Materials Chemistry Frontiers最新文献

In this work, two iridium(III) complexes, (2-pymICz)₂Ir(tmd) and (4-pymICz)₂Ir(tmd), using 2-(pyrimidine-2-yl)indolo[3,2,1-jk]carbazole (2-pymICz) and 2-(6-(methyl)pyrimidine-4-yl)indolo[3,2,1-jk]carbazole (4-pymICz) as the main ligands, which incorporate the rigid indolo[3,2,1-jk]carbazole (ICz) unit and 2,2,6,6-tetramethyl-3,5-heptanedione (tmd) as an ancillary ligand were synthesized. The Ir(III) complexes exhibit green photoluminescence (PL) with emission peaks at 515 and 523 nm, and relatively narrow full width at half maximum (FWHM) bands of 53 and 57 nm, and PL quantum yields (PLQYs) of 70% and 73%, respectively, in dichloromethane solutions. When these complexes were doped into the bipolar host 2,6DCzPPy (2,6-bis(3-(9H-carbazol-9-yl)phenyl)pyridine), the PLQYs of the resulting films significantly increased to 98.5% and 92.5%, accompanied by narrower FWHMs of 38 and 43 nm. Organic light-emitting diodes (OLEDs) based on these two emitters display good performance characteristics. Notably, the device based on (2-pymICz)₂Ir(tmd) exhibits better performances with a maximum external quantum efficiency (EQE_max) of 31.3%. Even at a high brightness of 10 000 cd m⁻², the EQE of this device still can reach 30.4%, indicating an extremely low efficiency roll-off of below 3%. Both devices show narrow electroluminescence FWHMs of 40 and 44 nm, respectively. Overall, the study highlights the practicality of incorporating rigid ICz groups and nitrogen atoms into the main ligands of Ir(III) complexes as a viable strategy for achieving efficient OLEDs with narrow emission spectra, high efficiencies, and low efficiency roll-offs.

Considering the noxious effects of Pb²⁺ ions on living organisms as well as the environment, we focus our attention to achieve rapid and selective uptake of Pb²⁺ ions from aqueous solutions. In this direction, our current work describes an efficient synthetic protocol for the development of economically viable, three-dimensional (3D) ferrite-based hierarchical structures to eradicate Pb²⁺ ions from wastewater. These magnetic architectures exhibited high BET surface area of 39.5312 m² g⁻¹, good thermal stability up to 400 °C and flower shaped morphology. The synthesized iron oxide-based materials were systematically characterized through XRD, SEM, VSM, TEM, FT-IR, EDS, XPS, and ED-XRF to elucidate their physio-chemical properties. The designed SALDETA@CPTMS@Fe₃O₄ adsorbent displayed excellent performance, faster kinetics, rapid separation, high selectivity, and good recyclability for the sorption of Pb²⁺ ions. Adsorption equilibrium results were justified by the Langmuir model, which indicated the maximum adsorption capacity of 415.5 mg g⁻¹ and conformed to pseudo second order kinetics. Sorption investigations disclosed that the functionalities available on the surface of the developed sorbent and its hierarchical structure played an active role in the uptake of metal ions and readily removed (within 8 min) Pb²⁺ ions from solution. Different variables such as pH, amount of sorbent, contact time, eluting agent, effect of interfering ions, etc. were optimized to achieve the best results. This 3D magnetic adsorbent was successfully employed for the elimination of Pb²⁺ ions in real water samples with good selectivity and efficiency. Furthermore, experimental exploration also indicated that the fabricated material could be advantageous for industrial applications due to its high stability, good regeneration ability (5 runs) and fast sorption-desorption cycle.

Chevrel phases (CPs) with the chemical formula of M_xMo₆T₈ (T = S, Se, and Te) have drawn great interest as noble-metal-free electrocatalysts in recent years owing to their unique open crystal structure and versatile functionalities. Herein, the representative efforts and progress made on CP electrocatalysts are overviewed, focussing on how the crystal structure and surface configurations affect the efficiency. In brief, the crystal structure of CPs is introduced first, and then the design and fabrication of CPs and their prominent catalytic performance are discussed in detail. Finally, the prospects of CPs in electrocatalysis are offered. It is anticipated that this review would aid in gaining in-depth insights into CPs and inspire the exploitation of more cost-efficient catalysts.

Oxygen evolution reaction (OER), as the pivotal half-reaction in electrochemical water splitting, is the main bottleneck in the widespread application of water electrolysis due to the low energy efficiency caused by the sluggish kinetics of the four electron-coupled proton transfer process. Over the past decade, tremendous efforts have been made in developing advanced OER catalysts. Clarifying the underlying origins of the slow kinetics, the structure–activity relationship is essential for designing OER catalysts. In this review, we aim to first comprehensively understand the electronic structures of catalysts involved in different mechanisms. We then discuss the origin of the scaling relation in the adsorbate evolution mechanism (AEM); further, the development on predicting and screening catalysts based on e_g orbital occupation and d-band center descriptors along with strategies beyond the scaling relationship is reviewed. Furthermore, we summarize the state-of-the-art strategy to develop catalysts by surface/interface engineering. Finally, the industrial progress and issues in exploiting OER catalysts to split water are summarized and analyzed. Through this comprehensive overview, we provide insights into designing alkaline OER catalysts from their fundamental electronic structures to industrial applications.

Proton exchange membrane (PEM)-based water electrolysis currently requires the use of iridium (Ir) as the anodic catalyst. Among the various iridium-based electrocatalysts, ultrafine metallic Ir nanoparticles have gained considerable attention due to their high acidic oxygen evolution reaction (OER) activity. Although recent progress has enabled the preparation of metallic Ir nanoparticles using surfactants, which can block the active sites of catalysts, the preparation of metallic Ir nanoparticles without surfactants is uncommon. Herein, we report an ultrafine metallic iridium electrocatalyst (UF-Ir/IrO_x) prepared via a surfactant-free hydrothermal reaction. During the OER, UF-Ir/IrO_x undergoes significant structural reconstruction, which is clearly revealed by X-ray photoelectron spectroscopy (XPS) and in situ Raman characterization. The amorphous IrO_x layer generated during the OER displays outstanding acidic OER activity and stability. We uncovered that the catalysis of UF-Ir/IrO_x follows the adsorbate evolution mechanism (AEM).

Perovskite solar cells (PSCs) have attracted increasing attention in the past decade due to their low cost and ease of manufacture, which make them promising candidates for next-generation photovoltaic technologies. However, the long-term stability of PSCs is still a major challenge that needs to be addressed before they can be commercialized. Interface engineering is a promising strategy to improve the performance and stability of PSCs. Here, we review the latest progress of interface modifications in PSCs, focusing on electrode interface layers. We discuss energy band alignment, carrier transport dynamics, interfacial defect passivation, and device stability in relation to electrode interface modifying materials. Finally, we discuss the challenges and opportunities of electrode interface modifications in PSCs based on recent advances.

The stabilization of Li metal anodes via dendrite-free Li deposition is a prerequisite for the commercialization of lithium metal batteries (LMBs). Among the various strategies to suppress Li metal anodes, electrolyte modification has been highlighted as a feasible method because it can be easily applied to conventional manufacturing processes. Tremendous efforts have been devoted to achieving dendrite-free Li deposition via various concepts of electrolyte modification. In this study, we first introduce potassium bis(trifluoromethanesulfonyl)imide (KTFSI) as an electrolyte additive for LMBs, which enables an electrostatic shielding effect. In addition, our study focuses solely on the individual effect of the cation (K⁺), excluding the influence of the anion (TFSI⁻), thus not considering the synergetic effect of both the anion and cation. As a result of comprehensive analysis and systematic experiments, we confirmed the effects of the KTFSI concentration on the electrostatic shield and determined the optimal concentration that can successfully suppress Li dendrite growth by controlling the deposition behavior of Li. The potassium cation controls the Li deposition behavior and results in surface stabilization of the Li metal anode, which is visually confirmed in in situ optical microscopy (in situ OM) and field-emission scanning electron microscope (FE-SEM). Consequently, our designed electrolyte showed outstanding performance overall during electrochemical testing, such as the Li | Cu asymmetric cell, Li | Li symmetric cell, and Li | LiFePO₄ (LFP) full cell, compared to the lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) electrolyte.

As the population ages, Alzheimer's disease (AD) has become a serious health problem worldwide. However, there is almost no effective method in the clinic for AD therapy due to the complicated pathogenesis and the multiple physiological barriers for brain drug delivery, especially the presence of the blood–brain barrier (BBB). Nowadays, nanotechnology has been explored for its great potential in brain drug delivery via improving bioavailability, overcoming the BBB, precise targeting and achieving drug co-delivery. In this review, we briefly introduce the widely studied targets of AD at first. Then, we summarize the recent advances in nanotechnology for AD treatment; strategies are broadly categorized according to the therapeutic targets, including toxic protein modulation, cell targeting in AD lesion sites or microenvironment modulation. Finally, the challenges and our perspectives for future directions of nanotechnology to combat AD are also discussed.

The increasingly severe environmental problems urge human beings to develop clean energy to replace the traditional fossil-based energy. “Green hydrogen”, which is generated from water by renewable energy, is one such promising candidate; however, its wide production is seriously hindered by the scarce and expensive Pt-based electrocatalysts currently used. In dealing with this demand, we recently developed a novel cobalt phosphide-based Ru single-atom electrocatalyst (Ru_SA@CoP_x) for hydrogen evolution reaction (HER). Characterizations revealed that the atomically dispersed Ru atoms could induce charge transfer to the CoP_x support, which was composed of CoP and Co₂P, thereby generating a strong metal–support interaction (SMSI). It was also found that the SMSI could be tuned by temperature, rendering Ru_SA@CoP_x-350 with an overpotential of 26 mV to deliver a current density of 10 mA cm⁻² for HER in alkaline medium, which was superior to the commercial Pt. Density functional theory calculations showed that the Ru single-atom could drastically reduce the energy barrier for water dissociation, leading to a more favorable Volmer step than for Pt. Further study revealed that the charge transfer from Ru to CoP(200) was disadvantageous to HER because of the exacerbated H* adsorption strength; whereas, the slightly negatively charged Ru could help to achieve a more thermoneutral adsorption energy on the Co site in Ru–Co₂P(111). This study provides a promising strategy for tuning the SMSI effect in the development of highly efficient single-atom catalysts.