Directional surface reconstruction of C and S Co-Doped Co2VO4/CoP for the cooperative enhancement of hydrogen production via seawater electrolysis.

The endeavor to architect bifunctional electrocatalysts that exhibit both exceptional activity and durability heralds an era of boundless potential for the comprehensive electrolysis of seawater, an aspiration that, nevertheless, poses a substantial challenge. Within this work, we describe the precise engineering of a three-dimensional interconnected nanoparticle system named SCdoped Co2VO4/CoP (SCCo2VO4), achieved through a meticulously arranged hydrothermal treatment sequence followed by gas-phase carbonization and phosphorization. The resulting SCCo2VO4 electrode exhibits outstanding bifunctional electrocatalytic stability, attributed to the strategic anionic doping and abundant heterogeneous interfaces. Doping not only adjusts the electronic structure, enhancing electron transfer efficiency but also optimizes the surface-active sites. This electrode prodigiously necessitated an extraordinarily minimal overpotential of merely 92 and 350 mV to attain current densities of 10 and 50 mA cm-2 for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively, in 1 M KOH solution. Noteworthily, when integrated into an electrolyzer for the exhaustive splitting of seawater, the SCP-Co2VO4 manifested an exceptionally low cell voltage of 2.08 V@50 mA cm-2 and showcased a durability that eclipses that of most hitherto documented nickel-based bifunctional materials. Further elucidation through Density Functional Theory (DFT) analyses underscored that anion doping and the inherent heterostructure adeptly optimize the Gibbs free energy of intermediates comprising hydrogen, chlorine, and oxygen (manifested as OH, O, OOH) within the HER and OER paradigms, thus propelling the electrochemical kinetics of seawater splitting to unprecedented velocities. These revelations unfurl a pioneering design philosophy for the creation of cost-effective yet superior catalysts aimed at the holistic division of water molecules, charting a course towards the realization of efficient and sustainable hydrogen production methodologies.

Electric Field-Enhanced Ion Rejection Rate in Freeze Desalination.

Freeze desalination is an appealing method for seawater desalination through freezing seawater. The percentage of ions in the liquid phase, which is termed ion rejection rate, is a critical factor affecting the performance of freeze desalination. Improving the ion rejection rate is an important topic for freeze desalination. In this work, we investigate the effects of electric fields on the ion rejection rate during the freezing of seawater through molecular dynamics simulations.  It is found that the ion rejection rate increases with increasing electric field strength.  The enhanced ion rejection rate is due to the reduction of the energy barrier at the ice-water interface caused by the electric field, which affects the orientation of water molecules and ion-water interactions. However, the electric field hinders the ice growth rate, which affects the productivity of freeze desalination. Nevertheless, the finding in this work offers a new idea to improve the ion rejection rate. Practically, a trade-off needs to be found to optimize the overall performance of freeze desalination.

Construction of an interface interaction in a g-C3N4/CdS/NiS for photoreforming of plastic and clean hydrogen regeneration.

Converting plastics into organic matter by photoreforming is an emerging way to deal with plastic pollution and produce valuable organic matter. Water shortage can be alleviated by using seawater resources. To solve these problems, we synthesize a ternary heterostructure composite g-C3N4/CdS/NiS. Heterojunctions are formed between graphitized carbon nitride (g-C3N4), cadmium sulfide (CdS) and nickel sulfide (NiS), which effectively improve the problem of fast charge recombination of pure g-C3N4 and CdS. The results of the g-C3N4/CdS/NiS photocatalytic tests show that the hydrogen production rates in seawater and pure water for 5 h are 30.44 and 25.79 mmol/g/h, respectively. In stability test, the hydrogen production rate of the g-C3N4/CdS/NiS in seawater and pure water is similar. This suggests that seawater can replace pure water as a source of hydrogen. While H2 is generated, the lactate obtained by polylactic acid (PLA) hydrolysis is oxidized to form small organic compounds such as formate, acetate and pyruvate. Our study shows that g-C3N4/CdS/NiS can not only use seawater as a hydrogen source to produce H2, but also photoreformate plastics dissolved in seawater into valuable small organic molecules. This has a positive impact on the production and use of clean energy, as well as on plastic pollution and water scarcity.

Inhibiting dissolution strategy achieving high-performance sodium titanium phosphate hybrid anode in seawater-based dual-ion battery.

Aqueous sodium-ion batteries (ASIBs) show great promise as candidates for large-scale energy storage. However, the potential of ASIB is impeded by the limited availability of suitable anode types and the occurrence of dissolution side reactions linked to hydrogen evolution. In this study, we addressed these challenges by developing a Bi-coating modified anode based on a sodium titanium phosphate (NTP)-carbon fibers (CFs) hybrid electrode (NTP-CFs/Bi). The Bi-coating effectively mitigates the localized enrichment of hydroxyl anion (OH-) near the NTP surface, thus addressing the dissolution issue. Notably, the Bi-coating not only restricts the local abundance of OH- to inhibit dissolution but also ensures a higher capacity compared with other NTP-based anodes. Consequently, the NTP-CFs/Bi anode demonstrates an impressive specific capacity of 216.8 mAh/g at 0.2 mV/s and maintains a 90.7 % capacity retention after 1000 cycles at 6.3 A/g. This achievement sets a new capacity record among NTP-based anodes for sodium storage. Furthermore, when paired with a cathode composed of hydroxy nickel oxide directly grown on Ni foam, we assembled a seawater-based cell exhibiting high energy and power densities, surpassing the most recently reported ASIBs. This groundbreaking work lays the foundation for a potential method to develop long-life NTP-based anodes.

Seawater quality criteria derivation and ecological risk assessment for dichlorvos in China.

Dichlorvos (DDVP) is a widely used organophosphorus pesticide (OPP) that has been frequently detected in the marine environment of China. Water quality criteria (WQC) is however not available for this emergent pollutant in the marine environment, which hinders its ecological risk assessment. This study, therefore, screened toxicity values of DDVP and conducted toxicity tests on six marine species to supplement toxicity data. The WQC for DDVP was derived with the species sensitivity distribution (SSD) methodology, based on which the ecological risk of DDVP in the seawater of China was assessed. The results showed that the recommended short-term (SWQC) and long-term water quality criteria (LWQC) for DDVP were 1.47 and 0.0521 µg/L, respectively. Most marine waters of China showed low or negligible risk (HQ < 1, ORP < 2 %), whereas some estuarine waters warrant further concern due to higher risk. This study provides the scientific basis for seawater quality standard formulation and ecological risk management for DDVP.

Enhancing CO2 storage and marine carbon sink based on seawater mineral carbonation.

Human activities emitting carbon dioxide (CO2) have caused severe greenhouse effects and accelerated climate change, making carbon neutrality urgent. Seawater mineral carbonation technology offers a promising negative emission strategy. This work investigates current advancements in proposed seawater mineral carbonation technologies, including CO2 storage and ocean chemical carbon sequestration. CO2 storage technology relies on indirect mineral carbonation to fix CO2, involving CO2 dissolution, Ca/Mg extraction, and carbonate precipitation, optimized by adding alkaline substances or using electrochemical methods. Ocean chemical carbon sequestration uses natural seawater for direct mineral carbonation, enhanced by adding specific materials to promote carbonate precipitation and increase CO2 absorption, thus enhancing marine carbon sinks. This study evaluates these technologies' advantages and challenges, including reaction rates, costs, and ecological impacts, and analyzes representative materials' carbon fixation potential. Literature indicates that seawater mineral carbonation can play a significant role in CO2 storage and enhancing marine carbon sinks in the coming decades.

From capture to detection: A critical review of passive sampling techniques for pathogen surveillance in water and wastewater.

Water quality, critical for human survival and well-being, necessitates rigorous control to mitigate contamination risks, particularly from pathogens amid expanding urbanization. Consequently, the necessity to maintain the microbiological safety of water supplies demands effective surveillance strategies, reliant on the collection of representative samples and precise measurement of contaminants. This review critically examines the advancements of passive sampling techniques for monitoring pathogens in various water systems, including wastewater, freshwater, and seawater. We explore the evolution from conventional materials to innovative adsorbents for pathogen capture and the shift from culture-based to molecular detection methods, underscoring the adaptation of this field to global health challenges. The comparison highlights passive sampling's efficacy over conventional techniques like grab sampling and its potential to overcome existing sampling challenges through the use of innovative materials such as granular activated carbon, thermoplastics, and polymer membranes. By critically evaluating the literature, this work identifies standardization gaps and proposes future research directions to augment passive sampling's efficiency, specificity, and utility in environmental and public health surveillance.

Antibacterial Janus cellulose/MXene paper with exceptional salt rejection for sustainable and durable solar-driven desalination.

The scarcity of freshwater resources and increasing demand for drinking water have driven the development of durable and sustainable desalination technologies. Although MXene composites have shown promise due to their excellent photothermal conversion and high thermal conductivity, their high hydrophilicity often leads to salt precipitation and low durability. In this study, we present a novel Cellulose (CF)/MXene paper with a Janus hydrophobic/hydrophilic configuration for long-term and efficient solar-driven desalination. The paper features a dual-layer structure, with the upper hydrophobic layer composed of CF/MXene paper exhibiting convexness to serve as a photothermal layer with exceptional salt rejection properties. Simultaneously, the bottom porous layer made of CF acts as an efficient thermal insulation. This unique design effectively minimizes heat loss and facilitates efficient water transportation. The Janus CF/MXene paper demonstrates a high evaporation rate of 1.11 kg m-2h-1 and solar thermal conversion efficiency of 82.52 % under 1 sun irradiation. Importantly, even after 2500 h of operation in a simulated seawater environment, the paper maintains a stable evaporation rate without significant salt deposition and biodegradation due to an antibacterial rate exceeding 90 %. These findings highlight the potential of the Janus CF/MXene paper for scalable manufacturing and practical applications in solar-driven desalination.

Dissolved and particulate metals and metalloids in the eastern Mekong Delta, Vietnam.

The article reports the concentration levels of particulate and dissolved metals and metalloids (Be, Se, Sb, Tl, V, Pb, Cd, Cu, Zn, Ni, Mo, Co, Fe As, Ag) in the eastern region of the lower Mekong Delta (Vietnam) in order to assess their possible influence on the environmental quality of river water. To measure the concentrations of trace elements, a mass spectrometric method was used. The critical particulate elements had included V, Cu, Ni, Co, Pb, Cd and potentially critical - Mo, Ag, Se, Tl. In the dissolved phase these were Cu, Zn, and Pb, Cd, Co, Ag, Se respectively. The high accumulation ability of studied elements to suspended particulate matter (102-107) suggests their important role in the distribution of elements. The water salinization boundary in the riverbeds of the delta moves upstream 30-50 km further in the dry season compared to the wet season.

Full-length 16S rRNA gene sequencing reveals the operating mode and chlorination-aggravated SWRO biofouling at a nuclear power plant.

Reverse osmosis (RO) membrane fouling and biological contamination problems faced by seawater desalination systems are microbiologically related. We used full-length 16S rRNA gene sequencing to assess the bacterial community structure and chlorine-resistant bacteria (CRB) associated with biofilm growth in different treatment processes under the winter mode of a chlorinated seawater desalination system in China. At the outset of the winter mode, certain CRB, such as Acinetobacter, Pseudomonas, and Bacillus held sway over the bacterial community structure, playing a pivotal role in biofouling. At the mode's end, Deinococcus and Paracoccus predominated, with Pseudomonas and Roseovarius following suit, while certain CRB genera still maintained their dominance. RO and chlorination are pivotal factors in shaping the bacterial community structure and diversity, and increases in total heterotrophic bacterial counts and community diversity in safety filters may adversely affect the effectiveness of subsequent RO systems. Besides, the bacterial diversity and culturable biomass in the water produced by the RO system remain high, and some conditionally pathogenic CRBs pose a certain microbial risk as a source of drinking water. Targeted removal of these CRBs will be an important area of research for advancing control over membrane clogging and ensuring water quality safety in the future.

Temporal dynamics of contaminants in an estuarine system affected by acid mine drainage discharges.

The estuary of Huelva is constituted by the common mouth of the Odiel and Tinto rivers, which are extreme cases of acid mine drainage contamination due to the Iberian Pyrite Belt, the world's largest sulfide mineral province. The drained acidic waters are subjected to seawater mixing and thus, to dilution and precipitation processes that drive the load of contaminants entering the oceanic environment. This research reports the distribution of major metal(loid)s present in the highly acidic waters across the entire Tinto and Odiel estuarine systems as they are subjected to acid mine drainage neutralization, until reaching the ocean. The datasets presented are divided in low- and high-flow periods, corresponding to dry/warm and wet/cold seasons, respectively. Iron and Al were almost entirely removed from solution with pH increase at both periods due to their precipitation as schwertmannite and basaluminite, respectively. These mineral phases also, controlled the behavior of As, Cu and Pb, which were removed from solution, with >90 % of their concentration ending up in the particulate phase due to sorption processes. However, at pH >7, As returned entirely to the dissolved phase at both sampled seasons because of desorption, similarly to Cu at the low-flow period. On the other hand, concentrations of Zn, Cd, Mn, Co and Ni in solution decreased only by dilution with seawater, with null partitioning to any sorption processes during estuarine mixing until reaching the Atlantic Ocean.

Different fates of particulate matters driven by marine hypoxia: A case study of oxygen minimum zone in the Western Pacific.

The oxygen minimum zone (OMZ) is an important representative of marine hypoxia in the open ocean, and it is developing rapidly under the context of global warming. However, the research on OMZ in the Western Pacific is still deficient. This study focused on its basic characteristics and impact on the degradation of particulate matters in the M4 seamount of Western Pacific. The results showed that the OMZ is located at 290-1100 m, just below the high-salinity area and thermocline. The M4 seamount has a weak impact on the OMZ, and only the bottom waters contacting with the seamount have a weak decrease in dissolved oxygen (DO). With the increase of water depth, particulate nitrogen and phosphorus decrease first above and in the OMZ and then increase below the OMZ, while particulate organic carbon (POC) gradually decreases. The low-DO environment in the OMZ is not conducive to the degradation of particulate matters, which promotes the transport of particulate matters to the deep sea, and most particulate matters have the lowest degradation rate here. The waters above the OMZ have the fastest change rate of particulate matters, in which particulate organic phosphorus (POP) and particulate inorganic phosphorus (PIP) are preferentially degraded, and the degradation rate of them is significantly higher than particulate organic nitrogen (PON) and particulate inorganic nitrogen (PIN). The particulate nitrogen and phosphorus in the waters below the OMZ continue to increase, while PON/total particulate nitrogen (TPN) and POP/total particulate phosphorus (TPP) increase significantly, and the increase rate of PIN and PIP is far lower than PON and POP, indicating that the increase of organic matters in particulate matters is more significant. It is speculated that this phenomenon might be related to the input of Antarctic Bottom Water or the in-situ production by microorganisms. This study revealed the relationship between OMZ and different particulate matters, which may provide a valuable pathway for the biogeochemical effects of OMZ in the Western Pacific.

Experimental Study of the Flexural Performance of GFRP-Reinforced Seawater Sea Sand Concrete Beams with Built-In GFRP Tubes.

The use of seawater sea sand concrete (SSSC) and fiber-reinforced polymer (FRP) has broad application prospect in island and coastal areas. However, the elastic modulus of FRP reinforcement is obviously lower than that of ordinary steel reinforcement, and the properties of SSSC are different from that of ordinary concrete, which results in a limit in the bearing capacity and stiffness of structures. In order to improve the flexural performance of FRP-reinforced SSSC beams, a novel SSSC beam with built-in glass FRP (GFRP) tubes was proposed in this study. Referring to many large-scale beam experiments, one specimen was used for one situation to illustrate the study considering costs and feasibility. Firstly, flexural performance tests of SSSC beams with GFRP tubes were conducted. Then, the effects of the GFRP tubes' height, the strength grades of concrete inside and outside the GFRP tubes, and the GFRP reinforcement ratio on the flexural behaviors of the beams were investigated. In addition, the concept of capacity reserve was proposed to assess the ductility of the beams, and the interaction between the concrete outside the GFRP tube, the GFRP tube and concrete inside the tube was discussed. Finally, the formulas for the normal section bearing capacity of beams with built-in GFRP tubes were derived and verified. Compared to the beam without GFRP tubes, under the same conditions, the ultimate bearing capacities of the SSSC beam with 80 mm, 100, and 200 mm height GFRP tubes were increased by 17.67 kN, 24.52 kN, and 144.42 kN, respectively.

Spatial distribution of lipophilic shellfish toxins in seawater and sediment in the Bohai Sea and the Yellow Sea, China.

Lipophilic shellfish toxins (LSTs) are widely distributed in marine environments worldwide, potentially threatening marine ecosystem health and aquaculture safety. In this study, two large-scale cruises were conducted in the Bohai Sea and the Yellow Sea, China, in spring and summer 2023 to clarify the composition, concentration, and spatial distribution of LSTs in the water columns and sediments. Results showed that okadaic acid (OA), dinophysistoxin-1 (DTX1) and/or pectenotoxin-2 (PTX2) were detected in 249 seawater samples collected in spring and summer. The concentrations of ∑LSTs in seawater were ranging of ND (not detected) -13.86, 1.60-17.03, 2.73-17.39, and 1.26-30.21 pmol L-1 in the spring surface, intermediate, bottom water columns and summer surface water layers, respectively. The detection rates of LSTs in spring and summer seawater samples were 97% and 100%, respectively. The high concentrations of ∑LSTs were mainly distributed in the north Yellow Sea and the northeast Bohai Sea in spring, and in the northeast Yellow Sea, the waters around Laizhou Bay and Rongcheng Bay in summer. Similarly, only OA, DTX1 and PTX2 were detected in the surface sediments. Overall, the concentration of ∑LSTs in the surface sediments of the northern Yellow Sea was higher than that in other regions. In sediment cores, PTX2 was mainly detected in the upper sediment samples, whereas OA and DTX1 were detected in deeper sediments, and LSTs can persist in the sediments for a long time. Overall, OA, DTX1 and PTX2 were widely distributed in the water column and surface sediments in the Bohai Sea and the Yellow Sea, China. The results of this study contribute to the understanding of spatial distribution of LSTs in seawater and sediment environmental media and provide basic information for health risk assessment of phycotoxins.

A new suggestion to marine gold extraction: Utilizing reduced graphene oxide membranes within seawater desalination processes.

Traditional mining practices not only cause severe environmental issues, but also face the problem of insufficient production capacity of gold to meet its growing demand. The proposed alternative strategies for gold production, such as the extraction of gold from seawater, still keep a formidable challenge due to their strong dependence on adsorbent materials with high capacity, selectivity, and sensitivity, while also needing to meet the demands of being environmentally friendly and cost-effective. In practice, the direct extraction of gold from seawater is limited by its extremely low yield and high energy expenditure. However, if the combination of gold extraction techniques with seawater desalination can substantially reduce the energy consumption, the extraction of gold from seawater will become economical and feasible. In this paper, we evaluate the feasibility of marine gold extraction using reduced graphene oxide membranes (rGOM) during the seawater desalination process. The rGOM can adsorb almost all Au3+ from the solutions with trace concentrations of Au3+ ranging from 10 ppb to 200 ppb. The adsorption quantity is linearly related to the concentration, indicating that the adsorption capacity of rGOM is much higher than the total amount of Au3+ in the solution. Additionally, the rGOM can selectively adsorb 99 % of Au3+ in the mixed solution while hardly adsorbing other common elements in seawater. More importantly, the rGOM exhibits the long-term stability over 30 days when being immersed in the solution, making it directly compatible with the existing seawater desalination processes. These specific properties allow the rGOM to be an ideal candidate for combining the extraction of gold from seawater with seawater desalination processes. Our findings provide a methodology for enhancing the economic efficiency of the extraction of gold from seawater and hold promise for addressing the problem of gold scarcity.

Harmful Ostreopsis cf. ovata blooms could extend in time span with climate change in the Western Mediterranean Sea.

Fast environmental changes and high coastal human pressures and impacts threaten the Mediterranean Sea. Over the last decade, recurrent blooms of the harmful dinoflagellate Ostreopsis cf. ovata have been recorded in many Mediterranean beaches. These microalgae produce toxins that affect marine organisms and human health. Understanding the environmental conditions that influence the appearance and magnitude of O. cf. ovata blooms, as well as how climate change will modify its future distribution and dynamics, is crucial for predicting and managing their effects. This study investigates whether the spatio-temporal distribution of this microalga and the frequency of its blooms could be altered in future climate change scenarios in the Mediterranean Western basin. For the first time, an ecological habitat model (EHM) is forced by physico-chemical climate change simulations at high-resolution, under the strong greenhouse gas emission trajectory (RCP8.5). It allows to characterize how O. cf. ovata may respond to projected conditions and how its distribution could shift over a wide spatial scale, in this plausible future. Before being applied to the EHM, future climate simulations are further refined by using a statistical adaptation method (Cumulative Distribution Function transform) to improve the predictions robustness. Temperature (optimum 23-26 °C), high salinity (>38 psu) and high inorganic nutrient concentrations (nitrate >0.25 mmol N·m-3 and phosphate >0.035 mmol P·m-3) drive O. cf. ovata abundances. High spatial disparities in future abundances are observed. Namely, O. cf. ovata abundances could increase on the Mediterranean coasts of France, Spain and the Adriatic Sea while a decrease is expected in the Tyrrhenian Sea. The bloom period could be extended, starting earlier and continuing later in the year. From a methodological point of view, this study highlights best practices of EHMs in the context of climate change to identify sensitive areas for current and future harmful algal blooms.

Degradation Behaviors of Polylactic Acid, Polyglycolic Acid, and Their Copolymer Films in Simulated Marine Environments.

Poly(lactic acid) (PLA) and poly(glycolic acid) (PGA) are extensively studied biodegradable polymers. However, the degradation behavior of their copolymer, poly(lactic-co-glycolic acid) (PLGA), in marine environments has not yet been confirmed. In this study, the changes in macroscopic and microscopic morphology, thermal properties, aggregation, and chemical structure of PLA, PGA, PLGA-85, and PLGA-75 (with 85% and 75% LA content) in simulated marine environments were investigated. Results revealed that degradation occurred through hydrolysis of ester bonds, and the degradation rate of PGA was faster than that of PLA. The amorphous region degraded preferentially over the crystalline region, leading to cleavage-induced crystallization and decreased thermal stability of PLA, PLGA-85, and PLGA-75. The crystal structures of PLGAs were similar to those of PLA, and the higher GA content, the faster was the degradation rate. This study provides a deeper understanding of the seawater degradation behaviors of PLA, PGA, and their copolymers, and provides guidance for the preparation of materials with controllable degradation performance.

Superwetting PVA/cellulose aerogel with asymmetric structure for oil/water separation and solar-driven seawater desalination.

Extracting clean water from oily wastewater and seawater is one of the effective strategies to alleviate the freshwater crisis. However, achieving both high separation efficiency and excellent salt resistance remain challenges for materials. Herein, a novel methyltrichlorosilane-modified polyvinyl alcohol/cellulose aerogel (MPCA) was prepared by freeze drying, chemical cross-linking, and chemical vapor deposition (CVD) methods. The superwetting MPCA presented an asymmetric structure, in which the small dense pores at the top surface facilitated the efficient separation of water-in-oil (W/O) emulsions and the large pores on the bottom surface were beneficial for brine exchange. The as-prepared superwetting aerogel was suitable for the separation of various W/O emulsions with excellent separation flux (631.9-2368.7 L·m-2·h-1) and outstanding separation efficiency (99.5 %). In addition, MPCA achieved a high evaporation efficiency of 1.39 kg·m-2·h-1 and a satisfactory energy conversion efficiency of 89.7 %. Moreover, the unique asymmetric structure endowed the evaporator excellent salt resistance and could self-dissolve the accumulated salt in 20 min. The as-prepared MPCA could achieve efficient W/O emulsion separation as well as produce freshwater in seawater, providing a new strategy for oily waste seawater purification.

The cobalt-based metal organic frameworks array derived CoFeNi-layered double hydroxides anode and CoP/FeNi2P heterojunction cathode for ampere-level seawater overall splitting.

The seawater electrolysis technology powered by renewable energy is recognized as the promising "green hydrogen" production method to solve serious energy and environmental problems. The lack of low-cost and ampere-level current OER (oxygen evolution reaction) and HER (hydrogen evolution reaction) catalysis limits their industrial application. In this work, a unique tri-metal (Co/Fe/Ni) layered double hydroxide hollow array anode catalyst (CFN-LDH/NF) and the CoP/FeNi2P heterojunction hollow array cathode are successfully prepared via one in-situ growth of Co-MOF on nickel foam (Co-MOF/NF) precursor, which exhibits excellent catalytic performance. The η1000 values of 352 and 392 mV are achieved for CFN-LDH/NF (OER catalyst) in 1.0 M KOH and alkaline seawater solution, respectively. The CFNP/NF with a low overpotential of 281 mV is required to reach 1000 mA cm-2 current density for HER in 1.0 M KOH solution, while the η1000 in alkaline seawater solution is 312 mV. The CFN-LDH/NF||CFNP/NF electrolyzer exhibits excellent long-term durability over 100 h, achieving current density of 500 mA cm-2 at 1.825 V in 1.0 M KOH solution. The construction of hollow tri-metal LDH and phosphides heterostructures may open a new and relatively unexplored path for fabricating high performance seawater splitting catalysis.

Complementary Multisite Turnover Catalysis toward Superefficient Bifunctional Seawater Splitting at Ampere-Level Current Density.

The utilization of seawater for hydrogen production via water splitting is increasingly recognized as a promising avenue for the future. The key dilemma for seawater electrolysis is the incompatibility of superior hydrogen- and oxygen-evolving activities at ampere-scale current densities for both cathodic and anodic catalysts, thus leading to large electric power consumption of overall seawater splitting. Here, in situ construction of Fe4N/Co3N/MoO2 heterostructure arrays anchoring on metallic nickel nitride surface with multilevel collaborative catalytic interfaces and abundant multifunctional metal sites is reported, which serves as a robust bifunctional catalyst for alkaline freshwater/seawater splitting at ampere-level current density. Operando Raman and X-ray photoelectron spectroscopic studies combined with density functional theory calculations corroborate that Mo and Co/Fe sites situated on the Fe4N/Co3N/MoO2 multilevel interfaces optimize the reaction pathway and coordination environment to enhance water adsorption/dissociation, hydrogen adsorption, and oxygen-containing intermediate adsorption, thus cooperatively expediting hydrogen/oxygen evolution reactions in base. Inspiringly, this electrocatalyst can substantially ameliorate overall freshwater/seawater splitting at 1000 mA cm-2 with low cell voltages of 1.65/1.69 V, along with superb long-term stability at 500-1500 mA cm-2 for over 200 h, outperforming nearly all the ever-reported non-noble electrocatalysts for freshwater/seawater electrolysis. This work offers a viable approach to design high-performance bifunctional catalysts for seawater splitting.