Oxidation Research Articles

Dry‐Solid‐Electrochemical Synthesis: A General Method for Large Scale Synthesis of Single‐Atom Catalysts with High Metal loadings

AbstractSingle‐atom catalysts (SACs) with high metal loadings are highly desirable but still challenging for large scale synthesis. Here we report a new technique named as dry‐solid‐electrochemical synthesis (DSES) for a general large‐scale synthesis of SACs with high metal loadings in an energy‐conservation and environment‐friendly way. With it, a series of pure carbon‐supported metal SACs (Platinum up to 35.0 wt %, Iridium 21.2 wt %, Ruthenium 20.4 wt % and Iron 17.6 wt %) with high metal loadings were obtained. Particularly, a Pt SAC with Pt 23.9 wt % and remarkable oxygen reduction reaction (ORR) performance in fuel cells is synthesized on kilogram scale. Based on multiple control experiments, a unique redox mechanism for DSES process is proposed: metal precursors on conductive supports are reduced to metals via a homolytic cleavage of metal‐halogen bonds by the attacking of electrons flowing through the dry solid phase. Such versatile technique paves a new economical and environment‐friendly pathway for fabricating high‐metal‐loading SACs or atomic dispersion catalysts.

Integrated metabolomic and transcriptomic strategies to reveal adaptive mechanisms in barley plant during germination stage under waterlogging stress.

Barley (Hordeum vulgare L.) is an important cereal crop used in animal feed, beer brewing, and food production. Waterlogging stress is one of the prominent abiotic stresses that has a significant impact on the yield and quality of barley. Seed germination plays a critical role in the establishment of seedlings and is significantly impacted by the presence of waterlogging stress. However, there is a limited understanding of the regulatory mechanisms of gene expression and metabolic processes in barley during the germination stage under waterlogging stress. This study aimed to investigate the metabolome and transcriptome responses in germinating barley seeds under waterlogging stress. The findings of the study revealed that waterlogging stress sharply decreased seed germination rate and seedling growth. The tolerant genotype (LLZDM) exhibited higher levels of antioxidase activities and lower malondialdehyde (MDA) content in comparison to the sensitive genotype (NN). In addition, waterlogging induced 86 and 85 differentially expressed metabolites (DEMs) in LLZDM and NN, respectively. Concurrently, transcriptome analysis identified 1776 and 839 differentially expressed genes (DEGs) in LLZDM and NN, respectively. Notably, the expression of genes associated with redox reactions, hormone regulation, and other biological processes were altered in response to waterlogging stress. Furthermore, the integrated transcriptomic and metabolomic analyses revealed that the DEGs and DEMsimplicated in mitigating waterlogging stress primarily pertained to the regulation of pyruvate metabolism and flavonoid biosynthesis. Moreover, waterlogging might promote flavonoid biosynthesis by regulating 15 flavonoid-related genes and 10 metabolites. The present research provides deeper insights into the overall understanding of waterlogging-tolerant mechanisms in barley during the germination process.

Rational Design Strategy of Multicomponent Si/FeSeOx@N‐Doped Graphitic Carbon Hybrid Microspheres Intertwined with N‐Doped Carbon Nanotubes as Anodes for Ultra‐Stable Lithium‐Ion Batteries

Herein, an efficient synthesis approach is introduced for the fabrication of a hybrid anode consisting of porous microspheres with biphasic silicon (Si)‐amorphous iron selenite (Si/FeSeOx) nanocrystals enveloped within an N‐doped graphitic carbon (NGC) matrix and encased by well‐grown, highly intertwined N‐doped carbon nanotubes (CNTs) (Si/FeSeOx@NGC/N‐CNT). Si and FeSeOx serve as the active components, contributing to the overall discharge capacity of the hybrid anode. Additionally, FeSeOx not only enhances the structural integrity of the nanostructure by channelizing the drastic volume variation of Si, but also expedites the diffusion of lithium ions, thereby promoting kinetically favored redox reactions. The NGC matrix serves as the primary pathway for efficient electron transfer within the electrode, whereas the well‐grown N‐CNTs network acts as a secondary pathway for subsequent electron transfer to the current collector. The porous structure achieved via selective removal of amorphous carbon ensures the smooth diffusion of charged species by shortening the effective charge diffusion length and accommodating the substantial volume changes during cycling. Correspondingly, the Si/FeSeOx@NGC/N‐CNT anodes demonstrate significant enhancements in electrochemical performance, including one‐order higher diffusion coefficients (≈10−12 cm2 s−1), exceptional rate capability (till 30 A g−1), and extraordinary cycling stability at 0.5, 1.0, and 3.0 A g−1.

Unveiling mechanistic insight into boosting oxygen species activation over CeO2/Mn2O3 p-n heterojunction for efficient photothermal mineralization of toluene.

The activation mechanism of oxygen species activation (including lattice oxygen and gaseous oxygen) in the photothermal catalytic reaction process is important for boosting the efficient removal of VOCs. Herein, we have successfully synthesized a p-n heterojunction photothermal catalyst CeO2/Mn2O3 for exploring the activation of molecular oxygen and lattice oxygen in toluene catalytic reaction under full spectrum conditions. Various characterization tests and theoretical calculations showed that the formed composite has enhanced light absorption ability, oxygen species migration and transformation ability as well as nice redox cycles, which is conducive to the fast replenishment of surface lattice oxygen and continuous capture and activation of molecular oxygen. Meanwhile, the results of in-situ DRIFTS tests not only confirmed the enhanced activation process of surface lattice oxygen and molecular oxygen under the synergistic effect of light and heat, but also revealed the pathway and mechanism of photothermal catalytic toluene over CeO2/Mn2O3.

Persistent Metabolic Changes Are Induced by 24 h Low-Dose Lead (Pb) Exposure in Zebrafish Embryos

Lead (Pb) is a heavy metal associated with a range of toxic effects. Relatively few studies attempt to understand the impact of lead on development from a mechanistic perspective. Danio rerio (zebrafish) embryos are a model organism for studying the developmental consequences of exposure to chemical agents. This study examined the metabolome of developing zebrafish embryos exposed to 5 ppb, 15 ppb, 150 ppb, and 1500 ppb Pb concentrations during the first 24 h post fertilization, followed by 24 h of unexposed development and harvest at 48 h. Untargeted metabolomics and multivariate analysis revealed that various Pb exposures differentially affected the embryonic metabolome. Pathway analyses showed the dysregulation of biopterin, purine, alanine, and aspartate metabolism. Inductively coupled plasma mass spectrometry demonstrated Pb accumulation in embryos. Additionally, decreases in oxidation–reduction ratios were observed in 5–150 ppb groups but not in the 1500 ppb exposure group. This finding, along with several metabolite abundances, suggests a hormetic effect of Pb concentrations on the developing zebrafish metabolome. Together, these data reveal persistent global changes in the embryonic metabolome, pin-point biomarkers for Pb exposure, unveil dose-dependent relationships, and reflect Pb-induced changes in cellular energy. This work highlights aberrant processes and persistent changes underlying low-dose heavy metal exposure during early development.

Highly efficient bifunctional zeolitic imidazolate framework-derived carbon-supported platinum-based nanocatalysts for enhancing methanol oxidation reaction and oxygen reduction reaction

Highly efficient bifunctional zeolitic imidazolate framework-derived carbon-supported platinum-based nanocatalysts for enhancing methanol oxidation reaction and oxygen reduction reaction

Inhibitors of NADH-O-methylquinone compound a class of antitubercular drugs.

Disruption of the mycobacterial redox homeostasis leads to irreversible stress induction and cell death. Hydroquinone scaffolds, as a new type of redox cycling anti-tuberculosis chemotypes, exhibit potent bactericidal activity against non-replicating, nutrient-deprived phenotypically drug-resistant bacteria. Evidences from microbiological, biochemical, and genetic studies indicate that the redox-driven mode of action relies on the reduction of quinones by type II NADH dehydrogenase (NDH2), generating reactive oxygen species (ROS) of bactericidal level. This study demonstrates that (S)-Peniphenone D possesses significant resistance to Mycobacterium marinum (M. marinum) infection, as it enables redox cycling within M. marinum cells, ROS production, and reduction of intracellular NADH levels. The results suggest that hydroquinone compounds, due to their distinctive biological activities, could serve as novel sources for antibacterial drugs, particularly in developing scaffolds for new anti-tuberculosis agents.

Modelling H2S induced catalyst contamination in polymer electrolyte fuel cells: performance degradation and regeneration with ozone

ABSTRACT Under steady-state isothermal conditions, a numerical simulation has been conducted to predict the performance of a Polymer Electrolyte Fuel Cell in the presence of 100 ppm of H2S along anode stream. The simulated polarisation curves are in good agreement with the experimental results. The simulated results are presented as distribution contours, illustrating liquid water activity, membrane water content, reaction heat, and current density. The contours were captured at a voltage of 0.65 V and are illustrated in the cathode catalyst layer interface. The simulated results indicate that the H2S contaminants block active catalyst sites, hindering ion passage and preventing the Oxygen Reduction Reaction and leads to membrane dehydration. Additionally, the reaction rate slows down due to catalyst poisoning affecting proton conductivity, membrane water content, and current density distribution. A theoretical investigation using DFT was conducted to understand the atomic-level interaction of the PGM catalyst with H2S contaminant, assessing the poisoning effect and reaction mechanisms involved in catalyst degradation. Pt-Sads gets strongly adsorbed on the Pt catalyst layer by a value of −6.05 eV resulting in performance degradation. Furthermore, the DFT analysis of the O3 cleaning of the contaminated catalyst reveals that SO2 is most likely released during the process

One‐Pot Synthesis of Fully Conjugated Covalent Organic Frameworks via the Pictet–Spengler Reaction for Boosting H2O2 Photogeneration in Real Seawater

AbstractPhotosynthesizing H2O2 from real seawater is a promising and green avenue but suffers from salt‐deactivated effects with limitations on stability and photocatalytic activity. Herein, by the Pictet–Spengler reaction, two fully conjugated thieno[3,2‐c]pyridine‐linked covalent organic frameworks (named TBA‐COF and TCA‐COF) are synthesized for seawater H2O2 photoproduction for the first time. Without sacrificial agents in real seawater and O2, TBA‐COF and TCA‐COF exhibit impressive H2O2 generation rates of 8878 and 6023 µmol g−1 h−1 with the solar‐to‐chemical conversion efficiency of 0.62% and 0.42%, respectively, superior to their Schiff base analogs. Further experimental and theoretical investigations reveal that, compared to the imine‐linkage counterparts, in one‐pot cyclized TBA‐COF and TCA‐COF, the Pictet–Spengler reaction improves their charge carrier separation efficiency, alters the photoreduction center from the triazine and benzene parts to the pyridine units, modulates the energy band structures to drive the H2O2 photoproduction by 2e− oxygen reduction reaction and 2e− water oxidation reaction, and thereby enhances the H2O2 photosynthetic activity. Notably, seawater‐produced H2O2 by flow reactors packed with TBA‐COF can be directly utilized for E. coli sterilization. The present study highlights the one‐pot construction of robust COFs with thieno[3,2‐c]pyridine linkage via the Pictet–Spengler reaction and sustainable producing H2O2 from seawater.

Mechanoredox‐Catalyzed Organic Synthesis with Piezoelectric Materials: Quo Vadis?

AbstractPiezoelectric materials offer great promise due to their ability to generate electric fields under mechanical stress, producing surface charges that drive otherwise kinetically sluggish redox reactions. The strained surfaces of these materials provide a unique advantage in controlling product selectivity and enabling reaction pathways that are unattainable with conventional methods. This perspective highlights advancements, challenges, and the future potential of piezoelectric materials in synthetic organic chemistry, with a focus on designing materials optimized for piezocatalyzed organic synthesis. Piezocatalysis is industrially relevant because of its operational simplicity, enabling mild, gram scale synthesis with reusable catalysts, minimal solvent use, and air tolerant conditions. It involves redox cycles that facilitate one electron redox events without requiring light exposure or electrical bias. Despite significant progress, many fundamental aspects are yet to be fully understood. One example is the correlation between piezoelectricity and catalytic activity, which is not always linear, as demonstrated by the comparison between tetragonal and cubic BaTiO₃. While cubic BaTiO₃ is not piezoelectric, it shows excellent catalytic activity in certain redox reactions such as arylation, dicarbonylation, and cyclization under mechanochemical conditions comparable to that of piezoelectric tetragonal BaTiO₃. Considering all these aspects, this perspective aims to stimulate discussion to advance this promising field in the right direction.

Operando Synchrotron X-Ray Absorption Spectroscopy: A Key Tool for Cathode Material Studies in Next-Generation Batteries.

Rechargeable batteries are central to modern energy storage systems, from portable electronics to electric vehicles. The cathode material, a critical component, largely dictates a battery's energy density, capacity, and overall performance. This review focuses on the application of operando X-ray absorption spectroscopy (XAS) to study cathode materials in Li-ion, Na-ion, Li-S, and Na-S batteries. Operando XAS provides real-time insights into the local electronic structure, oxidation states, and coordination environments, which are crucial for understanding complex electrochemical processes, such as redox reactions, phase transitions, and structural degradation. The review highlights the strengths of hard and soft XAS techniques in probing transition metal (TM) and anionic redox processes, particularly in layered oxide cathodes, where reversible oxygen redox and TM behavior are pivotal. The role of operando XAS is also explored in analyzing conversion-type S-based cathodes, where it helps unravel the intricate reaction mechanisms. Furthermore, the review addresses the challenges of in situ cell design for operando XAS, especially under ultrahigh vacuum conditions for soft XAS. By discussing recent advancements and future directions, this review underscores the critical role of operando XAS in driving innovation and improving the design and performance of next-generation battery technologies.

Frankfurters Manufactured with Valorized Grape Pomace as a Substitute of Nitrifying Salts

This study investigated the use of grape/wine pomace as a potential substitute for nitrifying salts in the production and preservation of frankfurters. Red wine pomace (RWP) from Tempranillo and white wine pomace (WWP) from Cayetana grapes were added to frankfurters made with Iberian pig backfat—an underutilized fat rich in oleic acid—at two levels (0.5% and 3% w/w). These new formulations were compared with a control (containing only meat, salt, and spices) and a commercial formulation containing nitrites and ascorbic acid. Analyses were conducted immediately after production and following 45 days of refrigerated storage to evaluate microbiological, color, physicochemical, and textural changes in the frankfurters. The addition of pomace slightly reduced the pH of the frankfurters but did not affect microbial counts during the manufacturing process. Frankfurters with pomace displayed a similar color to the control but showed lower redness compared to the commercial formulation with nitrites. Importantly, pomace reduced lipid and protein oxidation during production and storage. The reduction in lipid oxidation due to the pomace was comparable to the effect of nitrites and ascorbic acid. Furthermore, pomace effectively reduced protein oxidation, unlike nitrites and ascorbic acid, which primarily targeted lipid oxidation. Significant differences in texture were observed between commercial frankfurters and those containing pomace. Despite these variations in the appearance and the texture, the strong protective effect of pomace against oxidative reactions highlights its potential as a natural alternative to synthetic additives, offering a promising solution for the meat industry.

Unraveling nitrogen metabolism, cold and stress adaptation in polar Bosea sp. PAMC26642 through comparative genome analysis

Nitrogen metabolism, related genes, and other stress-resistance genes are poorly understood in Bosea strain. To date, most of the research work in Bosea strains has been focused on thiosulfate oxidation and arsenic reduction. This work aimed to better understand and identify genomic features that enable thiosulfate-oxidizing lichen-associated Bosea sp. PAMC26642 from the Arctic region of Svalbard, Norway, to withstand harsh environments. Comparative genomic analysis was performed using various bioinformatics tools to compare Bosea sp. PAMC26642 with other strains of the same genus, emphasizing nitrogen metabolism and stress adaptability. During genomic analysis of Bosea sp. PAMC26642, assimilatory nitrogen metabolic pathway and its associated enzymes such as nitrate reductase, NAD(P)H-nitrite reductase, ferredoxin-nitrite reductase, glutamine synthetase, glutamine synthase, and glutamate dehydrogenase were identified. In addition, carbonic anhydrase, cyanate lyase, and nitronate monooxygenase were also identified. Furthermore, the strain demonstrated nitrate reduction at two different temperatures (15°C and 25°C). Enzymes associated with various stress adaptation pathways, including oxidative stress (superoxide dismutase, catalase, and thiol peroxidase), osmotic stress (OmpR), temperature stress (Csp and Hsp), and heavy metal resistance, were also identified. The average Nucleotide Identity (ANI) value is found to be below the threshold of 94-95%, indicating this bacterium might be a potential new species. This study is very helpful in determining the diversity of thiosulfate-oxidizing nitrate-reducing bacteria, as well as their ability to adapt to extreme environments. These bacteria can be used in the future for environmental, biotechnological, and agricultural purposes, particularly in processes involving sulfur and nitrogen transformation.

6,6′-{[Ethane-1,2-Diylbis(azaneylylidene)]bis(methaneylylidene)}bis[2-(4-Oxy(2,2,6,6-Tetramethylpiperidin-1-Oxyl)butyloxy)phenolato] Cobalt(II)

Salen-type complexes with transition metals and corresponding polymers attract great scientific interest due to their outstanding electrochemical properties and catalytic potential. Cobalt complexes of this kind are known as catalysts for a large variety of redox reactions, including oxygen reduction. Herein, we report the preparation of a modified cobalt Salen-type complex, modified by TEMPO pendants linked to the core by flexible butylenedioxy linkers. The resulting product was characterized by electrospray–high-resolution mass spectrometry and Fourier-transform infrared spectroscopy.

High Capacity and Ultralong Lifespan Aqueous Lithium-Bromine Batteries Realized by Low-Cost Concentrated Electrolyte Coupled with Dependable Lithium Titanium Phosphate.

Aqueous halogen batteries are gaining recognition for large-scale energy storage due to their high energy density, safety, environmental sustainability, and cost-effectiveness. However, the limited electrochemical stability window of aqueous electrolytes and the absence of desirable carbonaceous hosts that facilitate halogen redox reactions have hindered the advancement of halogen batteries. Here, a low-cost, high-concentration 26 m Li-B5-C15-O6 aqueous solution incorporating lithium bromide (LiBr), lithium chloride (LiCl), and lithium acetate (LiOAc) was developed for aqueous batteries, which demonstrated an expanded electrochemical stability window of ca. 2.5 V. In addition, the electrochemical performance of the electrolyte in various carbonaceous hosts (graphene, activated carbon, and nitrogen-doped activated carbon (NAc)) was systematically investigated. In-depth analysis using X-ray photoelectron spectroscopy and Raman spectroscopy revealed that the NAc host promoted the redox kinetics of active bromine species and improved the delivery capacity of the battery. Results revealed that the electrolyte in the NAc host achieved a discharge specific capacity exceeding 376 mA h g-1 while maintaining a capacity retention rate of up to 97% after 7800 cycles. When paired with hierarchically porous LTP@C/CNTs anode material, a LTP@C/CNTs-NAc full cell was constructed, which delivered a discharge specific capacity of 238.4 mA h g-1 and an average output voltage of 1.24 V. Moreover, it demonstrated a reversible specific capacity of 158.2 mA h g-1 with near-complete Coulombic efficiency over more than 10,000 cycles.

The Pseudomonas ligninolytic catalytic network reveals the importance of auxiliary enzymes in lignin biocatalysts

Lignin degradation by biocatalysts is a key strategy to develop a plant-based sustainable carbon economy and thus alleviate global climate change. This process involves synergy between ligninases and auxiliary enzymes. However, auxiliary enzymes within secretomes, which are composed of thousands of enzymes, remain enigmatic, although several ligninolytic enzymes have been well characterized. Moreover, it is a challenge to understand synergistic lignin degradation via a diverse array of enzymes, especially in bacterial systems. In this study, the coexpression network of the periplasmic proteome uncovers potential accessory enzymes for B-type dye-decolorizing peroxidases (DypBs) in Pseudomonas putida A514. The catalytic network of the DypBs-based multienzyme complex is characterized. DypBs couple with quinone reductases and nitroreductase to participate in quinone redox cycling. They work with superoxide dismutase to induce Fenton reaction for lignin oxidation. A synthetic enzyme cocktail (SEC), recruiting 15 enzymes, was consequently designed with four functions. It overcomes the limitation of lignin repolymerization, exhibiting a capacity comparable to that of the native periplasmic secretome. Importantly, we reveal the synergistic mechanism of a SEC-A514 cell system, which incorporates the advantages of in vitro enzyme catalysis and in vivo microbial catabolism. Chemical analysis shows that this system significantly reduces the molecular weight of lignin, substantially extends the degradation spectra for lignin functional groups, and efficiently metabolizes lignin derivatives. As a result, 25% of lignin is utilized, and its average molecular weight is reduced by 27%. Our study advances the knowledge of bacterial lignin-degrading multienzymes and provides a viable lignin degradation strategy.

A special two-working-electrode system: a summary of recent development in fabrication and application of interdigitated array electrodes.

The utilization of dual-working-electrode mode of interdigitated array (IDA) electrodes and other two-electrode systems has revolutionized electrochemical detection by enabling the simultaneous and independent detection of two species, accompanied by the exhibition of unique characteristics. In contrast to conventional dual-potential electrodes, such as the rotating ring disk electrodes (RRDE), IDA electrodes demonstrate analogous yet vastly improved performance, characterized by remarkable collection efficiency and sensitivity. Notably, due to the distinctive microscale structure of IDA electrode, the special "feedback" effect makes IDA a unique signal amplifier. In recent decades, the research surrounding IDA electrodes has garnered escalating interest due to their attractive attributes. This review centers its focus on the fabrication and applications of IDA electrodes. In fabrication, two critical breakthroughs are poised for realization: the achievement of reduced dimensions and the diversification of materials. Established fabrication methods for IDA electrodes encompass photolithography, inkjet printing, and direct laser writing, each affording distinct advantages in terms of size and precision in IDA construction. Predominantly employed materials for IDA electrodes include gold, platinum, and carbon, with the selection of fabrication methods guided by considerations such as material properties, desired dimensions, cost-efficiency, and specific application requisites. In terms of applications, IDA electrodes, capitalizing on their distinctive attributes, have found utility in diverse fields. This review summarizes the applications of IDA electrodes based on their fundamental working principles, encompassing redox cycling, resistance modulation, capacitance variations, and more. The potential for further development of this specialized tool to exhibit enhanced properties holds substantial promise.&#xD.

Rational Regulation of High-Entropy Perovskite Oxides through Hole Doping for Efficient Oxygen Electrocatalysis.

Due to the high configuration entropy, unique atomic arrangement, and electronic structures, high-entropy materials are being actively pursued as bifunctional catalysts for both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in rechargeable zinc-air batteries (ZABs). However, a relevant strategy to enhance the catalytic activity of high-entropy materials is still lacking. Herein, a hole doping strategy has been employed to enable the high-entropy perovskite La(Cr0.2Mn0.2Fe0.2Co0.2Ni0.2)O3 to effectively catalyze the ORR and OER. Hole doping experiments rely on the substitution of Sr2+ for La3+. The optimized La0.7Sr0.3(Cr0.2Mn0.2Fe0.2Co0.2Ni0.2)O3 displays remarkable activity for the ORR and the OER, with a low potential difference of 0.880 V between the half-wave potential of the ORR and the OER potential at 10 mA cm-2, exceeding the majority of perovskite bifunctional catalysts. Further analysis of the electronic structures reveals that hole doping could regulate the eg-orbital filling of the transition-metal cations in high-entropy perovskites to an ideal position and thereby generate many highly active sites to promote the redox activity of oxygen. The assembled rechargeable ZAB with the targeted high-entropy perovskite as the cathode affords a specific capacity of 774.5 mAh gZn-1 under 10 mA cm-2 and durability for a period of 300 cycles, comparable to that of the 20%Pt/C + RuO2 ZAB. This work offers an important approach for the advancement of efficient high-entropy perovskites for ZABs.

Intrinsic Mechanical Effects on the Activation of Carbon Catalysts.

The mechanical effects on carbon-based metal-free catalysts (C-MFCs) have rarely been explored, despite the global interest in C-MFCs as substitutes for noble metal catalysts. Stress is ubiquitous, whereas its dedicated study is severely restricted due to its frequent entanglement with other structural variables, such as dopants, defects, and interfaces in catalysis. Herein, we report a proof-of-concept study by establishing a platform to continuously apply strain to a highly oriented pyrolytic graphite (HOPG) lamina, simultaneously collecting electrochemical signals. Notably, we establish, for the first time, the correlation between the surface strain of graphitic carbon and its activation effect on the oxygen reduction reaction (ORR). Our results indicate that while in-plane and edge carbon sites in HOPG could not be further activated by applying tensile strain, a strong and repeatable dependence of catalytic activity on tensile strain was observed when the structure incorporated in-plane defects, leading to a significant ∼35.0% improvement in ORR current density with the application of ∼0.6% tensile strain. Density functional theory (DFT) simulations reveal that appropriate strain on specific defects can optimize the adsorption of reaction intermediates, and the Stone-Wales defect on graphene is correlated with the observed mechanical effect. This work elucidates fundamental principles of strain effects on the catalytic activity of graphitic carbon toward ORR and may lay the groundwork for the development of carbon-based mechano-electrocatalysis.

Modulating Electronic Spin State of Perovskite Fluoride by Ni─F─Mn Bond Activating the Dynamic Site of Oxygen Reduction Reaction.

Establishing the relationship between catalytic performance and material structure is crucial for developing design principles for highly active catalysts. Herein, a type of perovskite fluoride, NH4MnF3, which owns strong-field coordination including fluorine and ammonia, is in situ grown on carbon nanotubes (CNTs) and used as a model structure to study and improve the intrinsic catalytic activity through heteroatom doping strategies. This approach optimizes spin-dependent orbital interactions to alter the charge transfer between the catalyst and reactants. As a result, the oxygen reduction reaction (ORR) activity of NH4MnF3 on CNTs is significantly enhanced by partial substitution of Mn sites with Ni, such as a half-wave potential (E1/2) of 0.86V and a limiting current density of 5.26mA cm-2, which are comparable to those of the commercial Pt/C catalysts. Experimental and theoretical calculations reveal that the introduction of Ni promotes lattice distortion, adjusts the electronic states of the active Mn centers, facilitates the transition from low-spin to intermediate-spin states, and shifts the d-band center closer to the Fermi level. This study establishes a novel approach for designing high-performance perovskite-based fluoride electrocatalysts by modulating spin states.