Kinetics Of Reduction Research Articles

Nitrophenol Reduction with Silver Oxide Nanostructures as a Sustainable Approach to Environmental Remediation.

We propose silver oxide as a cost-effective and sustainable alternative to noble metals for the catalytic reduction of nitroaromatics. In the present investigation, we adopt a facile and green synthetic route for the synthesis of silver oxide nanostructures. The prepared nanostructures were found to crystallize in the cuprite phase and exhibit absorbance across the entire visible range of the electromagnetic spectrum. The catalytic potential of the silver oxide was evaluated by following the kinetics of nitrophenol reduction under ambient conditions and is observed to follow pseudo-first order kinetics with the apparent rate constant s-1 at minimum concentration of the catalyst. We attribute the observed catalytic activity to the freshly generated catalytic surface featuring a partially reduced form of silver oxide during reaction. The findings highlight the efficacy of silver oxide in mitigating the environmental pollution originating from the recalcitrant nitroarenes.

Transforming Cu into Cu2O/RuAl intermetallic heterojunction for lowering the thermodynamic energy barrier of the CO2 reduction and evolution reactions in Li-CO2 battery

The Li–CO2 battery has been under the spotlight of future battery technologies since it can achieve CO2 utilization and energy conversion simultaneously. However, its advancement is hampered by poor energy efficiency and limited reversibility due to the sluggish kinetics of the CO2 reduction and evolution reactions. Herein, a multiscale nanoporous interpenetrating‑phase nanohybrid of RuAl intermetallic and Cu2O (MP-Cu2O/RuAl) was carved by driving synchronous phase and microstructure evolutions through dealloying of one RuCuAl master alloy. The built-in RuAl intermetallic and Cu2O closely stack to form abundant nano-interfaces with revolutionized electronic structure. The theoretical simulations reveal that the Cu2O/RuAl interface can distinctly reduce the energy barrier of the Li2CO3 decomposition reaction. The interconnected pore channels with large surface area can enhance catalytic site accessibility, mass transfer, and uniform deposition of the discharge products. In situ differential electrochemical mass spectrometry discloses that the CO2-to-electron ratio during charging coincides with the theoretical value of 3/4, demonstrating the high efficacy of MP-Cu2O/RuAl in achieving the recycling of CO2. The dealloying protocol provides an affordable platform to empower transition metal oxides into high-efficiency electrocatalysts by hybridizing with metallic nano-sponge for advancing the application of Li–CO2 batteries.

A new highly active and CO2-stable heterostructure cathode material for solid oxide fuel cells developed from bismuth ion-modified cation-deficient Nd0.9BaCo2O5+δ

Efficient oxygen reduction kinetics as well as excellent stability are the main goals of current electrode materials for solid oxide fuel cells (SOFCs). Here, we present the latest findings regarding the augmentation of performance in SOFC through utilization of a novel heterogeneous cathode, consisting of an excess cation-deficient double perovskite Nd0.9BaCo2O5+δ (NBC90) backbone and in situ exsolved BaCo1-yBiyO3-x nanoparticles modified by bismuth (NBC90+B). The anisotropic growth of such self-assembled nanoparticles and the formation of multiple heterointerfaces exhibit an extremely strong activation effect. The in situ formed BaCo1-yBiyO3-x nanoparticles and cation-deficient NBC90 parental perovskite significantly enhance the catalytic activity and durability of the cathode toward oxygen reduction. The structural stability and CO2 tolerance of the cathode are greatly enhanced, which is attributed to the penetration of the high acidic Bi ions in the separated phase and the synergistic effect of the two-phase interface. The results unequivocally demonstrate the exceptional stability and efficiency of the NBC90+B composite as a promising cathode candidate for SOFCs.

General Method for Fitting Kinetics from the SECM Images of Reactive Sites on Flat Surfaces.

Scanning electrochemical microscopy (SECM) is a technique for imaging electrochemical reactions at a surface. The interaction between electrochemical reactions occurring at the sample and scanning electrode tip is quite complicated and requires computer modeling to obtain quantitative information from SECM images. Often, existing computer models must be modified, or a new model must be created from scratch to fit kinetic parameters for different reactive features. This work presents a method that can simulate the SECM image of a reactive feature of any shape on a flat surface which is coupled to a computer program which effectuates the automated fitting of kinetic information from these images. This fitting program is evaluated along with several methods for estimating the shapes of reactive features from their SECM images. Estimates of the reactive feature shape from SECM images were not sufficiently accurate and produced median relative errors for the surface rate constant that were >50%. Fortunately, more precise techniques for imaging the reactive features such as optical microscopy can supply sufficiently accurate shapes for the fitting procedure to produce accurate results. Fits of simulated SECM images using the actual shape from the simulation produced median relative errors for the surface rate constant that were <10% for the smallest reactive features tested. This method was applied to the SECM images of aluminum alloy AA7075 which revealed diffusion-limited kinetics for ferrocene methanol reduction over inclusions in the surface of the alloy.

FeMnO3/CNT as a synergistic bifunctional electrocatalyst for oxygen reduction and oxygen evolution reactions in alkaline medium

The development of highly effective and low-cost electrocatalysts for energy conversion and storage devices is triggered by the sluggish kinetics of oxygen reduction and evolution reactions. Perovskite-based oxides are identified as potential ORR and OER electrocatalysts in an alkaline medium. Thus, the present study discusses the synthesis and characterization of FeMnO3/CNT as a bifunctional catalyst with a low potential gap of 0.89 V. The FeMnO3/CNT composite was synthesized by the solution combustion method and characterized using spectroscopic and electron microscopic techniques. The increase in the ID/IG ratio obtained from the Raman spectra of the FeMnO3/CNT composite with respect to bare CNT indicates the functionalization of CNT. The ORR and OER characteristics of the FeMnO3/CNT composite were analyzed with rotating ring disc electrode and rotating disc electrode measurements. The LSV curve of the FeMnO3/CNT composite synthesized with 0.3g of CNT show better ORR and OER activity. The ORR activity measurements of the composite done in 0.1 M KOH electrolyte show a good onset potential of 0.95 V vs. RHE and a half-wave potential of 0.74 V. The HPRR studies show that the ORR reaction mechanism follows a 2e− + 2e− reduction pathway. The OER measurements in an alkaline medium show an onset potential of 1.63 V vs. RHE with a Tafel slope of 115.3 mV dec−1. Also, this work gives an insight into the fundamental understanding of the synergy between the perovskite and CNT, leading to an enhanced ORR and OER catalytic activity. In addition, the material exhibits good stability for ORR and OER stability studies.

TiO2 and Reducing Gas: Intricate Relationships to Direct Reduction of Iron Oxide Pellets

In response to the imperative for sustainable iron production with reduced CO2 emissions, this study delves into the intricate role of TiO2 in the direct reduction of iron oxide pellets. The TiO2-dependent reducibility of iron oxide pellets utilizing H2 and CO gas across varied temperatures and gas compositions is thoroughly investigated. Our findings unveil the nuanced nature of the TiO2 effect, underscored by its concentration-dependent behavior, revealing an optimal range between 1 and 1.5 pct TiO2, where a neutral or positive impact on reduction kinetics and diffusion coefficient is observed. Notably, the synergistic interplay of CO and H2 at 1000 °C emerges as particularly efficacious, suggesting complementary effects on the reduction process. The introduction of H2 into the reducing atmosphere regulated by CO not only extends the transition range but also markedly expedites the rate of reduction. Furthermore, our study highlights the temperature sensitivity of the TiO2 effect, with higher TiO2 content correlating with prolonged reduction time in a 100 pct H2 atmosphere at 900 °C. In a 100 pct H2 atmosphere, the non-contributory role of TiO2 stems from the water-gas shift reaction. Conversely, introducing H2 into a CO-controlled reducing atmosphere with TiO2 enhances the transition range and expedites the reduction rate. Additionally, our findings underscore the role of total iron content, revealing a direct correlation with the reduction process.

Kinetics of selenate reduction mediated by underpotentially deposited Cu on polycrystalline Au electrodes in aqueous perchloric acid

The reduction of selenate, SeO42−(aq),in 0.1 M HClO4 solutions, induced by underpotential deposition, UPD, of Cu on polycrystalline Au electrodes was investigated using the rotating ring-disk electrode, RRDE, technique. Design and implementation of electrode potential-rotation rate protocols made it possible to determine the rates of SeO42−(aq)reduction as a function of Cu coverage, θCu, as determined by the Bruckenstein method (Swathirajan et al. J. Phys. Chem.1982,86, 2480–2485). In agreement with the results reported recently for Au(111) film electrodes (Strobl et al. Electrochimica Acta2024,493, 144,298), the reaction was found to proceed only for θCu above a critical value, i.e. ca. 0.39, in this case, and the mechanism is consistent with an initial reversible formation of adsorbed Cu|SeO42−(ads),followed by its subsequent irreversible reduction, to yield a yet to be identified species denoted as Cu|Se(ads), as the rate determining step. Best fits of the kinetic model yielded values of the equilibrium constant for adduct formation, K, and first order rate constant for adduct reduction, kET, in the range (2.4 – 45) × 106 cm3 mol−1 and (0.55 – 30) × 10−3 s−1, respectively, which are close to those found for Au(111). This unique electrocatalytic effect has been attributed to a shift in the potential of zero charge of the bare substrate toward more negative values, induced by the metal UPD, which promotes the adsorption of the oxyanion at potentials more negative than those found for the bare substrate, making it possible to access overpotentials large enough for its further reduction to ensue.

Synergetic regulation of interfacial electronic structure of Cu, N co-doped carbon modified TiO2 for efficient photocatalytic CO2 reduction

TiO2 was a promising candidate material for CO2 photoreduction, but its development was greatly limited due to inherent defects such as high recombination rate of photogenerated charge carriers and limited number of active sites. In this study, a method involving chelation of metal ions with amino acids followed by high-temperature pyrolysis was employed to prepare Cu, N co-doped carbon-modified TiO2 composite materials, aiming to enhance the photocatalytic CO2 reduction performance of TiO2. The introduction of Cu, N co-doped carbon effectively improved the surface morphology of TiO2, increased the specific surface area and porosity, and enhanced the adsorption capacity of CO2. Simultaneously, the modification of TiO2 by Cu, N co-doped carbon optimized the electronic structure of catalysts, facilitating the separation and transfer of photogenerated electron-hole pairs, reducing charge carrier recombination, and thereby synergistically improving the thermodynamics and kinetics of CO2 reduction. Photocatalytic performance tests revealed that 10 % Cu-TiO2 exhibited the best CO2 reduction performance at a calcination temperature of 450 °C, with a CO production rate of up to 46 μmol·g−1·h−1, approximately 18 times that of pure TiO2. Density functional theory (DFT) calculations further confirmed that the introduction of Cu, N co-doped carbon reduced the Gibbs free energy of the CO2 reduction reaction, promoting the reaction. This study provides a simple, cost-effective strategy for developing efficient photocatalytic CO2 reduction materials.

Galvanostatic Electroshock Synthesis of Low Loading Au-Pt Nanoalloys onto Gas Diffusion Electrodes as Multifunctional Electrocatalysts for a Glycerol-Fed Electrolyzer.

Water electrolysis is increasingly considered a viable solution for meeting the world's growing energy demands and mitigating environmental issues. An inventive strategy to mitigate the energy requirements involves substituting the energy-intensive oxygen evolution reaction (OER) with biomass-derived glycerol electrooxidation. Nonetheless, the synthesis of electrocatalysts for controlling the selectivity towards added-value chemicals at the anode and efficient H2 generation at the cathode remains a critical bottleneck. Herein, we implemented a galvanostatic electroshock synthesis approach to control the reduction kinetics of Au(III) and Pt(IV) to grow ultra-low amount of gold-platinum alloys on a gas diffusion electrode (12-26 µgmetal cm‒2) for glycerol-fed hydroxide anion exchange membrane based electrolyzer. The symmetric GDE-Au100-xPtx||GDE-Au100-xPtx systems showed a notable improvement in electrolyzer performance (GDE-Au64Pt36 = 201 mA cm-2) as compared to monometallic versions (GDE-Au100Pt0 = 18 mA cm-2, GDE-Au0Pt100 = 81 mA cm-2). Chromatography (HPLC) analysis underscores the critical importance of bulk electrolysis methodology (galvanostatic vs potentiostatic) for the efficient conversion of glycerol into high-value-added products. Regarding the electrical energy required to produce 1 kg of H2 for such an electrolyzer fed at the anode with glycerol, our results confirm a drastic decrease by a factor of at least two compared with conventional water electrolysis.

Steering sulfur reduction kinetics of lithium-sulfur batteries by interfacial microenvironment modulation

Catalytic conversion of lithium polysulfides (LiPSs) is considered as an effective avenue to suppress the shuttle effect of lithium-sulfur (Li-S) batteries, for which the interfacial microenvironment constructed by the interaction between electrocatalysts and LiPSs plays a pivotal role in modulating the sulfur reduction kinetics. However, most of previous reports mainly focused on modulating the band structure of electrocatalysts or LiPSs alone to enhance the catalytic activity rather than considering the interfacial microenvironment as a whole. Herein, we propose a binary descriptor composed of the energy difference between d-band of electrocatalysts and p-band of LiPSs (ΔεM-S) and the antibonding filling degree (εABF), which capture the energy band contributions from both electrocatalysts and LiPSs, to reveal the influence of interfacial microenvironment on sulfur reduction kinetics. Among different designed electrocatalysts, NiO presents a moderate LiPSs anchoring capacity and rapid electron transfer kinetics owing to the optimal ΔεM-S and decreased εABF after interacting with LiPSs, which lead to a robust interfacial microenvironment and thus guarantee a continuous catalytic conversion of LiPSs in the long-term cycling. Such a fundamental understanding of catalytic activity toward LiPSs from the viewpoint of interfacial microenvironment provides an alternative avenue for designing highly efficient electrocatalysts for Li-S batteries.

Green Ironmaking at Higher H2 Pressure: Reduction Kinetics and Microstructure Formation During Hydrogen-Based Direct Reduction of Hematite Pellets

Hydrogen-based direct reduction (HyDR) of iron ores has attracted immense attention and is considered a forerunner technology for sustainable ironmaking. It has a high potential to mitigate CO2 emissions in the steel industry, which accounts today for ~ 8–10% of all global CO2 emissions. Direct reduction produces highly porous sponge iron via natural-gas-based or gasified-coal-based reducing agents that contain hydrogen and organic molecules. Commercial technologies usually operate at elevated pressure, e.g., the MIDREX process at 2 bar and the HyL/Energiron process at 6–8 bar. However, the impact of H2 pressure on reduction kinetics and microstructure evolution of hematite pellets during hydrogen-based direct reduction has not been well understood. Here, we present a study about the influence of H2 pressure on the reduction kinetics of hematite pellets with pure H2 at 700 °C at various pressures, i.e., 1, 10, and 100 bar under static gas exposure, and 1.3 and 50 bar under dynamic gas exposure. The microstructure of the reduced pellets was characterized by combining X-ray diffraction and scanning electron microscopy equipped with electron backscatter diffraction. The results provide new insights into the critical role of H2 pressure in the hydrogen-based direct reduction process and establish a direction for future furnace design and process optimization.Graphical

Catalytic effect of nickel oxide nanoparticles from Lupinus Albus extract on green synthesis and photocatalytic reduction of methylene blue: kinetics and mechanism

Green synthesis of nanomaterials is advancing due to their ease of synthesis, cheapness, nontoxicity, and renewability. An environmentally friendly biogenic method has been developed for the green synthesis of nickel oxide nanoparticles (NiO NPs) using phytochemical-rich bioextract. They are rich in bioextract phenolics, flavonoids, and berberine. These phytochemicals successfully reduce and stabilize NiNO3 into NiO NPs. In this study, NiO NPs were synthesized by the green synthesis method from Lupinus Albus. Characterization of NiO NPs was carried out by TEM, XRD, SEM, UV, XRF, BET, and EDX analyses. According to XRD analysis, TEM results also support this, where the NiO NPs particle size diameter is 5 nm. It was determined by the Tauc equation that the band energy gap of NiO NPs is 1.69 eV. It was determined that the BET surface area of NiO NPs was 49.6 m2/g. NiO nanoparticles synthesized from Lupinus Albus extract by the green synthesis method were used as catalysts in the photocatalytic reduction of methylene blue with NaBH4. In the photocatalytic reduction of methylene blue with NaBH4, it was determined that there was no color change in 48 h without a catalyst, and in the presence of NiO nanoparticle catalyst, methylene blue was reduced by 97% in 8 min. The kinetics of the photocatalytic reduction of methylene blue with NaBH4 is a pseudo-first-order kinetic model and the kinetic rate constant is determined as 0.66 min−1, indicating that the catalytic effect of NiO NPs is very high at this value. NiO NPs were used five times in the photocatalytic reduction of methylene blue with NaBH4 and it was determined that the reduction of methylene blue was over 90% in each use.

Highly oxygen reduction activity and CO2 resistance of Fe-based cathode electrocatalysts for solid oxide fuel cells

The insufficient electrocatalytic activity and CO2 resistance hinder the application of cathode material for solid oxide fuel cells (SOFCs). In this study, we introduce a series of Pr-doped perovskite Bi0.8–xPrxCa0.2FeO3–δ (BPCFx, x=0, 0.10, 0.15, 0.20) as candidate cathode materials, with a focus on its phase structure, oxygen desorption ability, catalytic activity, and electrochemical reduction kinetics. Among all the components, the Bi0.6Pr0.2Ca0.2FeO3–δ (BPCF0.20) catalyst shows impressive oxygen reduction reaction (ORR) activity, with a low polarization resistance of 0.06 Ω cm2 at 700 °C and peak power density of 810 mW cm−2 at 800 °C. Moreover, the BPCF0.20 cathode shows outstanding CO2 resistance in different CO2 concentrations (1%–10%) due to the larger average bond energy and higher relative acidity of Bi, Pr, and Fe ions. These findings demonstrate that BPCFx are advanced cathode electrocatalysts for SOFCs.

Simultaneous natural attenuation of Cr(VI) and nitrate in the hyporheic zone sediments from an upstream tributary of the Jinsha River in the Sichuan Basin

The coexistence of hexavalent chromium (Cr(VI)) and nitrate (NO3−) in groundwater and surface water presents a considerable challenge for the natural attenuation of these two contaminants because their interactions in nature remain contentious. This study investigated the interplay between Cr(VI) and NO3− in hyporheic zone (HZ) sediments by integrating Cr(VI) reduction kinetics, NO3− transformation, microbial community structure, and a three-rate model. The concurrent natural attenuation of Cr(VI) and NO3− in the sediments was significantly influenced by their initial concentrations and redox conditions. The reduction of low concentrations of Cr(VI) (37.1 and 96.2 μM) was slightly enhanced by NO3−, while inhibitory effects were observed at high concentrations of Cr(VI) (200.0 μM). However, except for an initial low concentration of Cr(VI) (37.1 μM) and NO3− (450 μM), the reduction of NO3− was adversely affected by Cr(VI). The reduction rates and efficiencies of Cr(VI) and NO3− were noticeably lower under aerobic conditions than under anaerobic conditions. This phenomenon can be attributed to the presence of O2, which decreased the selectivity of sediments-associated Fe(II) towards Cr(VI) and NO3− and induced alterations in the microbial community structure, leading to subsequent changes in NO3− transformation. Furthermore, the three-rate model represents a robust approach for elucidating the reduction of Cr(VI) in the presence of co-contaminants, such as NO3− contamination under diverse redox conditions. This study provides further insights into the interaction mechanism between Cr(VI) and NO3− within the HZ, necessitating the consideration of the microbial toxicity of Cr(VI) and electron competition among Cr(VI), NO3−, and O2.

Hydrogen Reduction Behavior and Microstructure Characteristics of WO3-NiO-CuO Powder Mixture

The characteristics and hydrogen reduction behavior of W-0.8 wt% Ni-0.4 wt% Cu powder synthesized from WO3-NiOCuO composite powder have been investigated. The metal oxide powder mixtures were prepared using a ball milling process. XRD analysis and HR-TEM revealed that the oxide powders are changed to W and CuNi alloy powders with an average particle size of about 100 nm by hydrogen reduction. To understand the reduction behavior of oxide powders, TG analysis was performed, and the reduction kinetics was evaluated by the amount of peak shift with heating rates. The activation energies for the reduction of WO3-NiO-CuO, estimated by the slope of the Kissinger plot, were measured as 60.6-114.4 kJ/mol depending on reduction steps.

Enhanced Photocatalytic Removal of U(VI) from Real Radioactive Wastewater by Modulating the Surface Charge Microenvironment in Porphyrin-Based Hydrogen-Bonded Organic Framework.

Reduction of soluble U(VI) to insoluble U(IV) based on photocatalysts is a simple, environmentally friendly, and efficient method for treating radioactive wastewater. The present study involved the systematic comparison of the photoelectric properties of three metalloporphyrins with different metal centers and the synthesis of a novel porphyrin-based hydrogen-bonded organic framework (Ni-pHOF) photocatalyst by modulating the surface charge microenvironment in porphyrin for enhanced photocatalytic removal of U(VI) from wastewater. Compared to the metal-free HOF, the surface charge microenvironment around the Ni atom in Ni-pHOF accelerated the reduction kinetics of U(VI) under visible light illumination at the initial moment, showing a high removal rate, even in air. The removal rate of U(VI) from aqueous solution by Ni-pHOF can achieve over 98% in the presence of coexisting nonoxidizing cations and only decreased by less than 8% after five cycles, exhibiting high selectivity and good reusability. Furthermore, Ni-pHOF can remove 86.74% of U(VI) from real low-level radioactive wastewater after 120 min of illumination, showcasing practical application potential. Density functional theory (DFT) calculations and electron paramagnetic resonance (EPR) spectra indicated that modulating the surface charge microenvironment in Ni-pHOF through porphyrin metallization is conducive to improving the charge separation efficiency, prompting more e- and •O2- to participate in the reduction reaction of U(VI). This work provides new insights into the metallization of porphyrin-based HOFs and paves a new way for the tailoring of porphyrin-based HOFs/COFs by modulating the surface charge microenvironment to achieve efficient recovery of U(VI) from real radioactive wastewater.

Dimensionally Intact Construction of Ultrathin S-Scheme CuFe2O4/ZnIn2S4 Heterojunctional Photocatalysts for CO2 Photoreduction.

The conversion of CO2 into carbon-neutral fuels such as methane (CH4) through selective photoreduction is highly sought after yet remains challenging due to the slow multistep proton-electron transfer processes and the formation of various C1 intermediates. This research highlights the cooperative interaction between Fe3+ and Cu2+ ions transitioning to Fe2+ and Cu+ ions, enhancing the photocatalytic conversion of CO2 to methane. We introduce an S-scheme heterojunction photocatalyst, CuFe2O4/ZnIn2S4, which demonstrates significant efficiency in CO2 methanation under light irradiation. The CuFe2O4/ZnIn2S4 heterojunction forms an internal electric field that aids in the mobility and separation of exciton carriers under a wide solar spectrum for exceptional photocatalytic performance. Remarkably, the optimal CuFe2O4/ZnIn2S4 heterojunction system achieved an approximately 68-time increase in CO2 conversion compared with ZnIn2S4 and CuFe2O4 nanoparticles using only pure water, with nearly complete CO selectivity and yields of CH4 and CO reaching 172.5 and 202.4 μmol g-1 h-1, respectively, via a 2-electron oxygen reduction reaction (ORR) process. The optimally designed CuFe2O4/ZnIn2S4 heterojunctional system achieved approximately 96% conversion of BA and 98.5% selectivity toward benzaldehyde (BAD). Additionally, this photocatalytic system demonstrated excellent cyclic stability and practical applicability. The photogenerated electrons in the CuFe2O4 conduction band enhance the reduction of Fe3+/Cu2+ to Fe2+/Cu+, creating a microenvironment conducive to CO2 reduction to CO and CH4. Simultaneously, the appearance of holes in the ZnIn2S4 valence band facilitates water oxidation to O2. The synergistic function within the CuFe2O4/ZnIn2S4 heterojunction plays a pivotal role in facilitating charge transfer, accelerating water oxidation, and thereby enhancing CO2 reduction kinetics. This study offers valuable insights and a strategic framework for designing efficient S-scheme heterojunctions aimed at achieving carbon neutrality through solar fuel production.

Multistep kinetic study of magnetite reduction by hydrogen based on thermogravimetric analysis

The utilization of hydrogen-based direct reduction methods for magnetite ore smelting is an important way to achieve the goal of reducing carbon emissions. At present, the coupling mechanism of the multi-step reaction during the reduction process is unclear, which restricts the understanding of the rate-limiting steps and the accurate description of kinetic parameters. In this paper, the reaction characteristics and multi-step kinetics of isothermal reduction of magnetite by hydrogen with varying concentrations are investigated at 600–900 °C. Results indicate that the coupling relationship between Fe3O4→FeO and FeO→Fe two steps is temperature-dependent. In the low-temperature range (600–700 °C), the coupling relationship between the two steps can be described by the parallel model. In the high-temperature range (750–900 °C), the coupling relationship can be described by the series model. Meanwhile, the first-step reaction Fe3O4→FeO is controlled by the nucleation or chemical reaction model, and the apparent activation energies are determined to range from 27.25 to 48.59 kJ/mol. The second-step reaction FeO→Fe is controlled by the combination of nucleation and diffusion models, and the apparent activation energies are determined to range from 30.70 to 45.14 kJ/mol.

Reconstructing Solvation Structure by Steric Hindrance‐Coordination Push‐Pull of Dipolymer‐H2O‐Zn2+ toward Long‐life Aqueous Zinc‐Metal Batteries

AbstractAqueous zinc‐metal batteries are prospective energy storge devices due to their intrinsically high safety and cost effectiveness. Yet, uneven deposition of zinc ions in electrochemical reduction and side reactions at the anode interface significantly hinder their development and application. Here, we propose a solvation‐interface attenuation strategy enabled by a frustrated tertiary amine amphiphilic dipolymer electrolyte additive. The configuration of superhydrophilic segments with covalently bonded lipophilic spacers enables coupled steric hindrance/coordination, which establishes a balanced push‐pull dynamic of dipolymer‐H2O‐Zn2+. Such interplay reconstructs the solvation structure of Zn2+ and allows the formation of a stable dipolymer‐inorganic hybrid solid electrolyte interface (SEI) layer. This SEI layer effectively shields the zinc‐metal anode from water and anions, significantly reducing side reactions. In addition, the dipolymer adsorbed at the zinc‐metal anode interface regulates the interfacial electrochemical reduction kinetics and ensures uniform zinc deposition. As a result, the Zn−Zn symmetric cells with dipolymer‐containing electrolyte exhibit remarkable cycling stability exceeding 5800 h (242 days). The Zn‐NVO batteries and Zn‐AC hybrid ion supercapacitors also deliver stable cycling for up to 1440 h (60 days) with high‐capacity retention over 80 %. This research demonstrates the potential to facilitate the development and commercialization of zinc‐based energy storage devices.

Reconstructing Solvation Structure by Steric Hindrance-Coordination Push-Pull of Dipolymer-H2O-Zn2+ toward Long-life Aqueous Zinc-Metal Batteries.

Aqueous zinc-metal batteries are prospective energy storge devices due to their intrinsically high safety and cost effectiveness. Yet, uneven deposition of zinc ions in electrochemical reduction and side reactions at the anode interface significantly hinder their development and application. Here, we propose a solvation-interface attenuation strategy enabled by a frustrated tertiary amine amphiphilic dipolymer electrolyte additive. The configuration of superhydrophilic segments with covalently bonded lipophilic spacers enables coupled steric hindrance/coordination, which establishes a balanced push-pull dynamic of dipolymer-H2O-Zn2+. Such interplay reconstructs the solvation structure of Zn2+ and allows the formation of a stable dipolymer-inorganic hybrid solid electrolyte interface (SEI) layer. This SEI layer effectively shields the zinc-metal anode from water and anions, significantly reducing side reactions. In addition, the dipolymer adsorbed at the zinc-metal anode interface regulates the interfacial electrochemical reduction kinetics and ensures uniform zinc deposition. As a result, the Zn-Zn symmetric cells with dipolymer-containing electrolyte exhibit remarkable cycling stability exceeding 5800 h (242 days). The Zn-NVO batteries and Zn-AC hybrid ion supercapacitors also deliver stable cycling for up to 1440 h (60 days) with high-capacity retention over 80%. This research demonstrates the potential to facilitate the development and commercialization of zinc-based energy storage devices.