Environmental Chemistry•2026•DOI: 10.7524/j.issn.0254-6108.2025062404
To investigate the pollution characteristics and temporal variations of water-soluble ions in atmospheric fine particulate matter (PM2.5) during autumn and winter in Taiyuan City, continuous sampling and analysis were conducted using a Swiss Metrohm ion chromatograph in autumn and winter 2023. The results show that the daily mean concentration of nine water-soluble ions was 26.04 μg m−3, accounting for 52.1% of the average PM2.5 mass concentration. Ion concentrations ranked in descending order: NO3−, NH4+, SO42−, Cl−, K+, Na+, Ca2+, F−, and Mg2+. Secondary inorganic ions (SNA) constituted 87.6% of total water-soluble ions. The mass ratio of NO3− to SO42− reached 1.83, indicating a shift from sulfate-dominated to nitrate-dominated aerosol chemistry. During pollution episodes, water-soluble ion concentrations increased exponentially, with distinct ion-specific trends: on moderately polluted days, SO42− increased to 5.31 times that on clean days, whereas on heavily polluted days, NO3− increased to 5.37 times, highlighting nitrate as a primary driver of severe pollution. Comparison with historical data reveals a recent increase in the proportion of water-soluble ions in PM2.5, with higher proportions during more polluted periods. Analysis of NH4+ forms and PM2.5 acidity suggests that acidic components contribute more under heavier pollution. Positive matrix factorization (PMF) identified four major sources: secondary sources, combustion and motor vehicles, industrial sources, and dust. The secondary source contributions were 45.4%, 64.7%, and 63.4% on clean, lightly polluted, and moderate-to-heavy polluted days, respectively, indicating a significantly higher secondary contribution on polluted days.
Journal of Environmental Engineering Technology•2026•DOI: 10.13205/j.hjgc.202605013
The escalating eutrophication of aquatic systems has intensified algal blooms, leading to substantial release and accumulation of algal-derived dissolved organic matter (ADOM), which profoundly influences carbon cycling and pollutant transport. Iron minerals, particularly ferrihydrite, are recognized as critical mediators of DOM sequestration, yet the adsorption fractionation of ADOM under varying environmental conditions remains poorly understood. This study systematically investigated the effects of pH (2.0–10.0) and initial dissolved organic carbon (DOC) concentration (2–100 mg C/L) on the adsorption capacity and selectivity of ADOM onto ferrihydrite, employing UV-Vis spectroscopy and excitation-emission matrix fluorescence with parallel factor analysis (EEM-PARAFAC). Results demonstrated that adsorption capacity increased with pH from 2.0 to 7.0, reaching a maximum of 21.59 mg C/g at pH 7.0, followed by a decline at pH > 7.0 due to enhanced electrostatic repulsion. Within the environmentally relevant pH range of 3.0–9.0, selective fractionation intensified with increasing pH, favoring highly aromatic, high-molecular-weight chromophoric DOM (CDOM) and protein-like/aromatic amino acid fluorescent DOM (FDOM) with high humification and autochthonous characteristics. With increasing initial DOC concentration, adsorption exhibited non-linear growth, with preferential uptake of low-aromaticity, high-molecular-weight CDOM and protein-like FDOM of lower humification and stronger autochthonous features. These findings elucidate that ferrihydrite can effectively sequester reactive ADOM components via pH- and concentration-dependent selective adsorption, potentially altering DOM composition and reactivity in eutrophic waters, thereby providing fundamental data for understanding iron mineral-mediated internal carbon sequestration.
SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-025-3966-0
The development of low platinum-loading catalysts for the economically viable hydrogen evolution reaction (HER) remains challenging. Herein, a precursor dilution strategy is used to fabricate Pt nanoclusters anchored on Ni-embedded porous carbon microspheres. The approach begins with the facile synthesis of Zn/Ni-based coordination polymers (Ni-BTC-Zn) due to the isomorphic substitution of Zn2+ and Ni2+. During pyrolysis, the evaporation of zinc species results in a highly porous carbon structure with well-dispersed nickel nanoparticles. Subsequent solvothermal treatment allows for the uniform deposition of Pt nanoclusters to form the final bimetallic PtNi catalysts (PtNi-BTC-C). Among them, the optimized PtNi-BTC-C10 exhibits exceptional alkaline HER performance, requiring an overpotential of only 41 mV to achieve 10 mA cm−2 and a low Tafel slope of 31.1 mV dec−1. It also demonstrates outstanding durability with a current retention of 90.7% after 70 h, far exceeding Pt/C. Extensive characterization confirms that moderate Zn dilution optimally modulates the Ni particle size and dispersion, leading to maximized active sites and enhanced charge transfer. Combined with DFT calculations, the Pt-Ni-cluster model for PtNi-BTC-C10 possesses an optimized electronic structure with a shifted d-band center, which facilitates water dissociation and optimizes H* desorption with the most favorable energetics (0.262 eV). This work provides a fundamental understanding of precursor dilution engineering and offers a versatile pathway for designing advanced noble-metal-based bimetallic electrocatalysts.
Journal of Fuel Chemistry and Technology•2026•DOI: 10.1016/S1872-5813(26)60752-9
Methanol steam reforming (MSR) is a pivotal process for efficient hydrogen production. This study employs density functional theory (DFT) calculations to comparatively analyze the MSR reaction mechanism on PdCu(111) and PtCu(111) bimetallic surfaces. The investigation unveils how alloying modulates reaction pathways and overall catalytic performance. Notably, Cu sites stabilize adsorption of OH and CH2O species, whereas Pd/Pt sites exhibit preferential affinity for CO. This spatial site separation facilitates progression along the formate pathway. PdCu(111) demonstrates superior overall catalytic performance compared to PtCu(111), with water dissociation identified as the rate-determining step (RDS), featuring an activation energy of only 0.74 eV. The bimetallic synergy breaks the inherent contradiction between activity and selectivity of monometallic catalysts: Cu sites serve as a source of hydroxyl groups, while Pd/Pt sites enhance C–H bond cleavage efficiency, ultimately enabling high methanol conversion alongside low CO formation. From the perspectives of electronic structure and geometric configuration, this study establishes a theoretical framework to guide rational design of high-performance bimetallic catalysts for MSR.
SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-026-4118-0
Polymer composite dielectrics are key materials for high-temperature film capacitors, yet their energy storage capability is severely constrained at elevated temperatures. Molecular fillers that simultaneously integrate deep-level trapping (high electron affinity, Ea), strong insulation (large bandgap, Eg), and high thermal stability are rarely available, posing a major challenge for improving high-temperature energy storage performance. To address this challenge, we screen and identify hexaazatriphenylene hexacarbonitrile (HAT-CN) as a promising candidate that fulfills the above critical requirements from numerous commercial organic molecules. When incorporated into a high glass transition temperature (Tg) polymer fluorene polyester (FPE), the resulting all-organic composite exhibits simultaneously suppressed high-temperature conduction loss and preserved mechanical robustness. Consequently, the optimized composite achieves record-high discharged energy densities of 7.31 J cm−3 at 150 °C and 6.14 J cm−3 at 200 °C (η≥90%) with a low cost and scalable process. This work demonstrates that the filler design based on synergistic key properties provides a potent pathway to break the longstanding high-temperature performance bottleneck in polymer dielectrics.