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Functioning as nanoscale "conductors", 2D transition metal carbides (MXenes) orchestrate interfacial charge-carrier transport between semiconductors. This capability enables precision-engineered control over photocatalytic processes by regulating charge-carrier separation and migration dynamics. However, existing techniques inadequately resolve photogenerated carrier dynamics, hindering rational MXene photocatalyst design. This study addresses this limitation using in situ nanoscale imaging with Kelvin probe force microscopy (KPFM) on a model TiO₂@MXenes system. We demonstrate that the charge transfer direction is governed by work function (W_F) difference, allowing for utilizing MXenes as electron- or hole-accepter by tuning the work function of MXenes. Glycerol treatment increases surface ─OH density, lowering MXene W_F to 1.31 eV and strengthening hole-extracting electric fields. By doing so, Pt/TiO₂ modified with low-W_F MXenes, showing 70.7%-91.7% reduction in charge transfer resistance, displayed the electron-hole transport, which vastly outperforms the electron-electron transport mode. This work offers a quantitative design paradigm linking surface terminations to W_F to carrier transport pathways for developing efficient MXene-based heterojunction photocatalysts.

Rheumatoid arthritis (RA) progressively develops from inflammatory synovitis to irreversible osteochondral destruction, with current clinical interventions offering only transient immunosuppression and lacking regenerative potential. Herein, we develop a bioadhesive scaffold integrating inflammation-responsive methotrexate (MTX) nanoparticles and chondrogenic miRNA-140 delivery systems for synergistic immunomodulation and osteochondral regeneration in advanced RA. The adhesive scaffold matrix consists of collagen and polydopamine-modified-hyaluronic acid (PDA/HA), crosslinked with polyethylene glycol diglycidyl ether (PEGDE), which provides robust mesenchymal stem cell adhesion and prolongs nanomedicine retention while establishing a regenerative microenvironment. The engineered system features MMP-labile polydopamine-doped lipid nanoparticles (PLNP) that rapidly release MTX in inflammatory conditions to suppress synovitis, working in concert with reactive oxygen species-scavenging gallic acid-modified chitosan nanoparticles (GC) that protect and effectively deliver miRNA-140 to restore chondrogenesis. In collagen-induced advanced arthritis models, this dual-stage therapy demonstrated sequential therapeutic action by initial immunomodulation followed by structural regeneration, yielding complete osteochondral restoration characterized by hyaline cartilage formation with physiological matrix features and integrated subchondral bone restoration. This work represents a significant progress in advanced RA treatment by transitioning from symptomatic management to true disease modification, combining precise immunomodulation with functional tissue regeneration through intelligent biomaterial design.

PbS colloidal quantum dots (QDs) have become promising materials for short-wave infrared (SWIR) detection and imaging due to their solution processability and monolithic integration with readout circuits. As the light-absorbing materials, PbS QDs serve as the core components for imaging chips, thus synthesis of high-quality PbS QDs is crucial for the development of QD imaging technology. Current synthetic methods of PbS QDs cannot achieve efficient surface passivation, high monodispersity, accurate size control, and high reproducibility, simultaneously. In the present work, a highly reproducible synthesis of high-quality PbS QDs is developed, by applying ethyl ziram (EZ) as the sulfur source. The most striking feature of this synthesis is the self-terminated growth, rendering it with high reproducibility. The self-terminated growth arises from a stable surface configuration, including surface atom arrangement and ligand-surface atom interaction. The as-synthesized PbS QDs show higher photoluminescence quantum yields than those synthesized by the cation exchange method, confirming the stable surface configuration. Due to the excellent surface passivation, these PbS QDs also exhibit better photodetector performance, demonstrated by lower dark currents and higher external quantum efficiencies. Finally, monolithically integrated SWIR imaging chips are fabricated using the PbS QDs synthesized from EZ, demonstrating excellent imaging performance.

Development of advanced anodes for sodium-ion batteries (SIBs) remains challenging due to the sluggish kinetics and severe volume expansion. Here, we report the rational design of bimetallic Co/Cu sulfides embedded in N/S-doped carbon matrices, via chemical vapor sulfurization of MOF precursor. The optimized CuCo₂S₄ electrode achieves exceptional sodium storage performance, delivering a high capacity of 573.3 mA h g^-1 at 0.2 A g^-1 and maintaining 504.2 mA h g^-1 at 5 A g^-1 after 3000 cycles with 85.6% capacity retention. Interestingly, the CuCo₂S₄ and the other Cu/Co mixed sulfides obtained after Cu incorporation show greatly enhanced sodium storage capacity, cycling stability, and rate capability, as compared with the single metal sulfides (CoS_x or CuS_x). DFT calculations reveal that CuCo₂S₄ displays smaller energy barriers for Na⁺ migration and higher polysulfide adsorption capability than those for CoS_1.035. The synergistic interaction of bimetallic Co/Cu sulfides greatly enhances the redox reactivity with fast Na⁺ transport kinetics, lower charge transfer resistance, and suppressed polysulfide shuttle effect during cycling, which corroboratively contributes to the superior cycling performance of CoCuS-2. Moreover, the CoCuS-2||Na₃V₂(PO₄)₃ full cell demonstrates good cycling performance, delivering 255.9 mA h g^-1 at 1 A g^-1 after 700 cycles with 80.9% capacity retention.