SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-025-3746-x
The polyanionic compound Na3V2(PO4)2O2F (NVPOF) possesses a stable three-dimensional framework, high theoretical specific capacity, and favorable operating voltage, yet its sluggish Na+ diffusion kinetics and low electronic conductivity impede industrial application. This study proposes a dual regulation strategy combining carbon coating and heat treatment temperature to synergistically enhance crystallinity and electrochemical performance. NVPOF@C-400 and NVPOF@C-600 were synthesized via in-situ dopamine hydrochloride coating followed by heat treatment at 400 °C and 600 °C, respectively. Carbon coating at 600 °C significantly improved crystallinity and increased electronic conductivity by three orders of magnitude through the carbon layer's conductive network. The ~4.5 nm carbon layer effectively suppressed abnormal grain growth and secondary crystallization aggregation at high temperatures, maintaining uniform particle size of approximately 0.36 μm, which shortens Na+ diffusion pathways and prevents ion transport obstruction. Consequently, NVPOF@C-600 delivered a high discharge capacity of 102.5 mAh g−1 at 20 C and retained 96.5% capacity after 10,000 cycles. In a full-cell configuration with hard carbon (HC), NVPOF@C-600//HC achieved an impressive 89.3% capacity retention after 9,000 cycles. This work provides critical insights for practical implementation of high-performance NVPOF cathodes in sodium-ion batteries.
The Chinese Journal of Process Engineering•2026•DOI: 10.12034/j.issn.1009-606X.225213
Gas-liquid stirred tanks are widely used in oxidation, hydrogenation, and other chemical processes, where the gas dispersion state directly affects production efficiency. This study systematically investigated the effects of impeller type, impeller installation height, and rotational speed on gas-liquid dispersion in a stirred tank equipped with a porous tube sparger. Two typical impellers, a wide hydrofoil (WH) and a half-elliptical disk turbine (HEDT), were tested at various installation heights (L/D ratios) and gassing rates. The critical rotational speed for complete gas dispersion, agitation power consumption, and overall gas holdup were measured. Results showed that for both impellers, the critical Froude number (Fr) decreased significantly with increasing gas flow number (FlG). Under the same gassing rate, the HEDT impeller generally required a higher critical Fr and greater agitation power for complete dispersion compared to the WH impeller. Relative power demand (RPD) decreased as FlG increased, with a more pronounced decline at higher L/D ratios. At different impeller positions, the RPD of the HEDT impeller was higher than that of the WH impeller, indicating that the HEDT impeller's power was less affected by gas. Notably, the impeller installation height significantly influenced gas holdup and power consumption. When L/D = 0.75, higher gas holdup and lower power consumption were observed. This work provides crucial theoretical and data support for optimizing the design of gas-liquid stirred tanks with gas sparging, offering clear engineering value for enhancing mass transfer efficiency and energy-saving operation in chemical processes.
Journal of Fuel Chemistry and Technology•2026•DOI: 10.1016/S1872-5813(25)60623-2
Oxidative coupling of methane (OCM) is a promising route for direct conversion of methane to C2–C3 hydrocarbons, but conventional thermal catalysis suffers from insufficient conversion and selectivity. Here, we report a novel Mn2O3-TiO2-Na2WO4/SiO2+SiC microwave catalyst prepared by ball-milling, which enables efficient OCM under microwave irradiation. At 700 °C, the microwave catalytic reaction mode (MCRM) achieves a CH4 conversion of 26.6%, a C2–C3 selectivity of 76.5%, and a C2–C3 yield of 20.4%, significantly outperforming the conventional reaction mode (CRM) under identical conditions (12.3%, 61.9%, and 7.5%, respectively). The catalyst exhibits stable performance for 20 h in MCRM, maintaining CH4 conversion above 25% and C2–C3 selectivity above 76%. Characterization (XRD, XPS, O2-TPD, Raman) reveals that calcination promotes Mn–Ti interaction, increasing peroxy species and lattice oxygen (Oγ), which enhance reactivity and selectivity. Notably, microwave irradiation reduces the apparent activation energy from 173 kJ/mol (CRM) to 27.5 kJ/mol, facilitating free radical coupling and suppressing deep oxidation. These findings provide a low-temperature, energy-efficient strategy for methane valorization, contributing to sustainable chemical manufacturing.
Journal of Environmental Engineering Technology•2026•DOI: 10.13205/j.hjgc.202608027
The relocation of numerous industrial enterprises in China has left behind soil contamination, particularly by volatile organic compounds such as BTEX, whose migration and health risks are of great concern. Coastal plains, characterized by high groundwater tables and interbedded sedimentary strata, exhibit contaminant distribution and migration patterns distinct from inland regions. This study investigated a decommissioned resin plant site in the Yangtze River Delta coastal plain, systematically analyzing the spatial distribution, migration, and health risks of soil BTEX. Seven BTEX compounds were detected with detection rates ranging from 24.3% to 47.1%. Maximum concentrations of benzene, ethylbenzene, and m/p-xylene exceeded China's Class I construction land screening values. The contaminant plume was predominantly located in the southern product warehouse area, while the potential source was traced to the upstream wastewater treatment unit, indicating a 'source-sink' spatial mismatch. Vertically, contaminants exhibited a 'shallow-layer volatilization, middle-layer enrichment, and deep-layer retardation' pattern, with significant enrichment in silty clay at 3–6 m depth and sharp concentration declines in mucky clay. Membrane Interface Probe (MIP) multi-parameter detection revealed that benzene and toluene migrated as a whole, whereas chlorobenzene lagged due to strong adsorption. Benzene posed the most significant health risk, with carcinogenic risk up to 7.42×10⁻⁴ and non-carcinogenic hazard quotient up to 38.24, both exceeding acceptable levels. Inhalation of indoor air contaminated by vapor intrusion from underlying soil contributed over 87% of benzene's total risk, dominating the exposure pathway. This study elucidates the unique migration and risk formation mechanisms under high water table and interbedded strata, providing a scientific basis for precise investigation, risk assessment, and remediation of similar contaminated sites.
SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-026-4088-y
Silicon nitride (Si3N4) is a strong, thermally stable covalent ceramic typically regarded as brittle with limited deformability. Recent experimental and density functional theory (DFT) studies indicate that the α/β interface undergoes a β→α transformation via sliding followed by bond-switching, suggesting a pathway to achieve plasticity, but DFT's spatiotemporal reach prevents a full mechanistic picture. Here, we develop a physics-informed high-accuracy neural network interatomic potential (NNAP) model with DFT-level accuracy for phase transformations and use it to perform large-scale atomistic simulations. NNAP-guided simulations show that structural relaxation during relative sliding between α- and β-phases at the interface triggers pronounced atomic-layer rearrangements and lowers the energy barrier by nearly 60%. We further find that the ensuing phase transformation does not proceed by isolated layer-by-layer switching but instead follows in-plane nucleation and growth mediated by a bilayer cooperative mechanism, which further reduces kinetic barriers and facilitates the transformation. CI-NEB calculations reveal that the bilayer cooperative pathway has an energy barrier of 0.018 eV/Ų, lower than the independent layer-by-layer manner (0.020 eV/Ų), indicating enhanced kinetic accessibility. These results provide new atomistic insights into interface-driven phase transformations in dual-phase Si3N4 and offer guidance for designing more deformable covalent ceramics.