Functional Materials Letters

${\mathrm{\text{BaTi}}}_5{\mathrm{\text{O}}}_{11}$ nanocrystals were synthesized by a hydrothermal method, and their photocatalytic performance was investigated by degradation of methylene blue (MB) under UV-light irradiation. About 82% MB was photodegraded after 30 min irradiation, which indicated that the ${\mathrm{\text{BaTi}}}_5{\mathrm{\text{O}}}_{11}$ nanocrystals had good photocatalytic performance due to the distorted ${\mathrm{\text{TiO}}}_6$ octahedra in the monoclinic ${\mathrm{\text{BaTi}}}_5{\mathrm{\text{O}}}_{11}$ crystal structure and nano-size ${\mathrm{\text{BaTi}}}_5{\mathrm{\text{O}}}_{11}$ particles. It indicated that the ${\mathrm{\text{BaTi}}}_5{\mathrm{\text{O}}}_{11}$ nanocrystals were promising candidates as UV-light photocatalysts.

${\mathrm{\text{BaTiO}}}_3/{\mathrm{\text{Nb:SrTiO}}}_3$ thin film oxides have been deposited on ${\mathrm{\text{SrTiO}}}_3$ substrates using a pulsed laser deposition system. Different annealing methods were thereafter used to assess the ferroelectricity of the grown films. The residual polarization value, 2Pr, of 4.205 $\mu$C/cm² and saturated residual polarization value, 2Pmax, of 15.484 $\mu$C/cm² were obtained using in-situ annealing. After performing rapid thermal annealing (RTA) annealing, the residual polarization value rose to 4.676 $\mu$C/cm² and the saturated residual polarization value rose to 18.723 $\mu$C/cm². Furthermore, a comparison of results showed that the saturation test frequency of the in-situ annealing was 10 times higher than the saturation test frequency of the RTA. This could be explained by the fact that the secondary high-temperature annealing led to a decrease in the conductivity of the doped oxide and, thereby, a decrease in the effective electric field that was applied to both ends of the BTO (${\mathrm{\text{BaTiO}}}_3$) film. Thus, a lower frequency was required to ensure a flip of all ferroelectric domains within the BTO film. By testing the fatigue frequency at 100 kHz, ${10}^{12}$ stable cycles in both annealing methods and the results confirmed the good stability of the device performance. A linear fit analysis of the $I$ – $V$ curves showed under in-situ annealing the presence of both a bulk-limited current mechanism that was dominated by the space charge limited current (SCLC) and Pool–Frenkel (PF) mechanisms, and an interface-limited current that was dominated by the Fowler–Nordheim (FN) mechanism in the structure. After RTA annealing, the conducting mechanism is ohmic contact at low electric field and the SCLC mechanism at high field strength. The results show that after RTA annealing, the quality and ferroelectric properties of the films are significantly improved compared to those under in-situ annealing. These results showed that the BTO/NSTO/STO (${\mathrm{\text{BaTiO}}}_3/{\mathrm{\text{Nb:SrTiO}}}_3/{\mathrm{\text{SrTiO}}}_3$) structure had a standard test frequency as well as reliable stability. The BTO/NSTO/STO structure showed, therefore, promising applications in future nonvolatile information memory devices.

A palladium ion (${\text{Pd}}^{2+}$)-mediated nitrogen-doped graphene quantum dots (N-GQDs/Pd${}^{2+}$) was developed as a fluorescent “off–on” probe for methimazole (MZ). Fluorescent N-GQDs interact with Pd${}^{2+}$ through coordination interactions, leading to weak photoluminescence (PL) owing to the quenching ability of Pd${}^{2+}$. Upon introducing MZ, the stronger binding between N-GQDs and Pd${}^{2+}$ destroys the N-GQDs/Pd${}^{2+}$ complex and restores the PL of N-GQDs. The probe exhibits a linear PL response to MZ concentrations from 3.0 to 50.0 $\mu$M with a detection limit down to 4.5 nM. In addition, the probe has been used to detect MZ in real samples including natural water sources and human urine.

Reaction injection molding method is employed to improve flame retardancy and mechanical properties of three-dimensional braided glass fiber (3D-braided-GF) reinforced in situ polymerized polyamide 6 (PA6) composites. The kernel lies in adding flame retardants, hexaphenoxycyclotriphosphazene (HPCTP), to the reactive monomers to allow it to be in situ filled into composites during preparing PA6 through anionic polymerization, which enables flame retardants to achieve better dispersion. In addition, extremely low-viscosity reactive monomers are easier to immerse in 3D-braided-GF, ameliorating interfacial adhesion between GF and PA6. The preliminary research indicates that samples with 10 wt.% HPCTP concentration can achieve the best mechanical properties and a satisfied flame-retardant grade (UL 94 HB). However, with the incorporation of 15 wt.% HPCTP into samples, the optimum flame-retardant grade (UL 94 V2) and the reduced mechanical performance are obtained. Furthermore, a dual flame retardancy mechanism in both gaseous and condensed phases of samples is further elucidated. This study can provide a reference for scenarios with high requirements for the flame-retardant and mechanical properties, such as high-speed rail and aircraft.

The synthesis of ultrasmall tantalum mononitride (TaN) quantum dots (QDs) is achieved using a straightforward liquid exfoliation technique, starting from bulk TaN. This work presents the evidence of generating an ultrafast laser by employing TaN QDs as a saturable absorber (SA) within an Erbium-doped fiber laser for the first time. Stable ultrashort pulses are generated, exhibiting a center wavelength of 1566.92 nm, a pulse duration of 713 fs, and a cavity repetition rate of 41.39 MHz. Furthermore, the utilization of TaN QDs as an SA in the device exhibits good nonlinear saturable absorption properties with a modulation depth of 1.37%. Those results presented in this study add to the existing literature on the investigation of nonlinear optical characteristics of ultrasmall QDs and also highlight the potential for future development in ultrafast photonic technology.

The development of new technologies for effective propylene production is a highly important scientific and industrial task nowadays. In this study, the conversion of ethylene to propylene (ETP reaction) was explored over rhenium-containing catalysts supported on a ZrO₂ carrier at temperatures 100°C–200°C and atmospheric pressure using a flow catalytic reactor with a fixed catalyst bed without the use of any other hydrocarbons or dilutants. The effect of rhenium presence in the catalysts on the activity and propylene selectivity was examined.

All inorganic lead halide cesium perovskite quantum dots (QDs) have attracted much attention due to their excellent luminescence properties, but further development is restricted by their stability and the existence of toxic element lead. In this paper, F/Mn-doped $\mathrm{\text{CsPb}}{(\mathrm{\text{Br}}/\mathrm{\text{Cl}})}_3$ QDs glass was prepared by melt quenching and heat treatment, with reduced Pb content effectively. The result shows that the spectrum of the QD glass is adjustable between 450 nm and 515.4 nm by changing the feeding ratio of Mn-Pb ion and heat treatment temperature. Moreover, the indraught of ${\text{Mn}}^{2+}$ effectively improves the PLQY of $\mathrm{\text{CsPb}}{(\mathrm{\text{Br}}/\mathrm{\text{Cl}})}_3$ QDs glass and serves as a red-emitting. The prepared composites not only maintain good fluorescence characteristics, but also greatly improve the stability of QDs. And successfully coupled with blue LED chips to synthesize WLED, Under 20 mA current, the color coordinate is (0.3446, 0.3389).

A straightforward solvothermal methodology was employed to synthesize ${\mathrm{\text{Fe}}}_3{\mathrm{\text{O}}}_4$ microspheres and ${\mathrm{\text{Fe}}}_3{\mathrm{\text{O}}}_4$@C hybrids, where amorphous carbon encapsulated ${\mathrm{\text{Fe}}}_3{\mathrm{\text{O}}}_4$ microspheres. This encapsulation was achieved by meticulously controlling the reaction duration and glucose concentrations within the hydrothermal process. Analysis via X-ray diffraction and Raman spectroscopy confirmed that all specimens retained a homogeneous ${\mathrm{\text{Fe}}}_3{\mathrm{\text{O}}}_4$ phase. Following encapsulation, the ${\mathrm{\text{Fe}}}_3{\mathrm{\text{O}}}_4$ particles were uniformly distributed across the amorphous carbon spheres, with fine particle sizes in the hybrids measuring less than 20 nm. Magnetic characterization revealed that parameters such as saturation magnetization, remanent magnetization, and coercivity of the ${\mathrm{\text{Fe}}}_3{\mathrm{\text{O}}}_4$ microspheres could be significantly adjusted by varying the hydrothermal reaction time. Notably, the hybrids exhibited a 5- to 10-fold increase in both coercivity and remanent magnetization when compared to the pristine ${\mathrm{\text{Fe}}}_3{\mathrm{\text{O}}}_4$ microspheres. Nonetheless, the saturation magnetization of the hybrids reached up to 90% of that observed in bulk ${\mathrm{\text{Fe}}}_3{\mathrm{\text{O}}}_4$. These magnetic properties are predominantly influenced by the size effect associated with the nanostructured ${\mathrm{\text{Fe}}}_3{\mathrm{\text{O}}}_4$.

Metal-organic framework (MOF) glasses, are attracting increasing attention in the gas separation field due to their component flexibility, ease of processing and porous structures. In this work, a series of bimetallic MOF glass membranes were synthesized and the impact of the metal node ratio (Co/Zn) on the gas separation performance of the membranes was investigated. It is found that the replacement of Zn nodes by Co in the ZIF-62 glass membrane leads to a nonlinear increase in the separation selectivity for ${\mathrm{\text{CO}}}_2/{\mathrm{\text{CH}}}_4$ and ${\mathrm{\text{H}}}_2/{\mathrm{\text{CH}}}_4$. Such a phenomenon corresponds to the mixed-metal node effect found in the MOF glass. Through the structural characterization results, we found that the different affinities of the central metal nodes towards gas molecules and the diversity in porosity of the Zn/Co-ZIF-62 membranes could be the two main reasons for the evolution of the gas separation properties in the ZIF-62 glass membranes. This work gives a new approach to developing MOF glass membranes with high-performance gas separation.

In this study, a novel method is introduced for preparing the poly (N-isopropylacrylamideco-methacrylic acid) (PNIPAM) hydrogel catalyst (PNMC-Ag) with embedded silver nanoparticles (Ag NPs), by employing in situ reduction of Ag+ in polymeric network. The prepared hydrogel catalyst exhibits both thermal and pH responsiveness, facilitating precise control of catalytic efficiency in reducing pollutants such as 4-nitrophenol (4-NP) under varying environmental conditions. The embedded Ag NPs demonstrate remarkable stability against self-aggregation due to their confinement within the polymeric network, thus maintaining their exceptional catalytic performance over time. Leveraging the dual-responsive nature of the PNMC-Ag catalyst, tunable catalytic activity can be achieved by adjusting the temperature and pH of the reaction environment. Specifically, the Ag NPs-hydrogel catalyst exhibits high catalytic activity (21 min, 98.5%) in low-temperature ($T$< 32°C) at neutral pH and alkaline (pH = 9) conditions at room temperature, while its activity is attenuated in high-temperature ($T$> 32°C) at neutral pH or acidic (pH $\le$4) environments at room temperature owing to the hydrogel’s thermal and pH-responsive characteristics. This distinctive feature enables precise control over the catalytic reaction, offering an effective approach for the removal of 4-NP from wastewater using a noble-metal-containing stimuli-responsive hydrogel (SRH) catalyst. Overall, this work represents a significant step towards the development of intelligent catalytic materials with superior environmental remediation capabilities.