Iron-based Materials Research Articles

An iron-based fluorophosphate cathode material for K-ion batteries.

The development of a tavoritestructured K- transition metal (TM)- fluorophosphate, having earth-abundant Fe as the only TM, crystallizing in the orthorhombic crystal system and facilitating stable-cum-reversible electrochemical K-extraction/insertion, has been reported here. Synthesized using low-cost precursors, KFePO4F has also been found to be air-stable. Detailed information pertaining to the bonding/structure, including lattice site occupancy, have been obtained via diffraction, Raman spectroscopy and FTIR, with XPS and ESR revealing the oxidation states of Fe in the as-synthesized condition and upon being subjected to electrochemical potassiation/depotassiation. The electrochemical K-insertion/extraction, supported by reversible Fe-redox, leads to a reversible K-storage capacity of ~102 mAh/g (within 1.5-4.0 V), along with a 1st cycle Coulombic efficiency (CE) of ~93% (with CE >99.9% from 2nd cycle). Ex-situ X-ray diffraction, as well as operando synchrotron diffraction during galvanostatic cycling, indicates reversible changes in peak positions upon electrochemical K-extraction/insertion, with no evidence for structural change. When used as cathode material in K-ion 'full' cell (with hard carbon-based anode), a discharge capacity of ~68 mAh/g, along with capacity retention of ~70% after 50 cycles, has been obtained; which confirms that this newly-developed earth-abundant Fe-based potassium fluorophosphate can be utilized for potential application in sustainable battery chemistries, like K-ion batteries.

Iron-Based Materials Synthesized by Mechanical Ball Milling for Environmental Contaminants Removal: Progress and Prospects

Iron-Based Materials Synthesized by Mechanical Ball Milling for Environmental Contaminants Removal: Progress and Prospects

Iron complexes synthesized from FeOCl with carboxylic acid based ligands as Fenton-like catalysts for the highly efficient degradation of organic dyes over a wide pH range

Iron-based materials have garnered significant attention as Fenton-like catalysts for the degradation of organic dyes. However, challenges remain in optimizing hydroxyl radical (•OH) utilization and broadening the effective pH range for practical applications. In this study, three iron-based catalysts (complex 1, 2, 3) were synthesized via a hydrothermal method, utilizing iron oxychloride (FeOCl) as the metal ion source and 4,5-imidazole dicarboxylic acid, furan-2,5-dicarboxylic acid, and 5-hydroxyisophthalic acid as ligands, respectively. The results indicate that these synthesized Fe-based catalysts exhibit enhanced visible light absorption and superior photo-Fenton activity, outperforming FeOCl in the degradation of rhodamine B (Rh-B), crystal violet (CV), and methylene blue (MB). Moreover, the Fe-based catalyst system operates effectively over a wide pH range (1–8) and efficiently degrades organic dyes. In free radical scavenging experiments, hydroxyl radicals (•OH) and superoxide radicals (•O2-) were identified as the primary agents responsible for photocatalytic degradation. Among the catalysts, complex 1 displayed notable stability, retaining its catalytic activity after three reuse cycles. This work presents a promising approach for designing highly efficient and stable Fenton-like catalysts, offering excellent environmental remediation capabilities across a broad pH range.

Recent Progress in Molecular Oxygen Activation by Iron-Based Materials: Prospects for Nano-Enabled In Situ Remediation of Organic-Contaminated Sites

Recent Progress in Molecular Oxygen Activation by Iron-Based Materials: Prospects for Nano-Enabled In Situ Remediation of Organic-Contaminated Sites

Photocatalytic remediation of fluoranthene contaminated soil by eco-friendly GQDs/TiO2/α-FeOOH composite photocatalyst: Efficiency, influence factors, mechanism, and toxicity analysis

Polycyclic aromatic hydrocarbons (PAHs), as a persistent organic pollutant, have adverse effects on soil environment and human health. In this study, a new type of iron-based material graphene quantum dots (GQDs)/TiO2/α-FeOOH was used to construct a photocatalytic system to achieve effective degradation of fluoranthene in soil. The hydrothermal method and sol–gel method were used to synthesize GQDs/TiO2/α-FeOOH composite photocatalyst, which exhibited enhanced photocatalytic activity by promoting charge transfer, increasing specific surface area, and broadening light absorption range. The degradation ratio of fluoranthene in soil suspension by GQDs/TiO2/α-FeOOH was 67.37 % under the condition of 24 h of simulated sunlight irradiation, water/soil ratio of 10:1, and catalyst dosage of 50 mg/g. •O2– and h+ played the major roles in degradation process, and the catalytic mechanism was proposed. The degradation products and degradation pathway of fluoranthene were analyzed by GC–MS detection and DFT calculation, and the toxicity of degradation products was predicted by simulation calculation. The effect of remedial soil on seed germination was investigated through germination test of tomato seeds, and results showed that the productivity of fluoranthene contaminated soil was recovered in a certain extent.

Synergetic effect of pyrrhotite and zero-valent iron on Hg(Ⅱ) removal in constructed wetland: Mechanisms of electron transfer and microbial reaction

Effective removal of mercury (Hg) from wastewater is significant due to its high toxicity, especially methylmercury (MeHg). Reducing of Hg(II) to Hg(0) in constructed wetlands (CWs) using iron-based materials is an effective strategy for preventing the formation of MeHg. However, the surface passivation of zero-valent iron (ZVI) limits its application. Herein, synergetic ZVI and pyrrhotite were utilized to enhance Hg removal in CWs. Results indicated that the removal of total Hg, dissolved Hg, and particulate Hg in CWs with ZVI and pyrrhotite were improved by 21.68 ± 0.76 %, 13.02 ± 0.88 %, and 22.27 ± 0.76 % compared to that with single ZVI or pyrrhotite. Pyrrhotite increased the surface corrosion of ZVI, thereby facilitating the process of iron reduction. The redox of iron promoted the generation of EPS, which could provide electrons for Hg(II) reduction. The sulfur also participates in electron transfer by driving the methylation of Hg and provides sulfides to form FeS-Hg complexes and HgS precipitation. The abundance of key enzymes that involved in iron reduction and Hg transformation was enhanced with the addition of ZVI and pyrrhotite. The synergetic of pyrrhotite and ZVI enhances the removal of Hg in CW, offering a promising technology for high-efficiency treatment of Hg.

Non-radical oxidation driven by iron-based materials without energy assistance in wastewater treatment.

Chemical oxidation is extensively utilized to mitigate the impact of organic pollutants in wastewater. The non-radical oxidation driven by iron-based materials is noted for its environmental friendliness and resistance to wastewater matrix, and it is a promising approach for practical wastewater treatment. However, the complexity of heterogeneous systems and the diversity of evolutionary pathways make the mechanisms of non-radical oxidation driven by iron-based materials elusive. This work provides a systematic review of various non-radical oxidation systems driven by iron-based materials, including singlet oxygen (1O2), reactive iron species (RFeS), and interfacial electron transfer. The unique mechanisms by which iron-based materials activate different oxidants (ozone, hydrogen peroxide, persulfate, periodate, and peracetic acid) to produce non-radical oxidation are described. The roles of active sites and the unique structures of iron-based materials in facilitating non-radical oxidation are discussed. Commonly employed identification methods in wastewater treatment are compared, such as quenching, chemical probes, spectroscopy, mass spectrometry, and electrochemical testing. According to the process of iron-based materials driving non-radical oxidation to remove organic pollutants, the driving factors at different stages are summarized. Finally, challenges and countermeasures are proposed in terms of mechanism exploration, detection methods and practical applications of non-radical oxidation driven by iron-based materials. This work provides valuable insights for understanding and developing non-radical oxidation systems.

Insights into the relationship between Nitrilotri(methylphosphonic acid) (NTMP) adsorption and physicochemical properties of iron oxides

Non-reactive phosphorus (e.g., phosphonate) contributes to eutrophication, while little attention has been paid to its control. The iron-based materials are highly efficient in orthophosphate removal from water, while the correlation between their physicochemical properties and selective phosphonate (e.g. Nitrilotri(methylphosphonic acid) (NTMP)) adsorption is still unclear. In this study, Fe3O4 (magnetite), FeOOH (goethite) and Fe2O3 (hematite) with different crystal structures, particle sizes and surface area were synthesized for NTMP adsorption. The physicochemical properties of the three kinds of iron oxides were characterized. The batch experiments were applied to explore the NTMP adsorption and desorption performance. The maximum adsorption capacity of NTMP on Fe3O4, FeOOH and Fe2O3 were 4.14, 1.91 and 0.99 mg-P/g, respectively. Results implied the crystal structure and surface area of iron oxides determined the maximum NTMP adsorption capacity. The NTMP adsorption on the three iron oxides was spontaneous, endothermic and randomness increase. The iron oxides showed high selectivity towards NTMP adsorption in water containing anions, while the co-existing Ca2+ and Mg2+ remarkably increased the adsorption capacity. The successive adsorption-desorption cycles suggested a favorable reusability of the above iron oxides and a high NTMP desorption efficiency. The specific NTMP adsorption capacity followed the sequence of FeOOH > Fe2O3 > Fe3O4, and was highly dependent on surface OH− proportion. The NTMP adsorption mechanism was mainly attributed to inner-sphere complexation. This study provides insights into the iron-based adsorbents design for selective phosphonate adsorption in the future.

N-coordinated iron sites dispersed in porous carbon frameworks to activate peroxymonosulfate for efficient sulfisoxazole degradation and real hospital wastewater decontamination

Herein, an N-coordinated Fe site dispersed in porous carbon frameworks (Fe-NC) fabricated from zeolitic imidazolate frameworks encapsulated with iron acetylacetonate (Fe(acac)3 @ZIFs) was employed to activate peroxymonosulfate (PMS) for the attenuation of sulfisoxazole (SIZ) and treating real hospital wastewater. The constructed Fe-NC/PMS system exhibited good catalytic stability for SIZ degradation, maintaining excellent degradation performance over multiple cycles with virtually no leaching. The quenching experiments, electron paramagnetic resonance (EPR) capture analyses, and semi-quantitative measurements showed that singlet oxygen (1O2) and high-valent metal-oxo species were mainly responsible for SIZ degradation by Fe-NC/PMS. Significantly, ultra-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS/MS) was used to trace 134 pharmaceutical contaminants in real hospital wastewater. Effective degradation was achieved for 87 % of the pharmaceutical contaminants by the Fe-NC/PMS process. Seventy-four pharmaceutical contaminants were eliminated. Taken together, this work successfully established the Fe-NC/PMS technology using the developed iron-based materials and explored its application to real hospital wastewater treatment, providing an eco-friendly and effective strategy for treating wastewater.

Effective activation of PMS by encapsulating monodispersed Fe3O4 within N, S heteroatoms co-doped carbon chamber for ROX removal dominated by the non-radical pathway

Developing the eco-friendly catalyst-adsorption iron-based materials with improved catalytic activity and minimal Fe leaching is fascinating for roxarsone (ROX) removal. Herein, Fe3O4 nanoparticles were encapsulated in flexible N, S-modified carbon chamber (Fe3O4@NS4C) through the “hydrothermal + pyrolysis” process to form a catalyst with multi-active sites. ROX could be degraded nearly 100 % at pH 5.0 − 11.0 and secondary inorganic As species concentration is lower than 0.09 mg/L by efficient adsorption. Especially, the Fe ion leaching concentration in Fe3O4@NS4C/PMS after ROX removal is decreased to 0.08 mg/L. Combined with quenching experiment, EPR, Raman spectroscopy and electrochemical analysis, the non-radical activation mechanism dominated by 1O2 and electron transfer was determined. The synergistic interaction between the N doped sites and the S anchored sites within the carbon matrix not only improves the adsorption of PMS on the catalyst but also facilitates the direct activation of PMS to 1O2, while the surface electron transfer improves the Fe2+/Fe3+ redox cycling in PMS activation. The active sites of ROX attacked by 1O2 were examined through Fukui function computations. Combined with HPLC-MS, the ROX degradation pathway was determined, and the toxicity of intermediates was evaluated. Furthermore, the removal performance of ROX in Fe3O4@NS4C/PMS system was also assessed in different environment for practical application, indicating that the advantages in the synergy between N, S co-doping carbon chamber and encapsulated iron oxide for water purification.

Investigation of acid-activated iron-based bentonite materials for the oxidation mechanism of dimethyl disulfide

Due to its low olfactory threshold and high volatility, Dimethyl disulfide (DMDS) is a well-known malodorous compound in pesticides and organic synthesis. This study utilizes sodium bentonite as catalyst support, treating it with acid activation and iron-based modification to create a catalytically active bentonite material. Following modification, the bentonite maintains its fundamental structure while integrating iron ions, resulting in an expanded interlayer spacing and increased specific surface area from 60.371 m2/g to 314.539 m2/g, thereby enhancing catalytic activity. Kinetic modeling fitting demonstrates that combining iron-based acid-activated bentonite with hydrogen peroxide (H2O2) produces the most efficient oxidative system, with the highest reaction rate constant（K = 0.08038 min−1） for DMDS degradation. The best degradation effect was achieved when the ratio of Fe-H-Bent to hydrogen peroxide was 1:5, the pH was 3, and the reaction temperature was 40 °C, and the removal rate was up to 98.9%. Electron paramagnetic resonance (EPR) spectroscopy confirms that hydroxyl radicals (·OH) are this system's primary driver of oxidation. Theoretical computations and product analyses provide insight into the oxidation pathway of DMDS, showing that initial oxidation occurs at the first sulfur atom, forming an intermediate that further oxidizes to dimethyl sulfoxide and ultimately to sulfur dioxide. This research offers a practical method for the effective removal of DMDS in pesticide plants and chemical industrial parks.

Phosphorization of α-Fe2O3 Boosts Active Hydrogen Mediated Electrochemical Nitrate Reduction to Ammonia.

Inexpensive iron-based materials are considered promising electrocatalysts for nitrate (NO3 -) reduction, but their catalytic activity and spontaneous corrosion remain challenges. Here, the α-Fe2O3 active surface is reconstructed by gradient phosphorization to obtain FePx with higher electrochemical activity. FeP2.0 optimizes the adsorption energy of NO3 - and its reduction intermediates, meanwhile promote the generation of active hydrogen (*H) but inhibit its generation of H2. More importantly, Fe and P can serve as binding sites for NO3 - and *H, respectively, which improves the electron utilization of NO3 - deoxygenation and the efficiency of the subsequent hydrogenation for the selective synthesis of NH3. 91.7% NO3 - conversion rate is achieved for the reduction of 100mL 200mg L-1 NO3 --N, 99.3% ammonia (NH3 selectivity (yield of 1.79 mg h-1 cm-2), and 91.4% Faraday efficiency in 3 h. The high-purity solid NH4Cl is finally extracted by gas extraction and vacuum distillation (81.4% recovery). This study provides new insights and strategies for the conversion of NO3 - to NH3 products over iron-based electrocatalysts.

Mechanistic insights into Fe3O4-mediated inhibition of H2S gas production in sludge anaerobic digestion

The addition of iron-based conductive materials has been extensively validated as a highly effective approach to augment methane generation from anaerobic digestion (AD) process. In this work, it was additionally discovered that Fe3O4 notably suppressed the production of hazardous H2S gas during sludge AD. As the addition of Fe3O4 increased from 0 to 20 g/L, the accumulative H2S yields decreased by 89.2 % while the content of element sulfur and acid volatile sulfide (AVS) respectively increased by 55.0 % and 30.4 %. Mechanism analyses showed that the added Fe3O4 facilitated sludge conductive capacity, and boosted the efficiency of extracellular electron transfer, which accelerated the bioprocess of sulfide oxidation. Although Fe3O4 can chemically oxidize sulfide to elemental sulfur, microbial oxidation plays a major role in reducing H2S accumulation. Moreover, the released iron ions reacted with soluble sulfide, which promoted the chemical equilibrium of sulfide species from H2S to metal sulfide. Microbial analysis showed that some SRBs (i.e., Desulfomicrobium and Defluviicoccus) and SOB (i.e., Sulfuritalea) changed into keystone taxa (i.e., connectors and module hubs) in the reactor with Fe3O4 addition, showing that the functions of sulfate reduction and sulfur oxidation may play important roles in Fe3O4-present system. Fe3O4 presence also increased the content of functional genes encoding sulfide quinone reductase and flavocytochrome c sulfidedehydrogenase (e.g., Sqr and Fcc) that could oxidize sulfide to sulfur. The impact of other iron-based conductive material (i.e., zero-valent iron) was also verified, and the results showed that it could also significantly reduce H2S production. These findings provide new insights into the effect of iron-based conductive materials on anaerobic process, especially sulfur conversion.

Interfacial engineering for the construction of iron sulfide/boride nanosheets heterostructure bifunctional electrocatalysts for high-efficiency overall water splitting

Iron-based materials have been extensively studied and applied as electrocatalysts. However, the electronic structure of iron itself is not conducive to effectively activating adsorbed intermediates, leading to slower kinetic steps. In this study, a heterogeneous composite catalyst with a nano-sheet array structure consisting of iron boron/sulfide (FeS@Fe2B/IP) was successfully prepared through a two-step process involving boriding and sulfidation of iron plates. The nanosheet array structure provides numerous catalytic active sites, promotes effective contact between electrolytes and catalytic sites, and enhances the apparent reaction rate of the catalyst. Additionally, the heterogeneous interface of FeS/Fe2B plays a crucial role in regulating the electronic structure of the metal Fe site, improving charge transfer rates, and accelerating electrocatalytic reaction kinetics. Ultimately, FeS@Fe2B/IP demonstrates outstanding water splitting performance, with only 177 and 191 mV overpotential providing 10 mA cm−2 toward HER and OER, respectively. Furthermore, it achieves a high current density of 500 mA cm−2 at 473 and 520 mV overpotentials for HER and OER, respectively. In addition to its excellent performance in water splitting applications, a bipolar alkaline cell was constructed using the FeS@Fe2B/IP bifunctional catalyst. This achieved current densities of 10 and 100 mA cm−2 at potentials of 1.63 and 1.75 V. Moreover, the catalytic stability of the FeS@Fe2B/IP system remained consistent for nearly 50 hours at current densities of 10 and 100 mA cm−2. These results confirm that FeS@Fe2B/IP is indeed a high-performance bifunctional electrocatalytic material which can significantly improve energy utilization efficiency in various applications.

Synthesis of oleic acid – coated zinc – doped iron boride nanoparticles for biomedical applications

Although various iron-based magnetic materials have been extensively studied in biomedical field for many years, iron boride compounds with interesting chemical and magnetic properties are relatively less explored, and their potential applications are not as widely known. In this study, the synthesis, coating, surface modification, and cytotoxicity tests of the Fe–Zn–B system were presented. Iron boride-based nanoparticles (NPs) containing elemental zinc (Zn) were developed by using a direct chemical synthesis of FeCl3, ZnCl2 and NaBH4, and investigated for potential use in biomedical applications. Powders having the phases of pure FeB with small amount of elemental Zn were obtained with a uniform morphology and an average particle size of 68 nm. The NPs were then coated with oleic acid (OA) and surface modified with sodium tricitrate, to increase their stability and biocompatibility, and well-dispersed NPs were obtained with sizes below 30 nm. TEM investigations revealed the presence of hybrid clusters with nanoparticle – OA structures, indicating that FeB nanoparticles were stabilized by being embedded in OA clusters, forming both agglomerated sub-micron and free nano-sized structures. Obtained NPs showed ferromagnetic property, with a saturation magnetization of 25.9 emu/g and a low coercivity of 90 Oe. As a result of testing different types of healthy and cancer cell lines with NPs, Zn-doped-FeB@OA NPs exhibited a high biocompatibility. Results suggested that highly biocompatible and magnetic OA-coated Zn-doped FeB particles can be potential candidates for biomedical applications such as medical imaging or drug delivery systems.

Perfluorooctanoic acid efficient chain reaction degradation in multifunctional iron-sulfur mineral augmentation geobiochemical remediation system

Serious contamination of perfluorooctanoic acid (PFOA) has aroused global concern. General biotransformation or iron-based materials did not meet efficient PFOA elimination. Here, specific green and low-carbon microorganism-biochar pellets, multi-component and multifunctional iron-sulfur (FexSy) mineral pellets, and a microbe-FexSy interaction device were developed to solve this problem. The multi-scale (molecular, interface, and column scales) research method combined with the multi-process reaction model was constructed to explore PFOA removal mechanism. Results revealed that microbe-FexSy interaction achieved excellent PFOA degradation performance and retention effect, with degradation rate λ (0.213 h−1) increased by 113 % than FexSy (0.100 h−1) device. The distribution coefficient Kd and kinetic adsorption α increased by 18.54 % and 22.61 %; the fraction of kinetic sorption increased by 63.83 % in microbe-FexSy device (77 %) than alone FexSy (47 %) device. Delftia and Pseudomonas combined with Fe2+ drove an efficient cycle chain reaction for PFOA. Quantitative structure–activity relationship (QSAR) model prediction results indicated that intermediates exhibited lower biotoxicity than PFOA. Furthermore, NO3– further increased the retention effect of microbe-FexSy device for PFOA with little reaction rate fluctuation, making it promising for eliminating PFOA contamination, especially in NO3– type of groundwater. It provided an efficient technology and device based on microbe-mineral interaction in remediating PFOA-contaminated groundwater.

An integrated exploration from microstructure to mechanics in austenite to pearlite transformation of high carbon steel under high magnetic fields

The effects of a high magnetic field (12 T) on the microstructural evolution and mechanical properties of high carbon steel during isothermal pearlitic transformation at 720 °C were investigated. The application of a high magnetic field effectively promotes pearlitic transformation and leads to a reduction in the lamellar spacing and the geometrically necessary dislocation density (GND) as well as to a slight increase in the grain size of the pearlite, which leads to a decrease in hardness. This is because the magnetic field reduces the magnetic Gibbs energy of ferrite and cementite, resulting in an increase in the driving force of phase transformation, which shortens the pearlite maturation time and reduces the nucleation barriers of pearlite, thereby accelerating the growth rate of pearlite. In addition, the interfacial energy of ferrite/cementite was found to be increased by the magnetic field from the thermodynamic point of view, and the mechanism of action of the magnetic field -induced precipitation of cementite in the form of particles and short rods was elucidated. The present work will enhance the understanding of the mechanism of magnetic field-induced phase transformation in iron-based materials.

Atomic-level insight into the carburization process of iron-based catalysts: A ReaxFF molecular dynamics study

Transition metal carbide catalysts have garnered widespread attention due to their outstanding catalytic performance. The carbide catalysts, such as FexC and MoxC are typically obtained from their oxide carburization. The reduction and carburization processes are key steps during the activation of oxide precursors, which determine the activity and stability. An understanding of the carburization process mechanism is very important for the optimization of carbide catalysts. Iron-based catalysts are widely used in the large-scale coal-to-liquid industry because of their low price and high activity. In this paper, the carburization process of iron oxide nanoparticles was simulated by the Reactive force field (ReaxFF) molecular dynamics method. The results illustrate that the competition between CO dissociation and reduction of oxides occurs at the 100 ps time scale, which can be tuned by particle size and oxygen vacancy. We have explained the counter-intuitive finding that small oxide particles are more difficult to achieve fully carburization than larger ones; this is because rapid carbon accumulation on the surface blocks the oxygen diffusion channels from bulk to surface. The atomic distribution heat map was carried out to demonstrate the carbon and oxygen penetration processes. Meanwhile, the volumetric strain analysis reveals the driving force comes from the strong tendency to form Fe-C bonds. The dependence on surface orientation was further systematically investigated. This work provides microscopic insights into the carburization process of iron-based materials and the fundamental knowledge for the optimization of catalyst synthesis procedures.

Understanding Performance Limitation of Liquid Alkaline Water Electrolyzers

Green hydrogen production via water electrolysis powered by renewable energy is a critical technology in the pursuit of a net-zero emission economy1. Liquid alkaline water electrolyzers (LAWEs), being the most commercially mature electrolyzer technology, play a pivotal role in large-scale green hydrogen production2. The utilization of earth-abundant and cost-effective nickel and iron-based materials as cell components of LAWEs reduces capital cost of large-scale electrolyzer cells3. However, LAWEs suffer from low operational efficiency, primarily due to low intrinsic activity of unoptimized electrode materials, as well as high ohmic resistance introduced by separators and gas bubbles within thick electrodes. Herein, we used a lab-scale LAWE cell in combination with various electrode configurations to gain a deeper understanding of the limiting factors affecting conventional LAWE performance. Our results show that the electrochemical active surface area (ECSA), chemical compositions, and pore structure of the electrodes are key design parameters to achieve high efficiencies for advanced LAWEs. Besides, particular attention should be paid to the micro-gaps in between electrode and separator, which can be minimized through using electrodes with lower surface porosity and smaller pore size. Consequently, these enabled us to build LAWEs that are capable of sustaining 2 A cm-2 at 2.2 V and operating steadily at 1 A cm-2 for nearly 600 h with negligible performance decay. These findings establish essential criteria for selecting electrodes to achieve high-performance in LAWE and, in turn, expedite the adoption of LAWE technology in green hydrogen production and the transition towards a low-carbon economy. Acknowledgement The authors acknowledge the Department of Energy-Office of Energy Efficiency and Renewable Energy-Hydrogen and Fuel Cell Technologies Office (DOE-EERE-HFTO) and the H2 from Next-generation Electrolyzers of Water (H2NEW) consortium for funding under Contact Number DE-AC02-05CH11231.

Development of Iron-Based Single Atom Materials for General and Efficient Synthesis of Amines.

Earth abundant metal-based heterogeneous catalysts with highly active and at the same time stable isolated metal sites constitute a key factor for the advancement of sustainable and cost-effective chemical synthesis. In particular, the development of more practical, and durable iron-based materials is of central interest for organic synthesis, especially for the preparation of chemical products related to life science applications. Here, we report the preparation of Fe-single atom catalysts (Fe-SACs) entrapped in N-doped mesoporous carbon support with unprecedented potential in the preparation of different kinds of amines, which represent privileged class of organic compounds and find increasing application in daily life. The optimal Fe-SACs allow for the reductive amination of a broad range of aldehydes and ketones with ammonia and amines to produce diverse primary, secondary, and tertiary amines including N-methylated products as well as drugs, agrochemicals, and other biomolecules (amino acid esters and amides) utilizing green hydrogen.