Test Electrolyte Research Articles

High-Performance Composite Membranes: Embedding Yttria-Stabilized Zirconia in Polyphenylene Sulfide Fabric for Enhanced Alkaline Water Electrolysis Efficiency.

Due to their excellent alkali resistance and chemical stability, polyphenylene sulfide (PPS) fabric membranes are widely used in alkaline water electrolysis (AWE) for hydrogen production. However, traditional PPS membranes suffer from poor hydrophilicity, low airtightness, and high area resistance, resulting in high energy consumption and reduced safety in industrial applications. This study addresses the aforementioned issues by coupling 3-(2,3-epoxy propoxy) propyl trimethoxy silane (KH560) via self-condensation to the PPS membrane and blending it with self-synthesized yttrium-stabilized zirconia nanoparticles (YSZNPs). The YSZNPs are loaded onto the modified PPS fiber surface through dip-coating and hot-pressing processes, forming a micro-mechanical interlocking structure that enhances the overall performance of the membrane in practical hydrogen production applications. The findings indicate that the developed composite membrane demonstrate outstanding hydrophilicity, minimal area resistance (0.21 Ω cm2), and elevated bubble point pressure (2.93224bar). Significantly, tests on gas purity indicate that the produced hydrogen and oxygen attain purities of 99.90% and 99.75%, respectively, when evaluated at a current density of 1.5 A cm-2. Moreover, after 500h of electrolysis testing in a simulated industrial environment, minimal decline in membrane performance is observed, highlighting the competitive edge of this composite membrane in the current AWE market.

Flooding Control by Electrochemically Reduced Graphene Oxide Additives in Silver Catalyst Layers for CO2 Electrolysis.

Electrolyte flooding in porous catalyst layers on gas diffusion electrodes (GDE) limits the stability and high-current performance of CO2 and CO electrolyzers. Here, we demonstrate the in situ electroreduction of graphene oxide (GO) to reduced graphene oxide (r-GO) within a silver catalyst layer on a carbon GDE. The r-GO introduces hydrophobicity regions in the catalyst layer that help mitigate electrolyte flooding during high current density CO2 electrolysis to CO. The flooding-resistant r-GO/Ag-coated GDE achieves a sustained Faradaic efficiency of CO at 94% for more than 8 h, compared to a rapid drop from 95% to 66% in an Ag-coated GDE without r-GO at 100 mA·cm-2. We found that GO enhances the electrochemically active surface area of the catalyst layer during CO2 electrolysis tests because the incorporation of GO increases the roughness of the catalyst layer. The in situ method of electrochemically reducing GO to r-GO provides a low-cost, practical approach that can be applied during standard spray-deposition procedures to develop flooding-resistant GDEs.

Bis-cationic crosslinked anion exchange membranes based on carbazole-containing polyaromatics with excellent ionic conductivity for alkaline water electrolysis

As the core component in anion exchange membrane water electrolyser (AEMWE), anion exchange membrane (AEM) directly determines the electrolysis performance and long-term durability of AEMWE. Herein, we synthesized novel poly(carbazole-p-terphenylpiperidine) (PCTP-x) copolymers and then prepared a series of bis-cationic cross-linked AEMs (QPCTP-x-bpip) using the Menshutkin reaction between the cross-linker 4,4′-trimethylenebis(1-methylpiperidine) and the alkyl bromide on the polymer side chains. For comparison, non-crosslinked AEMs containing alkylpiperidinium side chains (QPCTP-x-pip) were prepared via a grafting reaction of alkyl bromide with 1-methylpiperidine. The bis-cationic crosslinked membrane exhibited high hydroxide conductivity of 190.0 mS cm−1, and demonstrated outstanding alkaline stability in a 1 M KOH solution at 80 °C, retaining more than 90 % of the initial hydroxide conductivity and tensile strength after 2200 h alkaline treatment. Meanwhile, the flexural carbazole backbone enhanced polymer solubility, enabling the utilization of QPCTP-20-pip as an anion exchange ionomer (AEI) in AEMWE. For the water electrolysis testing, AEMWE employing QPCTP-20-bpip as the AEM and QPCTP-20-pip as the AEI exhibited excellent performance, achieving a current density of 2910 mA cm−2 at 2.0 V using a 1 M KOH feed at 80℃. Moreover, the voltage increase during the in-situ durability test over 200 h was a mere 0.65 mV/h, demonstrating its promising potential for AEMWE applications.

Electrochemical activation of Pt electrode for efficient and stable anion exchange membrane ammonia electrolyzer

Replacing the oxygen evolution reaction in water electrolysis with ammonia oxidation reaction enables low voltage hydrogen production. Pt is a promising catalyst for the ammonia oxidation reaction due to its superior dehydrogenation and low affinity for *N, but Nads poisoning deactivates the Pt surface. This study proposes a method to improve ammonia oxidation performance and stability through electrochemical activation, introducing cathodic corrosion and recovery conditions. The half-cell results showed a peak current density of 74.2 mA cm−2 and retention ratio of 17 %. Adjusting the lower and upper cell voltage in a membrane electrode assembly based single cell optimized surface cleaning and inhibits further poisoning by O/OHads above 0.75 Vcell. Furthermore, incorporation of recovery conditions can enhance the stability of poisoned electrode compared to that in chronoamperometry test. The results of pulsed ammonia electrolysis tests incorporating recovery conditions suggested a novel approach to practical hydrogen production by stabilizing catalysts with a 83 % Faradaic efficiency at 0.1 A cm−2

Understanding Mass Transport at High Current Densities in an Industrial Scale PEM Electrolysis Test Cell - a Segmented Along-the-Channel Approach

Industrial PEM water electrolysis stack designs can suffer from an unevenly distributed water amount over the cell area. This can lead to performance differences and thermal hot spots due to the lack of reactant supply and poor thermal management. Undersupplied spots could also degrade more quickly [1,2]. Especially in the water flow direction, gradients are expected due to the water consumption and gas evolution and accumulation along the supply channels.To face these issues, we built up a segmented along the channel (AtC) PEM electrolysis test cell in industrial scale for locally-resolved investigations. The cell has a length of 30 cm at 2 cm cell width with a straight parallel flow field. To minimize transverse currents the cell is divided into 10 equal segments along the channels. The main focus of our investigation is locally-resolved electrochemical impedance spectroscopy (EIS). With a shunt resistor approach, it is feasible to measure the impedance of each segment and the mean cell in parallel. Additionally, it is possible to measure the current density and temperature distribution of the anodic bipolar plate highly resolved using 120 sensors over the cell length.With this test cell we want to understand mass transport processes along the channel in industrial scale. Diffusion and mass transport overpotentials are usually dominant at high current densities. To be able to face extreme conditions and investigate possible future operation points the cell was designed up to 10 A∙cm-2 (600 A absolute) and successfully tested. Furthermore, an operation of 10 bar differential and equal pressure is possible.Figure 1 shows the cell design (a), the mean cell polarization curve of the AtC cell (60 cm²) in comparison with measurements of the same setup in our 4 cm² test cell (b) and locally-resolved high frequency resistance (HFR) free EIS at 7 A∙cm-2 (c). It is noticeable, that the here used commercially available materials do not show high mass transport limitations, neither in the 4 cm² ISE-reference cell nor in the 60 cm² AtC cell. An increase of the slope of the polarization curve towards higher current densities remains out, see Figure 1 (b). Instead of this the slope of the polarization curve is constantly decreasing. This can not only be explained by the temperature increase of the catalyst-coated membrane (CCM) due to higher heat dissipation. Using EIS, we here can detect an additional electrochemical process at low frequencies of inductive type which is increasing with increasing current density. In the locally-resolved EIS in Figure 1 (c) the inductive process (positive imaginary values) is detectable as the so called “inductive loop”. This phenomenon has a negative resistance magnitude and therefore a beneficial impact on the cell performance. Inductive Loops are discussed in several electrochemical applications, like batteries and fuel cells [3,4]. Despite this, in PEM electrolysis this process has not been discussed yet. We could show that this phenomenon is reproducible and has an important impact on the cell performance and impedance-based performance analyses when operating at current densities > 1 A∙cm-2 [5].For diffusion analyses, the inductive loop is essential to be considered since both processes happen at similar frequencies. In Figure 1 (c) an increasing of the number of time constants at frequencies < 100 Hz is detectable towards the cell outlet (e.g. segment 9 and 10). These slow processes are most likely diffusion related.Our upcoming investigations will face locally-resolved measurements with varying structural parameters of porous transport layers (PTL) and CCMs with different anodic catalyst loadings to gain a better understanding of mass transport processes for future PEM electrolysis cells along the channel.Reference List:[1] IMMERZ, C., et al. Experimental characterization of inhomogeneity in current density and temperature distribution along a single-channel PEM water electrolysis cell. Electrochimica acta, 2018, 260. Jg., S. 582-588.[2] VERDIN, B., et al. Operando current mapping on PEM water electrolysis cells. Influence of mechanical stress. International Journal of Hydrogen Energy, 2017, 42. Jg., Nr. 41, S. 25848-25859.[3] KLOTZ, Dino. Negative capacitance or inductive loop?–A general assessment of a common low frequency impedance feature. Electrochemistry Communications, 2019, 98. Jg., S. 58-62.[4] GERLING, Christophe, et al. Experimental and Numerical Investigation of the Low-Frequency Inductive Features in Differential PEMFCs: Ionomer Humidification and Platinum Oxide Effects. Journal of The Electrochemical Society, 2023, 170. Jg., Nr. 1, S. 014504.[5] HENSLE, Niklas, et al. On the role of inductive loops at low frequencies in PEM electrolysis. Electrochemistry Communications, 2023, 155. Jg., S. 107585. Figure 1

Cobalt recovery from spent lithium-ion batteries using a rotating cylindrical electrode reactor

Abstract The cobalt electrodeposition from a leaching containing cathode-powdery of spent laptop lithium-ion batteries (LIBs) of different commercial brands, collected from local laptop repair shops, was investigated. Citric acid (0.14 M) and hydrazine (0.1 M) were employed as complexing and reducing agents in the leaching during 24 h. Cobalt, manganese and nickel concentrations in the leachate, obtained by the flame method in an atomic absorption spectrometer, are reported. A rotating cylindrical electrode reactor which consists of a rotating open bottom as cathode and a static outer cylindrical as anode was employed. The numerical flow patterns and cathode velocities that induce the presence of Taylor vortices inside and/or outside the cathode were investigated. RANS equations with the standard k−ε turbulence model and enhanced wall treatment was used. Electrical power measurements were performed to validate simulations. Cyclic voltammetry experiments with synthetic solutions were applied to determine the reduction potential of cobalt (found in −1.2 V vs SCE). Subsequently, electrolysis experiments were carried out at predetermined cathode speeds (50, 75, and 125 rpm), imposing a working cathodic potential of −1.2 V versus SCE during 12 h. Experimental results indicate that the best cobalt recovery rates and current efficiency coincide with the presence of Taylor vortices both inside and outside the cathode, i.e., at 50 rpm. The peak performance in cobalt recovery and current efficiency was recorded at 49 % and 47.3 %, respectively. Finally, the deposits obtained from each electrolysis test were removed from the cathode and analyzed via energy dispersive spectroscopy. The range of purity of Co obtained in the electrodeposit film were between 56.75 % and 74.8 %.

PEM electrolysis: Degradation study of N1110 assemblies for the production of green hydrogen

The production of hydrogen through proton exchange membrane water electrolysis (PEMWE) is seen as a key solution for sustainable energy generation. However, the durability and stability of Proton Exchange Membrane (PEM) cells components, particularly Membrane-Electrode Assemblies (MEAs), remain crucial challenges to overcome for scalability. In this study, the degradation of a 25 cm2 CCM-type MEA was systematically investigated, using N1110 as the polymeric electrolyte and an anodic and cathodic loading of 3 mg/cm2 of PtB. A PEM electrolysis test bench was subjected to controlled operating conditions corresponding to 2 V and 60 °C for two stages of 168 h each, conducting a detailed analysis of performance behavior before, during, and after each degradation period. Electrochemical techniques were employed to characterize the performance stability: chronoamperometry, linear polarization curves, and electrochemical impedance spectroscopy (EIS). The EIS experimental results were fitted to equivalent electrical circuits and the parameters corresponding to ohmic resistances, charge transfer, and diffusional processes were determined. An increase in the resulting time constants and ohmic resistance was depicted because of the degradation.After a straightforward treatment rinsing the assembly with a 1 mol/L H2SO4 solution, the MEA partially regained its initial performance, depicting a degradation rate six times slower than one observed before regeneration in acidic media. This point suggests that the temporary decline in performance of the MEA is primarily due to reversible contamination.

Sistem Kontrol Dan Monitoring Hidrogen - Oksigen (HHO) Generator Berbasis Internet Of Things (IoT)

Electrolysis is a way to separate water (H2O) into hydrogen (H2) and oxygen (O2) gas by using an electric current through the water. The aim of this research is to create an Internet of Things (IoT) based prototype system that can monitor and control the hydrogen gas (H2) production process using the water electrolysis method. This research was carried out in several stages starting with a technology survey, then continuing with prototype design (including hardware design, software design, and circuit schematic design). This monitoring system device is designed with 3 sensors, namely: MQ-8 gas sensor, ACS712 current sensor, and BME280 pressure-temperature sensor. The MQ-8 sensor is set with a reading scale of 200-1000 ppm (parts per million) with an RMSE value obtained of 0.0288%. The ACS712 current sensor has an accuracy of 88.35% with a reading scale of 0-3.3 amperes, and the BME280 sensor has an accuracy of 94.47% for temperature and 99.37% for pressure with an ambient air reading scale. The results of water electrolysis testing of the entire system show that the system can work well in measuring parameters in accordance with the data sheet provisions, as well as providing flexibility in monitoring for users via smartphone.

One-Step Synthesis of High-Efficiency Oxygen Evolution Reaction Catalyst FeSx(Y/MB) with High Temperature Resistance and Strong Alkali

Given the energy crisis and escalating environmental pollution, the imperative for developing clean new energy is evident. Hydrogen has garnered significant attention owing to its clean properties, high energy density, and ease of storage and transportation. This study synthesized four types of catalysts—FeS(DI/MB), FeS(ET/MB), Fe(DI/MB), and Fe(ET/MB)—using two distinct solution systems: DI/MB and ET/MB. The FeS(DI/MB) catalyst, synthesized using the layered solution system (DI/MB), demonstrates a uniformly distributed and dense nanosheet structure, exhibiting excellent resistance to strong bases and superior catalytic properties. The FeS(DI/MB) electrode showed OER overpotentials of 460 mV and 318 mV in 1 M and 6 M, respectively, at current densities of up to 500 mA cm−2. Under industrial electrolysis test conditions, the FeS(DI/MB) electrode required only 262 mV to achieve a current density of 500 mA cm−2, operating in a high-temperature, strong alkaline environment of 6 M at 60 °C. Furthermore, the FeS(DI/MB) electrode exhibited excellent OER catalytic activity and stability, as evidenced by a 60 h stability test These findings provide valuable insights into the preparation of iron nickel sulfide-based catalysts, and further in-depth and comprehensive exploration is anticipated to yield the excellent catalytic performance of these catalysts in the realm of electrolytic water hydrogen production.

Sulfur poisoned PtNi/C catalysts toward two-electron oxygen reduction reaction for acidic electrosynthesis of hydrogen peroxide

Selective electrocatalysis of two-electron oxygen reduction reaction (2e– ORR) has been recognized as a sustainable and on-site process for hydrogen peroxide (H2O2) production. Great progress has been achieved for 2e– ORR in alkaline media. However, it is challenged by insufficient activity and selectivity of the catalysts in acidic electrolytes. Herein, we report sulfur-poisoned PtNi/C catalysts (PtNiSx/C) that could regulate ORR from the 4e– to 2e– pathway. The identified PtNiS0.6/C offers high activity in terms of onset potential of ∼0.69 V (vs. RHE) and ∼80 % selectivity. The mass activity is also comparable and outperforms representative Pt-based precious and transition-metal-based catalysts. In addition, it is interestingly found that the Faradaic efficiency further increased to 95 % during the long-term electrolysis test due to Ni atom surface migration. The electrochemical production of the H2O2 system was applied to the electro-Fenton process, which has realized the effective degradation of organic pollutants. This work offers a strategy by sulfur poisoning PtNi/C catalyst to realize Pt-based 2e– ORR active catalysts to electrolysis of H2O2 in acidic media.

Macromolecular reinforcement of alkaline ion-solvating polymer electrolytes

Alkaline ion-solvating polymer electrolyte membranes derived from poly(isatin biphenyl) and polybenzimidazole (m-PBI) blends with different ratios were prepared, characterized, and evaluated as electrode separators in alkaline water electrolysis. The physicochemical properties could be tuned by varying the composition of the blend, and the membrane with a poly(isatin biphenyl) content of 25 % showed a suitable balance between conductivity and mechanical robustness. The polarization behavior was comparable to that of state-of-the-art separators, with significantly lower H2 permeability. No signs of degradation could be observed after 70 h of electrolysis testing in 30 % aqueous KOH at 80 °C, supporting that macromolecular reinforcement is a promising way forward in the development of high-performing and durable alkaline ion-solvating membranes for water electrolysis.

Matched Kinetics Process Over Fe2O3‐Co/NiO Heterostructure Enables Highly Efficient Nitrate Electroreduction to Ammonia

AbstractTandem nitrate electroreduction reaction (NO3−RR) is a promising method for green ammonia (NH3) synthesis. However, the mismatched kinetics processes between NO3−‐to‐NO2− and NO2−‐to‐NH3 results in poor selectivity for NH3 and excess NO2− evolution in electrolyte solution. Herein, a Ni2+ substitution strategy for developing oxide heterostructure in Co/Fe layered double oxides (LDOs) was designed and employed as tandem electrocataltysts for NO3−RR. (Co0.83Ni0.16)2Fe exhibited a high NH3 yield rate of 50.4 mg ⋅ cm−2 ⋅ h−1 with a Faradaic efficiency of 97.8 % at −0.42 V vs. reversible hydrogen electrode (RHE) in a pulsed electrolysis test. By combining with in situ/operando characterization technologies and theoretical calculations, we observed the strong selectivity of NH3 evolution over (Co0.83Ni0.16)2Fe, with Ni playing a dual role in NO3−RR by i) modifying the electronic behavior of Co, and ii) serving as complementary site for active hydrogen (*H) supply. Therefore, the adsorption capacity of *NO2 and its subsequent hydrogenation on the Co sites became more thermodynamically feasible. This study shows that Ni substitution promotes the kinetics of the NO3−RR and provides insights into the design of tandem electrocatalysts for NH3 evolution.

Matched Kinetics Process Over Fe2O3-Co/NiO Heterostructure Enables Highly Efficient Nitrate Electroreduction to Ammonia.

Tandem nitrate electroreduction reaction (NO3 -RR) is a promising method for green ammonia (NH3) synthesis. However, the mismatched kinetics processes between NO3 --to-NO2 - and NO2 --to-NH3 results in poor selectivity for NH3 and excess NO2 - evolution in electrolyte solution. Herein, a Ni2+ substitution strategy for developing oxide heterostructure in Co/Fe layered double oxides (LDOs) was designed and employed as tandem electrocataltysts for NO3 -RR. (Co0.83Ni0.16)2Fe exhibited a high NH3 yield rate of 50.4 mg ⋅ cm-2 ⋅ h-1 with a Faradaic efficiency of 97.8 % at -0.42 V vs. reversible hydrogen electrode (RHE) in a pulsed electrolysis test. By combining with in situ/operando characterization technologies and theoretical calculations, we observed the strong selectivity of NH3 evolution over (Co0.83Ni0.16)2Fe, with Ni playing a dual role in NO3 -RR by i) modifying the electronic behavior of Co, and ii) serving as complementary site for active hydrogen (*H) supply. Therefore, the adsorption capacity of *NO2 and its subsequent hydrogenation on the Co sites became more thermodynamically feasible. This study shows that Ni substitution promotes the kinetics of the NO3 -RR and provides insights into the design of tandem electrocatalysts for NH3 evolution.

Preparation of Fe‐Doped Ni3S2/Ni(OH)2/Ni/NSG Composites and Enhanced Water Splitting Performance

Herein, Fe‐doped Ni3S2/Ni(OH)2/Ni@NSG electrocatalysts are prepared by dealloying Ni–Al precursors followed by magnetic stirring. It is found that the hydrogen precipitation reaction (HER) of NSG‐Fe‐25 is 148 mV at a current density of 10 mA cm−2 and the oxygen evolution reaction (OER) is 274 mV at a current density of 50 mA cm−2 compared to NSG‐Fe‐5, NSG‐Fe‐45, Ni‐NN‐Fe, and Ni‐NN‐Fe@NSG. The Tafel slopes for the HER are 81.6 mV dec−1, and the Tafel slope of OER is 61.6 mV dec−1, while the Cdl value of NSG‐Fe‐25 is larger and the resistance value is smaller. Therefore, NSG‐Fe‐25 has the optimal performance. The heterostructure of Fe‐doped Ni3S2/Ni(OH)2/Ni@NSG provides abundant active sites for surface HER and OER, which enhances the electronic conductivity of the electrode. Meanwhile, long‐term constant‐current electrolysis test experiments show that NSG‐Fe has good stability in use. The present study opens a new window for the design and preparation of total hydrolysis electrocatalysts.

Excellent Bifunctional Water Electrolysis Activities of α-MoO3/AC Nanocomposites

Electrocatalytic water splitting is a cost-effective and environment-friendly technique for producing oxygen and hydrogen through the oxygen/hydrogen evolution reaction (OER/HER). Developing the highly active and stable electrocatalyst, particularly for bifunctional water electrolysis (i.e., both OER and HER), is still a formidable challenge. Herein, we demonstrated the enhanced bifunctional water splitting activities by utilizing the molybdenum trioxide-anchored activated carbon (MoO3/AC) nanocomposites. The MoO3/AC samples were fabricated by the ultrasonication method using sol-gel synthesized MoO3 and biomass-derived AC, and they displayed a nanostreusel-like morphology with spherical MoO3 nanoparticle-decorated AC nanosheets. For the water electrolysis test, the MoO3/AC nanocomposites exhibited the excellent bifunctional electrocatalytic OER and HER performances with low overpotential and small Tafel slope values. Through analyzing the material characteristics and the electrochemical properties of MoO3/AC, it was found that the superb bifunctional OER-HER activities were attributed to the synergistic effects from the hybridization of highly conductive AC and electrochemically active α-MoO3. The results pronounce that the MoO3/AC nanocomposites possess an aptitude as a superb bifunctional OER/HER electrocatalyst for high-performance water electrolysis.

Electrolytic Reduction of CO2 Using Perovskite-Type La-Based Oxide Anodes in Chloride Molten Salts

CO2 decomposition in molten salt is an attractive process as a new method for achieving carbon neutrality, for which the development of inert anodes and electrolytic bath suitable for CO2 decomposition is essential. Previous studies mostly investigated the electrode material but did not investigate the relationship between the electrolysis bath and electrode reaction. The effects of the electrolytic bath on anode reaction and the development of inert anode material with high current density were investigated in this study. Electrolytic bath of LiCl–CaCl2 and NaCl–CaCl2 with similar oxide solubilities were compared, finding that LiCl–CaCl2 melts exhibited higher oxidation current density in cyclic voltammetry and more stable potential transition in galvanostatic electrolysis. Among the five anodes with a perovskite-type La-based oxide were investigated, La0.6Sr0.4CoO3−δ showed the highest electrical conductivity and the largest increase in oxidation current density. CO2 decomposition tests were performed in LiCl–CaCl2 with CaO and CaCO3 added as a CO2 source at 873 K using La0.6Sr0.4CoO3−δ anode. Only C and O2 were recovered from CO2 by electrolysis test. The current efficiencies were 78.3% and 54.4%, respectively. The La0.6Sr0.4CoO3−δ anode exhibited excellent corrosion resistance, demonstrating its potential as a promising inert anode for CO2 decomposition.

Investigation of Electrocatalyst and Ionomer Interaction in Anion Exchange Membrane Water Electrolysis

Anion exchange membrane water electrolysis (AEMWE) is a type of electrolysis that involves the use of an anion exchange membrane (AEM) to separate the anode and cathode compartments. During the electrolysis process, water is split into hydrogen gas (H2) at the cathode and oxygen gas (O2) at the anode. AEMWE is an emerging technology that has the potential to play a significant role in the production of green hydrogen, which is a promising energy carrier for a variety of applications, including fuel cells and transportation.One of the benefits of AEMWE is that it can be used with a variety of water sources, including seawater and wastewater. Additionally, AEMWE has the potential to be more energy-efficient and cost-effective than other types of water electrolysis because it can operate at lower voltages and use cheap Ni-based materials [1]. Recently, there has been a significant amount of interest in the development of anion exchange ionomers (AEI) that conduct hydroxide ions [2]. We recently investigated the PPO-LC-TMA ionomer (poly(2,6-dimethyl-1,4-phenylene oxide) [3] backbone with amine-functionalized by trimethyl amine) [4] as an ionomer for Ni-based catalysts in AEMWE. Commercial Aemion, Fumion, and Nafion AEI were compared to the lab-synthesized ammonium-enriched anion exchange ionomer PPO-LC-TMA as an anode catalyst layer for oxygen evolution reaction (OER).Cyclic voltammetry results showed that the NiFe catalyst layer with PPO-LC-TMA AEI showed higher Ni(OH)2/NiOOH peak current density, while current density obtained over Ni90Fe10 catalysts was 11%, 17%, and 39% for Nafion, Fumion, and Aemion AEI, respectively [5]. This resulted in increased OER activity of Ni90Fe10 with PPO-LC-TMA AEI and a lower overpotential of 151 mV at 10 mA cm-2 in 1 M KOH. Ex-situ Raman spectroscopy of as prepared and spent catalytic layer confirmed that the electrode transitioned to the Ni-OOH phase after polarization.NiFe anode catalytic layers were tested in a 5 cm2 single-cell alkaline membrane water electrolysis (AEMWE) with varying amounts of PPO-LC-TMA (7, 15, and 25 wt %). AEMWE results revealed that 25 wt% PPO-LC-TMA is the best ionomer loading, achieving a cell voltage of 1.941 V at 600 mA cm-2 in 1 M KOH at 50°C.Both three-electrode electrochemical cell and alkaline membrane water electrolysis (AEMWE) tests revealed that the PPO-LC-TMA ionomer stabilized NiFe catalyst and improved its performance compared to Fumion and Nafion ionomers. These results will be presented and discussed, along with details of electrochemical and physical characterizations.References E. Cossar, F. Murphy, E.A. Baranova, J Chem Technol Biotechnol, 97 (2022) 1611–1624.Wright, A. G.; Fan, J.; Britton, B.; Weissbach, T.; Lee, H.-F.; Kitching, E. A.; Peckham, T. J.; Holdcroft, S. Energy Environ. Sci. 9 (2016) 2130−2142.A.R. Nallayagari, E. Sgreccia, L. Pasquini, M Sette, P. Knauth and M. L. Di Vona ACS Appl. Mater. Interfaces, 14, 41 (2022) 46537–46547.R.-A. Becerra-Arciniegas, R. Narducci, G. Ercolani, E. Sgreccia, L. Pasquini, M. L. Di Vona, and P. Knauth, J. Phys. Chem. C, 124, 2 (2020) 1309–1316.E. Cossar, F. Murphy, J. Walia, A. Weck, E.A. Baranova, ACS Applied Energy Materials, 5 (2022) 9938−9951.

Casting Electrodes on PEEK Reinforced Sulfonated Polyphenylsulfone Membrane

Researchers are exploring the potential of proton exchange membranes made from hydrocarbon polymers that do not contain fluorine. These polymers possess desirable properties that could make them more environmentally friendly and cost-effective compared to current perfluorinated sulfonic acids (PFSA). Hydrocarbon polymers have a unique structure that maintains high proton conductivity while reducing gas crossover, thus presenting a promising alternative to PFSA membranes [1]. Previous studies have demonstrated the potential of hydrocarbon membranes in electrolyzers using sulfonated polyphenylene sulfone (sPPS) [2]. However, sPPS has a high ion exchange capacity (2.17 – 3.57 meq/g), leading to excessive water uptake that causes the membrane to swelling and impedes upscaling, such as casting anodes directly onto the membrane. To overcome this issue, a woven, open-mesh PEEK substrate was incorporated into the membrane. The reinforced membrane exhibited a significant reduction in water uptake of up to 53% at room temperature and 43% at 60°C compared to the initial membrane. This improvement made it possible to cast the anode directly onto the membrane, resulting in a homogeneous surface (Fig. 1 left). In addition, preliminary electrolysis tests showed promising performance with low membrane resistance of 69 mΩcm² for a 74 µm thick membrane (Fig. 1 right). Literature: [1] Miyake, J.; Taki, R.; Mochizuki, T.; Shimizu, R.; Akiyama, R.; Uchida, M.; Miyatake, K. Design of flexible polyphenylene proton-conducting membrane for next-generation fuel cells. Sci. Adv. 2017, 3(10), eaao0476. DOI: 10.1126/sciadv.aao0476[2] Klose, C.; Saatkamp, T.; Münchinger, A.; Bohn, L.; Titvinidze, G.; Breitwieser, M.; Kreuer, K.; Vierrath, S. All‐Hydrocarbon MEA for PEM Water Electrolysis Combining Low Hydrogen Crossover and High Efficiency. Adv. Energy Mater. 2020, 10 (14), 1903995. DOI: 10.1002/aenm.201903995 Figure 1

Optimizing water electrolysis activity in Mo-doped Sr2FeCoO6-δ perovskites by balancing oxygen vacancies and structural stability

Perovskite-based solid oxide electrolysis cells (SOECs) are promising for efficacious hydrogen production. This work explored how varying molybdenum (Mo) content impacts the structure and performance of Sr2FeCo1-xMoxO6-δ (SFCMx) perovskites for SOEC water electrolysis. SFCMx (x = 0.1–0.5) were synthesized via sol-gel method and incorporated into symmetrical cells. Electrolysis testing showed SFCM0.3 had the highest activity, achieving 2.09 A cm−2 at 2.0 V and 800 °C, compared to 0.964 and 0.847 A cm−2 for SFCM0.1 and SFCM0.5 respectively. This optimal performance with 0.3 Mo doping was put down to simultaneous variations in oxygen vacancy concentration and crystalline structure stability. Lower Mo doping accelerated charge transfer but destabilized the structure, while higher doping stabilized the cubic perovskite structure but reduced vacancies and electrocatalytic activity. This work demonstrates that balancing activity and stability by optimizing dopant concentration is critical to maximize SOEC performance. This provides new insights for enhancing water electrolysis through controlled doping and tuning of the perovskite structure.

1T-MoS2/C composite as an efficient electrocatalyst for hydrogen evolution reaction under alkaline condition

1T-MoS2/C composites were prepared using a glucose-assisted one-step hydrothermal method. The morphology, structure and composition of 1T-MoS2/C composites were characterized using XRD, SEM and TEM. Water electrolysis tests were conducted to study the HER performance of 1T-MoS2/C composites under alkaline condition. The results indicate that the 1T-MoS2/C composites exhibited an overpotential of 260 mV at a current density of 10 mA cm−2, accompanied by a Tafel slope of 102.5 mV dec−1 when evaluated in a 1 M KOH solution.