–NiS/Mo 2 S 3 requires only overpotential of 142 mV to achieve a current density of 10 mA cm−2, and using Co–NiS/Mo 2 S 3 as both cathode and anode, only the potential of 1.574 V is required to drive a current density of 50 mA cm−2, with a relatively good durability over 15 h. Density functional theory (DFT) analysis show that the ΔG H* of Co–NiS is closer to 0 and its density of states near the Fermi energy level is higher, suggesting that Co–NiS improves the electrical conductivity of Co–NiS/Mo 2 S 3 and plays a significant catalytic action. This work proposes novel insights for the future exploration of novel sulfur-based composite electrocatalysts with excellent HER performance. In this paper, a series of M-NiS/Mo 2 S 3 (M = Co, Fe, Ce and Bi) materials was in situ grown on Ni foam by a two-step hydrothermal method, and the synthesized Co–NiS/Mo 2 S 3 material present excellent hydrogen evolution reaction (HER) properties. [Display omitted] • M-NiS/Mo 2 S 3 (M = Co, Fe, Ce and Bi) materials were successfully synthesized by hydrothermal processes. • Co–NiS/Mo 2 S 3 electrode shows excellent catalysis in the cathode reaction of water and water electrolysis. • Co–NiS/Mo 2 S 3 requires only overpotential of 142 mV to achieve a current density of 10 mA cm−2. [ABSTRACT FROM AUTHOR]

Layered double hydroxides (LDHs) are highly regarded catalysts for oxygen evolution reaction (OER), but the application is limited by low conductivity and stability characteristics. In this work, the CoP@NiFe LDH heterostructure is obtained by a simple electrodeposition-phosphorization-electrodeposition method, and the establishment of heterostructure regulates the electronic configuration, which promotes the catalytic performance and stability. In simulated seawater, CoP@NiFe LDH reaches 100 and 300 mA cm−2 at overpotentials of only 260 and 278 mV, with Tafel slope of 44.4 mV dec−1, while also demonstrating remarkable stability. In situ Raman spectra indicate the conversion of Ni(OH) 2 to Ni3+αOOH during the OER process, suggesting that the high valence Ni3+αOOH is the real active center, and the heterostructure efficaciously minimizes the overpotential that is necessary for the conversion to Ni3+αOOH, which is also confirmed by DFT calculations. Overall, this work presents a report on the process engineering and formulation of an energetic OER catalyst, which provides a viable solution for the industrialization of seawater electrolysis. [Display omitted] • CoP@NiFe LDH exposes an extremely rich set of active sites. • The heterostructure modulates electronic structure and produces synergistic effect. • CoP@NiFe LDH demonstrates excellent catalytic activity and stability. • The catalysts are analyzed by in situ Raman spectra and DFT calculations. [ABSTRACT FROM AUTHOR]

The exploration of highly efficient noble metal-free catalysts for overall water splitting in alkaline water/seawater at large-current density is critical for industrial application. In this work, FeCo-MOF derived hierarchical Co 4 S 3 /Fe 3 S 4 /MoS 2 nanosheet arrays on iron foam (IF) were prepared as efficient electrocatalyst for both HER and OER by solvothermal method. The CFM 0.3 nanosheet arrays exhibited the high HER performance with the Tafel slope of 70 mV dec-1 and extremely low overpotential of 241, 377 mV at 100 and 500 mA/cm2. The CFM 0.7 nanosheet arrays can deliver a high current density of 100 and 500 mA/cm2 at the overpotential as low as 220 and 305 mV and small Tafel slope (79 mV dec-1) for OER. Moreover, CFM0.3/CFM0.7 exhibited the low overpotentials of 270/380 mV for HER/OER at 100 mA/cm2 in simulated seawater. The CFM0.3//CFM0.7 delivered comparatively low cell voltage of 1.26/1.45 V at 10 mA/cm2 with excellent stability for 48 h in alkaline water/simulated seawater. Benefiting from the three-dimensional nanosheet arrays framework and the interface coupling interactions of trimetallic sulfides, the self-supporting robustness electrodes with abundant multimetallic electroactive centers can regulate charge/ion diffusion path and electronic structure for prompting HER and OER activity at high current density. Hence, this work would provide new ideas for exploration of highly-active MOF-derived non-noble metal bifunctional catalysts for energy-related applications. The Co 4 S 3 /Fe 3 S 4 /MoS 2 (CFM) nanosheet arrays on IF were prepared as an efficient electrocatalyst for both HER and OER. CFM 0.3 exhibited low overpotential of 241, 377 mV at 100 and 500 mA/cm2 for HER. CFM 0.7 showed low overpotential of 220 and 305 mV at 100 and 500 mA/cm2 for OER. CFM 0.3 and CFM 0.7 exhibited the low HER and OER overpotentials of 270 and 380 mV at 100 mA cm−2 in simulated seawater. CFM 0.3//CFM 0.7 delivered comparatively low cell voltages of 1.26 and 1.45 V at 10 mA/cm2 for overall water/seawater splitting. [Display omitted] • Co 4 S 3 /Fe 3 S 4 /MoS 2 nanosheet arrays were fabricated on IF by solvothermal method. • CFM0.3 exhibited 241(270)/377 mV at 100/500 mA/cm2 in 1.0 M KOH(seawater) for HER. • CFM0.7 exhibited 220(380)/305 mV at 100/500 mA/cm2 in 1.0 M KOH(seawater) for OER. • CFM0.3//CFM0.7 exhibited 1.26(1.45V) at 10 mA/cm2 for 48 h in 1.0 M KOH(seawater). [ABSTRACT FROM AUTHOR]

S-scheme heterojunction preserves strong redox capacity by the unique spatial separation of charge carriers, which will greatly boost the photocatalytic activity. In this study, Cu ions doped in Mn 0.5 Cd 0.5 S (MCS) nanorods (NRs) resulted in rich S vacancies in MCS. S vacancies can regulate the energy band structure of MCS and enable the transform of type-I MCS@CuS heterojunction into S-scheme Cu:MCS@CuS heterojunction. S-scheme Cu:MCS@CuS exhibited high light harvesting capability and the apparent quantum efficiency (AQE) under visible light, charge carriers separation and transfer ability and enhanced H 2 production efficiency and stability from seawater. The H 2 production rate of Cu: MCS @ CuS NRs in seawater under visible light reached up to 40.6 mmol g−1 h−1, and it could still remain above 80 % after six cycles. This study provides a new idea for the design and synthesis of high-efficiency catalysts for hydrogen production from seawater under visible light. [Display omitted] • Cu doping induced S-vacancies in MCS. • S-vacancies modulated the band structure of MCS. • Type I MCS@CuS transformed into S-scheme Cu:MCS@CuS heterojunction. • Cu:MCS@CuS exhibited high photocatalytic HER activity and stability in seawater. [ABSTRACT FROM AUTHOR]

Electrocatalytic water splitting is considered as a green and efficient way of hydrogen production. How to promote the performance of electrode and develop stable non-precious metal catalysts has caused extensive research. One of the effective strategies is combining two or more catalytic materials to build heterogeneous structures. In this paper, a series of Co 0.3 -Ni 3 S 2 /Ni 3 Sn 2 S 2 heterostructured materials were synthesized to in-situ grow Ni 3 S 2 /Ni 3 Sn 2 S 2 on Ni foam with a 3D porous structure by modulating the substance ratio of elemental cobalt and elemental sulfur through a one-step hydrothermal process. The materials have superior oxygen evolution reaction (OER) properties and urea oxidation reaction (UOR) performance. Under an alkaline electrolyte of 1 M KOH, for OER, Co 0.3 -Ni 3 S 2 /Ni 3 Sn 2 S 2 only requires overpotential of 251 mV to obtain a current density of 10 mA cm−2. In an alkaline solution of 1 M KOH +0.5 M urea, for UOR, only the potential of 1.326 V was demanded for the catalyst to reach a current density of 50 mA cm−2, but its stability over 15 h was average. Density Functional Theory (DFT) analyses suggest that Co–Ni 3 S 2 has better metallic properties and promote the dynamics in catalysis. This study put forward a new thought for future research on nickel-tin binary metal sulfide hybrid electrocatalysts with excellent freshwater, seawater and urea oxidation properties. In this paper, a series of Co x -Ni 3 S 2 /Ni 3 Sn 2 S 2 materials was in situ grown on Ni foam by a one-step hydrothermal method, and the synthesized Co 0.3 -Ni 3 S 2 /Ni 3 Sn 2 S 2 material present excellent water and urea oxidation properties. [Display omitted] • Co 0.3 -Ni 3 S 2 /Ni 3 Sn 2 S 2 materials were successfully synthesized by hydrothermal processes. • Co 0.3 -Ni 3 S 2 /Ni 3 Sn 2 S 2 electrode shows excellent catalysis in the cathode reaction of water and urea. • Co 0.3 -Ni 3 S 2 /Ni 3 Sn 2 S 2 requires only potential of 1.326 V to achieve a current density of 50 mA cm−2 for UOR. [ABSTRACT FROM AUTHOR]

Salinity poses a significant threat to modern agriculture because it stunts and impedes crop growth and development. This experiment was aimed at examining the morpho-physiological, biochemical, and adaptive responses of Vitex negundo (Chaste tree) to a gradient of seawater (4 dS m−1, 8 dS m−1, and 12 dS m−1) for different durations (90, 120, and 150 days). The results demonstrate that seawater had a detrimental effect on morphological parameters as plant height, number of leaves, number of branches, and dry matter in a time and dose-dependent approach. This negative impact was strongly connected with the considerable reduction of many physiological indices such as relative water content, water retention capacity, photosynthetic pigments and carbohydrates content. Conversely, higher concentrations of proline indicated that Vitex negundo had improved osmoprotective abilities to combat salinity-induced osmotic stress. Increased H 2 O 2 levels along with noticeably unaffected membrane fluidity suggest its function in detecting and adapting to stress at moderate salinity. Additionally, elevated antioxidant enzyme activity (SOD, CAT, and APX), DPPH, and ABTS+, along with elevated phenol and flavonoid levels, point to a coordinated role for antioxidant elements that are controlling ROS. In contrast, high salinity (12 dS m−1) resulted in an explosion of ROS, as seen by elevated levels of H 2 O 2 , MDA, and electrolyte leakage. In the ion analysis, salinity-exposed plants revealed that the majority of Na+ persisted in the roots, while K+, Ca2+, and Mg2+ were more heavily accumulated in the leaves than the roots that assist in the uptake of other significant minerals. These results imply that Vitex negundo has the ability to withstand moderate (8 dS m−1) salinity due to its enhanced antioxidant system, osmolytes which also activates protective enzymes and improves ionic homeostasis. [ABSTRACT FROM AUTHOR]

Unraveling ancient melting processes is key to understanding how the earliest, tonalite-trondhjemite-granodiorite (TTG)-dominated continental crust formed from partial melting of amphibolite. Application of silicon isotope analysis to ancient crust reveals that Archaean TTGs exhibit consistently high Si isotope values (δ30Si) compared to modern granitoids, attributed to seawater-derived silica introduced by either (a) partial melting of variably silicified basalts or (b) assimilation of authigenic silica-rich marine lithologies in the melt source. However, both mechanisms can introduce highly variable δ30Si, conflicting with the strikingly consistent δ30Si compositions of Archaean TTGs. This study investigates an alternative model, whereby the distinct mineralogy and chemistry of TTG melt sources impart a distinct silicon isotope composition to the melt, compared with "modern" granitoids. We measured δ30Si in component parts (melanosome and leucosome) of an Archaean (2.7 Ga) mafic migmatite and coeval amphibolites and mafic granulites from the Kapuskasing uplift, Canada, to explore how Si isotopes fractionate during incipient TTG melt formation. Our data reveal leucosome (i.e., melt) exhibits consistently high δ30Si values compared to a relatively isotopically lighter melanosome (i.e., residuum). We also derive inter-mineral silicon isotope fractionation factors for mineral separates that agree well with those of ab initio estimates for the same minerals and show that the magnitude of equilibrium fractionation between TTG source rock and melt replicates that in Phanerozoic granitoids. We conclude the effects of magmatic differentiation on δ30Si have remained consistent throughout Earth history, meaning that Archaean TTGs must require a source isotopically heavier than unaltered basalt, as reflected by our amphibolites and mafic migmatite components. The consistently heavy δ30Si of seawater through Earth history, and the high SiO 2 content of amphibolites relative to coeval leucosome-free granulites in our study area, imply seawater silicification is the source of the observed high δ30Si. Thus, the consistently heavy Si isotope compositions measured in Archaean melt products define a unique aspect of ancient crust formation: that of the silicification of TTG source rock, implying the intrinsic involvement of a primeval hydrosphere. [ABSTRACT FROM AUTHOR]

The calcium isotope composition of seawater (δ44/40Ca sw) records important information on the evolution of the calcium and carbon cycles over geologic time. Over the past two decades, many attempts have been made to reconstruct the Neogene δ44/40Ca sw variation using various calcium isotope records of seawater or seawater-like pore fluids. Nonetheless, large discrepancies still exist among these Neogene δ44/40Ca sw records. Here we report δ44/40Ca values in a suite of Neogene island dolomites (20.8–3.4 Ma, n = 18) from the South China Sea. Combining multiple geochemical proxies (δ44/40Ca, δ13C, and δ18O, this study; Sr/Ca, ∑REY, δ7Li, δ26Mg, 87Sr/86Sr, and Δ 47 , previous studies) and evidence from petrography, fluid inclusions, and magnetostratigraphy, we suggest that the dolomitization for these dolomites was buffered by seawater-like fluids in the shallow marine burial domain or even marine diagenetic domain (<180 m) over a considerable period of time (<2 Myr). Then, we apply the equilibrium calcium isotope fractionation factor between dolomite and seawater of −0.52 ± 0.20 ‰ (2SD, n = 13) estimated from the literature to these fluid-buffered dolomites and reconstruct a new Neogene δ44/40Ca sw record. After using the Locally Weighted Regression (LOWESS) curve fitting method, our dolomite-based δ44/40Ca sw record is consistent with the reconciled seawater record from other calcium isotope archives, including shark teeth, corals, foraminifera, brachiopods, barites, phosphates, and bulk pelagic carbonates. Our results support the use of fabric-retentive early marine diagenetic dolomites to trace the evolution of δ44/40Ca sw through Earth's history. [ABSTRACT FROM AUTHOR]

This study investigates the properties and chemistry of surface water in Hurghada and its adjacent areas, with a focus on assessing the potential impact of human activities on water quality by measuring the concentrations of heavy metals in surface water samples. A total of fifty-nine surface water samples were collected and analyzed for various heavy metals, including manganese (Mn), iron (Fe), nickel (Ni), copper (Cu), zinc (Zn), cadmium (Cd), mercury (Hg), and lead (Pb) using the AAS technique. The results indicate that at the Desert Rose Resort transect, the average total concentrations of heavy metals were within the following ranges: Fe (average of 26.96 μg/L), Cu (average of 0.61 μg/L), Zn (average of 6.31 μg/L), and Pb (average of 0.75 μg/L). Conversely, at the Abu-Shaar transect, Ni (0.87 μg/L) and Cd (average of 0.02 μg/L) were the dominant heavy metals, while Mn exhibited the highest mean value (1.80 μg/L) at the El-Samaka Village transect. Notably, Hg was not detected in any of the samples within the study areas. Comparative analysis of heavy metal concentrations in Hurghada's surface waters with data from the Red Sea coast and other global regions reveals that the study areas maintain heavy metal concentrations well below the maximum permissible values for the marine environment. These findings suggest that human activities have not significantly impacted heavy metal levels in the region's surface waters. Additionally, statistical assessments, such as correlation coefficients (r), were employed to explore the relationships between heavy metal concentrations in water and sediment. These relationships provide valuable insights into the dynamic balance of elements within the sediment and their potential direct or indirect transfer into the water. [ABSTRACT FROM AUTHOR]

In recent years, climate change has become more intense for society, and to mitigate this scenario, renewable energy sources have increased their installed capacity. In this context, green hydrogen, which can be obtained through water electrolysis, is considered one of the main alternatives to enable the replacement of fossil energy sources, acting as an energy vector to balance supply and demand for renewable energy. This study aims to mapping trends in direct seawater electrolysis technology by analyzing patents retrieved from the Derwent Innovations Index database between 1963 and 2022. As a result, 138 patent documents were identified and the analysis revealed an increase in patenting between 2016 and 2021 leading by China, South Korea, Japan, the United States, and the United Kingdom. The analysis also showed a trend towards research and development for electrocatalysts for direct seawater electrolysis in alkaline media, using materials not belonging to the platinum group metals. [Display omitted] • Growth in patenting from 2016. • Scientific publications and patent filings showed a similar pace. • Technological development of electrocatalysts focused on alkaline pH. • Trend towards non-platinum group metal materials for electrocatalysts. [ABSTRACT FROM AUTHOR]

The research and development of environmentally friendly, stable and low cost catalyst for water electrolysis is the general trend and imminent direction. In this paper, the cobalt-nickel phosphide with nanoflake (Ni 12 P 5 /Co 2 P@NF) was prepared by a simple hydrothermal reaction and low temperature phosphating process for the first time. As a catalyst for urea assisted water electrolysis, Ni 12 P 5 /Co 2 P@NF exhibits excellent hydrogen evolution reaction (HER) activity, providing a very small overpotential of 124 mV at a current density of 10 mA cm−2 in 1.0 M KOH solution containing 0.5 M urea. At the same time, it also present a very low Tafel slope (61.98 mA dec−1), which demonstrates that the faster the rate of charge transfer is, the better the reaction is. We also tested HER performance in seawater solution containing 0.5 M urea and 1.0 M KOH, and the overpotential was 146 mV at a current density of 10 mA cm−2. Moreover, the stability of the Ni 12 P 5 /Co 2 P@NF material for HER was also tested for a long time, and the result showed that the catalytic performance decreased first and then was relatively stable. Density functional theory (DFT) calculation demonstrates that the Ni 12 P 5 monomer presents the optimal Gibbs free energy for hydrogen, the introduction of Co 2 P promotes the conductivity of the electrode, and the synergistic catalysis of the Ni 12 P 5 and Co 2 P promotes the electrochemistry performance of the electrode. This work proposes a novel idea and strategy for designing reasonable metal phosphide as an environmentally friendly and stable electrode. Ni 12 P 5 /Co 2 P@NF exhibits excellent hydrogen evolution reaction (HER) performance, providing a very low overpotential of 124 mV at a current density of 10 mA cm−2 in 1.0 M KOH solution containing 0.5 M urea. [Display omitted] • Ni 12 P 5 /Co 2 P@NF was prepared by a simple hydrothermal reaction and low temperature phosphating process. • Ni 12 P 5 /Co 2 P@NF exhibits excellent HER performance, providing a very low overpotential of 124 mV at 10 mA cm−2. • The catalytic performance decreased first and then was relatively stable for Ni 12 P 5 /Co 2 P@NF. [ABSTRACT FROM AUTHOR]

The side reactions in seawater and the sedimentation of the photocatalyst in highly concentrated ionic solutions seriously affect the activity and stability of the photocatalyst to split seawater to produce hydrogen. In terms of these problems, we designed the super-hydrophilic mesoporous brookite/anatase TiO 2 photocatalyst accordingly. The characterization results of crystal phase and band structure confirmed that the transition from brookite/rutile type I hetero-phase junction to brookite/anatase type II hetero-phase junction. Without any sacrificial agents, the photocatalytic H 2 production rate from seawater splitting reached 6.59 mmol g−1 h−1, which was 2.5 times and 2.9 times higher than brookite/rutile TiO 2 and anatase/rutile TiO 2 (P25), respectively. Meanwhile, it was also 4.4 times, 11.8 times and 36.1 times higher than brookite, anatase and rutile nanoparticles. Furthermore, the contact angle test confirmed the superhydrophilicity of the photocatalyst, mitigating the side reactions induced by Cl− and ensuring the long-term stability (100 h) of the photocatalyst in seawater. [Display omitted] • A nanoscale super-hydrophilic mesoporous brookite/anatase TiO 2 was precisely synthesized. • The transition from type I hetero-phase junction to type II hetero-phase junction was realized. • Photocatalytic H 2 production rate from seawater splitting reached 6.59 mmol g−1 h−1. • Hydrophilicity enhanced the activity and stability of the photocatalysts in seawater. [ABSTRACT FROM AUTHOR]

Water electrolysis has a promising prospect in the production of green hydrogen energy, but its oxygen evolution reaction kinetics is relatively slow. Therefore, in this experiment, CuCo 2 O 4 @ACoNi-LDH (A = Fe, Cu, Zn, Cr) with heterogeneous core-shell catalytic material was firstly prepared by means of hydrothermal and calcination process, and its anodic oxidation reaction in freshwater, seawater and urea was investigated. In the oxygen evolution reaction (OER) of electrolytic water, CuCo 2 O 4 @CuCoNi-LDH displays the best catalytic activity. When the current density is 10 mA cm−2, only the overpotential of 199 mV is needed (potential of 1.429 V). The competitive oxidation and corrosion of chloride ions in seawater result in the decrease of catalytic activity. For urea oxidation reaction (UOR), CuCo 2 O 4 @FeCoNi-LDH displays the best catalytic performance, only potential of 1.292 V was required with the same current density, and the catalyst had good stability during the reaction for 12 h. Density functional theory calculation shows that CuCo 2 O 4 plays an important role in the catalytic process. The synergistic catalysis of FeCoNi-LDH and CuCo 2 O 4 results in the improvement of catalyst activity and stability. The CuCo 2 O 4 material plays a key role in catalyzing urea splitting and the FeCoNi-LDH material protects CuCo 2 O 4 from corrosion according to experimental results and density functional theory calculations. This experiment provides a new idea for the hydrogen production, exploration and the treatment of urea wastewater for transition metal oxides and layered hydroxides electrocatalyst with core-shell heterostructure. CuCo 2 O 4 @ACoNi-LDH (A = Fe, Cu, Zn, Cr) with heterogeneous core-shell catalytic material was firstly prepared by means of hydrothermal and calcination process, and its anodic oxidation reaction in freshwater, seawater and urea was investigated. [Display omitted] • CuCo 2 O 4 @ACoNi-LDH (A = Fe, Cu, Zn, Cr) synthesized by hydrothermal method was employed in OER and UOR. • The effects of iron doping was investigated both theoretically and experimentally. • CuCo 2 O 4 @FeCoNi-LDH showed notable activity as well as high stability. [ABSTRACT FROM AUTHOR]

The development of efficient electrocatalysts became vital to resolving the ongoing clean energy crises and environmental issues, wherein high-performance catalysts for the improved electrocatalytic hydrogen evolution reaction (EHER) are demanded. To meet this goal, an advanced and green ultrasonic-assisted pulsed laser ablation in liquid technique was used to prepare surface oxygen vacancy and Ti3+ defects in perovskite-based ternary nanocomposites (PTNCs) decorated with Au@SrTiO 3 /g-C 3 N 4. An effective cathode was designed using Au@SrTiO 3 /g–C 3 N 4 –decorated PTNCs for EHER that operated in an acidic media of 0.5 M H 2 SO 4. The optimized Au@SrTiO 3 /g-C 3 N 4 PTNCs revealed an improved EHER at a very low over-potential of 0.082 V at a cathodic current density (J) of −10 mA/cm2, high double-layer capacitance (679.8 μF/cm2), large electrochemical surface area (19.4 cm2), high mass activity (198.35 A/g), high specific activity (2.91 mA/cm2), high surface charge density (0.0404 C/cm2), high catalytic active sites (4.19 × 10−7 mol/cm2), and exceptional long-term stability at 50 h, respectively. The Tafel slope of 45.36 mV/dec confirmed the presence of the Volmer-Heyrovsky mechanism to explain the enhanced EHER cycle of the prepared PTNCs. The improved electrocatalytic EHER performance was attributed to the induced synergistic strong metal-support interaction (SMSI) effect of the surface oxygen vacancy and Ti3+ defects in PTNCs that increased electrochemical surface area, high exposure of abundant active sites, improved intrinsic kinetics, and fast charge transport, respectively. Moreover, Au@SrTiO 3 /g–C 3 N 4 –decorated PTNCs exhibit excellent natural seawater electrolysis in terms of EHER at a low over-potential of 0.300 V at a J = −10 mA/cm2 and long-term stability at 10 h, respectively. It is demonstrated that the proposed novel surface oxygen vacancy and Ti3+ defects in Au@SrTiO 3 /g-C 3 N 4 PTNCs are effective electrocatalysts can be beneficial for producing hydrogen from green technologies in future energy applications via interface engineering. • Defective Au@SrTiO 3 /g-C 3 N 4 PTNCs was prepared by ultrasonic-assisted PLAL method. • Surface oxygen vacancy and Ti3+ defects caused the formation of PTNCs. • Highest EHER with low over-potential of 0.082 V and Tafel slope of 45.36 mV/dec. • Enhanced EHER was due to the induced synergistic SMSI effect between PTNCs. • PTNCs exhibits excellent EHER under acidic and natural seawater conditions. [ABSTRACT FROM AUTHOR]

Aeolian transport of mineral dust is an important carrier of nutrients and trace metals to the surface ocean and, hence, affects the biogeochemical cycles of C and N therein. Studies focusing on the provenances of dust across the latitudinal gradients over the open ocean waters are essential for better constraining the biogeochemical effects of dust deposition. Here, we analyzed the radiogenic isotope composition of Sr (87Sr/86Sr) and Nd (ε Nd (0)) in the silicate fraction of mineral aerosols collected over the pelagic northern and southern Indian ocean waters during the GEOTRACES-India research expeditions (GI-01: March-April 2014 and GI-02: April-May 2014). Both tracers, 87Sr/86Sr and ε Nd (0), exhibited marked spatial variability for dust deposition to different basins, including the Bay of Bengal (BoB), Arabian Sea (AS), equatorial Indian Ocean (EIO), and the southern sector of the Indian Ocean (SIO). The dust deposited in the AS showed a narrow spread in both 87Sr/86Sr (0.71520–0.71642) and ε Nd (0) (−10.9 to −10.1), along with the air mass back trajectories, indicating transport from the Arabian Peninsula. Likewise, the dust collected over the BoB was mainly sourced from the Thar Desert (87Sr/86Sr > 0.72, −16 < ε Nd (0) 〈 −1 3), whereas the EIO received mineral dust from the Thar Desert and sand dunes in northern Australia (87Sr/86Sr: 0.72, ε Nd (0): −11) and Indonesian Archipelago. In contrast, the SIO appeared to receive dust deposition from three different source regions, including dust from Antarctica, western Australia (87Sr/86Sr: 0.712, −20 < ε Nd (0) <−16, and South Africa/South America (87Sr/86Sr: 0.708–0.710; −24.5 < ε Nd (0) >−8.4). These results have important implications for modelling the dust transport to pelagic Indian and southern Indian Ocean waters. [ABSTRACT FROM AUTHOR]

Organic complexation of iron plays a crucial role in preventing its precipitation, facilitating its transport, and modulating its reactivity and bioavailability in natural waters. Although humic substances (HS) complexes serve as the primary source of terrestrial iron reaching ocean waters, the transition from Fe-HS species to other forms of organic complexation with ocean autochthonous ligands has not yet been properly described. Taking advantage of the electrolability of Fe-HS complexes, we monitored the ligand exchange of iron-saturated Suwannee River fulvic and humic acids (SRFA and SRHA) after the addition of desferrioxamine B (DFOB) and other ligands for comparison. We observed that Fe-HS concentrations gradually decreased until reaching an apparent steady state, typical of a reversible reaction within 1 to 15 h. The dissociation kinetics and species partitioning of Fe-SRHS complexes at the equilibrium showed some features contrary to the current paradigm of HS iron complexation. The affinity of SRFA to bind iron is close to that of DFOB and for SRHA is even higher. The heterogeneity of the HS iron binding groups was confirmed, although experiments in NaCl solutions revealed that in seawater it is substantially caused by the interaction of major divalent ions. The different dissociation kinetics of Fe-SRHS complexes obtained with different competing ligands and the absence of Fe-DFOB dissociation in the presence of iron-free SRFA indicate an intimate associative mechanism of ligand exchange, with the presence of a ternary complex (SRHS-Fe-DFOB) that does not form if the departing complex is Fe-DFOB. We hypothesize that at the concentrations of HS and siderophores found in the open ocean, iron ligand exchange is limited and organic iron speciation will be close to being regulated on a "first come, first served" basis. Experiments conducted under saturation of all iron complexes support the formation of a permanent concentration of a ternary complex. Our findings show the real complexity of cation-ligand interactions in seawater, with implications for the interpretation of recent chromatographic and electrochemical measurements and for the understanding of iron partitioning in the presence of ubiquitous HS. [ABSTRACT FROM AUTHOR]

Electrodialysis (ED) is an electrochemical separation process mainly applied for water desalination. Simultaneously, hydrogen can be generated at the electrodes by a water-splitting reaction, but with a higher energy demand than conventional electrolysis processes. In this study, the desalination and generation of H 2 are evaluated in a conventional bench-scale ED system for application in classified industrial areas where H 2 is needed as a reactant and desalting water is also required. The effects of process variables, such as the electrolyte concentration in the feed and electrode streams, membrane type, and electrical current density, are investigated. The maximum specific production of H 2 (21.6 mL/h.cm2 electrode) is obtained at a current density of 469 A/m2, corresponding to a salt flux of 1,027 g/h.m2, thereby demonstrating the feasibility of coupling water desalination with H 2 generation. The lowest energy consumption per m3 of hydrogen produced is achieved with a solution containing 35 g/L of NaCl. [Display omitted] • Evaluation of hydrogen production during desalination of salt solution. • The performance of the process is investigated under various operating conditions. • The salinity of the feed has little effect on gas production. • Concomitant augmentation in gas production and salt flux with increasing current density. • An increase in the feed salt concentration reduces the energy consumption/m3 of H 2. [ABSTRACT FROM AUTHOR]

Seawater, one of nature's most bountiful resources, holds promise as a valuable and inexhaustible raw material for hydrogen production through water electrolysis. However, to combat chloride corrosion and maintain a stable operating state, it is essential to design strong and effective electrocatalysts appropriate for the hydrogen evolution reaction (HER). Herein, we demonstrate that Ni 40 Ti 20 Zr 38 Ag 2 alloy, after the successive arc-melting, melt-spinning, and dealloying treatments, generates a distinctive nanosheet structure. In alkaline seawater electrolyte (1 M KOH + natural seawater), this materials for HER not only could achieve a smaller overpotential of 69 mV driving 10 mA cm−2, but also possess excellent stability including the 10 mA cm−2 current density over 24 h and 3000 cycles measurement. This is mainly attributed to the array of cascading interconnected nanosheets and the incorporation of Ag, as well as the resulting electron transfer and changes in the chemical state of the elements on the catalyst surface. This work proposes a novel design strategy for alloy materials for preparing an efficient HER electrocatalyst in alkaline seawater. The dealloyed NiTiZrAg can be used as an efficient and stable electrocatalyst for hydrogen production in alkaline seawater. [Display omitted] • NiTiZrAg-20 electrocatalysts with nanosheet arrays were constructed by dealloying. • Ag promotes the electron transfer between components and changes in chemical states. • The NiTiZrAg-20 showed superior HER performance in alkaline seawater. [ABSTRACT FROM AUTHOR]

A facile one-pot microwave-assisted synthesis prepared a new noble metal-free heterostructure of In 2 S 3 /In 2 O 3 nanosheets for blue LED-light-induced photocatalytic water splitting. The appropriate InCl 3 concentrations and reaction temperatures can grow the In 2 S 3 /In 2 O 3 nanosheets with higher photocatalytic water splitting for hydrogen production under blue-LED light irradiation. In addition, the optimized In 2 S 3 /In 2 O 3 nanosheets exhibited a higher hydrogen production rate is 618.0 μmolh−1g−1 in seawater without adjusted pH values under blue-LED light irradiation. Furthermore, the reusability of In 2 S 3 /In 2 O 3 nanosheets revealed the gradual increase of photocatalytic hydrogen production efficiency in four cycles. This phenomenon shall be attributed to the reaction of In 2 S 3 /In 2 O 3 nanosheets and seawater to form In 2 S 3 /In 2 O 3 /In(OH) 3 nanosheets, which can improve the recombination of the photogenerated charge carriers and light-harvesting capacity to promote their photocatalytic hydrogen production. [Display omitted] • In 2 S 3 /In 2 O 3 nanosheets were prepared using one-pot microwave-assisted synthesis. • In 2 S 3 /In 2 O 3 nanosheets exhibited higher photocatalytic water or seawater splitting. • In 2 S 3 /In 2 O 3 /In(OH) 3 nanosheets can be synthesized under photocatalytic seawater splitting. • In(OH) 3 can enhance the separation charge carriers and light-harvesting capacity. [ABSTRACT FROM AUTHOR]

Replacing sluggish anodic oxygen evolution reaction by hydrazine oxidation reaction in seawater electrolysis is one of the smartest ways of getting multiple benefits as it offers an energy saving route for hydrogen production keeping the cell voltage way smaller than responsible voltage for corrosive chloride oxidation. Here, we report iron-doped Co 3 N as highly active electrocatalyst towards hydrazine oxidation reaction and hydrogen evolution reaction in wide pH range of 7–14. The two-electrode electrolyser system reached industry scale current density of 1000 mA cm−2 at ultralow cell voltage of 0.65 V, and found sustainable at 500 mA cm−2 over 95 h in hydrazine assisted alkaline seawater splitting. The electrolyser system also achieved 200 mA cm−2 current density at 0.75 V in hydrazine assisted neutral seawater medium. Interestingly, a thin amorphous iron oxide layer formed in Fe-doped Co 3 N provided much needed protection during electrocatalysis offering long term stability at industry level current density. [Display omitted] • Amorphous Fe-oxide surface layer protected Fe–Co 3 N developed as electrocatalyst. • HzOR-assisted seawater splitting offers an efficient way to avoid corrosive CER. • The electrocatalyst achieved 1000 mA cm−2 current density at 0.65 V in HzOS. • The electrocatalyst is efficient in wide pH range of seawater splitting. [ABSTRACT FROM AUTHOR]

Designing and developing high-efficient and durable non-precious-metal oxygen evolution reaction (OER) electrocatalysts is relevant for hydrogen generation from seawater splitting. Herein, a novel interfacial-coupled Fe-BDC/CoWO 4 /NF nanosheet array has been demonstrated via a two-step solvothermal method, which can effectively accelerate OER with an ultra-low overpotential of 254 mV at 100 mA cm−2 in 1.0 M KOH. More interestingly, it exhibits overpotentials of 290, 296, and 301 mV at 100 mA cm−2, when using 1.0 M KOH with 0.5, 1.0, and 2.0 M NaCl as simulated seawater and a lifetime of more than 250 h. The excellent performance for OER is benefit from the distinctive interfacial-structure, optimizing the OER process energy barrier of and lowering the adsorption energy of oxygen-containing intermediates, effectively speeding up the OER kinetics. This work opens a new strategy for designing versatile base metal OER electrocatalysts. [Display omitted] • Interface-coupled Fe-BDC/CoWO 4 /NF nanosheets arrays were successfully synthesized. • The catalyst has excellent OER activity and good corrosion resistance to Cl− in simulated seawater. • This work opens a new strategy for designing versatile base metal OER electrocatalysts. [ABSTRACT FROM AUTHOR]