Abstract Mitigating aviation’s carbon emissions remains challenging because air travel relies on energy-dense liquid fuels with limited substitutes. Here, we report a fermentation-based bioconversion process for producing isoprenol, a precursor to 1,4-dimethylcyclooctane (DMCO), a sustainable aviation fuel blendstock with Jet-A-comparable fuel properties and O-ring swelling behavior, which can substitute for aromatic additives and derived from lignocellulosic biomass at 25 °C. Ambient alkaline pretreatment achieved greater than 89% xylan deacetylation and 79–93% glucan digestibility across all feedstocks, without the formation of furan inhibitors. An engineered Escherichia coli strain directly fermented the unpurified biomass hydrolysate to isoprenol without requiring hydrolysate detoxification, demonstrating compatibility of the alkaline pretreatment stream with the fermentation step. The ambient pretreatment conditions produced no detectable furfural or HMF, enabling an isoprenol titer of 0.38 g/L (28 mg/g sugar consumed), comparable to pure sugar controls. This biochemical process is effective across corn stover, rice straw, and hemp hurd. This work establishes ambient alkaline pretreatment as a low-energy approach compatible with direct microbial isoprenol production across diverse feedstocks, providing a reduced-step route toward lignocellulose-derived sustainable aviation fuel.
Abstract Understanding the molecular structure of bio-oil is essential for improving upgrading strategies, predicting physicochemical properties, and designing efficient production pathways. This work introduces an integrated experimental-analytical-modeling framework that translates multimodal characterization data into large-scale, structure-resolved molecular representations of bio-oil. The approach combines elemental analysis, quantitative 13C NMR, GC-MS, FT-ICR MS/Orbitrap MS petroleomics, ESI(−)-MS molecular weight distribution, and bulk property measurements, including density and viscosity, to constrain the model composition and phase heterogeneity. A database of nonvolatile structures was generated using reactive molecular dynamics simulations and subsequently expanded through chemically consistent aging reactions, enabling broad coverage of experimentally observed molecular formulas. Two modeling strategies were evaluated: (i) treating the entire nonvolatile fraction as a single data set and (ii) using a subfraction-resolved formulation that incorporates the experimentally measured contributions of dehydrated sugars and pyrolytic lignin (dimer, trimers, tetramers, humins). Both approaches reproduced independent experimental constraints, including elemental composition, functional-group and molecular weight distributions, with errors below 10%. The resulting molecular ensembles captured key features of bio-oil behavior, including multiphase organization, micelle aggregation, and the role of hydrogen bonding in structural evolution. Additional validation through predicted 1H NMR and HSQC-NMR spectra showed strong agreement with experimentally observed chemical-shift regions, supporting the fidelity of the reconstructed molecular ensembles. This framework provides a chemically consistent pathway for resolving bio-oil complexity and generating predictive atomistic representations for downstream simulation and process-design applications.
Abstract Smoldering, as an emerging technology, exhibits significant potential for the efficient disposal of organic solid waste with high moisture content; however, theoretical models targeting multi-source blended fuels remain scarce. This work systematically investigates the smoldering characteristics and kinetic behaviors of municipal sludge (MS) and electroplating sludge (ES) under different airflow rates. The aim is to provide theoretical insights and model support for applying smoldering technology to various sludge feedstocks. An experimental smoldering reactor was constructed to examine the smoldering of both individual and blended sludges. Kinetic parameters were extracted using the smoldering isothermal fitting method (SIFM), and the activation energy asymptotic (AEA) simplified model was employed to predict and validate the smoldering temperatures of different sludges. The results demonstrate that MS and ES can achieve stable smoldering at specific blending ratios, thereby facilitating the synergistic co-disposal of multi-source sludges. As the MS proportion increases, the smoldering temperature rises and propagation stability is enhanced. Kinetic analysis reveals that the activation energy of blended sludge decreases with increasing MS content. When these parameters are input into the AEA model, the predicted results show good agreement with experimental data, with minor deviations under certain airflow conditions. Overall, the smoldering kinetic parameters obtained via SIFM are more suitable for the AEA model than those from non-isothermal thermogravimetric analysis (TGA), with deviations within ±6%. This agreement validates the model’s applicability to smoldering processes of different sludge types.
Abstract To address the bottlenecks of poor electrical conductivity in transition metal layered double hydroxides (LDHs) and the susceptibility of transition metal sulfides to structural degradation at high oxidation potentials, this work proposes an interface engineering and multi-component synergistic strategy. Through a two-step hydrothermal-sulfidation process a Co9S8/Ni3S2@NiFe-LDH composite electrocatalyst with a hierarchical “nanorod-nanoflower” heterostructure was successfully constructed. Experimental and characterization results indicate that this three-dimensional core–shell structure not only significantly increases the electrochemically active surface area but also induces strong interfacial electronic coupling that lowers the reaction energy barrier, accelerating charge transfer and reaction kinetics. Electrochemical measurements demonstrate that in a 1.0 M KOH electrolyte, the catalyst requires an overpotential of only 96 mV for the hydrogen evolution reaction (HER) with a Tafel slope of 88.77 mV dec–1 at a current density of 10 mA cm–2; for the oxygen evolution reaction (OER), the overpotential is 174 mV with a Tafel slope of 44.96 mV dec–1. In an alkaline seawater medium, the catalyst maintains excellent bifunctional activity, delivering HER and OER overpotentials of 108.5 mV and 153.5 mV, respectively, exhibiting good tolerance to ionic interference and structural stability. Overall water splitting tests reveal that the cell voltages required to achieve a current density of 10 mA cm–2 in alkaline and seawater systems are only 1.39 and 1.43 V, respectively, and the operating voltage remains highly stable during a 50 h durability test.
Abstract Silicon quantum dots (SiQDs) with an ultrasmall size and high specific surface area exhibit great application in enhanced oil recovery, especially in foam flooding. In this study, a series of amphiphilic silicon quantum dots (C3SPX-n) with tunable surface modification degrees were synthesized by using polyethylene glycol (PEG) and propyltrimethoxysilane (PTMS) as functional modifiers to enhance the foam stability of the nonionic surfactant PMIE. The chemical structure, surface composition, thermal stability, particle size distribution, and morphology of C3SPX-n were systematically characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), dynamic light scattering (DLS), and transmission electron microscopy (TEM). Foam volume, foam half-life, film drainage half-life, Turbiscan Lab analysis, and microscopic foam morphology demonstrated that C3SP400-1.0 could more effectively enhance the stabilization of PMIE foam, even at a reduced surfactant concentration. Dynamic surface tension, wettability, and interfacial dilatational modulus measurements revealed that the 0.1% PMIE + C3SP400-1.0 system possessed superior interfacial adsorption behavior, improved surface viscoelasticity, and enhanced liquid film strength. The C3SP400-1.0-reinforced PMIE foam exhibited excellent tolerance under harsh reservoir conditions and efficiently increased crude oil recovery by 21.41% in sandpack flooding experiments. This work provides a new strategy for developing low-concentration, high-stability foam flooding systems and offers valuable guidance for achieving efficient water control and oil production enhancement.
Abstract High-temperature (>100 °C) operation of proton exchange membrane fuel cells simplifies water and thermal management, accelerates electrode kinetics, and improves impurity tolerance. However, the degradation mechanism of the membrane electrode assembly (MEA) under such conditions remains unclear. Here, a high-temperature-resistant MEA based on a phosphoric–sulfonic acid copolymer membrane is investigated through an accelerated stress test at 105 °C for 50 h. The initiation and propagation of crack networks within the cathode catalyst layer are identified as a critical bottleneck in performance degradation. Mass transport loss is the most pronounced degradation mode. This loss arises from crack formation, ionomer degradation, and carbon corrosion. The MEA exhibits a voltage decay of 35.23% at 2 A cm–2 and an electrochemical surface area loss of 62.9%. Chemically, cracks initiate from the transformation of disordered carbon into ordered carbon in the carbon support (ID/IG decreasing from 1.1268 to 0.4735) and the detachment of sulfonic acid side chains from the ionomer (I1060/I1210 decreasing from 0.483 to 0.133). Physically, Ostwald ripening of platinum particles (mean size increasing from 3.48 to 4.29 nm) and stress concentration induced by temperature and humidity cycling drive crack growth. Finite-element simulations using a cohesive zone model reveal that cracks propagate steadily along the ionomer/catalyst interface─the path of least energy dissipation. This study establishes a direct link from microstructural evolution to macroscopic performance degradation. Crack network formation is highlighted as a key bottleneck. These findings provide guidance for material design and lifetime prediction of high-temperature-resistant MEAs.
Abstract Converting CO2 into value-added carbon nanomaterials offers a compelling strategy for long-term carbon sequestration by generating commercially valuable products. Here, we demonstrate tandem plasma–thermocatalytic reactors for the coconversion of CO2 and C2H6 into carbon nanotubes (CNTs) and carbon nanofibers (CNFs). A dielectric barrier discharge plasma reactor activates a C2H6/CO2 feed mixture, generating reactive intermediates that serve as precursors for downstream thermocatalytic production of CNT over Co/Al2O3 at 750 °C and CNF over Co12K5/CeO2 at 450 °C. Systematic variation of plasma power and thermocatalytic reactor zone length reveals that these parameters strongly influence reactant conversion, product distribution, and carbon weight gain, enabling independent optimization of the plasma activation and thermocatalytic carbon growth. The tandem configuration enables CNT and CNF synthesis at lower temperatures than conventional chemical vapor deposition processes. An energy and CO2 footprint analysis demonstrates that, when powered by renewable electricity, the plasma–thermocatalytic system offers a modular, electrified pathway for carbon-negative sequestration. These results establish tandem plasma–thermocatalytic reactors as a flexible platform for reacting CO2 with light alkanes to produce carbon nanomaterials.
Abstract The sodium storage performance of hard carbon anodes is dependent on the precise modulation of their closed-pore architecture and surface chemistry. Herein, we propose a synergistic cross-linking strategy to synthesize nitrogen-doped hard carbon enriched with uniform closed-pore structure using polyvinyl chloride (PVC) and cellulose. During the solvothermal stage, urea not only serves as a nitrogen source but also facilitates the construction of a cross-linking network alongside ZnCl2-catalyzed dechlorination and depolymerization. Upon carbonization, the robust framework confines the in situ pore formation to a nanoscale domain with average diameter of ∼1.26 nm and preserves an expanded interlayer spacing of 0.401 nm. The optimized PZNC anode delivers a high reversible capacity of 359 mAh g–1 at 0.2 C and excellent cycling stability for 99% retention after 400 cycles at 1 C, maintaining 209 mAh g–1 after 1200 cycles at 5 C. The expanded interlayer spacing reduces Na+ diffusion resistance and the closed-pore structure enhance the low-voltage plateau capacity, enabling an efficient three-stage Na+ storage mechanism. This work provides a new pathway for designing advanced hard carbon anodes through integrating precise closed-pore engineering with chemical doping.
Abstract To meet the stringent durability requirements of proton exchange membrane fuel cells (PEMFCs) for heavy-duty applications, sealing reliability must be evaluated beyond the initial assembly state and linked to the long-term evolution of interfacial contact and gas-loss behavior. This mini-review focuses on gasket–MEA frame sealing interfaces in PEMFCs, with particular emphasis on flexible–flexible contact. It systematically examines recent progress in multiscale geometric characterization and reconstruction, constitutive and contact evolution under assembly and service loads, the competition between interfacial leakage and bulk material permeation, and the development of predictive modeling strategies from deterministic simulations to uncertainty-aware and data-assisted frameworks. The review highlights power spectral density (PSD)- and fractal-based surface reconstruction methods, discusses visco-hyperelastic and chemo-thermo-mechanical descriptions relevant to elastomer aging and contact-pressure retention, and clarifies that gas-loss behavior depends on a service-dependent transition between pressure-driven interfacial leakage and temperature-sensitive bulk permeation. It further summarizes multiscale transport modeling approaches involving slip-flow and Knudsen-scale effects, as well as recent advances in fluid–structure interaction, stochastic tolerance analysis, and surrogate-assisted prediction. Finally, the review outlines key future needs in lifecycle-oriented interface modeling, in situ experimental validation, benchmark data sets, and the integration of physics-informed machine learning with multiscale leakage prediction for health-state assessment and predictive maintenance of PEMFC stacks.
Abstract A pentafluorophenyl- and thiophene-functionalized imine compound, pentafluorophenyl thiophene imine (FPTI), was investigated as an electrolyte additive in graphite/Li half-cells to enhance interfacial stability and electrochemical performance. The incorporation of FPTI facilitates the formation of a robust solid electrolyte interphase (SEI), characterized by reduced activation energy, lower charge-transfer resistance, and enhanced lithium-ion diffusion kinetics. As a result, the FPTI-containing cells exhibit a high-capacity retention of 95.6% at 0.5 C. Differential voltage and differential capacity analyses provide mechanistic insights into capacity fading, highlighting the suppression of parasitic side reactions in anodic half-cells. X-ray photoelectron spectroscopy (XPS) confirms the presence of sulfur- and imine-derived species within the SEI, indicating the active participation of FPTI in interphase formation. Furthermore, full-cell evaluation demonstrates an energy density of 233 Wh kg–1 at an optimal additive concentration of 4 mg mL–1.
Abstract Direct air capture (DAC) using amine-functionalized solid sorbents has emerged as a promising strategy for mitigating atmospheric CO2 emissions; however, the coupled influences of polymer architecture, hydration, and mesopore confinement on molecular adsorption and transport remain poorly understood. In this study, a multiscale computational framework combining density functional theory (DFT) and long-time scale molecular dynamics (MD) simulations was employed to investigate hyperbranched poly(ethylenimine) (HB-PEI)- and hyperbranched poly(propyleneimine) (HB-PPI)-loaded MCM-41 under humid DAC conditions. Thermodynamic analysis identified energetically favorable polymer loadings of approximately 34 wt % for HB-PEI and 37 wt % for HB-PPI, corresponding to an optimal balance among amine-site density, polymer organization, and mesopore accessibility. Spatial distribution analyses revealed that CO2 preferentially accumulates near polymer–void interfacial regions, whereas H2O strongly associates with silanol groups and amine functionalities, inducing competitive adsorption and humidity-dependent structural reorganization. Pair correlation analyses further demonstrated that secondary amines serve as the dominant local coordination sites for both CO2 and H2O under mesopore confinement. Transport analysis revealed pronounced anisotropic diffusion along the mesopore axis together with a nonmonotonic humidity dependence of CO2 mobility arising from the competing effects of polymer plasticization and H2O-induced steric obstruction. Although HB-PPI exhibits greater intrinsic segmental mobility, HB-PEI maintains higher CO2 diffusivity under humid conditions. This behavior is consistent with reduced transient steric obstruction arising from its more compact polymer organization. These findings demonstrate that intrinsic polymer mobility alone cannot predict CO2 transport under mesoporous confinement. Instead, CO2 transport emerges from the coupled effects of polymer architecture, confinement, hydration, and humidity-induced structural reorganization of the polymer matrix.
Abstract Developing binder-free, earth-abundant bifunctional electrocatalysts for alkaline overall water splitting is crucial for scaling alkaline water electrolysis beyond noble-metal electrodes. In this work, nonacobalt octasulfide (Co9S8) is directly grown on nickel foam through a binder-free, one-step galvanostatic electrodeposition method. The influence of deposition time on the catalytic behavior was systematically investigated. Structural and surface analyses (XRD, HRTEM/SAED, XPS) confirm Co9S8 as the dominant phase across all deposition times, while systematic electrochemical characterization reveals a clear structure–activity relationship; an intermediate deposition (20 min, CSN-20) produces an interconnected porous architecture that maximizes electrochemically accessible surface area (Cdl = 75 mF cm–2) and minimizes charge-transfer resistance. The optimized electrode (CSN-20, deposited at 100 mA cm–2 for 20 min) exhibits superior bifunctional activity, requiring overpotentials of 121 mV for HER and 267.4 mV for OER in 1.0 M KOH, indicating fast reaction kinetics. CSN-20 sustains this bifunctional activity for 120 h of continuous operation at 50 mA cm–2 under HER, OER, and full two-electrode conditions, with posttest XRD/XPS confirming that the bulk Co9S8 phase is retained while a surface oxy(hydroxide) layer forms during OER, consistent with a self-optimizing active surface rather than catalyst degradation. A two-electrode electrolyzer assembled with the optimized electrode (CSN-20||CSN-20) requires 1.66 V to deliver 10 mA cm–2. This study establishes a facile, ecofriendly, and scalable route for developing efficient alkaline water splitting electrodes, without heteroatom doping, heterostructuring, or postsynthetic treatment.
Abstract Ash deposition on heating surfaces can lead to clogging and corrosion of the incinerator and pipelines and heavy metal accumulation, significantly hindering the clean and stable running of municipal solid waste incineration (MSWI) systems. Relating deposit characteristics to operating descriptors is essential for developing evidence-based monitoring and mitigation strategies for heating surface deposition. In this study, ash samples were collected from heating surfaces along the flue gas path of seven full-scale MSWI plants. The correspondence between sampling conditions (location, temperature, aspect ratio, diagonal length, and flow rate) and the ash characteristics was discussed. According to the results, across all samples, the aspect ratio showed the clearest association with deposit roughness, while CaSO4 was the most frequently detected crystalline phase. The energy-dispersive spectroscopy data revealed a chloride-rich compositional pattern, although its strength varied across the sensitivity analyses. Pb showed the clearest decline with increasing temperature, whereas Cu, Zn, and As showed distinct associations with the flow rate or geometry. Integrated analysis separated carbonate- and chloride-rich patterns from sulfate- and metal-enriched patterns. Some of these overall relationships weakened when differences among plants were considered, highlighting the importance of the plant-specific conditions. Overall, geometry was more closely associated with deposit texture and capture-related patterns, whereas temperature was more closely associated with chemical evolution and volatile metal redistribution. This work provides an empirical framework for targeted deposit monitoring and corrosion risk assessment in full-scale MSWI systems.
Abstract Cu-based catalysts are promising for CO2-to-methanol conversion, but their activity and stability are usually compromised by the accumulation of byproduct water. Although physically mixing hydrophobic additives with Cu-based catalysts can facilitate water removal, how to regulate the water-removal kinetics in this process, as well as its impact on the reaction kinetics of CO2 hydrogenation to methanol, remains insufficiently understood. Herein, by modifying the polydivinylbenzene (PDVB) with porosity, we regulate the surface hydrophobicity of its mixture with a layered double hydroxide (LDH)-derived CuZnAlMg catalyst, thereby enhancing the water removal kinetics on the mixed catalyst surface. In contrast to nonporous PDVB, porous PDVB, with a substantially higher surface area and abundant mesopores, effectively creates additional H2O transfer channels. This facilitates rapid water removal, which in turn inhibits the oxidation of Cu nanoparticles and ensures the re-exposure of oxygen-vacancy active sites for sustained catalysis. Furthermore, water removal also accelerates the formation and subsequent hydrogenation of intermediates for higher activity. Consequently, a high space-time yield of methanol of 519.89 gMeOH kgcat–1 h–1 and a CO2 conversion rate of 26.35% are achieved at 5 MPa and 260 °C. The mixed catalyst exhibits excellent stability over 200 h of continuous operation. This work offers a simple yet robust strategy for regulating catalyst hydrophobicity toward efficient CO2 hydrogenation to methanol.
Abstract The simultaneous removal of SOx and NOx from flue gas has attracted considerable attention. A single wet absorption reactor employing NaClO2 as an oxidizing agent and Na2SO3 as a reducing agent was investigated to determine the optimal conditions for the simultaneous removal of SO2 and NOx. At the optimal additive concentrations of 0.1 M NaClO2 and 0.06 M Na2SO3, NOx removal efficiency reached 92.5%. SO2 also enhanced NOx removal through the reduction of NO2 to N2 via sulfite ions derived from SO2 absorption. However, the excessive use of additives led to interference between these reactions, thereby reducing the overall absorption performance. A two-stage wet absorption system was employed to investigate reactions that were difficult to distinguish in a single reactor setup, thereby elucidating these interactions and their underlying absorption mechanisms. The effects of various operating conditions on the SO2 and NOx removal efficiencies were examined. The highest removal efficiency with respect to each parameter was obtained with 5% O2, 200 ppm of SO2, and 20 °C. These optimal values were determined with each parameter varied individually while the other conditions were fixed. In the presence of CO2, the NOx removal efficiency decreased significantly owing to solution acidification. Adding Na2CO3 as a buffering agent stabilized the pH and improved NOx removal efficiency at a concentration of 0.1 M, demonstrating potential applicability to real flue gas treatment.
Abstract A series of novel grafted metal oxide nanohybrid pour point depressants (NPPD) was successfully synthesized, on a normalized surface area basis, via in situ free-radical polymerization of octadecyl acrylate-vinyl acetate (POA-VA) in the presence of 3-(trimethoxysilyl) propyl methacrylate-functionalized CuO, Al2O3, ZnO, and Fe3O4 nanoparticles. The performance of the resulting POA-VA grafted metal oxide nanoparticles (NPPDs) in mitigating wax deposition in natural gas condensate (NGC) was systematically compared, on a normalized surface area basis, with that of neat POA-VA using pour point analysis, coldfinger deposition, rheology, polarized light microscopy, and differential scanning calorimetry. Neat POA-VA decreased the pour point of the NGC from 23.6 to 18.5 °C, whereas incorporation of metal oxide nanoparticles led to further depression, with Fe-NPPD exhibiting the greatest reduction (16.0 °C). Followed closely by Cu-NPPD. In contrast, coldfinger deposition tests revealed a distinct trend, with Al-NPPD achieving the highest inhibition efficiency (42.88%) despite showing the weakest pour-point depression among the NPPDs. This apparent divergence reflects two largely independent inhibition pathways: Fe- and Cu-NPPD act primarily through redox-active surface chemistry that disrupts postnucleation wax network percolation in the bulk fluid, whereas Al-NPPD acts through strong Lewis-acidic interfacial adsorption that suppresses wax deposition directly at the cold metal surface, largely independent of bulk network structure. Microscopy and rheological measurements corroborated this mechanistic picture, showing the most fragmented crystal networks and lowest storage moduli for Fe- and Cu-NPPD, while Al-NPPD preserved a comparatively intact bulk crystal structure. These findings demonstrate that nanoparticle surface chemistry dictates a nanoparticle-specific inhibition mechanism rather than a uniform effect, providing design principles for selecting metal oxide NPPDs based on the dominant flow-assurance challenge (bulk gelation versus surface deposition).
Abstract Scale formation at wellheads often reduces oil production, damages equipment, and results in lost revenue. Scale formation can be mitigated by chemical treatment of oil production reservoirs with scale inhibitor (SI) compounds. To minimize the number of treatments the reservoirs must undergo, it is important to utilize scale inhibitors that are strongly retained in the reservoir media and then are slowly released over extended periods of time at concentrations high enough to halt the growth and deposition of mineral precipitates. To select the best scale inhibitor candidates, bench-scale squeeze tests are often performed to mimic field-scale oil production techniques, but these tests are time- and material-intensive, and to optimize injection concentrations, several tests must be completed. The objective of this work was to examine a commercial scale inhibitor, Flosperse MAS (FMAS), as a potential candidate for long-term protection against scale formation and to develop and apply a modeling framework for upscaled SI performance assessment. Squeeze tests were performed at four FMAS concentrations, revealing that when applied at an appropriate concentration, the compound exhibits extended release for several hundred pore volumes (PV) at concentrations above the minimum inhibitor concentration. Bayesian parameter estimation was used in conjunction with mathematical modeling of the experiments to build a predictive model of extended-release SI performance. Using the estimated kinetic and sorption parameters, the mathematical model successfully reproduced SI release across a range of experimental conditions. The modeling and calibration framework developed and applied in this work can be employed to assess potential SI performance at the reservoir scale, based upon data collected in laboratory experiments.
Abstract The electrochemical performance of LiNi0.5Mn1.5O4 (LNMO) is strongly influenced by the interplay between crystal structure and particle morphology, both of which are determined by thermal regulation. This study systematically investigates the influence of the cooling-rate regulation on hierarchical morphology, ordered-to-disordered phase formation, and electrochemical behavior of spherical LNMO synthesized via coprecipitation. The results reveal that the cooling-rate strategy balances the thermodynamic tendency toward crystal and morphological evolution. Slower cooling promotes the transformation from a highly disordered Fd3̅m spinel to a more ordered P4332 phase, thereby reducing Mn3+ formation and rock-salt impurities. In terms of morphology, rapid cooling produces small polyhedral grains and highly porous microspheres, whereas slow cooling yields larger, well-defined primary particles with smoother surfaces. Owing to this structural-morphological trade-off, neither rapid nor slow cooling provided optimal electrochemical performance. Instead, the LNMO sample synthesized at a moderate cooling rate (LNMO C5) achieved the optimal balance among partial cation disorder, controlled Mn3+ content, and a well-defined hierarchical spherical morphology, resulting in the lowest charge-transfer resistance and polarization. Consequently, LNMO C5 delivered a high discharge capacity of 96.36 mAh g–1 at 5C and excellent cycling stability with 97.90% capacity retention after 400 cycles at 0.5C. These findings highlight that cooling-rate regulation is a simple yet effective strategy for tailoring the thermodynamic and kinetics balance of LNMO, providing a reference for the future development and optimization of high-voltage LNMO cathode materials.
Abstract Depressurization using horizontal wells is widely recognized as the most economical and effective method for natural gas hydrate (NGH) production. However, research on ice formation during horizontal well depressurization remains limited, particularly under low-temperature hydrate-bearing layer (HBL) conditions. In this study, a field-scale numerical model considering ice formation during horizontal well depressurization in the HBL of the Lingshui 18-1 area, South China Sea, is developed using COMSOL Multiphysics. Comparative simulations are conducted for cases with and without ice formation. The results show that ice undergoes a cyclic process of formation and melting. Ice formation releases latent heat, slightly promoting hydrate dissociation, but the blockage of pores and pressure diffusion dominates, reducing the overall dissociation rate. Ice formation also suppresses water production more significantly than gas production, thus increasing the gas–water ratio and improving the energy efficiency. Compared with the TPL well system, the HBL well system achieves higher long-term gas production and gas–water ratios. In terms of well layout, the TPL well is suitable for short-term gas production, but the HBL well is better for long-term gas production. This study highlights the significance of considering ice formation in horizontal well hydrate production and demonstrates the feasibility and advantages of locating production wells in the HBL.
Abstract Chemical-looping CO2 conversion provides a promising route for sustainable CO production by separating reduction and oxidation into two steps. However, Fe-based redox materials often suffer from limited cyclic reactivity and structural degradation during repeated redox operation. In this work, Al2O3-modified Fe-based redox materials were prepared by ball milling and evaluated for chemical-looping CO2 conversion in a fixed-bed reactor. The effects of reaction temperature, support type, milling conditions, and Fe/Al molar ratio were systematically investigated. A reaction temperature of 650 °C provided nearly the maximum CO yield while avoiding unnecessary additional heat input. Ball milling alone increased the CO yield of Fe2O3 from 2.0–3.1 to 5.2–10.9 mmol g–1. Among the investigated additives, Al2O3 gave the best overall performance. The optimized FeAl-B sample with an Fe/Al molar ratio of 10:1 delivered an average CO yield of 11.82 mmol g–1 and maintained 10.24–12.21 mmol g–1 over 10 redox cycles. In comparison, ball-milled Fe without Al2O3 showed rapid deactivation. Structural characterization indicates that ball milling improves particle dispersion and Fe–Al contact, while Al2O3 helps suppress Fe coarsening and preserve the porous structure during cycling. Their combined effect improves redox reversibility and oxygen transfer. These results show that ball milling coupled with Al2O3 modification is an effective route to enhance the activity and short-term cyclic stability of Fe-based redox materials for chemical-looping CO2 conversion.
