Materials Chemistry Frontiers最新文献

Friedel oscillations (FOs) are quantum mechanical phenomena observed as oscillatory variations in electron density due to the presence of impurity or defect in a medium containing electron gas. FOs profoundly influence surface properties, including the ordering of adsorbates and surface-mediated interactions crucial for catalytic activity. We delve into both experimental and theoretical aspects of FOs, organizing our discussion around the physicochemical systems of interest, the decay pattern, wavelength, and amplitude of FOs caused by different perturbations. Additionally, we present a systematic derivation of perturbed charge density distributions in one-, two-, and three-dimensional systems and establish a conceptual link between FOs, electron delocalization, and the mesomeric effect, using the electron delocalization range function (EDR), offering insights into the reactivity of molecules featuring conjugated bonds. Finally, we propose an effective way to extend the analytical approach native to solid-state physics to describe charge oscillations in cumulenes and polyynes.

Broadband near-infrared (NIR) phosphors are essential for assembling portable NIR light sources. However, the development of efficient and stable broadband NIR phosphors remains a major challenge. This work designed an ultra-high efficient NIR-emitting Cs₂KSc_0.83Ga_0.1F₆:0.07Cr³⁺ phosphor by substituting Sc³⁺ with a Ga³⁺ ion. This cationic substitution strategy enables the internal quantum efficiency of NIR emission to reach a staggering high of 98.56%, almost 100%, along with excellent thermal quenching resistance (I_423K = 62.4%). The Ga³⁺ → Sc³⁺ replacement lowers the local site symmetry and overcomes the parity selection rule, rendering the electronic transitions with much larger oscillator strength and thus improved optical properties. The NIR phosphor conversion light emitting diode (pc-LED) based on Cs₂KSc_0.83Ga_0.1F₆:0.07Cr³⁺ demonstrated a premium photoelectric conversion efficiency of 31.46% at 40 mA. The potential of the pc-LED as a light source for night vision and anti-counterfeiting has also been demonstrated. These results highlight the phosphor's performance improvement via a cationic substitution strategy and demonstrate the practical application potential of the broadband Cr³⁺-based NIR phosphor in the design of high-efficiency devices.

Characteristic photon emissions in low-dimensional hybrid perovskites are strongly related to inherent distortions in the crystal lattice. These cooperative distortions, influenced by organic spacers and the confined BX₆ octahedral arrangement, allow for the manipulation and control of the emitted photon energy and its nature. Herein, we observed a complex dynamic where photon emissions at both low and high energies emerge, depending on octahedral distortion and the application of hydrostatic pressure. Our results demonstrated that samples featuring different octahedral sizes and distortions but having a common organic spacer (BA₂MAPb₂Br₇ and BA₂MAPb₂I₇) showed low-energy photon emission attributed to self-trapped excitons (STEs), which can be tuned towards free exciton (FE) states through pressure annealing. Experimental and theoretical results revealed that octahedral distortions in 2D perovskites played a crucial role in controlling emission, disclosing their complex structure and electronic relationship.

Multidrug-resistant (MDR) bacterial infection is currently one of the pressing threats to human health globally. Photodynamic therapy (PDT) based on AIE-active photosensitizers (PSs) has garnered significant attention as a competitive and promising alternative for microbial elimination because of its noninvasiveness, photoswitchable controllability, and minimal drug resistance. The existing molecular engineering strategies prevailingly focus on the tuning of donor/π bridges and/or peripheral rotors. However, the regional tuning of a positively charged center, as a critical point of photosensitizers (PSs), is of great meaning but still remains rarely reported. Herein, we tactfully developed two benzoquinolizinium-based regioisomeric PSs, TPA-BQZ-1 and TPA-BQZ-2, with differently located positive charge centers. The targeted regioisomers could be obtained through a one-step facile strategy with superior step- and atom-economy, in contrast to the widely developed linear-shaped D–π–A type antibacterial PSs, which require stepwise sequential binding of different functional segments via multi-step coupling reactions. The distinctive molecular structures endowed TPA-BQZ-1 and TPA-BQZ-2 with typical AIE features and high-efficiency ROS output ability by both type I and type II pathways. Both regioisomeric PSs could achieve effective MDR bacterial eradication yet dominated by different pathways, highlighting the critical role of the positively charged position in antibacterial PSs. By comparison, the antibacterial performance of TPA-BQZ-1 is dominated by phototoxicity. Conversely, the intrinsic dark toxicity of TPA-BQZ-2 exerted a great influence on the antibacterial efficiency, maybe stemming from the strong membrane interaction and the resulting membrane permeability. This study demonstrates an ingenious regioisomeric engineering strategy and offers useful guidance for the development of advanced antibacterial agents.

Exploring multifunctional absorbents for the concurrent detection and elimination of heavy metal ions (HMIs) presents a significant challenge. In this study, dual defective bimetallic metal–organic framework materials (D-D-UIO-66) are synthesized by the solvothermal method. The incorporation of an acid and Ce³⁺ simultaneously introduces ligand defects and lattice defects, which provides a massive defective synergistic effect to enhance the intrinsic properties of D-D-UIO-66. D-D-UIO-66 can simultaneously detect Pb(II), Cd(II), Hg(II), and Cu(II), exhibiting high sensitivities of 15.209, 10.092, 2.829, and 1.347 μA μM⁻¹, respectively. D-D-UIO-66 also demonstrate excellent stability and anti-interference capabilities, and it has been effectively applied in real water environments. On the other hand, D-D-UIO-66 can remove Pb(II) from the water environment and achieve a maximum adsorption of 667.04 mg g⁻¹. The mechanisms behind the electrochemical detection and adsorption activities of D-D-UIO-66 are explored, which reveal that the synergistic interplay between distinct defects enhances the electronic microstructure, consequently boosting both electrochemical detection and adsorption capabilities. This study presents a strategy for multifunctional adsorbents, advancing the understanding of defect engineering and its influence on the fundamental mechanisms of material behavior.

The α,β-unsaturated carbonyls are important precursors in pharmaceuticals, plastics, and lubricants. While traditional condensation of aldehydes and ketones requires extensive separation due to unwanted self-condensation of carbonyls, oxidative condensation of alcohols requires organic solvents and costly homogeneous catalysts. Electrochemical oxidative condensation of alcohols provides an alternative solution for the synthesis of α,β-unsaturated carbonyls, yet the performance needs to be enhanced for practical applications. Here, we present a two-electrode system for oxidative condensation of alcohols in aqueous KOH electrolyte, which enables direct synthesis and collection of α,β-unsaturated carbonyl solids under ambient conditions using low-cost electrocatalysts. The anode is a calcined NiFe layered double hydroxide (LDH), which promotes the oxidation of alcohols and avoids the oxygen evolution reaction from water oxidation at a low bias. The cathode is a CuFe-LDH that displays a decent HER performance and avoids the hydrogenation of the generated product. Additionally, the basic electrolyte accelerates the condensation of carbonyl intermediates into corresponding α,β-unsaturated carbonyl solids. The system only requires a voltage of 1.6 V for the synthesis of a variety of α,β-unsaturated carbonyls, rendering it a promising solution for sustainable synthesis.

Achieving uranyl photoreduction using copolymers with low exciton binding energy (E_b) from radioactive wastewater holds great promise, but is extremely challenging. Side chain engineering offers more opportunities for developing new copolymers with lower E_b. However, the introduction of side chains is not completely “painless” and often leads to molecular skeleton distortions, which significantly reduce photocatalytic activity. Herein, a promising strategy is employed to balance the twisted structures by enabling “hydrogen bond locks” on the side chains, thereby promoting exciton dissociation and enhancing uranyl photoreduction. As a proof of concept, two conjugated polymers with identical poly(benzene-benzothiadiazole) backbones but different side chains (methyl and methoxy) on the benzene ring are investigated. These variations in side chains greatly impact the optical gap, electronic structure, and exciton dissociation of the polymers. Through the intramolecular noncovalent O⋯H interactions between the oxygen atoms in methoxy groups and the adjacent hydrogen atoms in benzothiadiazole units, the methoxy functionalized copolymer (CP-OMe) with minimized E_b exhibits an exceptional uranium extraction capacity of 946.5 mg g⁻¹ without adding any sacrificial agent, surpassing those of most currently reported polymers.

Two-dimensional transition metal dichalcogenide (TMD) quantum sheets (QSs) with intrinsic characteristics promise new research topics and applications. However, their absolute photoluminescence quantum yield (PLQY) is far from being satisfactory. Herein, we report a general PL enhancement strategy based on passivation with polar solvent. The edge-passivated TMD QSs demonstrate solid-state fluorescence with high PLQYs. The material diversity of the passivation strategy is testified by using tungsten disulfide (WS₂), molybdenum diselenide (MoSe₂), bismuth selenide (Bi₂Se₃), and tungsten diselenide (WSe₂) as examples. Particularly, the passivated WS₂ QSs (P-WS₂ QSs) in poly(methyl methacrylate) exhibit an exceedingly high PLQY of 27.7% compared with that (4.1%) of the intrinsic WS₂ QSs. Furthermore, the P-WS₂ QSs are utilized in commercial light-emitting diodes (LEDs), enabling white-light emission which can be filtered into a sharp, blue emission, thus they function as highly luminescent blue LEDs. Note that the intrinsic WS₂ QSs are almost inert to commercial LEDs, which in turn indicates the unique contribution of the P-WS₂ QSs. Our work highlights the great potential of passivated TMD QSs in applications such as LEDs.

Herein, Zn was introduced to regulate the tetrahedral coordination of Co₃O₄ and then leached out via alkaline impregnation. Experimental characterization indicated that the generation of tetrahedral defects significantly enhanced the electrocatalytic oxygen evolution reaction (OER) activity. Theoretical calculations showed that these selective defects endowed the adsorption sites with a moderate d-band center, thus optimizing the binding strength of intermediates.

Efficient conversion of mechanical energy to electrical energy through piezoelectric catalysis has found diverse applications, such as sterilization, water treatment, organic synthesis, and biomass conversion. Among these, antibacterial agents based on piezoelectrically active materials have emerged as promising alternatives to conventional antibiotics for the treatment of bacterial diseases and remediation of water pollution caused by bacterial pathogens, with no bacterial resistance and side effects because of their fast and effective bactericidal actions. Herein, the general mechanisms of piezoelectric catalysis are reviewed, and commonly used piezoelectric antibacterial agents are highlighted, including semiconductors (metal oxides, metal sulfides, and ceramics), heterojunction composites (e.g., metal–semiconductor heterojunctions and semiconductor–semiconductor heterojunctions), and organic piezoelectric materials. Leading strategies for further enhancement of the materials’ piezoelectric properties are also discussed, such as doping, compositing, and structural coupling. We conclude the review with a summary of the remaining challenges and a perspective for future research.