Materials Chemistry Frontiers最新文献

Li-rich Mn-based cathode materials (LRMs) have garnered considerable interest for their high specific capacity. Nevertheless, the elevated operating voltage window presents a great hurdle to the high-voltage tolerance of the conventional electrolytes, and the induced issues such as rapid capacity and structure degradation also further impede their industrial application. In this regard, an efficient method to alleviate this problem is proposed via a cyano functional additive. By introducing the trimethylsilyl cyanide (TMS) additive into a carbonate electrolyte to construct a complex with TM–CN bonds on the cathode surface and form a low-impedance and durable cathode/electrolyte interphase (CEI), both electrolyte decomposition and cathode degradation are suppressed effectively. Moreover, harmful substances are also removed through the reaction between TMS and HF to purify the electrolyte. Therefore, the electrochemical performance of the LRM cathode is enhanced with a discharge capacity of 224 mA h g⁻¹ after 200 cycles at 1C. A high discharge capacity of 227 mA h g⁻¹ is also achieved after 50 cycles at 0.5C under a high mass loading of 13 mg cm⁻². This work presents a new path to develop high-voltage electrolytes for LRM cathodes.

Methanol oxidation-assisted direct seawater electrolysis has emerged as a potent technology for efficient hydrogen (H₂) production alongside high-value chemicals such as formic acid and formaldehyde. However, the large-scale application of this technology heavily relies on developing highly active and robust bifunctional electrocatalysts for methanol oxidation and hydrogen evolution reactions (MOR/HER). Herein, we report a simple hydrothermal-phosphorylation method to synthesize a heterostructured catalyst on copper foam, comprising CoP, MnP, and Cu₃P (CoP/MnP/Cu₃P@CF). The synergistic interaction among the heterogeneous components endowed CoP/MnP/Cu₃P@CF with excellent MOR, oxygen evolution reaction (OER), and HER performance in alkaline seawater electrolytes. Notably, the MOR-assisted CoP/MnP/Cu₃P@CF-based seawater electrolyzer catalyst required only 1.410 V to achieve a current density of 10 mA cm⁻², significantly lower than the 1.681 V required for an OER–HER seawater electrolyzer. Additionally, the MOR-assisted electrolyzer exhibits high faradaic efficiency and cycling stability, offering the potential for sustainable energy-efficient H₂ production.

Solar-blind ultraviolet (UV) nonlinear optical (NLO) crystals are urgently demanded for their important applications in modern lasers. Herein, a remarkable solar-blind UV NLO crystal, K[H₂N(CH₂COO)₂], was rationally obtained by tuning alkali metal cations. Interestingly, it was noted that the [H₂N(CH₂COO)₂] groups were held between the helical chains in an ordered arrangement that superimposed their microscopic second-order susceptibilities. Notably, K[H₂N(CH₂COO)₂] exhibited comprehensive NLO performance, including a strong phase-matching SHG response of 1.6 × KDP at 1064 nm and 0.6 × BBO at 532 nm, a suitable birefringence of 0.124 at 1064 nm, a high LDT up to 332 MW cm⁻², a distinct UV cutoff edge of 216 nm, a wide high-transparency window covering 246–1554 nm, the shortest phase-matching wavelength extending to 250 nm and easy growth of centimetre-sized crystals. K[H₂N(CH₂COO)₂] remained thermally stable up to 210 °C in an air atmosphere. This research offers a new approach to further explore solar-blind UV NLO crystals.

Stannate perovskites (MSnO₃), benefiting from their high production of HCOOH and the perovskite structure-enabled tunability of properties, are emerging as promising catalysts for electrochemical CO₂ reduction (CO₂R). However, optimizing the catalytic performance of MSnO₃ for CO₂R remains largely unexplored. Here, we systematically study the catalytic performance of MSnO₃ with a distinct A-site cation, M (M = Ba, Sr, and Ca), for CO₂R. Our experimental results show that the M cation dramatically affects the catalytic performance, especially the selectivity and stability. In particular, the CaSnO₃-based catalyst exhibits the highest selectivity to HCOOH and stability but the lowest activity. Further theoretical investigations reveal that the A-site cation can affect the selectivity of MSnO₃ for the CO₂R reaction and may impact the stability of MSnO₃. Both experimental and theoretical findings reveal that stannate perovskites can be effective and selective catalysts for CO₂R, while their stability needs to be considered carefully. These results should shed light on the rational design of perovskite catalysts with desired performance for CO₂R.

Bi-based halide perovskites have been considered as alternatives to Pb-based perovskites with the intention of avoiding the use of lead in the field of photovoltaics. Over the last few years, novel Bi-based halide perovskites have shown potential in reaching good photovoltaic performance, as suggested by their similar electronic structure to Pb-based perovskites. Nevertheless, their lower dimensionality entails poor charge carrier transport. It has been consistently stated that the role of the A-site should be further studied. To explore this proposition, we have synthesized three different Bi-based halides with substitution on the A-site by azetidinium cations. In this contribution we report fundamental observations of azetidinium bismuth halides, [(CH₂)₃NH₂]₃Bi₂I₉, [(CH₂)₃NH₂]₃Bi₂Br₉, and [(CH₂)₃NH₂]₃Bi₂Cl₉ with prospects in optoelectronics and photovoltaics. These new materials exhibit 0D and 2D crystal structures at a molecular level and the optical feature of an excitonic band state.

Smart hydrogels, known for their stimuli-responsive properties in drug delivery, tissue engineering, and sensors, are typically created using a top-down approach, which limits precise molecular control. In this study, we employ a bottom-up strategy to achieve greater molecular precision, enabling the development of innovative, multi-stimuli-responsive hydrogels. We designed and synthesized asymmetric cyanine amphiphiles incorporating diphenylimidazole as the donor and indole as the acceptor to create molecules with intramolecular charge transfer characteristics. These diphenylimidazole-indole amphiphiles, DPIIH and DPIIF, differ in that DPIIH lacks a fluorine atom at the indole terminal, while DPIIF includes this substitution. Additionally, diphenylimidazole reveals nonplanar conformations and twisted dihedral angles between the phenyl rings at the 4,5-position of imidazole, giving it aggregation-induced emission properties. In contrast to DPIIH, DPIIF can self-assemble into a hydrogel in water, probably due to the hydrogen bonding interactions between DPIIF and water molecules. Through detailed exploration of DPIIF, it was found to exhibit a reversible photochromic effect in polar solvents and can undergo reversible acid–base reactions. The photoisomerization and pH stimulus-response behaviors of DPIIF can be observed via colorimetric and fluorescence changes, making it suitable for applications such as invisible ink and pH sensors. In its hydrogel state, DPIIF reveals reversible photoswitching and pH-switching features, enabling reversible sol–gel transitions. These properties suggest potential applications in both cell culture (gel state) and cell recovery (solution state), offering versatile functionality in biomedical and research settings. Furthermore, the fluorescent properties of the hydrogel can be used to study and visualize cell–material interactions in detail, providing valuable insights for various biological studies.

In the pursuit of channel materials for high-performance n-type organic electrochemical transistors (OECTs), several challenges have been encountered, including difficulties in the modification of the material structure, relatively low performance, and poor stability. To address these issues, designing innovative electron-deficient building blocks is critical for constructing novel donor–acceptor organic semiconductors with low LUMO levels to achieve high-performing n-type OECTs. In this study, we have designed and synthesized a novel glycolated quinone-based electron-deficient building block derived from azaisoindigo (AQM2I), featuring a cross-conjugated planar backbone and low LUMO levels, attributed to enhanced O–H interactions and strong electron-withdrawing amide groups. By combining AQM2I with alternating electron-rich building blocks (T, TT, 2T and 2FT), a series of novel n-type polymers that possessed mixed ionic–electronic conductivity were prepared. The incorporation of various electron-rich building blocks effectively modulates the backbone structure, molecular energy levels and sodium doping capability of the polymers. Moreover, a mixed conducting property with a maximum μC* figure-of-merit value of 0.53 F V⁻¹ cm⁻¹ s⁻¹ for accumulation-mode n-type OECT was achieved, attributed to the high electron mobility induced by the enhanced lamellar stacking, smooth and dense film morphology. The design strategy for novel electron-deficient building blocks presented in this work provides insights for the development of high-performance materials for n-type OECTs.

Two characteristic types of extraordinarily thin upright-standing ZrO₂-based nanorods self-aligned on a substrate, differing in diameters (20/30 nm), lengths (90/120 nm), and population densities (1.1/4.6 × 10¹⁰ cm⁻²), were synthesized via the porous-anodic-alumina (PAA)-assisted anodization of Zr in 1.5 M selenic acid followed by selective PAA dissolution. A needle-like shape was achieved due to the unique formation of zirconium anodic oxide in extremely thin nanopores that grow only in selenic acid. The SEM, XPS, and Raman spectroscopy analyses revealed that the nanorods feature a core/shell structure in which the core is stoichiometric amorphous ZrO₂, and the shell is ∼6 nm thick hydroxylated zirconium dioxide ZrO_2−x(OH)_2x mixed with Al₂O₃. The core and shell incorporated electrolyte-derived selenate (SeO₄²⁻) ions, which replace up to 1% of the O²⁻ ions in the nanorod surface layer. Besides, nanoparticles of elemental Se were deposited on the top of rods during anodic polarization. A model was developed for the cooperative ionic transport and electrochemical and solid-state reactions during the PAA-assisted growth of zirconium oxide in selenic acid. The two Se-doped top-decorated zirconium-oxide nanorod arrays were examined as potential antibacterial nanomaterials toward G-negative E. coli and G-positive S. aureus, using direct SEM observations of the bacteria–surface interfaces and carrying out the modified Japanese Industrial Standard test for antimicrobial activity and efficacy, JIS Z 2801. While specific differences in interaction with each type of bacteria were observed, both nanostructures caused a significant harmful synergetic effect on the bacteria, acting as non-metallic (Se) ion-releasing bactericidal coatings along with repellent and contact-killing activities arising from extraordinary needle-like nanoscale surface engineering.

On-surface synthesis under ultra-high vacuum (UHV) conditions facilitates the fabrication of unique molecular compounds, replicating established in-solution protocols. However, the intramolecular hydroamination and cyclization (IHC) of alkynes on surfaces remain unexplored due to the challenges posed by the repulsion between the nitrogen lone pair and the alkyne π-system. Here we describe the first on-surface IHC of alkyne-functionalized molecular precursors in UHV environment on the Au(111) surface. Notably, the synthesis introduces two pyrrole groups into the quinoidal-based precursor, enabling the formation of two fused pyrrolo-benzoquinonediimine compounds not achievable in solution chemistry. To analyze the resulting reaction products, we utilized scanning tunneling microscopy and non-contact atomic force microscopy with single bond resolution, comparing these products to those obtained through traditional solution methods. In parallel to the experimental results, we provide a detailed computational description of the key role of single gold adatoms during the complete on-surface reaction.

Pure organic long-persistence luminescence has recently garnered significant attention due to its diverse potential applications. Nonetheless, the attainment of pure organic dual-mode long-persistence afterglow with high efficiency remains a significant challenge. Herein, we report the successful realization of high-efficiency, color-tunable dual-mode room-temperature phosphorescence (RTP) along with thermally activated delayed fluorescence (TADF) of approximately 50 ms, utilizing an aromatic furan organic host–guest system. Our investigation into this system reveals two key findings: (1) the heavy-atom effect of the host and guest molecules plays distinct roles in modulating the efficiency of the intersystem crossing (ISC) and reverse intersystem crossing (RISC) processes; and (2) the dual-mode long-persistence luminescence can be effectively adjusted by manipulating the energy gap between the excited triplet states of host and guest molecules. Additionally, we demonstrated the capability for color display utilizing this host–guest system through inkjet printing.