Inner Mongolia University

Algal-derived dissolved organic matter (ADOM) is a critical component of endogenous dissolved organic matter (DOM) in aquatic systems, distinguished by its characteristic fluorescence response and high photochemical reactivity. Hulun Lake, the fifth largest lake in China, has experienced recurrent algal blooms accompanied by elevated iron (Fe) concentrations, providing an ideal natural setting to investigate the coupled photochemical roles of ADOM and Fe. This study examines the dual photochemical effects, both upward (emission of gas-phase substance) and downward (release of dissolved or particulate matter), during iron-mediated photodegradation of ADOM. Using ADOM extracted from Hulun Lake algae, we conducted simulated photodegradation experiments to investigate how Fe influences reactive intermediates formation and ADOM degradation, and to elucidate the mechanisms governing greenhouse gases (GHGs) emissions and nutrient release, particularly phosphorus. Our results reveal that both Fe(III) and Fe(II) enhance hydroxyl radical (•OH) generation and ADOM mineralization. At low concentrations (0.3 mg·L^-1), Fe(III) saturates in quenching triplet-state ADOM (³ADOM*), while Fe(II) exhibits concentration-dependent inhibition. Fe(III) primarily drives free radical generation via complexation with ADOM, while Fe(II) mainly promotes the Fenton reaction, highlighting distinct photochemical pathways. Notably, the release rate of dissolved inorganic phosphorus (DIP) showed a significant positive correlation with •OH concentration (p < 0.001), indicating •OH-mediated oxidative transformation of dissolved organic phosphorus (DOP) to DIP. At an ADOM level of 10 mgC·L^-1, the directly released DIP exceeds the eutrophication threshold for surface water (>0.02 mg·L^-1). Furthermore, both Fe ions and ADOM concentration significantly enhance photochemical GHGs emissions, dominated by CO₂. The relative contributions of CH₄ and N₂O to global warming potential decreased initially before stabilizing under radical-driven reactions, a pattern linked to ADOM chemical structure. These findings provide a new perspective for in-depth understanding of the carbon-iron-phosphorus interaction and climatic effects, offering a scientific basis for ecological protection and sustainable management.

Two-dimensional (2D) topological half-metals (THMs) hold great potential for developing low-dissipation spintronics. Based on the structural derivation strategy inspired by experimentally synthesized quasi-2D kagome metals, we propose a promising 2D intrinsic ferromagnetic THM, the Fe₃SSe₄ monolayer, by first-principles calculations. Specifically, the stable Fe₃SSe₄ monolayer exhibits a robust ferromagnetic ground state with a Curie temperature of 210 K. It exhibits a sizable magnetic anisotropy energy of 3.72 meV per unit cell, significantly higher than that of several reported high-performance magnetic recording materials. Most strikingly, the calculated band structure reveals that the Fe₃SSe₄ system demonstrates coexisting half-metallicity and quantum anomalous Hall effect, characterized by a Chern number of C = 1. Furthermore, the Weyl cone is located very close to the Fermi level and is classified as type-I along the corresponding k path. The maximum Fermi velocity of 5.75 × 10⁵ m/s is higher than those of the 2D THMs reported to date. Our work would open up new opportunities for the design of other THMs.

Biological systems achieve macroscopic functionality through molecular machines operating within precisely organized scaffolds. Replicating this coordinated motion synthetically requires integrating high-performance molecular motors into structurally ordered, yet dynamically active, frameworks. We present a reticular design strategy for incorporating overcrowded alkene rotary motors into 3D covalent organic frameworks (COFs), creating JUC-666 as a prototype. This crystalline material maintains a unidirectional motor rotation in both solution and solid states, as confirmed by spectroscopic and kinetic analyses. The embedded motors enable dual-mode functionality: reversible CO₂ uptake modulation (>83% capacity variation at 273 K) under light-dark cycling, and precisely controlled drug release with light-dosage-proportional kinetics, showing a ∼50-fold increase in cumulative release. These results demonstrate how COFs can bridge molecular-scale motion to macroscopic responses, establishing a platform for designing adaptive functional materials.