SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-026-4202-3
Carbon dots (CDs) with absorption in the second near-infrared window (NIR-II, 900-1700 nm) hold promise for tumor theranostics, yet existing synthesis methods often involve complex procedures, harsh conditions, or lack precise control. Here we report a 'self-photooxidation-restructuring' strategy that enables structural reorganization of the carbon core in CDs, achieving a significant redshift of absorption into the NIR-II region. Under ultraviolet (UV) light irradiation, the precursor (B-CDs, absorption in UV region) generates singlet oxygen, which self-oxidizes aldehyde groups and the carbon skeleton of B-CDs to stronger electron-withdrawing carboxyl groups and carbon radicals, respectively. These processes facilitate the formation of new C=C bonds between isolated aromatic domains, thereby transforming B-CDs into novel CDs (N-CDs) characterized by enhanced donor-acceptor interactions and a redshift in absorption toward the NIR-II window. Various experimental data, including high-resolution XPS, FTIR, NMR, EPR, have proved the proposed formation mechanism. The novel N-CDs afforded a high photothermal conversion efficiency of up to 71.33%, which enabled 1064 nm laser-activated photoacoustic imaging (PAI)-guided photothermal therapy (PTT) in tumors. This work opens a new avenue for the synthesis and modulation of CDs in the NIR-II region.
SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-026-4369-1
Sodium-ion batteries (SIBs) are promising alternatives to lithium-ion batteries for large-scale energy storage due to sodium's abundance and low cost. Among cathode materials, polyanionic compounds like Na3V2(PO4)2O2F (NVPOF) offer high energy density and dual voltage plateaus at ~3.6 and 4.0 V, but suffer from low electronic conductivity and sluggish Na+ diffusion. Here, we report a dual-modulation strategy combining high-valence Nb5+ doping and polydopamine-derived carbon coating to synthesize Na3V1.94Nb0.06(PO4)2O2F-C (NVPOF-Nb-C) via a hydrothermal route. X-ray diffraction and Rietveld refinement confirm that Nb5+ doping induces slight lattice expansion without altering the tetragonal I4/mmm framework. Density functional theory calculations reveal that Nb5+ doping optimizes the crystal structure and reduces the Na+ diffusion barrier, while the uniform carbon coating enhances electron transport. Consequently, NVPOF-Nb-C exhibits remarkably improved electrochemical performance, including high reversible capacity, excellent rate capability, and ultralong cycling stability. In a full cell with hard carbon anode, it delivers a high energy density of 487.2 Wh kg−1 at 1C and retains 91.51% capacity after 3000 cycles at 20C. This work provides a synergistic strategy to overcome the intrinsic limitations of polyanionic cathodes for practical SIB applications.
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.
Environmental Chemistry•2026•DOI: 10.7524/j.issn.0254-6108.2025042703
This study investigated phosphorus (P) exchange at the sediment-water interface and its microbial driving mechanisms in aquaculture ponds of Chinese mitten crab (Eriocheir sinensis). Using diffusive gradients in thin films (DGT), labile P concentrations in the upper sediment were significantly higher than in overlying water from late July to mid-August and in October, indicating sediment acts as a P source during these periods. The duration of aquaculture was a key factor; P diffusion flux declined from late July to mid-August and further decreased by October. Analyses of labile Fe, P-Fe correlations, and bacterial community composition and function suggested that dissimilatory Fe(III) reduction mediated by Fe-reducing bacteria and chemical Fe(III) reduction driven by sulfate-reducing bacteria metabolites were important mechanisms for P release. Additionally, bacterial-driven organic P mineralization and inorganic P dissolution contributed. The results indicate a high risk of P release from sediment to overlying water from late July to mid-August, potentially significantly affecting water P concentrations. Therefore, controlling sediment P release during this period is crucial.
Environmental Chemistry•2026•DOI: 10.7524/j.issn.0254-6108.2025042504
This study investigated the effect of co-aging with common cations/anions and humic acid (HA) on the combined use of Vallisneria natans (VN) and lanthanum-modified bentonite (LMB) for controlling phosphorus (P) release from sediment. Results showed that co-aging significantly reduced the phosphate adsorption capacity of LMB, with the maximum unit adsorption capacity decreasing by 33.8% compared to the unaged material. Under the combined application of VN and unaged LMB, P in sediment could still be released into pore water via dissimilatory iron(III) reduction mediated by iron-reducing bacteria and chemical reduction of iron(III) induced by sulfate-reducing bacteria metabolites, subsequently migrating to overlying water. However, the combined treatment effectively inhibited P release, achieving an average reduction efficiency of 57.1% for dissolved reactive phosphorus (SRP) in overlying water and 74.0% for labile P in sediment (measured by DGT) at an LMB dosage of 89 g·m−2. Co-aging with common ions and HA diminished the P control efficiency of the combined treatment, primarily due to reduced phosphate adsorption capacity of LMB. Therefore, mitigating the negative effects of co-aging is crucial for enhancing the long-term P control performance of the VN-LMB combined technology.