Materials Chemistry Frontiers最新文献

Quantum dots are nano-sized semiconductor particles showing peculiar optical properties due to the quantum confinement effect. They can efficiently absorb photons and generate excitons, leading to a stable fluorescence emission decisive to designing light-sensitive devices, or they can exert a pronounced photoactivity that favors their use in photocatalysis and photodynamic fields. Among the inorganic quantum dots, ZnO ones show unique optical and electronic properties together with low toxicity, good biocompatibility, and excellent photochemical stability. These features can be deeply influenced by tuning their size, surface, and/or bulk defects as well as by doping. Doping with anionic atoms represents an intriguing alternative to cationic metals to improve ZnO activity. Here, the emission behaviour and photoactivity of fluorine-doped ZnO quantum dots were simultaneously studied as a function of fluorine content and synthesis conditions (e.g., wet-precipitation or solvothermal) adopted for the fabrication. The obtained results demonstrated that a low fluorine content (<5 nominal at%) was pivotal to induce a significant enhancement of the relative emission quantum yield of quantum dots from the wet-precipitation route, while a high photocatalytic activity was guaranteed for those obtained by a solvothermal strategy due to the bulk distribution of atomic defects.

Photocatalysis based on the organic polymer semiconductor, g-C₃N₄, is a green technology, but effective energy conversion is still limited by the small light absorption range and high photogenerated carrier complexation rate of g-C₃N₄ photocatalysts. The introduction of organic molecules into the g-C₃N₄ backbone has become a design hotspot for optimising g-C₃N₄ performance. In this review, recent developments in the morphology of g-C₃N₄-based composites as photocatalysts, strategies for the preparation of organic compound/g-C₃N₄ composites and the applications of organic compound/g-C₃N₄ composites in photocatalysis are introduced. The perspectives on future directions of organic compound/g-C₃N₄ composites are discussed.

Radiotherapy (RT) is a cornerstone of cancer treatment, and the radiation dose is the key factor determining its lethality. However, achieving ideal therapeutic effects requires balancing the radiation tolerance of tumor cells and the damage to surrounding healthy tissues by selecting the optimal radiation dose. Herein, we developed gold-coordinated porphyrin conjugated microporous polymers (Au-CMP) as novel radiosensitizers, aiming to achieve optimal therapeutic effects at low radiation doses. These polymers were synthesized and PEGylated to form nanoparticles (Au-CMP NPs) that enhance both photodynamic therapy (PDT) and RT by utilizing porphyrin structures for efficient singlet oxygen generation and superior radiation absorption by the high-Z element Au. In vivo studies with BEL-7402 tumor-bearing mice have confirmed that under the mediation of Au-CMP NPs, even a low dose of X-ray irradiation can exhibit significant tumor suppression effects. Furthermore, when combined with PDT, tumor proliferation is further inhibited, a finding that has also been validated in cellular experiments through increased DNA damage and reactive oxygen species generation. This research underscores the potential of Au-CMP NPs as a multifunctional, biodegradable platform to improve cancer treatment outcomes through integrated PDT and RT. The innovative approach of integrating Au-CMP NPs into cancer therapy may pave the way for more effective and less invasive treatment options, ultimately benefiting patients directly.

Defect engineering is a pivotal avenue to improve the efficiency and activity of photocatalysts in the realm of photocatalysis. In this work, we synthesized MoS₂ with different S defect concentrations by adding lithium iodide to the synthetic MoS₂ precursor solution. The existence of S defects and their concentration were confirmed by TEM and XPS techniques. The results showed that the defect concentration exhibits a volcano-type variation with the addition of lithium iodide. NMSL-6 (adding 6 mmol lithium iodide) has the highest total S defect concentration of 24.5%. Furthermore, we proved that NMSL-6 mainly existed in the type of S stripping defects by EPR techniques, while other samples were mainly composed of S point defects. NMSL-6 exhibited the best methylene blue adsorption capacity and photocatalytic activity due to its large specific surface area and S stripping defects. Compared to high concentrations of S point defects, S stripping defects on the one hand promote the separation of photogenerated electrons and holes, and on the other hand improve the adsorption capacity for O₂, which was 9.4 times that of S point defects, thereby augmenting the ability of NMSL-6 to generate H₂O₂ in photocatalytic reactions. In view of this discovery, this research broadens the field of defect design and provides a new design idea for the practical application of defect engineering in two-dimensional materials.

The insertion of a third component in bulk heterojunction solar cells has led to enhanced power conversion efficiencies (PCEs). However, the rationale beyond the superior performance of ternary solar cells (TSCs) is still a matter of debate and device design is usually based on qualitative considerations. Herein, we present an exhaustive analysis of the kinetics of interfacial charge and energy transfer elementary processes occurring in an archetypal ternary blend, composed of two donors (FG3 and FG4) and one acceptor (Y6). Using molecular dynamics (MD) simulations to generate realistic blend morphologies, coupled with a full quantum mechanical approach to compute reaction rates, we provide insights into the factors contributing to the final PCE of TSCs. Our results indicate that, for the system under study, the presence of two donors allows for more effective solar spectrum coverage, while Förster resonance energy transfer plays a key role in funneling the energy absorbed by FG3 towards a more kinetically efficient FG4:Y6 donor–acceptor pair. Indeed, the FG3:Y6 combination is hampered by slower charge transfer rates, primarily due to energy loss pathways. These findings indicate that even small differences between donor molecules (such as FG3 and FG4) can lead to dramatically different charge transfer kinetics, suggesting that the improved PCE observed in TSCs cannot be easily anticipated through qualitative assessments alone. Instead, device performance is highly sensitive to the intricate interplay of charge and energy transfer processes, highlighting the need for theoretical modeling to accurately predict outcomes. In this respect, we show that our protocol can provide useful elements for a deeper understanding of the physical effects concurring to determine the final PCE of a device, thus enabling a rational design of novel blends for organic solar cells.

In developing organic light-emitting diode (OLED) materials, the luminescence properties of organic emitters and their molecular orientation within the emissive layer significantly impact the luminous effect of the emitting molecules and the device's external quantum efficiency (EQE). This study employs molecular dynamics (MD) simulations to model the vacuum deposition process and density functional theory (DFT) to investigate the molecular characteristics of fluorescence and thermally activated delayed fluorescence (TADF) emitters. The investigation encompassed comprehensive emission molecules for OLEDs, including fluorescent compounds (NaphImide-n and BMA-n series) and donor–acceptor-type TADF derivatives (o-Cz–TRZ, o-DCz–TRZ, and o-TCz–TRZ). Through systematic simulations, we gained deep insight into the molecular deposition behavior, horizontal transition dipole moment distribution properties, emitter luminescence characteristics, and the correlations between these key factors. The molecular orientation and host-dopant interactions play a decisive role in governing the morphology and quantum efficiency of the resulting materials. During the deposition process, the molecular emitting dipole orientation increases following the enlargement of the horizontally oriented TDM of the dopant molecules and the intermolecular van der Waals interaction between the host and the dopant. This work successfully combined MD and DFT methodologies to enhance the understanding of the relationship between the molecular architecture and luminescence efficiency, providing insight for optimizing OLED materials and utilizing their potential for guiding the design of next-generation organic electronics for display and lighting applications.

Core–shell nanostructures are particularly interesting for the development of dual-property nanofillers for nanocomposites. In this study, advanced materials compatible with the commonly used fused deposition modeling (FDM) 3D printing technique are reported for heat dissipation applications. Core–shell nanowires based on a highly thermally conductive silver core coated with an electrically insulating silica shell are investigated. The heat dissipation performance of polycarbonate nanocomposites is analyzed using a comprehensive set of thermal, electrical, mechanical, and rheological characterization studies to determine the optimal silica nanolayer thickness. We demonstrate that these core–shell nanofillers give access to both high thermal conductivity of up to 2.08 ± 0.05 W m⁻¹ K⁻¹, and electrically insulating behavior (electrical resistivity >10¹² Ω cm) at only 3 vol% loading, while retaining very good mechanical strength. The high dispersion and interfacial cohesion of the nanomaterials with the matrix play a key role in achieving these performances. Moreover, thanks to the alignment of the 1D nanofillers during the FDM printing process, the thermal conductivity of the PC nanocomposite reaches an unprecedented value of 3.48 ± 0.06 W m⁻¹ K⁻¹ in the printing direction, i.e. a fifteen-fold increase over the thermal conductivity of neat PC.

In the quest to enhance the performance of white light-emitting diodes (WLEDs), the development of efficient red phosphors is essential. To address this issue, a series of co-doped garnet-type phosphors, NaY₂Ga₂InGe₂O₁₂:Tb³⁺,Eu³⁺ (NYGIG:Tb³⁺,Eu³⁺), were synthesized, utilizing structural confinement to achieve more precise energy transfer and improve luminescence performance. Comprehensive characterization techniques, including powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and elemental mapping, confirmed the structural and compositional features of the phosphors. Na⁺ ions occupy one-third of the eight-coordinated sites in NYGIG, separating Tb³⁺ and Eu³⁺ ions, which improves the precision of energy transfer. Statistical results demonstrate that Na⁺ increases the formation probability of Tb³⁺–Eu³⁺ pairs to 7%, effectively preventing the formation of long Tb³⁺–Tb³⁺ and Eu³⁺–Eu³⁺ chains while the probability of forming a Tb³⁺–Eu³⁺ pair is merely 3.12% in traditional garnets. When the Tb³⁺ doping concentration is 50%, the energy transfer efficiency reaches 95% at an optimal Eu³⁺ doping concentration of 7%. Moreover, the NYGIG:0.5Tb³⁺,0.07Eu³⁺ phosphor achieves a quantum yield of 70.4% and maintains strong luminescence intensity at elevated temperatures, retaining over 85% of its room temperature luminescence intensity at 425 K. The electroluminescence (EL) spectrum of the assembled WLED, powered using a 365 nm near-UV chip, shows balanced white light output with a high color rendering index (CRI ∼ 87) and CIE coordinates of (0.402, 0.380). These findings underscore the significant potential of NYGIG:Tb³⁺,Eu³⁺ phosphors for advancing highly efficient WLED technologies.

Several methodologies have been employed to boost the HER activity of metal–organic frameworks. Herein, iron-based ZIF-67 structures were synthesized with different iron contents, and their HER activity was evaluated in 1.0 M KOH, 0.5 M H₂SO₄ and seawater. Metal contents effectively enhanced the physical characteristics of the Fe@ZIF-67-2 structure, and electrolytic impacts were found to be significant. Structure of the Fe@ZIF-67-2 electrocatalyst exhibited a high specific surface area of 72.21 m² g⁻¹ and electrical conductivity of 14.29 μS cm⁻¹. Fe@ZIF-67-2 also displayed an overpotential of 45 mV and a Tafel slope of 32 mV dec⁻¹ in 1 M KOH electrolyte. Enhancement in the electrical conductivity, mesoporous nature, specific and electrochemical surface area promoted the flow of active charge carriers, facilitated the adsorption and desorption process at the active sites and led to a good electrocatalytic activity of the Fe@ZIF-67-2 structure. It also exhibited a greater turnover frequency of 129.35 ms⁻¹ at a fixed V_RHE of 0.8 V. Suitable intercalation of the electrolyte ions on the surface of the electrocatalyst is another significant factor in the production of H₂ molecule and led to an enhancement in the HER efficiency of Fe@ZIF-67-2. Hence, the electrocatalyst Fe@ZIF-67-2 showed a good electrocatalytic HER activity in 1 M KOH.

Mitochondria play an important role in regulating programmed cell death and various available mitochondrial-targeting photosensitizers are modified by cationic groups, especially triphenylphosphine (TPP). However, it's still a big challenge to develop novel mitochondrial-targeting photosensitizers, especially those that possess better performance than traditional TPP-modified photosensitizers. In this work, three cationic boron-dipyrromethene (BODIPY) nanoparticles with different mitochondrial-targeting groups (triphenylphosphine, trimethylamine and 1-methylimidazole) were designed and synthesized for enhanced photodynamic therapy. These BODIPY nanoparticles (BDPI NPs) could be endocytosed by various cancer cells and dissociated in the lysosomes. Subsequently, they escaped from the lysosomes due to the “proton-sponge” effect and were enriched on the inner membrane of mitochondria for enhanced photodynamic therapy. BDPI NPs could generate not only singlet oxygen (¹O₂) but also superoxide anions (O₂⁻˙), showing great type I and II photodynamic activity. Compared with TPP and the trimethylamine substitution, the 1-methylimidazole-modified nanoparticles (BDPI-IMA NPs) exhibited the most efficient mitochondrial-targeting capability and the most excellent photodynamic activity. This work highlights the great potential of 1-methylimidazole-modified photosensitizers and nanoparticles as highly efficient mitochondrial-specific probes and phototherapy agents.