Low-cost Materials Research Articles

Reused green glass for the production of low-density ceramic proppants

The reuse of waste to promote manufacturing processes that are respectful of the environment is a fundamental requirement in circular economy practices. In this work, it is assessed the feasibility of manufacturing ceramic proppants from a commercial red clay, sodium and potassium feldspars, and significant amounts of green bottle glass recovered from urban wastes.Different ceramic mixtures were formulated, and the sintering conditions were defined considering optical dilatometric, differential thermal, and thermogravimetric analysis. The obtained granules were characterised following the international standard for proppants, and also using X-ray diffraction, scanning electron microscopy, and individual diametral compression tests.The results show that competitive proppants are obtained, due to their low-density (2.5 g/cm3) and good breakage ratio (7.8 % at 5000 psi, or 34.5 MPa), but also considering the involved low-cost processing route and raw materials.

A Novel Synthesis and Quantitation Route of Belinostat

Introduction: This research article describes the production, quantification, and purification of belinostat from 3-nitrobenzaldehyde as the starting material. A cascade-step process produces higher yields when compared to all previous existing methodologies. Method: The procedure involved the following: Horner–Wadsworth–Emmons (HWE) reaction of aromatic aldehydes with triethylphosphonoacetate in the presence of potassium carbonate, reduction of the nitro group to the amino group, sulfochlorination by thionyl chloride, aniline-mediated sulfonamidation, and hydroxylamine amidation as the last step. Results: The prepared solid belinostat was purified, and an acceptable yield of 56-60% was obtained. Conclusion: The approach has several key benefits, including low-cost beginning materials, straightforward techniques, safer and more reliable results, and substantial environmental advantages.

Terahertz magneto-optical sampling in quartz glass.

In this Letter, we demonstrate terahertz (THz) magnetic field detection in fused silica with sensitivity that can be easily controlled by sample tilting (for both amplitude and polarization). The proposed technique remains in the linear regime at magnetic fields exceeding 0.3 T (0.9 MV/cm of equivalent electric field) and allows the use of low-cost amorphous materials. Furthermore, the demonstrated effects should be present in a wide variety of materials used as substrates in different THz-pump laser-probe experiments and need to be considered in order to disentangle different contributions to the measured signals.

Revealing the interfacial chemistry of silicon anodes with polysiloxane electrolyte additives

Silicon (Si) anodes are promising in lithium-ion batteries owing to their high specific capacity and suitable voltage platform. However, particle volume expansion (>300 %) and the continuous consumption of Li+ to form new interfacial layers result in poor cycle performance. We report a sustainable low-cost Si material derived from photovoltaic cutting waste, showing a high initial Coulombic efficiency (86.9 %). The cycle stability of Si/graphite is enhanced in terms of a 38 % capacity retention increase in the presence of vinyl-terminated polydimethylsiloxane (Vi-PDMS) additive. The C = C bond in Vi-PDMS plays a role in reacting with hydrogen fluoride (HF) by-products to prevent the side reaction between HF and solvent. The decomposed macromolecule Si-containing Li salt serves as a part of the solid electrolyte interphase film and has low interface resistance. This formed interphase layer effectively mitigates stress concentration at the contact surface between silicon particles and the current collector caused by expansion forces.

Natural and modified clays as low-cost and ecofriendly materials to remove salinomycin from environmental compartments

Antibiotics in the environment represent a substantial pollution threat. Among these emerging pollutants, ionophore anticoccidials are of special concern due to their potential ecological impact, persistence in the environment, and role in promoting antimicrobial resistance. To investigate the adsorption/desorption of the ionophore antibiotic salinomycin (SAL) on/from raw and modified clay adsorbents, batch-type experiments were performed using 0.5 g of clay adsorbent mixed with 10 mL of increasing doses of SAL solutions for each sample, at room temperature, with a contact time of 24 h. All measurements were conducted in triplicate employing HPLC-UV equipment. Three different natural (raw) and modified clay samples were investigated, which were denominated as follows: AM (with 51% calcite), HJ1 (with 32% kaolinite), and HJ2 (with 32% microcline). The experiments were carried out using three pH ranges: between 3.33 and 4.49 for acid-activated clays, 8.39–9.08 for natural clays, and 9.99–10.18 for base-activated clays. The results indicated that, when low concentrations of the antibiotic were added (from 5 to 20 μmol L−1), more than 98% of SAL was strongly adsorbed by almost all clays, irrespective of the physicochemical and mineralogical composition of the clays or their pH values. When higher SAL concentrations were added (40 and 100 μmol L−1), the adsorption of the antibiotic showed pH-dependent ligand adsorption mechanisms: (i) highly decreased as the pH raised (for the raw and base-activated AM and HJ1 clays), while (ii) slightly decreased as the pH decreased (on the acid-activated clays). Among the adsorption equations tested (Freundlich, Langmuir, and Linear), the Freundlich model was identified as the most suitable for fitting the data corresponding to SAL adsorption onto the studied clays. SAL desorption from clays was consistently below 10% for all the clay samples, especially for the acid-activated clays, due to cation bridging adsorption mechanisms, when the lowest concentration of the antibiotic was added. Additionally, it should be stressed that the desorption values can increase with rising SAL concentrations, but they always remain below 20%. Overall, the clays here investigated (both raw and modified) provide a cost-effective and efficient alternative for the removal of the veterinary anticoccidial antibiotic SAL, with potential positive and practical implications in environmental remediation and antibiotic pollution management, particularly by serving as amendments for contaminated soils to enhance their adsorption capacities against SAL. Additionally, using these clays in water treatment processes could improve the efficiency of mitigating antibiotic contamination in aquatic systems.

Impact of Magnetic Graphene Nanofluidic Electrolytes for I3 -/I - in Zinc/Iodide Redox Flow Batteries

Redox flow batteries (RFBs) stand out as a highly promising technology to tackle the growing challenges of intermittent energy supply, known for their extended cycle life, low environmental impact, scalability, and design flexibility1 , 2. Among various RFBs, aqueous zinc-iodide redox flow batteries (ZIRFBs), have been gaining increasing attention, due to their low material costs, high solubility (ZnI2 ~ 7M), rapid kinetics, and impressive theoretical energy density (322 Wh/L)3 , 4. However, the redox reactions of I3 -/I- on the graphite felt cathode in ZIRFBs exhibit poor reversibility and electro-activity compared to the Zn/Zn2+ pair at the anode5. This discrepancy results in significant electrode polarization resistance, a major hindrance to achieving high energy efficiency and a primary obstacle to commercialize large-scale ZIRFBs. To address this issue, researchers typically enhance the cathode’s electrochemical activity or conductivity to promote the I3 -/I- reaction, thereby reducing polarization resistance, by modifying the cathode with materials such as graphene quantum dots6, metal-organic frameworks5, and conductive polymers7.Unlike electrode modifications, electrolyte nanofluids have been relatively underexplored in the RFBs field, despite several studies on carbon-based nanofluids in all vanadium RFBs and polysulfide/iodide RFBs. These nanofluidic electrolytes have demonstrated superior conductivity and higher surface area compared to carbon felt, thereby enhancing battery performance. In this study, a magnetic graphene composite was developed using a self-assembly method facilitated by electrostatic force. The graphene was prepared by electrochemical exfoliation of graphite, modified with poly(diallyldimethylammonium chloride) (PDDA) to provide a positively-charged.Material characterization with X-Ray diffraction analysis (XRD), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscope (SEM) confirmed the successful synthesis of the composite. Flow cell experiments with a ZIRFB using a 3M solution revealed a notable improvement in the charge-discharge energy efficiency upon the addition of 0.3 mg/ml PDDA-graphene, from 72% to 82% at a current density of 30 mA/cm2, and from 47% to 60% at a current density of 70 mA/cm2. Performance improvements were also observed compared to unmodified graphene.This magnetic nanofluid holds promise for the easy separation of nanoparticles and electrolytes by a magnetic field, enabling the recovery and reuse of the nanoparticles. To endow nanoparticles with magnetism for cost-effective recovery, we further modified the PDDA-graphene with magnetite, using electrostatic self-assembly. The mass ratio of graphene to magnetite in the composite had a significant impact on the ZIRFB flow cell performance. At a mass ratio of 4:1, the nanofluid enhanced ZIRFB energy efficiency by 7.3% and 9.7% at current densities of 30 and 70 mA/cm2, respectively. Conversely, when the mass ratio was 1:1, adverse effects on battery performance were observed. In addition to the charge-discharge energy efficiency, the battery performance was also evaluated using polarization to determine the maximum power density, and electrochemical impedance spectroscope (EIS). Vinco, J. H., Domingos, A. E. E. da C., Espinosa, D. C. R., Tenório, J. A. S. & Baltazar, M. dos P. G. Unfolding the Vanadium Redox Flow Batteries: An indeep perspective on its components and current operation challenges. J. Energy Storage 43, 103180 (2021).Lourenssen, K., Williams, J., Ahmadpour, F., Clemmer, R. & Tasnim, S. Vanadium redox flow batteries: A comprehensive review. J. Energy Storage 25, (2019).Yang, Y., Liang, S. & Zhou, J. Progress and prospect of the zinc–iodine battery. Curr. Opin. Electrochem. 30, 100761 (2021).Khor, A. et al. Review of zinc-based hybrid flow batteries: From fundamentals to applications. Mater. Today Energy 8, 80–108 (2018).Li, B. et al. Metal-Organic Frameworks as Highly Active Electrocatalysts for High-Energy Density, Aqueous Zinc-Polyiodide Redox Flow Batteries. Nano Lett. 16, 4335–4340 (2016).Liu, Y. et al. Stable static zinc-iodine redox battery constructed with graphene quantum dots coated graphite felt. J. Power Sources 520, 230861 (2022).Yang, J., Song, Y., Liu, Q. & Tang, A. High-capacity zinc-iodine flow batteries enabled by a polymer-polyiodide complex cathode. J. Mater. Chem. A 9, 16093–16098 (2021).

Treatment of Se-Impacted Wastewater Using a Three-Dimensional Packed Bed Electrochemical Reactor

Selenium is an essential element for flora and fauna in trace amounts. It plays a crucial role in bolstering photosynthesis and facilitating thyroid hormone metabolism. However, excessive consumption of selenium can result in health concerns such as reproductive complications and cancer. Selenium usually coexists with minerals such as copper and coal in the natural environment. The associated activities, such as copper mining and coal combustion, have greatly accelerated the mobilization of selenium. The selenium released through coal combustion is mostly captured in the flue gas desulfurization (FGD) wastewater as inorganic selenite and selenate.Our lab previously validated the viability of direct electrochemical reduction (SeDER) to remove dissolved selenite from a simplified FGD water matrix using planar gold and graphite cathodes, where more than 94% of the aqueous selenite can be converted to elemental Se(0) deposited on the cathode surface. Graphite is eventually selected for its low material cost, decent removal performance, and minimum secondary pollution as compared to gold and other non-noble metal cathodes. This direct electrochemical deposition process provides many benefits that existing biological and indirect electrochemical methods lack, such as zero chemical addition and low to zero solid generation. However, this method is only suitable for wastewater with elevated temperatures necessary to generate conductive Se(0) for continuous reduction. The inclusion of a heating process adds complexity to the design, impeding the scalability of the SeDER system. Furthermore, the application of SeDER is constrained to Se-impacted wastewater with an elevated temperature.In this study, we propose a novel reactor design utilizing electrochemical reduction to treat Se-impacted wastewater at ambient temperature. The electrodes we used are made of graphite for the reasoning stated above. The reactor consists of a pair of planar graphite anode and cathode, and the inner chamber is filled with cylindrical graphite particle electrodes (PEs) separated by a nylon spacer to create an anodic chamber and a cathodic chamber. The PEs act as an extension of the planar electrodes, which offers numerous reaction sites and minimizes the travel distance for selenite ions to reach the electrode surface. In our 120-mL batch test with 0.1-mM selenite in 100-mM phosphate buffer, the exact system without filler removed 0% selenite at room temperature, while the filled 3D system removed on average 50% of the selenite in 3 hours. Using the same 3D system, we then investigated performance enhancement with a recirculating operation. The total working volume is fixed at 200 mL, while the flow rate and the applied voltage vary. The flow rate is set at the values with hydraulic retention time (HRT) fixed at 15 min, 30 min, and 60 min. The system-applied voltage is set at -1.9V (just enough for selenite reduction), -2.1V, and -2.3V. We found that the shortest HRT combined with -2.1V system applied voltage yielded the highest selenite removal performance in all tests, with an average of 47% removal in 3 hours. We hypothesized that the shorter HRT provides a faster flow rate that refreshes the PE’s surface from insulative Se(0) deposition, which provides sustainable reaction sites for the incoming selenite. At -2.1V, the potential is negative enough to allow selenite reduction while fewer parasitic reactions (e.g., hydrogen evolution reaction) occur compared to that under -2.3V.With the selected system voltage and flow rate, we eventually explored competing ion behavior and switched from a simplified water matrix to simulated Se-impacted wastewater. We found that of all the commonly found competing ions (i.e., sulfate, nitrate, and chloride), chloride significantly impacts selenite removal, with performance dropping to 10% removal in 3 hours. Nitrate slightly decreased the selenite removal, with an average Se removal performance of 23%. Sulfate, on the other hand, resulted in an increase in selenite removal after addition. We hypothesize that a high sulfate concentration in simulated wastewater could help alleviate the repulsing force from the cathode surface for the selenite ions. The double layer of the PEs could also be compressed by the high ionic strength, which decreases the capacitance and promotes selenite reduction. To confirm this hypothesis, we conducted an electrochemical impedance study to analyze the effect of competing ions on reaction kinetics and capacitance. We also performed surface analysis for the wasted planar electrodes and PEs to investigate the change in morphology and observed possible chemical residue. These characterizations will help us develop a regeneration protocol in long-term operation and help us scale up our prototype to manage actual Se-impacted wastewater.

Effect of Silicate Addition on ZnO Formation during Zn Discharging Process

Rechargeable zinc batteries have been attracting extensive attention as promising candidates for next-generation energy storage, owing to their intrinsic safety, mature recycling processes, low material cost and high theoretical energy density.[1] Nevertheless, there are still several issues holding back the development of zinc batteries, such as the capacity loss due to Zn passivation and poor cyclability caused by Zn dendrite formation. [2] In the past few years, efforts have been made to improve the performance of zinc batteries, among which electrolyte modification with additives is the most widely used. [3] For further development of zinc batteries towards practical application, it is also essential to deepen the understanding of chemical state changes in a working Zn electrode. In our previous work, Zn dissolution−passivation behavior with ZnO formation during Zn discharging process has been systematically elucidated via in-situ analysis. [4] Herein this work, through comparative studies with silicate addition in the electrolyte, the correlation between ZnO formation and the discharging performance of Zn anodes is further clarified, shedding new insights into further optimization of zinc batteries.Firstly, various electrolyte additives were evaluated during Zn discharging at a current density of 40 mA/cm2. As a result, potassium silicate addition with an optimum concentration of 100 mM effectively enhanced the discharge capacity of Zn anode. Effects of silicate addition on Zn discharging process were then further investigated. After 500 s of discharging, ZnO layer with a thickness around 7 um is formed on Zn anodes, which is attributed to the dehydration of supersaturated zincate ions. [4] It is observed that as-formed ZnO petals turned from sharp to round with silicate addition. Moreover, a porous ZnO layer was formed with silicate addition, while a compact one was obtained without any additives. Accordingly, it is assumed that silicate may form adsorption or coordination with ZnO particles, leading to morphology and porosity changes in ZnO.Further analyses were carried out to verify whether the chemical state of ZnO changes with silicate addition. The TEM-EDS mapping result and XPS depth profile indicate that Si is uniformly distributed within the ZnO layer. Moreover, the presence of Si-O bond is confirmed, along with both Zn 2p 2/3 and O 1s peak shifts towards higher binding energy side. Accordingly, the coordination between silicate and ZnO via the formation of Si-O-Zn bridge is suggested, which is also supported by the DFT calculation result, as a stable existence of silicate on ZnO can be achieved.On the other hand, it is noticed via XRD and HRTEM characterization that the crystallite size of ZnO became smaller with silicate addition. Moreover, ZnO formed with silicate addition presented lower crystallinity with higher defect contents, as evidenced by Raman spectra. Given the above, it is considered that silicate modulates the electronic structure of ZnO molecules via the Si-O-Zn bonding, thereby suppresses ZnO crystal growth and particle aggregation, which eventually contributes to a loose ZnO structure that can maintain the activity of Zn anodes. With the discussion of ZnO formation herein, we hope this work may open a new avenue for developing high-performance zinc batteries.AcknowledgementsThis study was supported by the Research and Development Initiative for Scientific Innovation of New Generation Batteries (RISING) Projects, RISING3 [JPNP21006], commissioned by the New Energy and Industrial Technology Development Organization (NEDO), Japan.[1] P. Ruan et al., Angew. Chem., 2022, 134, e202200598[2] W. Shang et al., Energy Storage Mater., 2020, 31, 44–57[3] S. Guo et al., Energy Storage Mater., 2021, 34, 545–562[4] T. Wang et al., Energy Environ. Mater., 2023, 0, e12481

(Invited) Epitaxial Growth of Quasi-Low Dimensional Materials for Novel Thermoelectric Films

Thermoelectric conversion devices or modules with high performance have been expected for the electrical power generation from wasted heat. Then, thermoelectric materials with high dimensionless figure of merit zT at temperature T , described as S 2 σT/κ have been intensively sought, where S is Seebeck coefficient, σ is electrical conductivity, and κ is thermal conductivity. Therein, intercorrelation among three thermoelectric properties has been a big barrier against high zT. In conventional approach, the heavy elements such as rare metals are used because they inherently bring small κ in the materials. Now, ecofriendly ubiquitous element materials without toxic, rare, or high cost elements, showing high zT, are expected in the application view.Introduction of nanostructures into materials is one of the promising ways to increase zT because of phonon scattering [1], quantum confinement effect in low dimensional materials and by energy filtering [2], and so on. Therein, structure design determines the properties, and then, this method can be expected to bring high zT in the ecofriendly and low-cost ubiquitous element materials. Furthermore, it is recently found that low dimensional materials and quasi-low dimensional materials such as layered materials with 2D structures in the unit cell show high zT values. Therefore, low and quasi-low dimensional materials for extraordinarily high zT values have been expected to be developed.We have been developing a lot of kinds of well-controlled nanostructure films by SiO2 film technique. One of the examples: Si-based films including ultrasmall semiconductor nanodots with controlled interfaces, strains, crystal orientations, and compositions [3]. Furthermore, we have developed the epitaxial growth method of quasi-low dimensional material films composed of ecofriendly group IV elements on Si substrates: FeGeγ including 1D Ge helical structure and Ca-intercalated multi-layered silicene films. Here, we will introduce the epitaxial growth results of quasi-low dimensional material films. Epitaxial growth of FeGeγ films on Si were achieved by using Ge epitaxial nanodots as seed crystals[4]. In the case of Ca-intercalated multi-layered silicene, silicene bucked structure was found to be deformed. The deformation enhanced Seebeck coefficient. As a result, this sub-angstrom atomic displacement brought power factor enhancement while keeping high electrical conductivity [5]. In this talk, we will present the epitaxial growth process of quasi-low-dimensional material films on Si substrates for thermoelectric film devices composed of ecofriendly and low-cost thermoelectric materials .[1] Y. Nakamura, et al., Nano Energy 12, 845 (2015).[2] T. Ishibe, et al., ACS Appl. Mater. Inter. 10, 37709 (2018).[3] Y. Nakamura, et al., Sci. Technol. Adv. Mater. 19, 31 (2018).[4] T. Terada, Acta Materialia 236, 118130 (2022).[4] T. Terada, et al., Adv. Mater. Inter. 9, 2101752 (2022).

Evaluating the efficiency of supplementary feeding as a management strategy for enhancing honeybee (Apis mellifera L.) colony growth and productivity

Sustaining honeybee colonies is challenging during dearth periods as their metabolic functions are reduced due to limited foraging activities. The experiment used honeybee colonies of Apis mellifera, and five different low-cost supplementary foods—sugar, banana, pumpkin, maize flour, and rice flour syrups—were introduced as treatments. Every box for each treatment received a daily 300-ml supplementary food syrup consisting of a specific amount of feeding materials along with 100 g of brown sugar and 20 g of honey. The amount of food consumed was assessed on the second day following the supplementation. Supplemental food with low-cost feeding materials significantly impacts the growth and strength of the colonies. Results revealed significant impacts on colony growth and strength, with all supplements contributing to food consumption over 78%. Despite variations in brood and pollen cells, all feeding supplements showcased efficiency in supporting honeybee feeding, indicating their potential utility in mitigating the challenges during the dearth period. Notably, pumpkin syrup emerged as the best supplement, offering cost-effectiveness compared to sugar and banana syrups, and it could reduce sugar syrup costs by 50% while enhancing brood, honey, and pollen cell production by 71.36%, 108.36%, and 58.73%, respectively. The findings of the economic analysis revealed that the cost of feeding materials was the highest for sugar syrup ($1.89), followed by banana ($0.91), pumpkin ($0.83), maize ($0.53), and rice ($0.53). This study suggests that supplementing honeybee colonies with low-cost feeding materials can positively impact colony growth and strength during dearth periods and advance the beekeeper’s decision as a cost-effective alternative to traditional sugar syrup.

Magnetic Field Mapping-Based Battery Management System (BMS) for Lead Acid Application

Lead Acid Batteries (LAB) are a widely used technology in Energy Storage Systems (ESS) due to their abundant and low-cost materials, non-flammable water-based electrolyte, and high recyclability rate. The main applications for LABs are in mobility, data centers, and telecommunications. According to the Consortium of Battery Innovation (CBI), the market for lead acid batteries is projected to increase 150 GWh between 2025 and 2030. Therefore, it is fundamental to identify emerging failure modes in LABs in ESS systems to reduce battery degradation and to extend the use life.An important failure mode in flooded LABs is acid stratification. This research explores H+ concentration changes in H2SO4 (sulfuric acid) electrolyte as a correlation of acid stratification. The objective is to develop a non-invasive, non-destructive, and accurate real-time battery monitoring system. The Magnetic Field Probing (MFP) technique, popular in the medical imaging field, shows a promising solution for ESS performance evaluation. This technique can measure induced magnetic field changes based on variation in H+ concentration in the cell during cycling. See Figure. 1 (a). MFP provides early onset notification of stratification in flooded LABs with capability to discern other failure modes in non-flooded lead batteries.A set of experimental trials measured pH and magnetic field variation of H2SO4 electrolyte. See Figure. 1 (a). The preliminary results demonstrated changes in electrolyte pH due to possible stratification. See Figure. 1 (b). A correlation between the output voltage resulting from the interaction of the induced magnetic field and the changes in the electrolyte concentration was found. See Figure 1(c) The optimal AC input frequency maximizes the induced magnetic field response. The value found for optimal AC input frequency was 32kHz, which depends on the physical properties of the magnetic field inductors (air core solenoid coils). The experimental results showed and concluded that the induced magnetic field across the tested cell is also inversely proportional to the distance between coils attached to the cell.Further research involves the use of magneto-resistors to establish a magnetic field mapping in lead acid cells as they are being cycled. Magnetic field response is measured while lead acid cells are cycled from 100% to 20% state of charge range. In the future, this study will provide insights and findings to model and predict cell stratification in lead acid cells with electrochemical computational simulations.Keywords: Energy storage systems, lead acid batteries, acid stratification, magnetic field, non-invasive method Figure 1

Electrochemical Conversion of CO2 to Fuels and Useful Chemicals over Metal Supported Solid Oxide Electrolyzers

Electrochemical conversion of CO2 and H2O to fuels and chemicals provides a promising approach to simultaneously mitigate greenhouse emission and store surplus energy, which reduces electricity network variation due to increased intermittent renewable energy (such as solar and wind) utilization. Metal supported solid oxide electrolyzers (MS-SOEs) developed at Lawrence Berkeley National Laboratory provide advantages of rapid start-up, mechanical ruggedness, redox tolerance, dynamic operation, and low-cost materials. A relatively high operating temperature range of 600 to 750°C promotes energy efficiency and allows utilization of thermal energy such as steam.In this work, efficient and stable catalysts developed at the University of South Carolina have been infiltrated in the symmetrical and porous MS-SOE architecture. The phase purity has been analyzed by X-day diffraction. The morphologies of these infiltrated and posttest catalysts have been examined by scanning electron microscopy. Optimization of cell structure, processing temperature, cell voltage, and catalyst infiltration cycles for better cell performance will be presented. The stability of MS-SOEs has been evaluated during continuous operation for >200 hours. The cell degradation mechanisms revealed by electrochemical impedance spectroscopy and high-resolution scanning electron microscopy techniques will be presented.In addition to pure CO2 electrochemical conversion, effects of additional water and hydrogen in CO2 feedstock will be analyzed. Faradic efficiency and chemical selectivity calculated from gas chromatograph and electrochemical analyses will be presented.

Tuning Oxygen Evolving Catalytic Activity of a Precious Metal-Free Nickel Boride by a Cost-Effective Method

The production of hydrogen (H2) by electrochemical water splitting [Green Hydrogen (Green H2)], if driven by green electricity, has attracted considerable interest as an alternative sustainable energy carrier, e.g., in fuel cells for electricity or power and heat generation [1]. However, the lack of satisfactory and cheap electrocatalysts (ECs) to drive the vital electrochemical reactions of hydrogen evolution (HER) and oxygen evolution (OER) in water splitting is the biggest challenge for this technology.Currently, the most advanced electrocatalysts for the two half-reactions of water electrolysis (HER and OER) are noble metal-based materials [2]. Despite the excellent catalytic properties of these noble metal catalysts, their high cost, and scarcity make their commercial use both uneconomical and impractical in low temperature water electrolysis (LT-WE) systems at industrial scale for green H2 as a clean energy alternative to cheaper fossil fuels[3]. In addition to addressing this issue by the development of precious-material-based with a low-loading of precious metal elements, the development of desirable and high-efficiency electrocatalysts (ECs) based on earth-abundant metal elements materials is paramount. However, their catalytic activity is often limited by poor electron transfer, low conductivity, low stability, and small surface area of these materials. Thus, it is crucial to develop earth-abundant metal elements-based materials that are more cost-effective to reduce the high cost of active catalysts for water electrolysis. Although several low-cost materials have already been designed, the potential required for the practical application of water splitting is still very high compared to the theoretical potential (1.23 V), which means that much energy is consumed, which theoretically could be reduced. Due to their remarkable advanced charge transfer and durability for water oxidation in alkaline media, electrocatalysts derived from metal borides-based materials have received a lot of attention as new high-performance catalysts for water oxidation.[4] These properties stem from the multi-dimensional covalent bonding of the metalloid with the surrounding metal atoms.We present here an approach to tune the OER of transition metal borides (TMBs) using the cost-effective and less energy-consuming method that is nevertheless a highly efficient material for OER (Fig. 1). We have developed a low-cost, rational and easily scalable method to enhance the catalytic activity of nickel boride (Ni–B), which requires an annealing process to optimize the catalytic activity. However, this method may have limited applicability on a large scale as it requires a highly inert environment and high-temperature treatment of Ni–B catalysts. We also elucidate a structure-activity relationship using scale-bridging techniques such as TEM and electrochemical characterization. The developed based on non-noble electrocatalysts are prepared by a simple method of chemical reduction of transition metal elements with boron in aqueous solution. The production is a one-step process and the material does not require any further treatment, yet this material shows comparable activity to the state of the art (precious metal-based materials) for OER in alkaline solution at a selected current density. This improved catalytic performance is further corroborated by the microstructural investigations in the TEM. The nanoparticles obtained have an improved porous structure compared to Ni–B and thus provide more available sites for the surface reactions and hence for the catalytic performance of the material. Furthermore, it is shown that activation enables the morphological and structural changes, while some transition metal elements act as sacrificial elements to provide more accessible and stable sites for oxygen-forming centers. This paves the way for a better understanding of metal boride-derived electrocatalysts for water oxidation, a crucial chemical reaction in water electrolysis and other electrochemical energy technologies. Acknowledgements: This project has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No 945422. We acknowledge the use of the DFG-funded Micro-and Nanoanalytics Facility (MNaF) at the University of Siegen (INST 221/131-1).

(Invited) Cost Reduction Strategies in Low Temperature Water Electrolysis with Improved Catalytic Activity

Proton exchange membrane water electrolysis (PEMWE) technology is especially advantageous for green H2 production as a clean energy vector. During the water electrolysis process, the oxygen evolution reaction (OER) requires a large amount of iridium (2-3 mgIr cm−2) as catalyst. This material is scarce and expensive, representing a major bottleneck for large-scale deployment of electrolyzers. Recently, Retuerto et al. have synthesized different Ir double perovskites (Sr2CaIrO6) with the Ir atoms in a high oxidation state (Ir6+/5+) 1 and their catalytic activity was extensively investigated. Specifically, a Ca-based double perovskite (Sr2CaIrO6) has showed the highest OER activity similar to those of Ir or Ir oxides-based catalysts while being stable for the OER in half cell measurements. We report the development of a membrane electrode assembly taking advantage of the high activity of the Sr2CaIrO6 catalyst that has only 0.2 mgIr cm−2, around 10 times lower compared to what it is used in the anodes of commercial PEMWE, showing superior performance and stability. The morphology/structure of the developed anode and Sr2CaIrO6 catalyst, before and after operation in PEMWE, were extensively characterized by X-ray diffraction (XRD, high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and X-ray absorption near edge structure (XANES). We discuss in this contribution how the finding of this work can provide a strategy to lower the Ir content in commercial PEMWE.Anion exchange membrane water electrolysis (AEMWE) combines the advantages of proton exchange membrane water electrolysis (PEMWE), i.e., high current density while maintaining high efficiency and fast dynamic response with the advantages of alkaline water electrolysis (AWE), i.e., low-cost materials. However, AEMWE technology is still depends on a supporting electrolyte and its durability is low. In this regard, the German Aerospace Center (DLR) is developing novel approaches and cell components. Raney-nickel electrodes were developed via vacuum plasma spraying, reaching performance and stability comparable to SoA MW size PEMWE. The electrodes were further refined, switching to lower cost atmospheric plasma spraying while maintaining high performance. Studying the effect of supporting electrolyte concentration it was found, that lowering the ohmic resistance is by far the largest challenge for high performance AEMWE, especially at low KOH concentrations and electrode kinetics are less impactful. Moreover, a 17% efficiency uplift was achieved by applying a carefully tuned, thermally sprayed, nickel-based macro porous layer (MPL) onto a traditional mesh porous transport layer. Both ohmic and mass transport resistances were found to be lowered by the MPL. FIB-SEM and µCT analysis revealed an ideal structure, i.e., 30-40% porosity, almost exclusively open pores, and a broad pore size distribution2. In a fundamental study3, the mechanism of the OER activity was investigated as well as the effect of trace amounts of iron in Ni(OH)2. X-ray diffraction (XRD) and Thermogravimetric analysis (TGA) TGA analysis lead to the conclusion, that iron stabilized the α-Ni(OH)2which is the most active. CV analysis showed that an important redox switching step is also accelerated by Fe-doping. M. Retuerto, L. Pascual, J. Torrero, M. A. Salam, Á. Tolosana-Moranchel, D. Gianolio, P. Ferrer, P. Kayser, V. Wilke, S. Stiber, V. Celorrio, M. Mokthar, A. S. Gago, K. A. Friedrich, M. A. Peña, J. A. Alonso, D. G. Sanchez, S. Rojas, Highly Active and Stable OER Electrocatalysts Derived from Sr2MIrO6 for Proton Exchange Membrane Water Electrolyzers. Nat. Commun. 2022, 13, 7935. Razmjooei, F.; Morawietz, T.; Taghizadeh, E.; Hadjixenophontos, E.; Mues, L.; Gerle, M.; Wood, B. D.; Harms, C.; Gago, A. S.; Ansar, S. A.; Friedrich, K. A., Increasing the performance of an anion-exchange membrane electrolyzer operating in pure water with a nickel-based microporous layer. Joule 2021, 5 (7), 1776-1799. Wang, L.; Saveleva, V. A.; Eslamibidgoli, M. J.; Antipin, D.; Bouillet, C.; Biswas, I.; Gago, A. S.; Hosseiny, S. S.; Gazdzicki, P.; Eikerling, M. H.; Savinova, E. R.; Friedrich, K. A., Deciphering the Exceptional Performance of NiFe Hydroxide for the Oxygen Evolution Reaction in an Anion Exchange Membrane Electrolyzer. ACS Applied Energy Materials 2022, 5 (2), 2221-2230.

(Invited) Towards Scalable and Low-Cost Direct Recycling of Lithium-Ion Batteries

The increasing amount of lithium-ion battery (LIBs) consumption will result in the resource shortage and price increase of lithium and precious transition metals that are critical for making high-performance LIBs. Also, future batteries that mainly use low-cost materials (Na, Fe, Mn) will have limited economic benefits to recycle even though the wastes generated from disposal of used batteries can cause severe environment pollution. In this context, design of low-cost and scalable recycling and regeneration process for spent batteries is attracting growing interest. This talk will focus on our recent progress on direct recycling and regeneration spent LIBs, which can lead to new electrode materials that can show the same level of performance as the native materials. We will show successful recycling of various battery materials, including cathode (LiMO2, LiMn2O4, and LiFePO4) and anode (graphite) using the direct regeneration approach. We will discuss how we integrate different operation steps into a pathway for scalable directly recycling.

High-Rate and Durable Zinc-Based Flow Batteries for Large-Scale Energy Storage

Large-scale energy storage is a key enabling technology for the widespread adoption of renewable energy such as wind and solar power. Among various technologies, zinc-based flow batteries stand out as one of the most promising candidates due to the high energy density, low cost, and use of earth-abundant active materials. However, the low operating current density and short cycle life resulting from notorious zinc dendrite formation, large internal resistance, and sluggish reaction kinetics pose a great challenge for their practical applications. Although great efforts have been made to address these issues, previous works mainly focused on one specific aspect, making it challenging to boost the overall performance of zinc-based flow batteries. In this presentation, a systematic study on the effects of key components on the electrochemical performance of zinc-bromine flow batteries will be presented. Our results show that all key components (electrodes, electrolytes, membranes, and flow fields) can exert a significant influence on the electrochemical performance. More impressively, a high areal capacity of >200 mAh/cm2 and an operating current density of as high as 400 mA/cm2 can be achieved by optimizing the design and operating parameters. Underlying mechanisms and perspectives for further improvement will be discussed during the presentation.

Nature-Derived Sulfur Carbons for Highly-Efficient Room Temperature Sodium-Sulfur Energy Storage

In recent years, a growing interest in “beyond-Li-ion“ batteries has caused a speedy development of alternative battery technologies based on other alkali metals. Room temperature sodium sulfur (RT Na-S) batteries are potential candidate for sustainable large-scale energy storage systems. They offer low cost, nontoxicity and natural abundance of both cathode and anode materials combined with high theoretical energy density. However, rapid capacity fading related to the irreversible shuttling of soluble polysulfides, poor reaction kinetics and low sulfur utilisation in the cathode materials significantly limit their practical application.In this work, a microporous sulfur-carbon complex is produced from sustainable natural precursors in a one-pot synthesis via stepwise thermally-induced inverse vulcanisation and condensation. The material exhibits a unique structure, with sulfur chains covalently anchored to the conductive carbon matrix and physically confined in ultra-micropores. An increase in sulfur content in the sulfur-copolymer alters the morphology and chemical composition of the final sulfur-carbon material, enhancing the amount of long-chain sulfur. The combination of optimal microstructure, good electrical conductivity and high content of electrochemically active sulfur translates to an unprecedented ~99% utilisation of sulfur and the highest reported capacity for a room temperature Na-S cathode, along with high rate capability, coulombic efficiency and long-term stability. This study offers an innovative approach towards the understanding of the key chemico-physical properties of the sulfur-carbon composite materials for the development of high-performance cathodes in RT Na-S batteries with an atom-efficient utilisation of sulfur.

Electrochemical Characterization of Non-Aqueous and Aqueous Gel Polymer Electrolytes for Zinc-Ion Fiber Batteries

The increasing miniaturization of integrated circuits has enabled a wide variety of new applications for embedded sensors and smart devices. Miniaturization of their power sources, however, has lagged in comparison. There are many challenges to devising a space-conscious battery, including the power density, mechanical stability, and chemical safety. Batteries made in fiber formats are of interest for use in wearable electronics. Recent studies have shown the feasibility of Li-ion battery chemistries in drawn polymer fibers via thermally induced phase separation (TIPS)1,2 but key performance gaps in safety and reliability of these fiber batteries remain.In addition to Li-ion, zinc-manganese dioxide (Zn-MnO2) chemistries are particularly good candidates for fiber format batteries due to their relatively low raw material cost, low reactivity, and tolerance of environmental contaminants such as water. Our work has focused on two Zn-MnO2 gel polymer electrolyte (GPE) cell formats: one non-aqueous polyvinylidene fluoride (PVDF) based gel polymer electrolyte, the other an aqueous polyvinyl alcohol (PVA) based GPE. In this work, we synthesize, characterize, and compare these two electrolyte formats head-to-head in both Zn-Zn symmetric cells and Zn-MnO2 full cells.After the GPEs were synthesized, thermo-gravimetric analysis was used to characterize the gels and evaluate the feasibility of drawing the GPE of interest into fibers. We synthesized zinc salt containing PVDF-based GPEs and characterized them in ionic blocking cells via electrochemical impedance spectroscopy (EIS), achieving conductivities of 1.8 mS/cm2. We also assembled Zn-Zn symmetric cells, investigated key performance characteristics such as the transport number and the electrochemical stability window, and stably cycled them for over 500 hours at 0.5 mA/cm2. Lastly, we assembled Zn-MnO2 full cells to confirm the battery performance.

Exploring the Role of Redox-Shuttle Mediators in Lithium-Sulfur Batteries

The lithium-ion battery (LIB) is widely acknowledged as the state-of-the-art battery technology today and is used in consumer electronics, stationary storage, and electrified transportation1,2. However, there is a drive towards developing technologies with higher energy densities. The lithium-sulfur battery is one of the most promising next-generation batteries for high-energy applications, due to its high theoretical gravimetric energy density of 2567 W h kg-1, low raw material costs, and reduced environmental impact3. Despite these potential advantages, lithium-sulfur batteries are still beset with difficulties, one of the most significant is the so-called “polysulfide shuttle effect.” Operation of the battery involves the conversion of sulfur to polysulfide species, which dissolve into the electrolyte and diffuse to the lithium metal electrode, leading to loss of active material. This results in poor cycle life, rapid capacity fading and low coulombic efficiencies4.The use of dissolved, electrochemically active redox mediators could mitigate these effects by catalysing sulfur redox reactions during cell cycling. While it is generally agreed that the redox potential of the mediators is a key factor in their operation, no report to date has conclusively demonstrated how mediators of varying potentials can target specific sulfur redox reactions. Herein, we report a study of the mediators 9-fluorenone (9-FO), duroquinone (DQ), 2,6-di-tert-butyl-1,4-benzoquinone (TBBQ) and 1,5-bis(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)anthra-9,10-quinone (AQT) to understand their interactions with sulfur, lithium polysulfides, lithium sulfide and lithium metal5. We use liquid-chromatography mass spectrometry (LC-MS) to isolate various polysulfide chain lengths after reaction with mediators. It is observed that high potential redox mediators, such as TBBQ, are better able to drive Li2S oxidation to higher polysulfide chain lengths, and low potential redox mediators such as 9-FO push sulfur towards lower chain polysulfides. This offers a novel and effective approach to screening suitable redox-active molecules. Galvanostatic cycling is employed to relate these chemical interactions to enhanced cell performance. Developing a fundamental understanding of how redox mediators operate in a cell will aid in the molecular design of novel redox-active compounds.[1] J. Vetter, P. et al: Ageing mechanisms in lithium-ion batteries, J. Power Sources, 2005, 147, 269–281.[2] D. Castelvecchi: Electric cars: the battery challenge, Nature, 2021, 596, 336–339.[3] P. G. Bruce et al: Li-O2 and Li-S batteries with high energy storage, Nat. Mater., 2012, 11, 19–29.[4] S. Zhang et al: Recent advances in electrolytes for lithium-sulfur batteries, Adv. Energy Mater., 2015, 5, 1–28.[5] Y. Tsao et al: Designing a quinone-based redox mediator to facilitate Li2S oxidation in Li-S batteries, Joule, 2019, 3, 872–884.

(Invited) Understanding the Effect of Cell Assembly and Operation on AEM Electrolyzer Performance and Durability

Water electrolysis to produce hydrogen is gaining significant attention due to a significant decrease in the cost of renewable energy sources such as solar, wind, and tidal etc. Among the existing water electrolysis technologies, anion exchange membrane water electrolysis has recently emerged due to its potential advantages over proton exchange membrane electrolysis and traditional alkaline electrolysis. Anion exchange membrane electrolyzers (AEMELs) can allow for the use of PGM-free electrocatalysts and low-cost component materials due to its less corrosive alkaline environment while also enabling electrochemical H2 compression.An overwhelming majority of the research that is going on related to AEMELs is the synthesis of advanced functional nanomaterials – e.g. new catalysts and membranes. Though these are critically important components of the cell, their function is supported by a multitude of other factors. For example, it is well-known that water and gas transport in the electrodes is highly dictated by the porous transport layers. The electrode fabrication technique controls the electrode morphology. The synthesis method for the catalyst determines its porosity and structure. The cell gasketing controls compression. The operating current density and temperature affect stress at the material and electrode level, and dictate other properties such as exchange current, ionic conductivity, water uptake, diffusivities, etc. Many of these properties are less reported and will be the subject of this presentation.This presentation will focus on understanding how various decisions that are made regarding electrode fabrication, cell assembly and cell operation affect the operating voltage and voltage stability of AEM electrolyzers. The goal of this talk is to combine electrochemical and physical characterization data to develop a series of guiding principles for AEMEL operation that can be used across polymer chemistries and catalyst selection.