Steel Mesh Electrodes Research Articles

From Waste to Power: Developing Structural Supercapacitors with Red Mud and Jute Stick.

Developing effective, cost-efficient, and eco-friendly energy storage solutions is crucial for sustainable building structures. Red mud, a waste material, was used as the electrolyte and separator in supercapacitors, alongside activated carbon derived from jute sticks coated on steel mesh electrodes. Tests on RM-enhanced supercapacitors showed that 20% by weight of RM was the best amount. This increased the modulus of elasticity by 33%, the tensile strength by 3%, and the compressive strength by 10%. Durability was largely unaffected, with minimal additional water absorption and slight shrinkage variation. The supercapacitor cell had an extended cell potential of 1.5 V and a maximum specific capacitance of 62.3 F g-1 at 0.4 A g-1, as shown by electrochemical tests. This improved energy density to 19.5 Wh kg-1, with a power density of 301.8 W kg-1 at 0.4 A g-1 and a maximum power density of 605.8 W kg-1 at 0.8 A g-1. The cell retained 77% of its initial capacitance after 450 continuous GCD cycles, demonstrating notable stability. This stability is due to the solid electrolyte and the synergy between JC and RM, indicating promising advancements for future energy storage devices.

Hydrothermal synthesized nickel tungstate (NiWO4) microflowers for supercapacitor and water-splitting

Herein, we have synthesized nickel tungstate microflowers (NWO MFs) using the hydrothermal route and used them as an electrode in electrochemical and electrocatalytic applications. In this article, we discuss the effects of the concentration of surfactant on the NWO MFs. Additionally, the resultant products are undergone to assess the energy storage and water-splitting phenomena. In addition, NWO-SM (steel mesh) electrode demonstrates the maximum specific capacitance (Cg) and specific capacity (Csp) of 712 F/g and 158 mAh/g at 5 mV/s with ∼95% capacitive retention over the 5000 cycles. Furthermore, the fabricated device reveals the maximum performance of the capacitance and capacity of 185 F/g and 75 mAh/g at 5 mV/s and 160 F/g and 53 mAh/g with the highest energy (Ed) and power densities (Pd) of 24 Wh/kg and 1600 W/kg at 5 mA/cm2 respectively. The hybrid device shows better capacitive properties with excellent stability (94% over 5000 cycles). The NWO-SM electrodes were tested for electrocatalytic activities using different techniques. The NWO-1 SM electrode exhibited strong electrocatalytic activity with a moderate overpotential value of 302 mV, a negligible Tafel slope (118 mV/dec), an acceptable electrochemical surface area (ECSA) value of 121 cm2, and exceptional stability over 10 hours.

Stainless steel as gas evolving electrodes in water electrolysis: Boosting the electrocatalytic hydrogen evolution reaction on electrodeposited Ni@CoP modified stainless steel electrodes

High efficient and durable electrocatalytic electrodes play a vital role in energy conversion and storage. In this concern, water electrolysis technology needs high performance electrodes with high activity and stability to implement this technology for green hydrogen production. Here, this study reports on the development of self-supported electrodes for the hydrogen evolution reaction (HER) based on sequential electrodeposition technique. First, the CoP has been deposited on stainless steel mesh (SSM) electrode followed by deposition of Ni to form Ni@CoP electrocatalysts standing on SSM. The loading amount of Ni was studied to achieve a high catalytic activity. The developed electrodes have been investigated with FE-SEM, EDX, XRD and XPS to identify their morphological properties as well as their chemical states and compositions. Electrocatalytic activity and durability have been studied in alkaline media by different electrochemical methods, such as LSV, EIS and CP. The results showed that the optimum deposition time of 10 min (10Ni@CoP) exhibited the higher catalytic activity in term of overpotential and Tafel slope giving a overpotential of 188 mV at 10 mA cm−2 with a small Tafel slope of 69 mV.dec−1 compared to CoP electrode with overpotential 266 mV and Tafel slope of 105 mV.dec−1 highlighting the role of Ni in enhancing the catalytic activity of the developed electrodes towards HER. Moreover, the Ni@CoP showed high stability under continues electrolysis at 50 and 100 mA.cm−2. These findings have been discussed in light of porous structure of the electrodes and introducing of Ni particles which led to creating more active sites and enhancing the hydrogen adsorption/desorption and thus facilitating the HER kinetics. The facial preparation method of self-supported electrodes and the obtained activity and stability of Ni@CoP electrodes render them as potent electrodes for HER in alkaline water electrolysis.

The Effect of Illumination, Electrode Distance, and Illumination Periods on the Performance of Phototrophic Sediment Microbial Fuel Cells (PSMFCs)

Microbial fuel cells (MFCs) can potentially be used to overcome issues with battery powered light buoys and their frequent maintenance. In this study, a phototrophic sediment microbial fuel cell (PSMFC) was chosen, as the microalgae provide oxygen to be reduced on the cathode and to release the necessary nutrients for the bacteria on the anode. To achieve this, we studied the effect of illumination, the period of the illumination, and the distance between 9-cm2 stainless steel mesh electrodes on the performance of the MFC. The illuminated cells were able to produce higher OCP (max. 205.2 mV) and higher power density (max. 0.68 mW/m2). However, the highest current was achieved during the unilluminated variation (max. 5.3 μA unilluminated and 3.3 μA illuminated). Prolonged illumination produced a higher OCP, current, and power density. A longer electrode distance produced a higher OCP, power density, and current. SEM analysis showed that biofilm formation tended to be scattered at lower electrode distance and more clumped (filling the anode area) at higher electrode distance. Through FTIR analysis, it was found that all MFC variations had the same organic matter, but a more concentrated organic content was found in the MFC at longer electrode distances.

Effect of the Magnetostriction Induced on the Crystalline Structure of Nanoparticulate TiO2 Films Supported on Stainless Steel Mesh Electrodes and Their Relationship with the Photocatalytic Decoloration of Aqueous Orange G Solutions

The study of ferromagnetism (FM) in non-cubic semiconductor oxides such as defective TiO2 is attractive due to their applications in photocatalysis [1]. FM can be activated in TiO2 nanomaterials by promoting oxygen vacancies (VO) located in paramagnetic defected sites Ti3+VOTi4+. In this context, the VO can induce in Ti3+-doped TiO2 structures remarkable magnetic anisotropy energy (MAE) of 6.51x106 erg/cm3, thus indicating the magnetic saturation should be achieved at magnetic fields (MFs) of ~425 gauss [2,3]. Therefore, magnetostriction can be observed in ferromagnetic TiO2 films as a phenomenon in which their dimensions and shapes are changed when they are magnetized. In this work, stainless steel mesh electrodes (ss) were modified by nanoparticulate TiO2 films (ssTiO2) enriched by Ti3+VOTi4+ sites, to gain an understanding of the effects of magnetostriction on the photocatalytic properties of ferromagnetic TiO2 electrodes. In this way, MFs having intensities (H) of 125, 250, 500, 1000, and 2000 gauss were applied to the ssTiO2 electrodes for 80 min under UV light illumination for increasing the number of Ti3+VOTi4+ sites. Our results revealed that the magnetic lines promoted compression of the TiO2 structure when achieving pressures p>4.67 GPa for H>425 gauss in p=1/2(MAE/4p gauss2)H 2. Consequently, the degree of disorder (0<b<1) of the electron traps at the intra-bandgap state's distribution along the thickness-axis(i.e. the x-axis) of TiO2 films decreased significantly because the fraction of trapped electrons f trap(x) at the quasi-Fermi level EF(x) was maximized according to f trap(x)=m[em (E F (x)-E F (0))-1], where m=kT/b (k and T are the Boltzmann constant and the absolute temperature) [4,5]. Later, it was observed a significant increase of trapped holes able to carry out the direct photocatalytic oxidation of aqueous orange G (without electron scavenger’s assistance, e.g. gaseous O2). On the other hand, the photogeneration of oxidant •OH radicals decreased dramatically while H increased [6].[1] Y. Bian et al., RCS Adv., 11(2021)6284.; [2] D. Kim et al., J. Phys.: Condens. Matter,21(2009)195405.; [3] B. Shao et al., J. Appl. Phys.,115(2014)17A915. [4] N. Kopidakis et al., J. Phys. Chem. B, 107(2003)11307. [5] J. van de Lagemaat et al., J. Phys. Chem. B,104(2000)4292. [6] K.-I Ishibashi et al., J.Photochem.Photobiol.A,134(2000)139-142. Acknowledgements The authors thank the National Council for Science and Technology (CONACyT) Mexico for the funding support (grants CB No. 258789 and FOINS No. 3838). JIVN thanks CONACyT for his doctoral fellowship support (grant No. 893260).

Unraveling the Enhanced Electrochemical Performances of Nickel Aluminum Sulfide Lattices for Overall Water Splitting and as Counter Electrode Materials for Dye-Sensitized Solar Cells

The development of a high-performance precious metal-free multifunctional electrocatalyst for overall water splitting is a promising sign for future energy research. Here, a new strategy has been followed for the synthesis of novel-structured binary metal chalcogenide electrocatalysts, such as nickel aluminum sulfide (NiAl2S4) or nickel aluminum selenide (NiAl2Se4) spinels. The new chalcogenides, NiAl2S4 or NiAl2Se4, were confirmed by different physicochemical characterizations. Using a 316 stainless steel (SSL) mesh electrode as a three-dimensional conducting substrate, the electrocatalytic overall water splitting reaction was studied. Here, NiAl2S4 spinel outperformed the other metal chalcogenide in terms of electrocatalytic activity and charge transport in the hydrogen evolution reaction (HER), the oxygen evolution reaction (OER), and overall water splitting in alkaline medium. Moreover, NiAl2S4 spinel provided the finest electrocatalytic efficiencies compared to other benchmark electrocatalysts with minimized overpotentials, such as 47 or 290 mV for HER or OER, respectively, to reach the current density of 20 mA cm–2. In overall water splitting studies, a two-electrode system was formulated to show a very low potential of 1.54 V at a current density of 20 mA cm–2. Further, the prepared NiAl2S4 electrocatalyst-loaded 316 SSL electrode demonstrated excellent durability in HER, OER, and overall water splitting reactions. The obtained Faradaic efficiency was 97%, which is due to the two-dimensional sheet-like morphology of NiAl2S4, enabling a high active surface area for efficient water electrolysis. Furthermore, NiAl2S4 spinel performed well as a counter electrode (CE) material in dye-sensitized solar cells, with an efficiency of 5.02% compared to Pt (5.38%) on the fluorine-doped indium tin oxide electrode.

Electrolysing mud: Membraneless electrolysis of water for hydrogen production using montmorillonite-rich marine mud

This paper describes a design for a low-cost membraneless water electrolyser for the production of green hydrogen that used a viscous electrolyte of naturally abundant montmorillonite-rich marine mud in a DEFT (divergent electrode flow through) geometry with stainless steel (304) mesh electrodes. The ratio of smectite to non-swelling clays in the mud was 1:2. The electrolyte was prepared by resuspending the mud in tap-water to remove the salt, and NaOH 1 M added to enhance the ionic conductivity, as measured by both Electrochemical Impedance Spectroscopy (EIS) and by the slope of DC current/voltage curves. Successful separation and collection of the hydrogen and oxygen gas was inferred from the ratio of 2:1 in the volumes of hydrogen and oxygen collected. Both acid and alkali treatments were trialled and it was found that, whereas acid treatment flocculated the mud, adding NaOH increased the dispersion, conductivity and viscosity, and reduced clogging. The conductivity of both the 24% dry mass alkali mud and a control 4% dry mass alkali bentonite suspension increased to that of pure NaOH 1 M when repeatedly electrolysed. Hydrogen and oxygen gas was collected for 10% and 24% dry mass muds. The less viscous 10% dry mass mud showed turbulent liquid-like behaviour which led to gas mixing but the 24% mud showed stable, solid-like flow and reliable gas separation. Three components of the energy efficiency of the electrolysis process are reported and discussed – the voltage efficiency of 42%, a gas collection efficiency of 50% and the auxiliary power efficiency of 60%. The overall energy efficiency due to these three contributing efficiencies, was 13% of the Higher Heating Value of 142 MJ/kg H2 for a current density of 45 mA/cm2. This mud electrolyser may still be considered worth developing for an off-grid, low budget site with a low-power source of renewable energy.

Convenient construction of porous dendritic Cu-doped Ni@PPy/stainless steel mesh electrode for oxidation of methanol and urea

In multifunctional catalysts, Ni-based alloys and compounds can be used for methanol oxidation reaction (MOR) and urea oxidation reaction (UOR). Herein, the porous dendritic NiCu@PPy/316L stainless steel mesh (SSM) electrode is prepared by dynamic hydrogen bubble template electrodeposition, followed by cyclic voltammetry electrodeposition of polypyrrole (PPy) conductive polymer on the electrode surface. Among them, dynamic hydrogen bubbles successfully assisted the formation of porous structures in the Ni-based deposition layer. In addition, the morphology of the resulting Ni-based layer further evolves from particle stacking to dendritic with high specific surface area with Cu doping. Eventually, 2-NiCu/SSM achieves current densities of 294.5 mA·cm−2 (MOR) and 278.6 mA·cm−2 (UOR) at 0.8 V, respectively. The PPy coating prevents the agglomeration of NiCu particles in the catalytic layer and further improves the persistence of the electrochemical performance. After 2000 cycles, the current densities of 2-NiCu @PPy/SSM in the new electrolyte are maintained at 89.1% (MOR) and 94.8% (UOR) of the original value, with a 10% increase for MOR and a 7% increase for UOR compared to the sample without PPy coating (2-NiCu /SSM).

Optimization of electroosmotic flow to enhance the removal of contaminants from low‑permeable soils

Electrokinetic is an effective method for the extraction of contaminants from low-permeable soils. This work examines the influence of Ca+2 ions on the electroosmotic flow and the effect of electric potential, current, and pH variations on the removal of Pb2+, Na+, and Clˉ ions from artificially contaminated soil during vertical electrokinetic experiments. The DC electric field of 1 Vcm−1 was applied across the soil specimen via steel mesh electrodes for 24, 48, and 72 h of the experiment. In this work, the vertical electrokinetic cell was used to avoid the deposition of Na+ and Pb +2 ions near the soil surface after the treatment. making it even less permeable. The results show that the formation of acidic and alkaline environments in soil specimens affects the transport of ionic species by reducing the effect of electromigration and electroosmotic water flow. The enhancement of electroosmosis using Ca+2 ions as an electrolyte increased the extraction efficiency of Pb2+ (i.e., 41%) and Na+ (i.e., 82%) ions instead of the Clˉ (i.e., 69%) ions due to the high electroosmotic flow (i.e., 81 mL) from anode to the cathode. For relatively low electroosmotic flow (i.e., 19 mL), the extraction efficiency of Clˉ ions (i.e., 76%) was higher than that of Pb2+ (i.e., 27%) and Na+ (i.e., 44%) ions. The results demonstrated that the extraction efficiency of ions and energy consumption increased with treatment time and were higher during the first 24 h of the experiments.Graphical Abstract

Electrocatalyst for oxygen evolution reaction and methanol oxidation using surface-oriented stable NiSnO3 nanospheres anchored g-C3N4 nanosheets

Transition metal oxides have arisen as smart and inexpensive electrocatalytic materials for water oxidation. In this work, a simple hydrothermal method is demonstrated for the first time to synthesize perovskite-type NiSnO3 nanospheres interacted with graphitic carbon nitride (g-C3N4) nanosheets with fruit-beared cherry tree like morphology and investigate its surface-oriented electrocatalytic performance such as oxygen evolution reaction (OER) and methanol oxidation reaction (MOR). First, the structural and morphological analysis of the as-synthesized nanohybrid has been studied using various physico-chemical techniques to confirm the bonding interaction between NiSnO3 nanospheres and g-C3N4. For comparison, NiO, SnO2, and NiO/SnO2 nanocomposites were also synthesized and studied. This study highlights the surface-derived synergistic interaction between g-C3N4 nanosheets and NiSnO3 nanospheres, which have absolutely led the prepared NiSnO3/g-C3N4 nanohybrid loaded on 316 stainless steel (SSL) mesh electrodes to excellent electrocatalytic performances, assessed using linear sweep voltammetry (LSV), cyclic voltammetry (CV), and impedance analysis. The nanohybrid loaded electrode needs a low overpotential of 240 mV to reach the current density of 10 mA cm−2 and a Tafel slope of 42 mV dec-1 for OER. In addition, the synthesized nanohybrid loaded electrode was tested for methanol oxidation, which shows an enhanced electrocatalytic performance with a current density of 295 mA cm−2. The produced nanohybrid electrode also demonstrates long-term stability for both OER and MOR, suggesting as an alternate to noble metal electrocatalyst.

Nano MnOx encapsulated pyrrole-carbazole copolymer and polyvinyl chloride/carbon-coated flexible electrodes for solid-state supercapacitor cell

Pyrrole (Py) and carbazole (Cz) monomers are polymerized simultaneously in the presence of MnOx nanoparticles synthesized chemically on a stainless steel mesh (SSM) electrode by the pulse galvanostatic method in an acetonitrile medium. The resulting p(Py-co-Cz)/MnOx composite is characterized by cyclic voltammetry EIS, GCD XPS, XRD, FESEM, BET, and TEM. Since the current is applied for short periods in the presence of both monomers, p(Py-co-Cz) copolymer chains occur in short lengths, suitable for supercapacitor electrodes. The copolymer has higher Cm and lower Rct values as well as higher porosity that improves ion transport, thus greater stability than the homopolymers. It may be due to tricyclic Cz segments located between Py segments in the chains, which inhibit degradation. During the synthesis, nano-sized MnOx is also encapsulated homogeneously into the p(Py-co-Cz) coating, where 5 % is the weight percentage of manganese. Since the composite combines the advantages of the conductive polymer and metal oxide, it has the lowest Rct and highest Cm values among the coatings here. The p(Py-co-Cz)/MnOx coating with 10 mg cm−2 exhibits a high specific capacitance of 352 F g−1 at 5 A g−1 as well as flexibility, as its specific capacitance remains nearly stable (99 %) up to a bending angle of 90°. The cathode prepared from polyvinyl chloride (PVC)/activated carbon/carbon black on SSM operates within a wide voltage range of 0 to −1.5 V at 98 % cycle stability after 1000 cycles. The asymmetric cell configuration with the flexible anode and cathode electrodes provides 38 kW kg−1 and 5.28 Wh kg−1 at 5 A g−1 at a wide potential range of 2.1 V in PVA/Na2SO4 gel electrolyte, and the cycling stability was 67 % after 1000 cycles.

Electrode Layout Optimization and Numerical Simulation of Cast Conductive Asphalt Concrete Steel Bridge Deck Pavement.

In order to obtain the optimal electrode layout and ice melting effect of cast conductive asphalt concrete steel bridge deck pavement, firstly, pouring conductive asphalt concrete was prepared; secondly, different electrode materials and layout methods were selected to test the heating rate of the specimen from start to 120 min, and the electrode materials and layout methods were optimized. Then, the finite element analysis software ANSYS was used to build the model for heating and ice melting simulation, and the indoor test was used to further verify the ice melting effect of the cast conductive asphalt coagulation with or without the insulation layer. Finally, the thermal-structural coupling analysis of cast conductive asphalt concrete steel bridge deck pavement was carried out using ANSYS finite element software. The results showed that the stainless steel electrode material had the best heating effect, and the electrode thickness in the range of 0.1~3mm had no effect on the heating effect. The intermediate heating rate of the upper surface of the stainless steel sheet electrode cast conductive asphalt concrete in the left and right external electrodes was 8 °C/h, while the intermediate heating rate of the upper surface of the stainless steel mesh electrode cast conductive asphalt concrete was 12.9 °C/h. The layout of the left and right buried stainless steel metal mesh was able to effectively improve the snow melting efficiency; ANSYS finite element ice melting simulation was used to obtain the variation law of ice melting efficiency and a temperature field of cast conductive asphalt concrete. The indoor ice melting test showed that when melting the same thickness ice layer at 50 V voltage, it took 240 min with an insulation layer and 720 min without an insulation layer, which was three times that of the ice with an insulation layer, which further verifies the superiority of its ice melting effect. The most unfavorable load position of pavement under load and temperature field was determined. The maximum tensile stress and compressive stress of the pavement surface were transverse, and the maximum shear stress of the pavement bottom was transverse.

Mesoporous sulfur-modified metal oxide cathodes for efficient electro-Fenton systems

Development of cathode materials with high activity, stability, and wide operating pH range is crucial for electro-Fenton reactions. Herein, mesoporous sulfur-modified metal oxides were coated onto stainless steel meshes and applied as a cathode to promote in-situ generation of H2O2 for electro-Fenton processes. Different mesoporous metal oxides with and without sulfur-modification were synthesized using Fe, Ni, and Zn precursors to investigate the effect of sulfur doping. Among them, sulfur doped Fe2O3 showed the best electrocatalytic performance, and it was attributed to several factors such as large specific surface area, high-efficiency oxygen reduction reaction activity, and enhanced electron/charge transfer. The effect of operational parameters such as applied voltage, catalyst dosage, initial pH, initial concentration of phenol, and electrolyte concentration on the catalytic performance was investigated in terms of degradation efficiencies and rate constants. The results indicate that for high concentration 100 ppm phenol solution, 78% removal efficiency with a rate constant of 0.186 h−1 was achieved with sulfur-doped Fe2O3 on stainless steel mesh electrode under optimal conditions in 8 h. This cathode worked effectively in a wide pH range (3–10) due to its pH self-control ability and exhibited superior stability and reusability with insignificant deterioration in the catalytic activity. This study offers an alternative approach to fabricate electrocatalysts with low-cost sulfur-doped metal oxides for electro-Fenton systems.

Revealing the Role of Brønsted Basicity by the Electrocatalytic Reaction via Li Insertion in the MgFe2O4 Lattice

In this work, the impact of improving Brønsted basicity of the MgFe2O4 spinel lattice through Li substitution has been explored to ease out hydrogen evolution reaction (HER) or methanol oxidation reaction (MOR) by the unique compositions of electrocatalytic materials synthesized using a solvothermal method by varying the ratios of Li and Mg precursors. The substitution of Li+ at the Mg2+ lattice in the MgFe2O4 spinel was deliberated by X-ray diffraction, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, high-resolution transmission electron microscopy, and Brunauer–Emmett–Teller analyses. The smaller-sized Li+ (alkali metal) ion substitution was enabled with ease as LixMg1–xFe2O4 led to increase in the Brønsted basicity as confirmed by pH studies. Among the prepared different electrocatalysts, the 3-D polyhedron chain-like Li0.5Mg0.5Fe2O4 loaded at a 316 stainless steel mesh electrode exhibits an enhanced electrocatalytic activity for HER or MOR. Importantly, the developed electrocatalyst needs an unresolved overpotential of 27 mV for HER activity which is very near to that of the bench mark Pt/C catalyst to reach a current density of 10 mA cm–2 and an excellent electrochemical activity for MOR with a current density of 171.3 mA cm–2. Besides, the faradaic efficiency for the Li0.5Mg0.5Fe2O4-loaded electrode was calculated as 97% that significantly revealed the existence of a synergistic effect between Li+ and Mg2+ ions where the effective participation of the Li and Mg lattice has enabled the spinel lattice to increase the Brønsted basicity and to enhance the electrocatalytic activities for HER or MOR.

Sono‐exfoliated graphene‐like activated carbon from hazelnut shells for flexible supercapacitors

Currently, more than 80% of commercial supercapacitors utilize chemically synthesized carbon nanomaterials which are expensive and necessitates non-renewable resources. Employing renewable, environment friendly and naturally available biomass feedstock as precursor for producing carbon materials is a low-cost and sustainable way for designing the electrodes of supercapacitors. In the present study, high surface area hierarchical porous multilayered graphene-like carbon is obtained via room temperature sono-exfoliation of the activated carbon synthesized via simple and environmentally friendly hydrothermal carbonization and potassium bicarbonate activation of waste hazelnut shells as the precursor. The high surface area graphene-like carbon showed excellent electrochemical performance with specific capacitance of 320.9 F g−1 at 0.2 A g−1 current density and exceptional capacitance retention of 77.8% at 2 A g−1 current density after 10 000 cycles in 1 M Na2SO4 electrolyte. Moreover, flexible supercapacitors fabricated using sono-exfoliated graphene-like activated carbon coated stainless steel mesh electrodes and biopolymer gel electrolyte exhibits an outstanding energy density of 38.7 W h kg−1 and power density of 198.4 W kg−1. These results show that mechanically exfoliated graphene-like activated carbon derived from hazelnut shells exhibit superior electrochemical performance that can compete with other activated carbon materials used in energy storage devices for real time applications.

Development of Pt coated SS316 mesh gas diffusion electrodes for a PEM water electrolyzer anode

Cell performance of the polymer electrolyte membrane water electrolyzers is highly depended on the transferred water amount through the cell. Thus, anode gas diffusion electrodes should be selected carefully due to its effect on the overpotentials like mass transfer limitations and ohmic losses inside the cell. In this study, to reduce the cost of polymer electrolyte membrane water electrolyzers systems, stainless steel mesh electrodes (SS316) were used for a cheaper option as an anodic gas diffusion electrode for the polymer electrolyte membrane water electrolyzers. Pressure change measurement experiments were conducted to select the best mesh electrode pore size. In the pressure change measurement experiments, the M1 sample had the lowest pressure drops around 1.02 kPa. After the pressure change experiments, the M1 sample was coated by Pt noble metal in different molar ratios using electrodeposition method, like 1 mM (Case 1), 2 mM (Case 2), and 3 mM (Case 3). At 1.9 V, the current density was improved around 300% compared to the uncoated electrode in Case 3 sample. According to the results, it was seen that the Pt coated stainless steel electrode could be used as an alternative cost-effective gas diffusion electrode in polymer electrolyte membrane water electrolyzer system.

Polysulfide-Permanganate Flow Battery Using Abundant Active Materials

A new flow battery is presented using the abundant and inexpensive active material pairs permanganate/manganate and disulfide/tetrasulfide. A wetted material set is identified for compatibility with the strongly oxidizing manganese couple at ambient and elevated temperatures. Both solutions allow high active material solubility, with cells tested at theoretical energy densities up to 43 Wh l−1 for the ∼1.2 V cell. Full cells built with nickel foam electrodes and sodium-exchanged Nafion 115 membranes deliver a baseline area-specific resistance of 2.7 Ω-cm2. Incorporation of high-surface-area cobalt-coated carbon paper and high-surface-area stainless steel mesh electrodes, and an expanded Nafion 115 membrane delivers cells with 44% lower resistance at 1.6 Ω-cm2. All cells show performance decay over the course of cycling. The Co-decorated carbon paper electrodes provide significant kinetic improvements, shifting electrode performance from non-linear with Ni-foam to linear with a volume-normalized exchange current density value of 3.2 A cm−3. The expanded membrane provides increased conductivity over the 13 mS cm−1 conductivity observed in as-received, sodium-exchanged Nafion 115. Although boiled membranes provide improved conductivity, it is at the cost of decreased Coulombic efficiency and poorer manufacturability. Full cell models suggest that similar cell resistances (1.7 Ω-cm2) should be feasible with as-received Nafion 115 and advanced electrodes.

Simultaneous phosphorus recovery, sulfide removal, and biogas production improvement in electrochemically assisted anaerobic digestion of dairy manure

Anaerobic digestion (AD) produces renewable biogas from organic-rich waste streams, but the resultant digestate has to be subject to further nutrient recovery processes for better valorization. In this study, an electrochemical treatment unit using stainless steel mesh electrodes was integrated with an up-flow anaerobic sludge blanket (UASB) reactor to treat liquid dairy manure for simultaneous phosphorus (P) recovery, methane production improvement, and hydrogen sulfide (H2S) removal. The 36-d batch AD trial showed that a large portion of total P and reactive P were removed from the liquid dairy manure and were recovered mainly on the cathode deposits in the form of phosphate-bearing minerals. In the continuous USAB trial with an applied voltage of 1.0 V, 65.1% of the total P in the feeding manure was removed, of which 96.7% was achieved by sludge bed accumulation and 3.3% in the cathode deposit. Increases in both biogas production rate (13.0%) and methane yield (10.9%) were observed in the electrochemically assisted UASB system as compared to the one without electrochemical treatment. The electrochemical assistance helped decrease the H2S concentration in biogas by 20.8% at an applied voltage of 0.5 V and by 50.3% at 1.0 V. This electrochemically assisted UASB system can produce more biogas with less H2S content and recover P-enriched sludge in the sludge bed and the cathode deposit.

Synthesis of CoOx from ethaline on a stainless steel mesh for supercapacitor applications

Room Temperature Ionic liquids (RTIL) are molten salts that are liquid at around room temperature and consist of asymmetric anions and cations. Low volatility and wide electrochemical potential behaviour of RTIL make them preferable in reaction synthesis and electrochemical applications. In this study, cobalt was electrochemically deposited on an inexpensive stainless steel mesh substrate. The resultant modified electrode was studied for supercapacitor applications by measuring its capacitance performance. Choline chloride and ethylene glycol-based ionic liquid called Ethaline was used as the deposition electrolyte, and the ionic liquid was contained a cobalt salt (CoCl2) for cobalt growth. The deposition conditions of cobalt in Ethaline ionic liquid were found by cyclic voltammogram study. The cobalt in an ionic liquid was obtained by applying − 1.50 V potential on the stainless steel mesh by potentiostatic method. The uncoated and cobalt-coated steel mesh electrodes were then tested in KOH electrolyte to find appropriate potential window of the modified electrode. The cobalt-based material coated mesh electrode was scanned in 1 M KOH electrolyte between − 0.20 and 0.60 V and reported to have high electrochemical activity than uncoated mesh. The surface morphology of coated and uncoated mesh electrode was examined. Electrochemical characterizations of modified mesh electrodes were investigated using cyclic voltammetry. As a result, the obtained cobalt-coated mesh electrode had an areal capacitance of 650 mF cm−2 at scan rate of 5 mV s−1. The cobalt-coated steel mesh electrode may have potential application in OH−-based electrolyte for energy storage devices.

Removal of Aniline Blue from Textile Wastewater using Electrocoagulation with the Application of the Response Surface Approach

This paper investigated the treatment of textile wastewater polluted with aniline blue (AB) by electrocoagulation process using stainless steel mesh electrodes with a horizontal arrangement. The experimental design involved the application of the response surface methodology (RSM) to find the mathematical model, by adjusting the current density (4-20 mA/cm2), distance between electrodes (0.5-3 cm), salt concentration (50-600 mg/l), initial dye concentration (50-250 mg/l), pH value (2-12 ) and experimental time (5-20 min). The results showed that time is the most important parameter affecting the performance of the electrocoagulation system. Maximum removal efficiency (96 %) was obtained at a current density of 20 mA/cm2, distance between electrodes of 1.75 cm, salt concentration of 462.5 mg/l, dye concentration of 50 ppm, pH value of 7, and time duration of 15 min. On the other hand, the electrocoagulation efficiency was directly proportional to current density, salt concentration, and contact time, while it was inversely proportional to dye concentration. Isotherm experiments showed that the equilibrium data are best fitted to Freundlich isotherm and sips isotherm; whereas the kinetics results showed that the rate of adsorption followed the pseudo-second-order with an R2 value of 98 %.