Direct Seawater Research Articles

Design, Operation and Simulation of a Passive Osmosis-Integrated Electrolyzer for Seawater Electrolysis

Abstract Utilizing abundant seawater for green hydrogen production through electrolysis is a promising pathway to produce a sustainable energy carrier. However, modern seawater electrolyzers have shown insufficient durability due to electrode corrosion and/or competitive production of chlorinated products that result from the presence of Cl-. In this work, a new cell, driven by osmotic separation, was designed and operated that can passively draw fresh water from seawater into compartments with high acid and/or alkaline concentration for electrolysis, thereby eliminating the need for an external energy source for desalination. The work focuses first on demonstrating the passive transport of water through membranes over a wide range of acid and base concentrations. Then, electrodes are integrated, and the cells are operated under multiple configurations and current densities. It is observed that some co-ion diffusion occurs, which is quantified through pH measurements and quantitative Cl- titration. Water transport and ion crossover experiments are supported by comprehensive continuum-level modeling. Finally, strategies for improving future performance are discussed. The findings in this work, a first step in the development of an osmosis-driven electrolyzer cell (ODEC), showcase the promise of this novel electrolyzer design for future direct seawater electrolysis.

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

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

Advancing the utilization of 2D materials for electrocatalytic seawater splitting

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

Accelerating the Hydrogen Evolution Kinetics with a Pulsed Laser-Synthesized Platinum Nanocluster-Decorated Nitrogen-Doped Carbon Electrocatalyst for Alkaline Seawater Electrolysis.

Efficient and durable electrocatalysts for the hydrogen evolution reaction (HER) in alkaline seawater environments are essential for sustainable hydrogen production. Zeolitic imidazolate framework-8 (ZIF-8) is synthesized through pulsed laser ablation in liquid, followed by pyrolysis, producing N-doped porous carbon (NC). NC matrix serves as a self-template, enabling Pt nanocluster decoration (NC-Pt) via pulsed laser irradiation in liquid. NC-Pt exhibits a large surface area, porous structure, high conductivity, N-rich carbon, abundant active sites, low Pt content, and a strong NC-Pt interaction. These properties enhance efficient mass transport during the HER. Remarkably, the optimized NC-Pt-4 catalyst achieves low HER overpotentials of 52, 57, and 53mV to attain 10mA cm-2 in alkaline, alkaline seawater, and simulated seawater, surpassing commercial Pt/C catalysts. In a two-electrode system with NC-Pt-4(-)ǀǀIrO2(+) as cathode and anode, it demonstrates excellent direct seawater electrolysis performance, with a low cell voltage of 1.63mV to attain 10mA cm-2 and remarkable stability. This study presents a rapid and efficient method for fabricating cost-effective and highly effective electrocatalysts for hydrogen production in alkaline and alkaline seawater environments.

Tuning the sulfide interface of MnCo2O4-based nanostructures enables efficient water/seawater electrolysis

Hydrogen generation through water electrolysis is greatly dependent on the development of energy and time-efficient techniques to construct stable and active electrocatalysts for oxygen evolution reaction (OER). Currently, major research focuses on producing hydrogen through direct seawater electrolysis instead of fresh water to build a sustainable society. However, competitive reactions such as chlorine evolution reaction (CIER) beyond OER and electrode erosion issues make seawater electrolysis more difficult. Here, we report an interfacial engineering strategy that constructs a MnCo2O4@CoS hybrid structure by sulfurization of the spinal MnCo2O4 nanowires. The hybrid structure demonstrates an excellent OER performance in electrolytes containing alkaline and saltwater. Specifically, the prepared catalyst needs overpotentials of 205 mV and 225 mV to deliver a current density of 10 mA cm−2 in 1 M KOH and alkaline seawater when used as OER electrocatalysts. This should be noted that the CoS layer on the surface of MnCo2O4 nanowires not only acts as a Cl‾ protective layer to impede electrode erosion and CIER but also provides metallic ions with a higher valence state to enhance the intrinsic catalytic activity of water oxidization. Thus, this type of electrocatalyst could represent a favorable choice, carrying substantial implications for hydrogen-based economies and environmental enhancement.

Upcycling of Spent LiFePO4 Cathodes to Heterostructured Electrocatalysts for Stable Direct Seawater Splitting.

The pursuit of carbon-neutral energy has intensified the interest in green hydrogen production from direct seawater electrolysis, given the scarcity of freshwater resources. While Ni-based catalysts are known for their robust activity in alkaline water oxidation, their catalytic sites are prone to rapid degradation in the chlorine-rich environments of seawater, leading to limited operation time. Herein, we report a Ni(OH)2 catalyst interfaced with laser-ablated LiFePO4 (Ni(OH)2/L-LFP), derived from spent Li-ion batteries (LIBs), as an effective and stable electrocatalyst for direct seawater oxidation. Our comprehensive analyses reveal that the PO4 3- species, formed around L-LFP, effectively repels Cl- ions during seawater oxidation, mitigating corrosion. Simultaneously, the interface between in situ generated NiOOH and Fe3(PO4)2 enhances OH- adsorption and electron transfer during the oxygen evolution reaction. This synergistic effect leads to a low overpotential of 237 mV to attain a current density of 10 mA cm-2 and remarkable durability, with only a 3.3 % activity loss after 600 h at 100 mA cm-2 in alkaline seawater. Our findings present a viable strategy for repurposing spent LIBs into high-performance catalysts for sustainable seawater electrolysis, contributing to the advancement of green hydrogen production technologies.

Upcycling of Spent LiFePO4 Cathodes to Heterostructured Electrocatalysts for Stable Direct Seawater Splitting

AbstractThe pursuit of carbon‐neutral energy has intensified the interest in green hydrogen production from direct seawater electrolysis, given the scarcity of freshwater resources. While Ni‐based catalysts are known for their robust activity in alkaline water oxidation, their catalytic sites are prone to rapid degradation in the chlorine‐rich environments of seawater, leading to limited operation time. Herein, we report a Ni(OH)2 catalyst interfaced with laser‐ablated LiFePO4 (Ni(OH)2/L‐LFP), derived from spent Li‐ion batteries (LIBs), as an effective and stable electrocatalyst for direct seawater oxidation. Our comprehensive analyses reveal that the PO43− species, formed around L‐LFP, effectively repels Cl− ions during seawater oxidation, mitigating corrosion. Simultaneously, the interface between in situ generated NiOOH and Fe3(PO4)2 enhances OH− adsorption and electron transfer during the oxygen evolution reaction. This synergistic effect leads to a low overpotential of 237 mV to attain a current density of 10 mA cm−2 and remarkable durability, with only a 3.3 % activity loss after 600 h at 100 mA cm−2 in alkaline seawater. Our findings present a viable strategy for repurposing spent LIBs into high‐performance catalysts for sustainable seawater electrolysis, contributing to the advancement of green hydrogen production technologies.

Stable Seawater Electrolysis Over 10000H via Chemical Fixation of Sulfate on NiFeBa-LDH.

Although hydrogen production through seawater electrolysis combined with offshore renewable energy can significantly reduce the cost, the corrosive anions in seawater strictly limit the commercialization of direct seawater electrolysis technology. Here, it is discovered that electrolytic anode can be uniformly protected in a seawater environment by constructing NiFeBa-LDH catalyst assisted with additional SO4 2- in the electrolyte. In experiments, the NiFeBa-LDH achieves unprecedented stability over 10000h at 400mAcm-2 in both alkaline saline electrolyte and alkaline seawater. Characterizations and simulations reveal that the atomically dispersed Ba2+ enables the chemical fixation of free SO4 2- on the surface, which generates a dense SO4 2- layer to repel Cl- along with the preferentially adsorbed SO4 2- in the presence of an applied electric field. In terms of the simplicity and effectiveness of catalyst design, it is confident that it can be a beacon for the commercialization of seawater electrolysis technology.

Electrocatalytic synergies of melt-quenched Ni-Sn-Se-Te nanoalloy for direct seawater electrolysis

The study focuses on the development of binary nanoalloys based on metal dichalcogenides (Sn30Se70, Ni30Te70) and quaternary nanoalloy (Ni15Sn15Se35Te35) using the melt quenching technique. The nanoalloys show extensive water splitting in fresh and real seawater. Sn30Se70-coated nickel foam achieved a benchmark current density of 349 mV for the oxygen evolution reaction (OER), while Ni15Sn15Se35Te35-coated nickel foam (NF) required only 185 mV for the hydrogen evolution reaction (HER) in 1 M KOH. The study also shows that a two-electrode system can achieve sustained total water splitting at higher current densities (1 A.cm−2). Modification with a CuSxlayer over NF at the OER end facilitated faster kinetics and mitigated chlorine corrosion enabling direct seawater splitting at 1.26 V. Continuous direct splitting of seawater at 100 mA cm−2 for 120 h required only 1.88 V, showing an efficiency of 92.9 % for H2production in real seawater.

S-doped amorphous multi-metal borophosphates for efficient alkaline seawater oxidation with a high corrosion resistance

Direct seawater splitting is a promising strategy for the production of green hydrogen to address water shortage and environmental concerns. However, the primary obstacle in direct seawater splitting is directly related to the high selectivity and durability of oxygen evolution reaction (OER) electrocatalysts. In this study, we developed sulfur-doped multimetal (Ni, Fe, and Co) borophosphates (BPOs) as high-performance OER catalysts for alkalized seawater electrolytes. The incorporated sulfur atoms act as precursors to enhance the corrosion resistance, as they form negatively charged polyanionic surface layers that block the chloride ions. The best catalyst demonstrates an overpotential of 278 mV in alkaline freshwater and 292 mV in alkalized seawater electrolytes when subjected to a current density of 100 mA cm−2. The overpotential disparity between the two media was only 14 mV, suggesting that the material has substantial resistance to chloride corrosion. Furthermore, excellent electrochemical durability was attained for the sulfurized and amorphized multi-metal BPOs, highlighting their high potential as promising catalysts for seawater oxidation.

20 Seconds to fabricate high-performance NiFe-based anode for seawater electrolysis via bidirectional pulse current method

Direct electrolysis of seawater to produce green hydrogen has attracted great attention. While the development of efficient and rapid manufacturing processes for high-performance electrodes, particularly for the oxygen evolution reaction (OER), remains trail. Here, we introduce an innovative approach to fabricate high-performance NiFe-based OER electrodes using an ultrafast and eco-friendly bidirectional pulse current (BPC) method, which remarkably shortens the production time to only 20 s. Our BPC method alternates oxidation and reduction currents within a single period, promoting the in-situ formation of porous NiFe(oxy)hydroxide nanosheets through dissolution/deposition processes. Moreover, this methodology creatively utilizes the “Cl− induced effect”, typically a hindrance in other electrochemical systems involving seawater or brine, to enhance the synthesis of electrodes from NaCl-based electrolyte devoid of additional Ni/Fe cations. The prepared NiFe-based electrode (NFF O-R 20 s) demonstrates remarkable OER catalytic activity, with optimal overpotentials (ηj) of 272, 308 and 367 mV at current densities (j) of 10, 100 and 1000 mA cm−2, respectively. Impressively, it maintains a low cell voltage of 1.59 V after enduring 1000 h of operation under the industrially current density of 300 mA cm−2, with a direct current energy consumption of 3.8 kWh Nm−3 H2 for overall alkaline seawater electrolysis. Our BPC preparation approach provides a promising path to construction high-catalytic activity, good-stability electrode, and low-energy consumption direct seawater electrolyzer.

S2−-modified hetero MOF-on-MOF of Ni-MOF/Fe-MOF with efficient seawater oxidation performance

Direct seawater electrolysis offers a viable solution to the excessive consumption of fresh water resources in existing industrial electrolytic water processes. However, electrolysis efficiency and material stability are affected by electrode material corrosion caused by chlorine evolution reactions (CER) at the anode positions. In this study, the prepared S-Ni-MOF/Fe-MOF material exhibits an exceptional performance in the oxygen evolution reaction (OER) both in alkaline solution and seawater. Specifically, the material achieves low overpotentials of 281 and 279 mV in 1.0 M KOH and alkaline seawater at 100 mA cm−2 current density, and maintains stability for at least 100 h in both electrolyte solutions. The electronic structure of MOF-on-MOF was modulated through the introduction of S2−, which induced a large number of vacancies. Furthermore, the reconstruction process on the material surface was accelerated by the formation of NiOOH and FeOOH, that served as protective layers and prevented the corrosion of the electrode material by Cl−, thereby enhancing its stability in seawater. Furthermore, computational studies have indicated that the Fe-Ni active sites at the heterointerface exhibit a synergistic effect, which has been confirmed by density functional theory (DFT) calculations. These results prove that this combination significantly reduces the energy barrier associated with the OER. Consequently, the reaction process is accelerated.

Multifunctional Design of Catalysts for Seawater Electrolysis for Hydrogen Production.

Direct seawater electrolysis is a promising technology within the carbon-neutral energy framework, leveraging renewable resources such as solar, tidal, and wind energy to generate hydrogen and oxygen without competing with the demand for pure water. High-selectivity, high-efficiency, and corrosion-resistant multifunctional electrocatalysts are essential for practical applications, yet producing stable and efficient catalysts under harsh conditions remains a significant challenge. This review systematically summarizes recent advancements in advanced electrocatalysts for seawater splitting, focusing on their multifunctional designs for selectivity and chlorine corrosion resistance. We analyze the fundamental principles and mechanisms of seawater electrocatalytic reactions, discuss the challenges, and provide a detailed overview of the progress in nanostructures, alloys, multi-metallic systems, atomic dispersion, interface engineering, and functional modifications. Continuous research and innovation aim to develop efficient, eco-friendly seawater electrolysis systems, promoting hydrogen energy application, addressing efficiency and stability challenges, reducing costs, and achieving commercial viability.

FeNiCo@lyocell-based carbon cloth cathode for enhanced seawater electrolysis with bipolar membrane

The formation of inorganic precipitates at the cathode is the most persistent problem in direct seawater electrolysis (DSWE) for hydrogen production. To address this issue, we demonstrate the combination of lyocell-based carbon cloth (CC, as a conductive substrate) and bipolar membrane (BPM)-based DSWE. The entire process, from fabricating lyocell-based CC to coating FeNiCo catalysts, is conducted to ensure stable adhesion between the CC surface and electrocatalysts, thereby enhancing charge transfer. The hydrogen evolution reaction activity of FeNiCo@lyocell-based CC in 1.0 M NaOH shows the overpotential of 152 mV at 10 mA/cm2, which is much lower than that (342 mV) of bare lyocell-based CC. When the FeNiCo@lyocell-based CC is used as a cathode in the BPM-DSWE, the growth rate of inorganic precipitates formed at the cathode is significantly reduced. As a result, the rate of increase in cathodic potential over 100 h at 100 mA/cm2 is approximately 6 %, which is more than four times smaller than that of Pt-coated Ti foam. The woven structure of the lyocell-based CC provides small holes densely distributed at regular intervals and empty spaces between carbon fibers arranged in the same direction. The unique structure is expected to help the protons generated from the BPM escape directly into bulk seawater. In this process, free protons can play a role in reducing the high pH formed at the interfaces of each fiber, slowing down the growth rate of inorganic deposits. If the empty space ratio of the porous structure and the three-dimensional connectivity are optimized for BPM-DSWE, lyocell-based CC is expected to be a promising conductive substrate that can suppress the formation of inorganic deposits even at higher current densities.

Development of High-Performance Bipolar Membranes with Optimal Junction Properties for Efficient Electro-Membrane Processes

A bipolar membrane (BPM) is a special type of ion-exchange membrane in which an anion-exchange layer (AEL) and a cation-exchange layer (CEL) are combined. Water molecules can be easily dissociated at the interface of the BPM by the strong electric field generated when a reverse bias voltage is applied through the membrane. Such dissociation leads to the generation of proton and hydroxide ions, which are then transported through the CEL and AEL, respectively, resulting in the production of acid and base solutions. Under a forward bias, these ions are drawn back to the bipolar interface, where they neutralize each other. The energy derived from this neutralization process, represented as a junction potential (JP) value, is a key factor in the BPM's efficiency. BPMs with ideal JP values are critical for achieving high separation and energy efficiencies in electro-membrane processes. Furthermore, for the prolonged operation of these processes, BPMs must possess a highly adhesive bipolar junction. Our work includes the development of a novel BPM with an ideal JP and a highly adhesive bipolar junction. This BPM has been applied to various electro-membrane processes, including an acid-base flow battery and direct seawater electrolysis. The BPMs are fabricated using poly(phenylene oxide) (PPO)-based ionomers, and incorporates an iron-based catalyst and a reinforcing material. These additions enhance the water-splitting performance and the durability of the interface between the ion-exchange layers. The prepared BPMs not only demonstrated excellent interfacial adhesiveness and mechanical properties but also achieved a water-splitting efficiency of 98% or higher. In comparison to commercial BPM, the electro-membrane processes utilizing the prepared BPM exhibited superior performance. This work was supported by the National Research Foundation of Korea (NRF) grants funded by the Korean government (MEST) (NRF-2022M3C1A3081178 & NRF-2022M3H4A4097521).

Selectivity Study of Anodic Seawater Electrolysis Catalysts Using the Rotating Ring-Disc Electrode Method

Water electrolysis generating green hydrogen will play a vital role in achieving the net-zero 2050 goal; however, freshwater electrolysis will further strain an already strained supply of clean freshwater.1 If seawater electrolysis can be scaled successfully, it would provide an important source of green hydrogen. Current research on untreated, direct seawater electrolysis is limited, and only recently have studies emerged analyzing catalyst performance at near-neutral pH.2 At industrially-relevant current densities, the formation of corrosive hypochlorite must be considered as a secondary reaction.3 Hypochlorite forms through the chloride oxidation reaction (ClOR), which competes with the oxygen evolution reaction (OER) in seawater electrolysis.2 In this work, we discuss the limitations of the current methods for determining anodic catalyst selectivity between OER and ClOR. The short lifetime of hypochlorite can cause faradaic efficiency measurement methods such as titration or oxygen gas capture to become unreliable, as these tests require that the hypochlorite remain stable. Using a rotating ring-disc electrode (RRDE), we measure the selectivity of common OER catalysts in-situ (Figure 1a). Real-time hypochlorite sensing overcomes the challenge of measuring catalyst selectivity posed by the short lifetime of hypochlorite. Remarkably, a PtRu catalyst outperformed more common OER catalysts with the best in OER selectivity and low overpotential, a novel development in the field of near-neutral water electrolysis. We also determine that elevated heat and low chlorine concentration are conducive to improved OER selectivity on an IrO2 catalyst (Figure 1b). We hope this work will set the standard in catalyst benchmarking for seawater electrolysis catalysts and could lead to the development of catalysts for efficient, scalable, and sustainable hydrogen production from seawater. H. Jin et al., Sci Adv, 9, eadi7755 (2023) https://www.science.org/doi/10.1126/sciadv.adi7755.F. Dionigi, T. Reier, Z. Pawolek, M. Gliech, and P. Strasser, ChemSusChem, 9, 962–972 (2016) https://onlinelibrary.wiley.com/doi/full/10.1002/cssc.201501581.J. Guo et al., Nature Energy 2023, 1–9 (2023) https://www.nature.com/articles/s41560-023-01195-x. Figure 1. a) LSV profiles of common OER catalysts (solid line) and the corresponding faradaic efficiency (dashed line) for the OER, measured using the ring current of the rotating ring-disc electrode. Catalysts were tested in 0.5 M NaCl and buffered with KHCO3 to pH 8.5. b) A ternary plot depicting the effect of varying Cl concentrations and temperatures on the selectivity of an IrO2 catalyst at pH 8.5. Figure 1

Simulation of a Passive Osmosis-Integrated Electrolyzer for Seawater Electrolysis

The requirement for extremely pure water in electrolysis, combined with the abundant presence of seawater, has prompted extensive research into the creation of direct seawater electrolysis technology for decades [1]. However, these efforts have had limited success due to other limiting issues that arise, including competition with the chloring evolution reaction, increased membrane resistance, corrosion of electrode materials and electrode scaling due to the presence of multivalent cations. To avoid these issues, seawater is typically first desalinated using reverse osmosis, but that comes with additional energy cost. Therefore, our project has proposed a new reactor that integrates passive osmosis (extracting fresh water from seawater) with electrolysis.In this presentation, we will discuss the operation of the osmosis-integrated electrolyzer and show theoretical predictions of the osmotic pressure differential and water flux/velocity profiles under different conditions. The numerical model that will be presented was applied to three different cell designs that have been physically developed. The first cell consists of two anion exchange membranes (AEMs) with two side chambers containing KOH and a middle chamber containing Sodium Chloride (NaCl). The second cell has KOH in one outer compartment and H2SO4 in the other. The central compartment containing NaCl is separated from KOH compartment by an AEM and the H2SO4 compartment by a cation exchange membrane (CEM). The third cell eliminates the central compartment and allows the osmosis to occur outside of the cell.The simulation results show that by increasing the concentration of KOH and H2SO4 in the side chambers for all three models, the amount of water transferred from the middle chamber, containing of NaCl to the side chambers increases. The simulation results were validated by experiments (Figure 1). In addition, the model is able to quantify the transport of ions in the system, including chloride ions through the AEM. Lastly, the mass transfer model is integrated with an electrochemical model where an anode and cathode are added to the system to consume the water that is transported through the membranes.Reference:[1] M. A. Khan, T. Al-Attas, S. Roy, M. M. Rahman, N. Ghaffour, V. Thangadurai, S. Larter, J. Hu, P. M. Ajayan, and M. G. Kibria, “Seawater electrolysis for hydrogen production: a solution looking for a problem?” Energy & Environmental Science, 14, 4831 (2021). Figure 1

Investigating Water and Ion Transport in a Novel Cell Design for Seawater Electrolysis

With increasing concerns about the climate change associated with the carbon dioxide emission from utilizing traditional fuels, hydrogen has become a preferred low-carbon energy carrier. For hydrogen to truly be a clean source of energy, it must be produced from a renewable source of energy through water electrolysis. Theoretically, for each kilogram of hydrogen to be produced 9 kg of high-purity water need to be consumed, thus the enormous use of clean water for H2 production may worsen the shortage of fresh water in many parts of the world.Owing to its abundance, seawater has received great attention in the field of hydrogen production; however, there are many challenges associated with the direct use of seawater for electrolysis. In traditional systems, the seawater is first deionized by reverse osmosis (RO) before being fed to the electrolyzer. The RO system adds complexity to the system and requires energy to be expended for the deionization. Therefore, modern systems have aimed to directly electrolyze seawater, but this comes with it own issues including electrode corrosion, scaling from the ions present in saline water, environmental concerns associated with competitive chlorine evolution reaction, and increased membrane resistance limiting the overall performance of saline water electrolysis. Several strategies have been proposed to overcome these challenges including developing selective electrocatalysts, blocking strategy, pH buffer strategy, etc.This project sought to overcome the issues with direct seawater utilization by designing a cell that is driven by osmotic separation, but does not require an external power source. In this device, high concentration acid/base concentrations are maintained in contact with another compartment containing seawater. The acid/base reservoirs act as draw solutions, taking water passively from seawater due to their differences in osmotic pressure. This talk will focus on the cell design and operation, and include both experimental and modeling results. The rate of water transport with various cell operating configurations was quantified alongside the rate of chloride ion crossover through the anion exchange membrane. New methods for chloride mitigation were explored – including cell operating conditions, membrane design and absorption. Multiple cell configurations will be shown and strategies for reducing the cell operating voltage will be discussed.

ANALISIS EFISIENSI BIAYA DALAM PENYEDIAAN AIR LAUT UNTUK OCEANARIUM KOTA: STUDI KASUS BXSea BINTARO

This research focuses on assessing how to procure seawater for the BXSea Bintaro Oceanarium, which is located far from natural seawater sources. The two main options analyzed were the purchase of seawater directly from the coast and the creation of artificial seawater. The research method used in this study was conducted through a qualitative, case study approach by combining literature study, field observation, and the researcher's experience as an oceanarium designer, to gain an in-depth understanding of the technical, economic, and environmental aspects associated with both ways of seawater procurement. The results show that the use of native seawater is more economical and environmentally friendly than artificial seawater. Analysis of the initial costs, long-term operational costs, and logistical and environmental implications of both methods showed the superiority of direct seawater procurement. This method is not only efficient in reducing logistical complexity and initial investment, but also has minimal environmental impact. The conclusions of this study confirm that natural seawater procurement is a cheaper option than the use of artificial seawater. Artificial seawater is significantly up to 5.58 times higher than natural seawater. This study makes an important contribution to the literature of seawater resource management in educational and recreational facilities, and underscores the importance of a sustainable approach in oceanarium development.

CrOx Modified Nickel Phosphides Electrocatalyst for Stable Hydrogen Evolution Reaction in Neutral Media

AbstractThe development of efficient and long‐term stable electrodes for hydrogen evolution reaction (HER) in seawater is highly desirable for hydrogen generation but remains challenging. In this work, a highly active CrOx@Ni2P‐Ni5P4/NF electrode is developed and investigated its dynamic reconstruction for HER in neutral electrolytes. The combination of in situ Raman spectra and electrochemical measurements revealed the dynamic surface reconstruction of the catalyst during HER. The CrOx modification not only effectively facilitates water dissociation but also stabilizes the structure post‐reconstruction, enabling rapid and stable hydrogen generation in neutral media. Remarkably, CrOx@Ni2P‐Ni5P4/NF exhibits overpotentials of 109 and 263 mV at current densities of 10 and 100 mA cm−2 in 1 m PBS, respectively. Concurrently, it exhibits stable operation for 500 h in 1 m PBS and 140 h in natural seawater at current densities of 50 and 100 mA cm−2, respectively. The proposed catalytic electrode and the mechanistic insights present a significant stride toward the realization of metal phosphides for direct seawater splitting.