Search Results (1,844)

In the Arabian Gulf region, saltwater desalination is considered to be a significant process in producing clean water. This paper presents a sustainable, combined process for upgrading a Doha reverse osmosis (RO) plant in Kuwait. A pilot-scale microbial desalination cell (MDC) stack is proposed as a pre-treatment unit prior to the RO process in order to improve plant performance. A cost–benefit analysis is conducted for the combined system to emphasize the significance of the MDC–RO process. In RO, the expected energy consumption is 2.6–13 kWh per m³ of desalinated water, whereas using MDC can reduce this to about 0.52–5.3 kWh/m³. Moreover, this new technology using catalytic MDCs can help in improving electric current production and reducing the amount of rejected brine and membrane fouling in the RO process. The electric current is improved by reducing MDCs’ internal resistance using a reduced graphene oxide/polyaniline composite-coated stainless steel mesh cathode electrode. Layer-by-layer electro-deposition can be applied to achieve these coatings. An intermediate zeolite filter is proposed to mitigate RO membrane fouling. The combined system’s natural zeolite-membrane filter improves water purification. In this study, we assessed the combined MDC–RO process for upgrading the Doha plant’s performance in terms of quality, cost, and time. The suggested catalytic MDC, using efficient, low-cost materials as cathode electrodes with an equivalent daily cost of 0.01 USD/m³ and a desalination efficiency of about 40%, acts as an alternative to high-cost platinum metal electrodes. The results also indicate that the equivalent daily cost of energy consumption using the MDC process is about 0.03 USD/m³, whereas the investment cost is about 0.4 USD/m³ daily for one year of cell operation. Full article

Electrodeposition of nanostructured metals often suffers from a trade-off between mechanical performance and efficiency. This study introduces ultranarrow slit-jet scanning electrodeposition (USJS-ECD), an additive-free technique employing a planar jet confined by a slit with opening width of <100 μm to scan the cathode. Numerical simulations coupling fluid flow and electric fields were conducted to optimize jet dynamics and scanning parameters. Experimental analyses reveal that USJS-ECD creates a highly localized, uniformly intensified energy field enabling direct fabrication of ultrahigh-strength nickel. The resulting deposits exhibit 98.82 wt% purity, an ultrafine grain size of 21.86 nm, and a mirror finish with surface roughness (Ra) of ~22 nm. Mechanical testing demonstrates a microhardness of 623 HV, a tensile strength of 756 MPa, and an elongation of 9.33%, achieving a superior strength-ductility synergy. Crucially, the deposition rate reaches 1.72 μm/min, significantly outperforming advanced ultrafine anode scanning electrodeposition (UAS-ECD) techniques. USJS-ECD presents a promising, efficient methodology for producing high-performance nanocrystalline metallic materials. Full article

In this work, the effect of chitosan concentration in chitosan/nickel composite coatings on their morphology and electrocatalytic activity in hydrogen evolution reaction (HER) was investigated. A series of Chitosan/Ni coatings with chitosan content from 0 to 0.7 wt.% was obtained by nickel electrodeposition onto a preformed biopolymer matrix, enabling targeted control of the roughness and specific surface area of the nickel layers. Morphology and roughness parameters were studied using atomic force microscopy and confocal microscopy. Electrochemical activity in the HER was examined by linear sweep voltammetry. Among the studied electrocatalysts, the Chitosan(0.6)/Ni system showed the best HER efficiency, with an overpotential of −200 mV at a current density of 10 mA/cm². Electrochemical impedance spectroscopy was used to determine the real surface area of the coatings. The Chitosan(0.6)/Ni sample exhibited the largest surface area, explaining its high HER activity. The obtained data revealed a correlation between chitosan concentration, composite morphology, and electrochemical activity, and allowed determination of the optimal composite composition. The results demonstrate the potential of chitosan as an effective structural modifier of nickel coatings and open up possibilities for the targeted design of composite materials with tailored electrochemical properties. Full article

Porous bilayer Ni–Co and sandwiched Ni–Co–Ni electrodes were fabricated by combining aqueous electrodeposition with high-temperature molten-salt Al deposition and subsequent electrochemical dissolution in NaCl–KCl–AlF₃ melt at 750 °C. The study aimed to determine how the initial layer architecture controls phase evolution, porous structure formation, and hydrogen evolution performance in alkaline media. SEM/EDS and XRD analyses showed that the two electrode designs followed different reaction pathways during molten-salt treatment. In the Ni–Co system, Al reacted predominantly with Co, leading mainly to Co–Al intermetallic formation and, after dissolution, to a highly open coral-like porous network. In contrast, the Ni–Co–Ni architecture promoted mainly Ni–Al phase formation and produced a more compact porous surface with a Ni-rich outer layer. Despite these morphological differences, both layered porous electrodes outperformed untreated Ni and porous Ni in 1 M NaOH. At −0.6 V vs. RHE, porous Ni–Co and NiCo–Ni reached current densities of −162 and −141 mA·cm⁻², respectively, compared with −87 mA·cm for porous Ni and −45 mA·cm for flat Ni. The Ni–Co–Ni sandwiched electrode showed the most favourable HER kinetics and benchmark performance, with the lowest Tafel slope (111 mV·dec) and the lowest potentials at −10 and −100 mA·cm (−0.132 and −0.556 V, respectively). These results demonstrate that the electrocatalytic response of molten-salt-derived porous Ni-based electrodes is governed not only by porosity development but also by the spatial arrangement of metallic layers prior to Al infiltration and dealloying. Full article

The subject of this study is the electrochemical synthesis of samarium–cobalt (Sm-Co) alloy coatings on a copper substrate from aqueous solutions using chronoamperometric methods. The study focused on assessing the effect of ecological complexing agents—L-arginine and glycine—on the deposition kinetics and quality of the deposits obtained within a potential range of −1.1 V to −1.8 V vs. Ag/AgCl. Morphological analyses indicated that the type of amino acid used determines the layer growth mechanism. It was found that exceeding the potential of −1.4 V results in a rapid increase in samarium content in the alloy, reaching maximum values of 29 at.% for the system with L-arginine and 35 at.% for the system with glycine at a potential of −1.8 V. X-ray Diffraction (XRD) structural studies confirmed the successful synthesis of the Co_8.5Sm intermetallic phase directly by electrodeposition, while X-ray Photoelectron Spectroscopy (XPS) analyses indicated the presence of oxides and hydroxides on the deposit surface. Despite obtaining a high samarium content, it was observed that intense hydrogen co-evolution at low potential leads to a decrease in current efficiency and the formation of internal stresses and cracks in the structure of the coatings. Full article

MnO₂ is widely investigated for electrochemical capacitors; however, its practical performance is often limited by low electrical conductivity and inefficient charge utilization in thick films. In this work, we investigate the combined effects of controlled electrodeposition and ionic liquid (IL)-assisted growth of MnO₂ films onto nickel foam at 0.6 V vs. Ag/AgCl for supercapacitor applications. The deposition time revealed a non-linear structure–performance relationship, with optimal electrochemical response obtained at an intermediate deposition time (240 s). The incorporation of ILs (e.g., [TEA-PS][BF₄] and [BMIM][BF₄]) enabled direct modulation of nucleation and growth dynamics. While [TEA-PS][BF₄] resulted in decreased performance, adding [BMIM][BF₄] significantly enhanced the electrochemical response. Our results reveal that without additives the films were dense and cracked; with [BMIM][BF₄], they became more open and nanostructured. Consequently, the optimized electrode exhibited a 25% higher specific capacitance, totaling 149.83 F·g⁻¹ at 10 mV·s⁻¹, compared to 119.87 F·g⁻¹ for the unmodified electrode. These findings demonstrate that IL-assisted electrodeposition is an effective strategy for optimizing MnO₂-based supercapacitor electrodes. Full article

Ferritic stainless steels are widely used as interconnects of solid oxide fuel cells (SOFCs) due to their high temperature stability and thermal expansion similar to that of the electrolyte. To help commercialise SOFCs, commercial-grade ferritic stainless steel with a coating, i.e., Type 430, has been considered a promising material for this application. In this work, we developed a Mn-Co oxide coating via anodic electrodeposition followed by heat treatment processes in Ar and oxygen at 800 °C. The proposed coating helped reduce the formation of Cr-rich oxide at the interface between the coating and substrate relative to a sample coated without annealing in Ar. It also provided a relatively dense coating layer and better withstood the applied load, provoking the first spallation of the coating layer assessed by the scratch test. A diagram used to assess the effects of pore density and size on the coating’s protectiveness is included in the manuscript. Full article

The hydrogen evolution reaction (HER) of hydrogen production by water electrolysis under alkaline conditions faces enormous challenges, namely, high catalyst overpotential and reliance on noble metal catalysts. As a transition metal, Ni has the advantages of low cost and excellent HER performance. This study aims to develop high-activity and low-cost HER catalysts to replace noble metal catalysts. In this work, a composite structured HER catalyst based on Ni and hybridized with Ni(OH)₂ and NiO was prepared by multi-field coupled electrodeposition. Under the reversible hydrogen electrode (RHE), low overpotentials of 248 mV and 341 mV were achieved at current densities of 500 mA·cm⁻² and 1000 mA·cm⁻², respectively, making it more suitable for industrial high-current-density water electrolysis for hydrogen production. Moreover, the catalyst achieves long-term stable operation at a high current density of 1000 mA⋅cm⁻² in industrial-grade ALK water electrolysis, with highly stable microstructure and chemical composition before and after the durability test. Theoretical calculations show that compared with the NiM catalyst, Ni@NiM enhances the adsorption capacity for water molecules, further optimizes the ion transport of the catalyst, and the complementarity and synergy in the electronic structure among these multiple components significantly improve the HER activity of the catalyst. Full article

Ammonia nitrogen is a key indicator for evaluating drinking water quality, and its accurate determination is of great significance for environmental monitoring and public health protection. In this work, a self-supported electrochemical sensor based on PtCo alloy nanosheets was fabricated on carbon cloth via a one-step electrodeposition strategy. The nanosheet structure facilitates the exposure of abundant electroactive sites and promotes efficient electron transfer. Electrochemical measurements indicate that the PtCo/CC electrode exhibits higher electrocatalytic activity toward ammonia oxidation than monometallic Pt, which can be attributed to the modulation of the Pt electronic structure induced by Co incorporation. Under linear sweep voltammetry, the optimized electrode exhibits a high sensitivity of 32.94 μA μM⁻¹ cm⁻² in the concentration range of 0.7–10 μM and 11.43 μA μM⁻¹ cm⁻² in the range of 10–100 μM, with a low detection limit of 77.9 nM. In addition, the electrode maintains good selectivity in the presence of common interfering ions, along with satisfactory reproducibility and stability. The feasibility of practical application is further confirmed by real water sample analysis. Overall, this work provides an effective strategy for the design of Pt-based alloy electrodes for ammonia nitrogen detection, with potential applications in drinking water quality monitoring. Full article

Precise control of copper electrodeposition is essential for electrochemical additive manufacturing based on layer-by-layer growth. In this work, the influence of selected organic additives, nicotinic acid, benzotriazole, thiourea and urea in sulfate-based electroplating baths was investigated with respect to their applicability in electrodeposition-driven 3D printing. Linear sweep voltammetry (LSV) was used to analyze the electrochemical behavior of Cu(II) reduction, while copper layers were deposited under potentiostatic conditions in a flow-assisted system (potential controlled conditions). The obtained deposits were characterized by SEM/EDS and quantitative measurements of layer thickness and dendrite height. The results show that the additives strongly affect both deposition kinetics and the morphology of electrodeposited layers. Benzotriazole acts as a strong inhibitor, producing fine-grained structures but reducing deposition efficiency and not fully suppressing vertical growth instabilities. Thiourea leads to highly unstable deposition with excessive dendritic growth and increased impurity incorporation. Nicotinic acid enables relatively thick deposits with moderate dendrite formation within an optimal concentration range. In contrast, urea provides the most stable growth, yielding uniform layers with minimal dendritic development and high copper purity. The dendrite height-to-layer thickness ratio proved to be an effective descriptor of electrodeposition growth stability. These findings highlight the critical role of additive selection in optimizing electroplating baths for electrochemical 3D printing applications. Full article

Hydrogen represents a promising clean and renewable energy source. Therefore, improving the efficiency of electrocatalysts is essential for effective hydrogen production. In this work, Ni electrocatalysts were synthesized via the electrodeposition method from ethaline deep eutectic solvent (DES) at 45 °C, 55 °C, and 65 °C under perpendicular (B_⊥) and parallel (B_‖) magnetic field directions relative to the electrode surface. Scanning electron microscopy (SEM) was employed to investigate the morphological study, which shows that Ni deposits under B_⊥ promote columnar grain growth, while B_‖ favors lateral, compact structures. Furthermore, moderate temperature (55 °C) in the case of using B_⊥ produced finer grains and smoother surfaces compared to other temperatures in the same direction, enhancing the catalytic performance for HER. Electrochemical techniques, including linear sweep voltammetry (LSV) and chronoamperometry, were employed to evaluate the catalytic performance for HER in 1 M NaOH and the adsorption–desorption process, respectively. The results suggest that efficient HER performance is associated with balanced hydrogen adsorption and desorption behavior. The Ni deposit at 55 °C under (B_⊥) exhibited the lowest overpotential (−215 mV) compared to the deposits at 45 °C and 65 °C under the same magnetic field direction, indicating superior overall HER performance. This performance is attributed to balanced hydrogen adsorption–desorption behavior despite the relatively high Tafel slope value (298 mV·dec⁻¹). However, the lowest Tafel slope among the whole samples prepared under both (B_⊥) and (B_‖) was found to be (219 mV·dec⁻¹), reflecting faster kinetics, which was obtained for the sample deposited at 45 °C under (B_‖). Full article

The growing demand for sustainable energy technologies has intensified interest in direct urea fuel cells as an environmentally friendly energy conversion system. In this work, a ternary NiCuZn electrocatalyst is synthesized via a single-step electrodeposition process, offering a rapid and scalable alternative to commonly used hydrothermal or multistep fabrication routes. Structural and compositional analyses (SEM, EDX) confirm the formation of coral-shaped particles of NiCuZn powders. Electrochemical evaluation in alkaline media demonstrates that powders of both tested variants exhibit clear anodic activity, with peak potentials in the range of 0.4–0.6 V_{vs Ag|AgCl (sat. KCl)}. Zinc presence was confirmed also after the process. Upon urea addition, a pronounced enhancement in anodic current density is observed. Notably, variant NiCuZn powder, which was produced using higher current density during electrodeposition, shows superior catalytic activity from approximately 0.4 V_{vs Ag|AgCl (sat. KCl)}, reaching a maximum of 10 mA/cm² near 0.75 V_{vs Ag|AgCl (sat. KCl)}, and stability, which are attributed to its highly homogeneous microstructure and dynamic surface activation mechanism uniquely by partial zinc leaching during operation. These findings demonstrate that electrodeposited NiCuZn systems can deliver competitive performance despite their structural simplicity, highlighting their potential as cost-effective and scalable anode materials for direct urea fuel cell applications. We address a critical bottleneck in fuel cell manufacturing by replacing time-intensive hydrothermal syntheses with a rapid, highly scalable electrodeposition method. Furthermore, the identification of zinc-leaching mechanisms provides crucial new insights into dynamic catalyst activation, moving beyond traditional, static anode designs. Full article

Aqueous electrochromic systems based on tungsten oxide (WO₃) have attracted increasing attention because of their high ionic conductivity, low cost, and improved safety compared with organic systems. However, the role of electrolyte pH in regulating the electrochromic behavior of hydrated WO₃ films remains insufficiently understood, particularly across cation systems with different valences. In this work, amorphous WO₃·2H₂O films were electrodeposited on ITO substrates and systematically evaluated in LiCl and ZnCl₂ aqueous electrolytes with different pH values, with acidic AlCl₃ used as a supplementary trivalent system. The results reveal pronounced pH-dependent electrochromic behavior in both the monovalent and divalent systems. In LiCl, acidic conditions, especially pH 2.0, gave the best overall performance, including high optical modulation and improved cycling stability, while the dominant pseudocapacitive charge-storage behavior was largely preserved. In ZnCl₂, films tested at pH 1.5–2.0 showed significantly better electrochromic performance than those at higher pH values, indicating a much stronger kinetic sensitivity to pH. Combined experimental and first-principles results show that electrolyte pH influences not only proton availability, but also the cation-dependent interfacial charge-compensation environment in hydrated WO₃ films. Full article

A combined pretreatment strategy involving alkaline chemical polishing and silane electrodeposition was proposed for regulating the surface state of aluminum foil and the formation of etched tunnels during DC tunnel etching. Electrochemical measurements and morphological characterization were used to evaluate the effects of this pretreatment on surface electrochemical activity and etched tunnel structure. The results showed that appropriate alkaline chemical polishing facilitated the removal of rolling-induced surface relief, improved the uniformity of surface electrochemical activity, and favored the uniform deposition of the silane film. In contrast, excessive polishing generated surface pits during the polishing process, and these preformed pits subsequently promoted tunnel merging during DC tunnel etching. Under the optimal processing conditions, the combined pretreatment significantly improved the distribution uniformity and dimensional consistency of etched tunnels and suppressed tunnel merging. Under the present testing conditions, the specific capacitance increased from 0.386 to 0.509 μF cm⁻², corresponding to an improvement of approximately 31.9%. This work provides an effective approach for optimizing etched tunnel structure and improving the capacitance-related performance of aluminum capacitor foil. Full article

In electrochemical nitrite detection, the strong oxidizing nature of nitrite often leads to high detection potentials, posing a significant challenge. To address this issue, this study successfully fabricated a nickel oxide/carbon cloth (NiO/CC) electrode using a one-step electrodeposition method followed by calcination. Taking advantage of the excellent electrocatalytic reduction properties of nickel oxide—particularly the surface oxygen vacancies that serve as active sites for efficient nitrite ion adsorption and promote the hydrogenation of the key intermediate (*NO)—the reaction energy barrier is substantially reduced. As a result, the NiO/CC electrode enables high-sensitivity nitrite detection at a low potential. Electrochemical evaluations reveal that the NiO/CC sensor performs excellently at −0.15 V (vs. Hg/HgO), featuring a linear detection range of 10–500 μM, a low detection limit of 0.091 μM (S/N = 3), and a high sensitivity of 2910 μA·mM⁻¹·cm⁻². These results highlight the promise of a catalytic reduction-based strategy for lowering detection potentials and provide a crucial foundation for the rational design of high-performance electrochemical sensing interfaces. Full article