Supported‐metal catalysts, pivotal for industrial applications, have their catalytic properties affected by metal‐support interactions (MSIs), which notably influence both their electronic and ...geometric characteristics. Therefore, understanding internal and external factors that influence MSIs is crucial for the rational design of catalysts. Our minireview focuses on the effects of the gas environment on the MSIs, particularly the morphological changes in metal nanoparticles, the migrating behavior of reducible supports (strong metal‐support interaction), and the compositional rearrangement of the catalysts (reactive metal‐support interaction). Future directions are suggested to elucidate the fundamental aspects of gas environment induced structural reconstruction of catalysts, including the quantitative analysis of dynamic behavior of both the surface and interface, atomic‐level insights into the structures of the metal, support, and interface under pertinent conditions through advanced in situ/operando characterization, and the in situ manipulation of structural reconstruction.
This minireview examines how gas environments impact metal‐support interactions in supported‐metal catalysts. It discusses morphological changes in metal nanoparticles, behavior of reducible supports, and compositional rearrangement of catalysts under various conditions. The review suggests future research for understanding gas‐induced structural reconstruction in catalysts, emphasizing the need for advanced in situ/operando characterization and quantitative analysis of dynamic surface and interface behaviors.
Chlorine activation-inefficient and the generation of disinfection by-products (DBPs) has indeed limited the application of UV/chlorine process. In this study, the typical metal-organic frameworks ...(MOFs) NH2-MIL53(Fe) were successfully modified with organic ligands containing sulfur functional groups and applied to construct a novel UV-LED-driven heterogeneous chlorine activation system. The generation of intermediate energy levels and the charge redistribution effect on Fe-S bond facilitated the excitation of electrons and realized the effective separation of photohole (hvb+) and photoelectron (ecb-). The involvement of S-NH2-MIL53(Fe) improved the efficiency of UV-LED/chlorine process by 6 times. The effective activation of HOCl/OCl- by hvb+ and ecb- significantly enhanced the yield of HO· and Cl·. More importantly, HOCl/OCl- played a dual role in UV-LED/chlorine/S-NH2-MIL53(Fe) process as a precursor for the generation of free radicals and a catalyst for the enhancement of HO· yield, which could achieve efficient removal of the target pollutants at lower chlorine doses. In addition, the presence of low-valent sulfur species and ecb- accelerated the cycle of Fe(II)/Fe(III) and in-situ generation of HO· and Cl·. The known generation of DBPs in UV-LED/chlorine/S-NH2-MIL53(Fe) process decreased by 37.9% compared to UV-LED/chlorine process. Developing novel UV-LED/chlorine/S-NH2-MIL53(Fe) processes provided a reliable strategy to efficiently purify actual micro-polluted water bodies.
Modulating the reaction selectivity is highly attractive and pivotal to the rational design of synthetic regimes. The defluorinative functionalization of
-difluorocyclopropanes constitutes a ...promising route to construct β-vinyl fluorine scaffolds, whereas chemo- and regioselective access to α-substitution patterns remains a formidable challenge. Presented herein is a robust Pd/NHC ligand synergistic strategy that could enable the C-F bond functionalization with exclusive α-regioselectivity with simple ketones. The key design adopted enolates as π-conjugated ambident nucleophiles that undergo inner-sphere 3,3'-reductive elimination warranted by the sterically hindered-yet-flexible Pd-PEPPSI complex. The excellent branched mono-defluorinative alkylation was achieved with a sterically highly demanding IHept ligand, while subtly less bulky SIPr acted as a bifunctional ligand that not only facilitated α-selective C(sp
)-F cleavage, but also rendered the newly-formed C(sp
)-F bond as the linchpin for subsequent C-O bond formation. These examples represented an unprecedented ligand-controlled regioselective and chemodivergent approach to various mono-fluorinated terminal alkenes and/or furans from the same readily available starting materials.
The endeavors to pursue a robust multitask model to resolve intertask correlations have lasted for many years. A multitask deep neural network, as the most widely used multitask framework, however, ...experiences several issues such as inconsistent performance improvement over the independent model benchmark. The research aims to introduce an alternative framework by using the problem transformation methods. We build our multitask models essentially based on the stacking of a base regressor and classifier, where the multitarget predictions are realized from an additional training stage on the expanded molecular feature space. The model architecture is implemented on the QM9, Alchemy, and Tox21 datasets, by using a variety of baseline machine learning techniques. The resultant multitask performance shows 1 to 10% enhancement of forecasting precision, with the task prediction accuracy being consistently improved over the independent single-target models. The proposed method demonstrates a notable superiority in tackling the intertarget dependence and, moreover, a great potential to simulate a wide range of molecular properties under the transformation framework.
Owing to the increasing application of high-performance and multifunctional mid-infrared (MIR) optoelectronic devices, it is important to achieve a high emission efficiency and broadband tunable ...luminescence. In this study, nanocrystalline units with unique properties were integrated into an amorphous frame with high transmittance and infinite ductility to achieve an enhanced MIR emission. In the single active ion-doped system, owing to the combination of the lower phonon energy of the crystal, the fixed position of the crystal lattice, and the glass transparency, a substantial increase in the infrared fluorescence intensity was achieved. Particularly, an excellent 3 μm luminescence was realized by the stable composite material. In the co-doped system, a bottom-up strategy was adopted to achieve full coverage of the 2 μm MIR atmospheric window, and the results confirmed that the spatial distribution of the optically active nanocrystal units in the glass frame effectively controlled the energy transfer processes.
Display omitted
•Four HBT-based Schiff base derivatives incorporating different substituents are synthesized.•The effects of different substituents on the luminescence properties and aggregate state ...of the molecules were investigated.•Compound HBT-4 has excellent detection performance for N2H4 by both absorbance and fluorescence spectra.•HBT-4 can be prepared into a simple test paper as an efficient tool for the rapid detection of N2H4 in real water samples.
Four 2-(2-hydroxyphenyl)benzothiazole-based Schiff base derivatives incorporating different substituents were synthesized. Their optical properties were characterized by UV–visible and fluorescence spectra. The electron-withdrawing and electron-donating actions of substituents can change the orbital energy level distributions of molecules resulting in the difference of their luminescence properties. And the fluorescence microscopic images showed that these derivatives had different aggregation behaviors to form aggregates of different shapes. Furthermore, compound HBT-4 has been proved to have excellent recognition performance for N2H4 in real aqueous solution. Finally, HBT-4 could be prepared into a simple test paper as an efficient tool for the rapid detection of N2H4.
This paper reviews the development history of alkali element doping on Cu(In,Ga)Se2 (CIGS) solar cells and summarizes important achievements that have been made in this field. The influences of ...incorporation strategies on CIGS absorbers and device performances are also reviewed. By analyzing CIGS surface structure and electronic property variation induced by alkali fluoride (NaF and KF) post-deposition treatment (PDT), we discuss and interpret the following issues: ① The delamination of CIGS thin films induced by Na incorporation facilitates CuInSe2 formation and inhibits Ga during low-temperature co-evaporation processes. ② The mechanisms of carrier density increase due to defect passivation by Na at grain boundaries and the surface. ③ A thinner buffer layer improves the short-circuit current without open-circuit voltage loss. This is attributed not only to better buffer layer coverage in the early stage of the chemical bath deposition process, but also to higher donor defect (CdCu+) density, which is transferred from the acceptor defect (VCu−) and strengthens the buried homojunction. ④ The KF-PDT-induced lower valence band maximum at the absorber surface reduces the recombination at the absorber/buffer interface, which improves the open-circuit voltage and the fill factor of solar cells.
Abstract In an effort to obtain a novel cyan‐emitting phosphor, the K 1‐x Rb x 3 GdSi 2 O 7 : yCe 3+ materials (x = 0, 0.1, 0.2, 0.3, 0.4, y = 0, 0.005, 0.01, 0.02, 0.03, 0.04) are synthesized via a ...solid‐state reaction pathway, and their crystal structure and luminescence behaviors are studied systematically. The chemical substitution of Rb + in the K + sites can enlarge the K 3 GdSi 2 O 7 host lattice and help to the blue‐shifting of emission band of Ce 3+ ions due to the decreased crystal field splitting effect. It is also confirmed that the Ce 3+ ions tend to enter Gd1O 6 and Gd 2 O 6 polyhedrons simultaneously. Consequently, the K 0.7 Rb 0.3 3 GdSi 2 O 7 : Ce 3+ phosphor yields a broadband cyan emission centered at 492 nm with the full width at half maximum (FWHM) of ∼115 nm upon 365 nm excitation. The optimal concentration of Ce 3+ dopant is determined to be 0.01, and the concentration quenching effect can be attributed to the dipole−dipole interactions. The white light emitting diode (WLED) device fabricated by employing the discovered K 0.7 Rb 0.3 3 GdSi 2 O 7 : 0.01Ce 3+ phosphor displays a high color rendering index (R a = 91.7) and a low correlated color temperature (CCT = 3749 K). This work may promote the development of cyan phosphors for near ultraviolet‐converted WLEDs with high performance.
In an effort to obtain a novel cyan‐emitting phosphor, the K1‐xRbx3GdSi2O7: yCe3+ materials (x = 0, 0.1, 0.2, 0.3, 0.4, y = 0, 0.005, 0.01, 0.02, 0.03, 0.04) are synthesized via a solid‐state ...reaction pathway, and their crystal structure and luminescence behaviors are studied systematically. The chemical substitution of Rb+ in the K+ sites can enlarge the K3GdSi2O7 host lattice and help to the blue‐shifting of emission band of Ce3+ ions due to the decreased crystal field splitting effect. It is also confirmed that the Ce3+ ions tend to enter Gd1O6 and Gd2O6 polyhedrons simultaneously. Consequently, the K0.7Rb0.33GdSi2O7: Ce3+ phosphor yields a broadband cyan emission centered at 492 nm with the full width at half maximum (FWHM) of ∼115 nm upon 365 nm excitation. The optimal concentration of Ce3+ dopant is determined to be 0.01, and the concentration quenching effect can be attributed to the dipole−dipole interactions. The white light emitting diode (WLED) device fabricated by employing the discovered K0.7Rb0.33GdSi2O7: 0.01Ce3+ phosphor displays a high color rendering index (Ra = 91.7) and a low correlated color temperature (CCT = 3749 K). This work may promote the development of cyan phosphors for near ultraviolet‐converted WLEDs with high performance.
The emission color of K1‐xRbx3GdSi2O7: Ce3+ phosphors can be tuned from green to cyan with increasing Rb3+ content. The fabricated WLED shows high CRI (Ra = 91.7) and low CCT (3749 K) by employing the broadband cyan‐emitting phosphor K0.7Rb0.33GdSi2O7: Ce3+.
PDF
