SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-025-3710-y
Layered transition metal oxide cathodes for sodium-ion batteries (SIBs) suffer from Jahn–Teller distortion of MnO6, Na+/vacancy ordering, and irreversible lattice oxygen loss, causing capacity fading and voltage decay. Here, we report a P2-type material, Na0.67Ni0.3Mn0.6Li0.09Sn0.01O2 (NNMO-Li0.09Sn0.01), co-doped with closed-shell Li+ and Sn4+ ions. Li+ increases the Mn4+/Mn3+ ratio, mitigating Jahn–Teller distortion, and disrupts Ni/Mn ordering, suppressing Na+/vacancy ordering. Sn4+ forms stronger Sn–O bonds (548 kJ mol−1), enhancing bonding between transition metal ions and oxygen, reducing oxygen loss. NNMO-Li0.09Sn0.01 delivers a specific capacity of 90.3 mAh g−1 with 62.9% capacity retention after 50 cycles at 0.1 C (1 C = 200 mA g−1), and 90.3% voltage retention. This closed-shell substitution strategy offers a viable approach for enhancing structural stability of wide-voltage layered oxide cathodes.
Chinese Journal of Environmental Engineering•2026•DOI: 10.12030/j.cjee.202507021
The accumulation of heavy metals in soil around municipal solid waste landfills poses potential risks to human health. This study selected a municipal solid waste landfill and monitored the concentrations of eight heavy metals (Zn, Pb, Cd, Ni, Hg, Cu, As, Cr) in surrounding soil. The geo-accumulation index method was used for pollution assessment, and a health risk assessment model recommended by the USEPA, combined with Monte Carlo uncertainty analysis, was employed to evaluate the pollution status and health risks to nearby residents. Results showed that among the eight metals, Pb, Ni, and Cd exceeded risk screening values at 4.26%, 6.38%, and 4.26% of sampling points, respectively. Geo-accumulation indices indicated overall clean conditions (mean < 0), but slight pollution by Pb, Zn, Ni, Hg, and Cd at some points. Probabilistic risk assessment based on Monte Carlo simulation revealed that for both adults and children, the cumulative non-carcinogenic risk was negligible, while carcinogenic risk was acceptable. However, there was a very low probability (approximately 0.2%) of non-carcinogenic risk for children, and probabilities of unacceptable carcinogenic risk were 0.64% for adults and 3.21% for children. Nickel was the primary contributor to carcinogenic risk, and children faced higher health risks than adults. These findings provide a reference for pollution prevention and health risk management of soil around municipal solid waste landfills.
The Chinese Journal of Process Engineering•2026•DOI: 10.12034/j.issn.1009-606X.225185
Sulfur hexafluoride (SF6), widely used as an insulating gas in high-voltage electrical equipment, possesses a global warming potential (GWP) 25,200 times that of CO2, necessitating efficient degradation technologies. This study employed computational fluid dynamics (CFD) to simulate the thermal catalytic degradation of SF6 in a fixed-bed reactor, integrating models for porous media, heat transfer, turbulence, and chemical kinetics. The simulations revealed significant radial non-uniformities in pressure, velocity, temperature, and species concentration distributions, with temperature identified as the dominant factor influencing degradation efficiency. Radial temperature gradients caused uneven reaction rates, with degradation rates near the wall substantially exceeding those at the central axis, thereby reducing overall SF6 conversion. To address this, structural optimizations were implemented, including reducing the reactor tube diameter and incorporating inert porous media with high thermal conductivity at both ends of the catalytic section. These modifications enhanced radial heat transfer, homogenized the temperature field, and improved the uniformity of reaction rates and species concentrations. Parametric studies on inlet gas velocity showed that both excessively low and high flow rates were detrimental: low velocities led to underutilization of the downstream catalyst and increased energy consumption, while high velocities deteriorated heat transfer and exacerbated radial temperature gradients. The optimal inlet velocity range was determined to be 0.4–0.8 m/s for a reactor tube inner diameter of 10 mm, balancing catalyst utilization, energy consumption, and degradation efficiency. This research provides data-driven guidance for the design and scale-up of SF6 catalytic degradation reactors.
Journal of Environmental Engineering Technology•2026•DOI: 10.13205/j.hjgc.202607014
Reducing ammonia emissions and recovering lost nitrogen are critical for enhancing nitrogen content in compost. Biological trickling filters, as end-of-pipe odor control, retain ammonia nitrogen in effluent, offering a reuse pathway. However, the impact of nitrogen-rich wastewater reuse within the optimal C/N range (20.0:1–30.0:1) remains unclear. This study composted biogas residue, sawdust, food waste, and mushroom residue, setting initial C/N as the control variable. Four groups were established: low C/N with nitrogen-rich wastewater (LRN), low C/N with deionized water (LRW), high C/N with nitrogen-rich wastewater (HRN), and high C/N with deionized water (HRW). Simulated wastewater (2000 mg/L NH4+-N and 2000 mg/L NO2−-N) was recycled. Results showed no inhibition of final maturity; pH (8.17–8.48) and seed germination index (GI) (90.85%–122.96%) met organic fertilizer standards. HRN reduced cumulative total greenhouse gases, N2O, and NH3 by 20.32%–30.35%, 0.67%–53.38%, and 52.14%–62.15% compared to LRN and LRW. Although HRN emissions were slightly higher than HRW (total GHGs +4.56%, NH3 +4.99%), HRN final nitrogen content (4691.27 mg/kg) exceeded HRW (4514.96 mg/kg), attributed to sufficient carbon enhancing microbial assimilation. Conversely, low C/N with nitrogen-rich wastewater increased NH3 and N2O emissions (LRN vs LRW: +26.43% and +112.99%) due to carbon limitation. Thus, high initial C/N with nitrogen-rich wastewater reuse effectively reduces gaseous nitrogen loss and greenhouse gas emissions while maintaining compost maturity.
Journal of Fuel Chemistry and Technology•2026•DOI: 10.1016/S1872-5813(26)60657-3
Fe-Mn catalysts have attracted considerable attention for industrial Fischer-Tropsch synthesis (FTS) due to their ability to modulate product spectra. Carbon adsorption and permeation on catalyst surfaces are critical elementary steps in the in situ formation of active iron carbide phases. Here, density functional theory (DFT) calculations systematically investigate the atomistic structures, thermodynamic stabilities, and electronic properties of carbon-deposited Fe-Mn alloy surfaces at the early stage of carburization. These surfaces exhibit distinct thermodynamic sensitivity to carbon atoms adsorbed on the surface and permeating into interstitial sites. By combining DFT with minima-hopping structural searches, we demonstrate that the initial stage of carbon permeation cannot trigger surface reconstruction to form iron carbide phases. The addition of manganese thermodynamically hinders carbon permeation. Although deposited carbon atoms modulate the electronic structure of metals, manganese retards the shift of d-band centers toward those of bulk iron carbide phases. This study provides atomic-scale insight into the in situ evolution of Fe-Mn catalyst surfaces during carbon deposition, indicating that manganese promoter has a noticeable effect on carbon permeation.