Materials Chemistry Frontiers最新文献

Exploiting the near-infrared (NIR) photochromic dithienylethenes (DTEs) triggered by visible light is urgently needed for various biological scenarios. However, all the NIR photochromic DTEs reported so far are located in the first NIR window (NIR-I, 700–900 nm), which usually shows shallower penetration in biological tissues due to autofluorescence and photon scattering compared to NIR light in the second window (NIR-II, 1000–1700 nm). Herein, we present a novel quinoxalinone-functionalized DTE derivative (QDTE) with acceptor (A)–DTE (D)–acceptor (A) structural features, in which electron-withdrawing quinoxalinone groups ensure visible light-driven NIR I photochromism. Besides, the facile protonation of the quinoxalinone moieties favors the formation of the more electron-deficient A′–D–A′-type DTE (QDTE-2H, where A′ is a stronger electron-withdrawing unit) for a unique NIR II photochromism by reducing the HOMO–LUMO energy gap of a closed isomer after protonation. As expected, the resulting QDTE displays a blue light-controlled NIR I photochromic performance in various solvents. Furthermore, an unprecedented green light-triggered NIR II photochromism for the in situ protonated QDTE-2H is successfully implemented in CHCl₃ and toluene in the presence of trifluoroacetic acid (TFA), representing the first case of NIR II photochromic DTE. By virtue of these properties, QDTE has been successfully applied in dual information encryption, demonstrating its versatility in functional materials.

The electrochemical CO₂ reduction reaction (CO₂RR) underlies a strategic approach to energy and environmental challenges. Large-sized materials offer industrial scalability due to their simplicity and cost-effectiveness. However, traditional large-sized Cu catalysts preferentially catalyze the hydrogen evolution reaction (HER) over the CO₂RR. Hence, the development of large-sized catalysts with enhanced reducibility is imperative for an efficient CO₂RR. In this study, a large-sized Cu@Ag catalyst was designed using electrodeposition, which enhanced the CO₂RR and suppressed the HER. The faradaic efficiency (FE) for hydrocarbons of the Cu@Ag catalyst was 59.8%, surpassing that of bare Cu nanoparticles by 21.4%. FE_H2 was notably reduced to 31.6%, compared to 63.0% for Ag foil and 55.2% for bare Cu nanoparticles. Theoretical calculations indicated a reconfiguration of Cu 3d orbitals in the Cu@Ag catalyst. The d_x²−y² orbital, being the highest occupied, modulated the affinity of CO₂ molecules and favored hydrocarbon formation. Additionally, the charge density at the Cu@Ag boundaries increased, facilitating C–C coupling. In particular, the C₂H₄/CH₄ ratio was enhanced by approximately 30-fold compared to using bare Cu nanoparticles. This study demonstrated that the synergistic mechanism of the Cu@Ag catalyst is key to enhancing the CO₂RR and inhibiting the competing HER, thus elucidating the molecular mechanisms for the conversion of CO₂ into valuable chemicals using large-sized Cu-based catalysts.

We report on the synthesis and investigation of new multifunctional Prussian blue (PB) nanoparticles coated by a mesoporous silica shell and loaded with a luminescent [(Tb/Eu)₉(acac)₁₆(μ₃-OH)₈(μ₄-O)(μ₄-OH)]·H₂O complex. These multifunctional nano-objects work as efficient photothermal nano-heaters able to provide macroscopic temperature rises remotely triggered by light irradiation at 808 nm (ΔT = 20.4 °C under irradiation for 3 min with a laser power of 1.83 W cm⁻²). Their specific heat capacity, the primary parameter influencing the heating properties of nanoparticles, was determined by using the photothermal properties and the measured heat capacity of PB nanoparticles, yielding a value of 1.13 ± 0.03 J g⁻¹ K⁻¹. This moderate value indicates that once heated, the nanoparticles can retain heat effectively, making them suitable for applications requiring sustained and controlled thermal effects. On the other hand, these multifunctional nanoparticles exhibit the characteristic temperature-dependent luminescence of Tb³⁺ and Eu³⁺ with improved Tb³⁺-to-Eu³⁺ energy transfer, making them efficient as luminescent ratiometric thermometers. These nanothermometers operate in the 20–80 °C range exhibiting a maximal relative thermal sensitivity of 0.75% °C⁻¹ at 20 °C.

Methanol fuel can be used as a clean alternative to conventional gasoline. However, vehicles using methanol fuel typically exhibit low exhaust temperatures during the cold start and idle phases, which may result in the emission of unburned methanol vapor. Herein, a series of CeO₂-based solid solutions doped with different metal ions (CeM, M = Mg, La, Bi, Zr) are synthesized by a hydrothermal synthesis method, and supported Pd/CeM catalysts with regular interfacial structures are prepared by a special assembly method for the low-temperature deep oxidation of methanol. The results of XRD, N₂ adsorption/desorption, Raman spectroscopy, XPS and H₂-TPR show that the crystal structure, specific surface area, defect concentration, surface oxygen vacancy content, high-valence Pd^δ+ (δ > 2) species content and redox performance of the Pd/CeM catalyst are closely related to the type of doped metal ions. The catalytic performance results show that the Pd/CeLa catalyst exhibits the best low-temperature methanol oxidation activity, with a light-off temperature (T₅₀) of 118 °C and full conversion temperature (T₉₀) of 155 °C, which is at a high level under the same conditions reported in the literature. This is mainly attributed to its high defect concentration, high oxygen vacancy and more hypervalent Pd^δ+ (δ > 2) species content as well as excellent low-temperature reduction performance. The results of this study demonstrate the promise of the Pd/CeLa catalyst for methanol oxidation and may offer guidelines for designing efficient catalysts for purification of methanol fuel from vehicle exhaust.

The tremendous potential of high-entropy alloys (HEA) in the electrocatalysis of the oxygen evolution reaction (OER) is well known, but many issues pertaining to building more reliable HEA systems to maximize its synergistic advantages and explaining their complex electrochemical interface behavior need to be discussed. Herein, a convenient composite metal–organic framework (MOF) co-pyrolysis method is designed to reconstruct the precursor in a high-temperature inert atmosphere and prepare a core–shell structure nitrogen-containing carbon nanotube-coated six-metal alloy (FeCoNiVCrZn HEA) as an excellent alkaline medium OER catalyst. It can achieve a working current density of 10 mA cm⁻² at 249 mV overpotential, and the current fluctuation range is less than 3.12% after constant voltage operation for an extended time in 1 M KOH electrolyte. Its electrocatalytic activity and stability surpass those of the same type of alloy catalyst and commercial IrO₂/C catalyst. We tracked the trend of the concentration and chemical state of metal ions between two phases during the electrochemical process and found that the interface reconfiguration of the high-entropy alloy is regulated by the characteristic transition metal migration behavior. On this basis, through density functional theory (DFT) calculation, we further explored the alkaline medium surface metal dissolution and surface reconfiguration behavior and verified that the active MOOH (M = Fe, Co and Ni) phase plays a key role in the reaction steps for the adsorption of the oxygen species. This work provides a unique perspective for the study of HEA in OER structure optimization and interface behavior and shows a new prospect for the development of advanced OER electrocatalysts.

The inherent structural instability of red-emitting cesium lead iodide (CsPbI₃) perovskite quantum dots (QDs) poses a significant hurdle for their integration into commercial optoelectronic devices. In this study, we improved the stability of the cubic CsPbI₃ QDs by coating them with a Cs_xFA_1−xPbI₃ (FA = formamidinium, x = 0.25 or 0.75) cluster via a facile direct arrangement synthesis method. The resulting CsPbI₃/Cs_xFA_1−xPbI₃ exhibited visible luminescence between 600 and 650 nm, a full-width half maximum of 38 nm, and a high photoluminescence quantum yield of 86.66%. Unlike in the case of bare CsPbI₃, no discernable photoemission peak shift was observed for CsPbI₃/Cs_0.25FA_0.75PbI₃ in particular at temperatures of up to 373 K and under UV illumination. Moreover, a more sustained luminescence of up to 25 min in the polar solvent was observed for CsPbI₃/Cs_0.25FA_0.75PbI₃ compared to CsPbI₃ in less than 5 min. These resistances to thermal stress and degradation in polar solvents were attributed to the passivation of the CsPbI₃ particles by the pseudo-orthorhombic Cs_xFA_1−xPbI₃ cluster. DFT calculations revealed that the addition of FA substantially changes the morphology of CsPbI₃, but FA itself does not contribute significantly to the electronic transitions within the crystal. Therefore, the Cs_xFA_1−xPbI₃ cluster on the surface of CsPbI₃ promoted their structural stability without any significant changes in its desired optical properties. These results offer unique optical characteristics while boosting the structural robustness of CsPbI₃ QDs by surface modification, which potentially could be used for optoelectronic devices.

Proton exchange membrane water electrolyzers (PEMWEs) play a key role in promoting the development of the clean hydrogen energy industry and accelerating the achievement of carbon neutrality goals due to their advantages of high efficiency, low energy consumption, ease of integration and fast response. In PEMWEs, the water oxidation reaction in the anode catalytic layer is the core process, and its catalytic efficiency directly determines the performance and stability of the electrolyzers. Therefore, enhancement of reactant transport, electron/proton transfer, and oxygen release by cross-scale optimisation of the anode catalytic layer is crucial for improving the efficiency of PEMWEs. This article highlights recent advances in optimizing the anode catalytic layer of PEMWEs through multi-scale engineering strategies. We first introduce the basic structure of PEMWEs and the importance of the anode catalyst. Subsequently, we discuss in detail the multiscale optimisation strategy of the anode catalyst layer, including the design of active sites at the atomic scale, the morphology regulation at the nano/micro scale, the catalytic layer optimization at the macroscopic scale and the comprehensive synergistic effect of multiscale engineering. Finally, we conclude and look forward to the existing challenges and future research directions for optimising anode catalyst layers by multiscale engineering.

This study presents an efficient low-temperature process for synthesizing Mo nano- and microspheres for various applications. The synthesis process involves the preparation of a MoO₃ + kZn mixture with an excess of zinc (Zn > 3) and processing to temperatures between 500 and 850 °C in an argon atmosphere. The growth kinetics of Mo particles are determined by analyzing the relationship between sphere diameter and processing time. Molybdenum nano- and microspheres are applied as electrocatalysts for the hydrogen evolution reaction (HER) and high electrocatalytic activity, including low overpotential (170–206 mV) and Tafel slope (40–50 mV dec⁻¹) are recorded in 0.5 M H₂SO₄ electrolyte. DFT calculation provides adsorption Gibbs free energy for (001), (110), and (211) surfaces of Mo and charge density plots on pure Mo and Mo–O surfaces. As for vacuum-distilled Zn, its microstructure is also studied for its reuse and to assess its potential for additive manufacturing.

Chiral optical materials enable simultaneous linear and nonlinear optical properties and have emerged as a new class of materials desirable for applications in chiroptical information technology. Herein, we developed two pairs of hybrid lead-bromide perovskites (R-/S-APD)PbBr₄ and (1R,2R-/1S,2S-DACH)2PbBr₆·2H₂O, and systematically investigated their linear and nonlinear chiroptical responses. Second-harmonic generation circular dichroism (SHG-CD) measurements reveal a high anisotropy factor (g_SHG-CD) of up to 1.58 for (1S,2S-DACH)₂PbBr₆·2H₂O, which is the highest value among those of the reported chiral perovskites to date. Notably, these perovskites display a high laser damage threshold (LDT) of up to 59.36 GW cm⁻². This study demonstrates that the 0D chiral hybrid lead-bromide perovskite system can simultaneously exhibit both high LDT and g_SHG-CD, thereby opening a new route for the design of high-performance chiral nonlinear optics.

Titanium species in titanosilicate zeolites exist in three forms: framework titanium species, framework-associated titanium species and anatase TiO₂. They dominate the catalytic properties. Generally, the framework titanium species are considered as the active centers for catalytic reactions. However, the latest research has unveiled that additional titanium species within the framework, such as penta-coordinated and hexa-coordinate titanium species, can also exert their influence on catalytic processes. The catalytic activities of various titanium species, including penta- and hexa-coordinated titanium, exhibit superiority over traditional tetra-coordinated framework titanium species in some reactions. The urgent necessity lies in establishing a comprehensive understanding of the formation principles of various titanium species, characterization, and investigating their catalytic properties across diverse reactions. This review provides a comprehensive overview of contemporary advances in titanosilicate zeolites. The regulatory strategies, detection methods, and catalytic properties of titanium species are comprehensively summarized. Furthermore, a universal analysis is conducted on the mechanism of titanium species in the hydrogen peroxide catalytic system, offering valuable insights into both catalytic mechanism and precise regulation of microenvironmental conditions and spatial distribution of titanium species.