Materials Chemistry Frontiers最新文献

Photocatalytic reactions are driven by excited charge carriers; therefore, their performance inherently depends on photocarrier behavior. In this study, we examine the relationship between photocarrier behavior and the photocatalytic activity of g-C₃N₄ loaded with single Cu atoms for the selective oxidation in water. As probed with transient microwave conductivity, the introduction of single Cu atoms enhances photoconductivity by increasing the mobility and extending the lifetimes of photoexcited electrons. This enhancement results in a greater population of mobile electrons. While pristine g-C₃N₄ exhibits no measurable photoconductivity, it is still capable of driving photocatalytic reactions. This suggests that in g-C₃N₄, photoexcited electrons are predominantly trapped rather than recombined, yet they are sufficiently reactive. The product of photoconductivity and electron lifetime shows a linear correlation with photocatalytic activity, demonstrating its potential as a promising descriptor for catalyst design. In terms of performance, our photocatalysts achieve a yield-to-power ratio of up to 1.1 mmol g⁻¹ h⁻¹ W⁻¹ for benzaldehyde production from benzyl alcohol under 455 nm irradiation with 100% selectivity and aromatic balance and an apparent quantum yield of 0.82%. The reaction proceeds under ambient conditions without the need for additives or external oxidants. Equally important, H₂O₂ is also produced at a rate as high as 0.26 mmol g⁻¹ h⁻¹.

Three-dimensional (3D) cell culture and cell spheroid models have recently emerged as more realistic experimental platforms in life sciences, bridging the gap between two-dimensional (2D) cell cultures and animal models. However, the formation of necrotic cores in cell spheroids presents a challenge for their wider use in drug testing. Here, we report a novel method of using an aqueous two-phase system (ATPS)-based capillary suspension to generate 3D structured cell networks which opens new possibilities for the assembly of tissues from adherent cells. We demonstrate the fabrication of 3D cell networks with different microstructures and morphologies from capillary cell suspensions. These were formed by the addition of a small volume fraction of dextran solution in culture media (DEX) as a secondary aqueous liquid phase to a concentrated cell suspension into a polyethylene glycol solution in culture media (PEG) as a primary immiscible aqueous phase. The formation of water-in-water (DEX-in-PEG) capillary bridges among the cells is responsible for transforming of the cell suspension into an innovative tissue-like biomaterial where the cells are connected in spanning networks. The wettability of adherent cells by the involved phases and their interfacial tension were investigated and correlated to the microstructures formed. Enhanced rheological properties were obtained at 2 vol% of DEX phase, where the maximal yield stress of the capillary cell suspension was achieved. Capillary cell suspensions with DEX phase volume percentage higher than 2 vol% changed their structure from cell networks to spheroidal cell aggregates, yielding cell spheroids. Cell viability was not impacted by long-term incubation in a DEX/PEG capillary suspension environment. We envisage how the present approach can pave the way for innovative and cost-effective preparation of cell structures for potential application in 3D cell culture and scaffold-free tissue engineering.

Silicon anodes are extensively investigated as a leading candidate for next-generation lithium-ion battery anode materials. However, challenges, including severe side reactions and substantial volume expansion, which result in rapid capacity fading, remain significant obstacles to their further application, particularly under high-rate charge/discharge conditions. In this study we designed a multifunctional sulfur-doped carbon layer (SDCL) on the silicon of particle surfaces. DFT demonstrates that sulfur doping modifies the carbon layer's electron cloud distribution to enhance electronic conductivity while reducing lithium-ion diffusion energy barriers, thereby facilitating fast-charging of the silicon anode. Moreover, the incorporation of sulfur promotes the formation of a more stable solid electrolyte interphase, which stabilizes the silicon structure and improves cycling durability. The resulting silicon-based anode material exhibits superior rate capability and retains 95% of its capacity after 200 cycles, with a specific capacity of 920 mA h g⁻¹. Finally, the full cell displays a capacity retention of 72.9% after 100 cycles at 2 C. In summary, this work highlights the impact of interface modification by sulfur doping on the silicon anode materials, hence offering a new approach for the development of fast-charging and durable silicon anodes in lithium-ion batteries.

Nitrogen doping of graphene is one of the most effective methods to open the zero-band gap of graphene, presenting a promising approach to modify its electronic structure. In this report, we introduce a novel method for growing large-area N-doped graphene directly on copper foil using atmospheric-pressure chemical vapor deposition (APCVD) using the pyrolysis of acetonitrile. In situ mass spectrometry combined with APCVD gave insights into the contribution and behavior of different species during the formation of N-doped graphene. Density functional theory calculations, paired with experimental results, were employed to study the growth mechanism of N-doped graphene with acetonitrile. Furthermore, the synthesized N-doped graphene was investigated as an electrode material for vanadium redox flow batteries (VRFB), focusing on its catalytic activity for the V(IV)/V(V) redox reaction. These findings not only deepen our understanding of the growth mechanisms of N-doped graphene but also provide a foundation for its application in energy storage systems, offering guidance for the synthesis of doped graphene and carbon nanotubes for advanced electrode materials in VRFB and beyond.

Carbon dot (CD)-based room temperature phosphorescence (RTP) materials have widespread applications in anti-counterfeiting, light-emitting diode (LED) lighting, and bioimaging due to their spectral tunability, long lifetime, and other excellent optical properties. However, challenges remain regarding their complicated preparation processes and unclear mechanism. In this work, we developed a one-step, in situ liquid-phase synthesis method using phthalic acid, formamide, and ethylene glycol to directly form RTP CDs@phthalamide composites with CD/organic crystal structures. The product required only filtration and drying without further post-processing, significantly simplifying the preparation procedure and facilitating large-scale production. The as-prepared CDs@phthalamide exhibit excitation-dependent phosphorescence with a naked-eye-visible afterglow of 5 s and a phosphorescence lifetime of 441 ms. The formation process and reaction mechanism of CDs@phthalamide were investigated by optimizing the reaction temperature and reaction time, calculating activation energies through theoretical simulations, and comparing the effect of different crystal structures of phthalamide and phthalimide crystals on luminescence. Unlike phthalimide, the phthalamide matrix effectively restricts the vibration and rotation of CD luminous centers, realizing efficient RTP emission. Density functional theory (DFT) calculations further verified that the N elements enhanced RTP performance. In addition, CDs@phthalamide shows potential application value in time-delayed LEDs and anti-counterfeiting.

Drug resistance and serious side effects are persistent obstacles in chemotherapy. Tumor microenvironment modulation is an emerging strategy to sensitize chemotherapy; however, the relevant side effects caused by chemotherapeutic drugs remain non-negligible. Herein, we constructed a cysteine-reactive, cyano-functionalized acenaphthopyrazine derivative for cisplatin sensitization and side effect reduction by regulating the tumor microenvironment. The developed cyano-functionalized acenaphthopyrazine derivative exhibited appropriate reactivity toward cysteine via an addition reaction. The incorporation of the cyano group not only improved the cellular uptake efficiency of cisplatin but also suppressed the drug inactivation behavior of tumor cells by reducing the expression of GSH within tumor cells. Moreover, selective inhibition of tumor cells was achieved due to the differing GSH dependence between normal and tumor cells. Most importantly, in vivo experiments revealed that the combination of the cyano-functionalized acenaphthopyrazine derivative with cisplatin could efficiently reduce liver and kidney damage during treatment. Our results demonstrated that cysteine consumption could serve as a general strategy for chemotherapy sensitization.

High-performance sodium-ion batteries (SIBs) represent an optimal energy solution for flexible wearable devices, with the design and development of advanced anodes being crucial in determining their overall performance. A major challenge for flexible electrodes is achieving both high energy density and long-term cycle stability. To address these issues, a Fe₇S₈ microsphere/N-doped carbonized silk textile as a self-supporting anode for SIBs is developed. Fe₇S₈ microspheres are anchored onto a three-dimensional carbon network derived from silk fabric via electrostatic adsorption followed by calcination. The as-prepared flexible self-supporting Fe₇S₈ microsphere/N-doped carbonized silk textile demonstrates exceptional mechanical durability, maintaining structural integrity and stable resistance after 2000 bending cycles. Electrochemical performance shows a notable areal capacity of 1.42 mA h cm⁻² at 0.3 mA cm⁻², along with impressive cycling stability. After 600 cycles at 5 mA cm⁻², it maintains 0.39 mA h cm⁻², with a modest capacity loss of 21% at high current density. It also demonstrates excellent rate performance, achieving reversible capacities of 1.67, 1.32, 1.12, 0.87, 0.71 and 0.37 mA h cm⁻² at current densities of 0.1, 0.3, 0.5, 1, 2 and 5 mA cm⁻², respectively. The microsphere structure of Fe₇S₈ ensures extensive contact with the electrolyte, enhancing ion accessibility and structural stability. The carbonized silk textile provides higher flexibility, which helps alleviate strain during deformation. Simultaneously, the N-doped carbon network derived from silk fabric offers additional Na⁺ adsorption sites, and facilitates efficient electron and ion transport. Moreover, the excellent mechanical flexibility of the electrode offers promising prospects for its potential application in flexible wearable electronic devices.

Crystallization within small volumes of solutions rather than bulk solutions is a common phenomenon found during material synthesis and biomineralization processes. However, the driving forces for mass transport and crystallization in confined environments remain elusive. Herein, inspired by the intrafibrillar collagen mineralization process, we investigate the infiltration and crystallization mechanisms of fluorapatite (FAP) within confined channels by comparing anodic aluminum oxide and track-etched templates with different surface properties. The results demonstrate that similar to intrafibrillar collagen mineralization, capillary force, along with a specific interaction between the confined channel surface and mineral precursors, is the main driving force for the initial infiltration of liquid precursors into confined channels, leading to the nucleation of FAP nanocrystals on the surface of the channels. We elucidate the critical role of negatively charged polyacrylic acid in promoting the formation of liquid precursors for successful infiltration into confined channels and controlling crystallization kinetics within the channels. The formation of FAP nanorods, followed by further promoting ion diffusion via a concentration gradient, resulted from the lower local concentration surrounding the FAP crystals. Furthermore, FAP nanocrystals exhibit progressive alignment along the channel direction during the subsequent crystal growth stage, and ultralong FAP nanorods with a length of more than 25 μm could be obtained. The collective findings underscore the pivotal role of the structure and surface properties of nanoscale confined environments in controlling the infiltration and crystallization pathways of inorganic crystals and establishing a foundation for the controlled synthesis of biomimetic materials under confinement.

An unprecedented approach for synthesizing strontium manganese perovskite oxides (ABO₃) and their B-site substituted variants (SrMn_1−xFe_xO₃) was employed using the molten salt synthesis route. This study aims to investigate the intrinsic property changes of perovskite oxide materials and their electrochemical response, particularly in the bifunctional oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Systematic substitution at the B-site induces a phase transition from hexagonal to trigonal, and then to orthorhombic, which was confirmed through Rietveld refinement of XRD data, along with SEM, TEM and XPS analyses. The multiple oxidation states of manganese (Mn³⁺/Mn⁴⁺) and iron (Fe³⁺/Fe²⁺) at the B-site play a crucial role in redox reactions. Furthermore, the orthorhombic brownmillerite phase (Sr₂MnFeO₅) promotes the ORR even without conductive support, which is attributed to its intrinsic conductivity stemming from the specific distribution of oxygen vacancies. The favorable adsorption/desorption energies of oxygen intermediates are a result of regulated electron filling in the d orbitals. The SrMn_0.7Fe_0.3O₃ variant was evaluated as a bifunctional electrocatalyst, showing an onset potential of 0.99 V vs. RHE for the ORR, and demonstrated excellent performance in rechargeable zinc–air batteries (ZABs), with a high peak power density of 114 mW cm⁻² and a long cycle life of over 262 hours, exhibiting a specific capacity of 680 mA h g⁻¹. The unique structural properties of SrMn_0.7Fe_0.3O₃ make it a promising candidate for ZAB applications.

The exploration of novel phosphors with excellent properties is of great significance for both fundamental research and practical applications in optoelectronic devices. In this study, we report the synthesis of a new 0 dimensional (0D) organic–inorganic hybrid metal halide (OIHMH), C₆H₁₄N₂ZnCl₄, doped with Mn²⁺ ions, which exhibits bright green emission centered at 535 nm, originating from the d–d transition of tetrahedrally coordinated Mn²⁺ ions. The sample exhibits a photoluminescence quantum yield (PLQY) of 70% at a doping concentration of 40% and demonstrates good thermal stability, with luminescence intensity restored after a heating–cooling cycle. The as-prepared Mn²⁺-doped C₆H₁₄N₂ZnCl₄ crystals were further utilized to fabricate white light-emitting diodes (WLEDs), which demonstrated good performance with a correlated color temperature (CCT) of 6003 K and a color rendering index (CRI) of 79. Additionally, the doped crystals showing bright green emission were explored for anti-counterfeiting applications, and they show promising potential in security marking. This work highlights the potential of Mn²⁺-doped OIHHPCs as high-performance phosphors for optoelectronic applications and security purposes.