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Optimization of the host lattice is a novel strategy to achieve efficient up‐conversion luminescence (UCL) with multi‐peak full‐spectrum emission. Herein, lattice optimization is performed in a non‐vacuum sulfur‐rich environment, where the ultra‐low phonon energy NaYS2 heterogeneous phase is forced to intergrow, which overcomes the limitations of the conventional vacuum preparation method and achieves high‐efficient UCL. Remarkably, the lattice sites are preferentially occupied by S2−, which causes lattice distortion and generates layered NaYS2/Y2O2S hybrid crystalline with high inversion asymmetry to reconfigure excitation mechanism and exhibit distinct luminescence centers at the multi‐peak full‐spectrum. Moreover, owing to longer lifetime of excited state energy levels of Er3+ after lattice modification and ordered segregation of Er3+ in the YS6 layer restricting the negative energy exchange process, the luminescence intensity is increased by about six times, and the remodeling of full‐spectrum‐efficient UCLs is realized. This work reports an innovative approach for lattice optimization and a facile preparation of ternary sulfides, which provides a new direction for achieving highly efficient UCLs with promising applications in biomedical imaging, near‐infrared detection, and temperature sensing synergy. [ABSTRACT FROM AUTHOR]

Perovskites with ultra‐low phonon energy have excellent radiation properties, while the population distribution of its luminescent initial state needs to be facilitated to further optimize the stokes fluorescence of Er3+ under high‐energy photons excitation. Herein, UV excitability of Er3+ is remodeled by building an energy transfer channel from Sb3+ to Er3+ in Cs2NaInCl6 (CNIC) microcrystal to realize the enhancement of stokes fluorescence of Er3+. Under UV excitation, the breakthrough boost of Er3+ is observed in Cs2NaInCl6:Sb3+‐Er3+ (CNIC:Sb‐Er), and the sensitization coefficient from Sb3+ to Er3+ in CNIC is derived to be as high as 112. Moreover, CNIC:Sb‐Er is embedded into functional fibers to enhance the crystal stability and the composite flexibility, which form fluorescence fibers with strong radiation transition probability. Finally, a high‐precision temperature sensing is achieved based on FIR (fluorescence intensity ratios) technology, and the maximum relative sensitivities of CNIC:Sb‐Er phosphors and CNIC:Sb‐Er/PAN fibers reach 1.13 and 1.10% K−1, respectively, indicating that CNIC:Sb‐Er and CNIC:Sb‐Er/PAN fibers have potential applications in optical temperature sensors. [ABSTRACT FROM AUTHOR]

Effective utilization of solar energy through photocatalytic oxidation is of great significance for environmental restoration and sustainable development. In order to realize the rapid separation of electron–hole pairs and improve the photocatalytic degradation activity, a multifunctional CsPbBr3/BiOI/TiO2 nanofiber photocatalyst with a symmetric double heterojunction structure is synthesized by combining electrospinning, hydrothermal and wet impregnation methods. Compared with powder photocatalysts, polyacrylonitrile (PAN) composite fibers work as a carrier offering the advantages of reusability, excellent flexibility, thermal stability, a controlled structure and a large specific surface area. Benefiting from the effective interfacial charge transfer and enhanced visible-light absorption, the obtained CsPbBr3/BiOI/TiO2@PAN nanofibers exhibit superior photocatalytic efficiency for rhodamine B, tetracycline hydrochloride, phenol and bisphenol A under simulated sun-light irradiation. Based on fluorescence intensity ratio (FIR) thermometry, the emission peaks of CsPbBr3 at 516 nm and PAN at 479 nm can be utilized for accurate non-contact temperature monitoring and real-time thermal feedback in complex degradation systems, and the maximum relative sensitivity SR is obtained as 0.0117 K−1 at 353 K. In conclusion, multi-selective photocatalysis fibers with real-time optical thermometry properties provide new application prospects for water purification in extremely harsh environments. [ABSTRACT FROM AUTHOR]

Herein, an electrospinning porous nanofiber with large specific surface area, excellent flexibility, remarkable tensile strength, and high stability of thermal degradation has been developed by loading Ho3+/Yb3+ co-doped BiOBr/g-C3N4 (BHY/CN) heterojunction photocatalysts on polyacrylonitrile (PAN) nanofibers. The optimized BHY/CN-2 nanofiber demonstrates outstanding photocatalytic activity for the degradation of 98.83% tetracycline (TC, 60 min) and 99.06% rhodamine B (RhB, 90 min) under simulated sunlight irradiation, and maintains a high level of reusability and recycling stability in three cycles. In addition, temperature monitoring of the catalytic degradation process can be feedback by (5F4, 5S2) → 5I8 and 5F5 → 5I8 radiation transitions of Ho3+ with excellent sensitivity. More importantly, the nanofiber luminescence performance is enhanced by the doping of g-C3N4, which maintain the effective upconversion luminescence properties even in water, providing a reliable reference for real-time monitoring and feedback of the operating temperature, and further expanding the application fields of photocatalysts. [ABSTRACT FROM AUTHOR]

The problem of water pollution caused by antibiotics urgently needs to be solved urgently. In this study, the Bi5O7I:Er3+-Yb3+ (BOIEY) nanoflowers with a diameter of 600–900 nm loaded flexible fibrous membrane has been synthesized via a combined hydrothermal and electrospinning process. It is noteworthy that the composite fibers successfully achieved efficient catalytic purification under real-time temperature monitoring. The BOIE0.5Y1.5/PAN composite fibers displayed the highest photocatalytic performance in the degradation of tetracycline hydrochloride (TC-HCl), with a removal rate of 91.83% in 80 min, which is 1.76 times that of pure BOI. The efficient photocatalytic performance was mainly attributed to the doping of rare earth ions and the special structure of the composite fibers. Er3+ and Yb3+ ions played the role of broadening the absorption spectrum by upconverting near-infrared light into visible light and promoted the separation of electron and hole pairs, thereby improving the photocatalytic efficiency. In addition, the unique structure of the hollow spherical-flower-loaded flexible fibrous membrane exhibited a larger specific surface area and stronger photon absorption capacity compared with traditional nanocrystals (NCs). Furthermore, based on the 2H11/2/4S3/2 → 4I15/2 radiative transitions of Er3+, the real-time temperature feedback of the degradation process in the 303–433 K ranges is evaluated and the relative temperature sensitivity reaches 0.63% K–1 at 353 K. The dual-function composite fibers provide insight into antibiotic removal in complex environments and ecological restoration. [ABSTRACT FROM AUTHOR]

(La1–x–yErxYby)2O2S polyacrylonitrile (LOS-EY/PAN) nanofibers enable the possibility of optical temperature sensing in microregions by introducing a dual temperature feedback fluorescence intensity ratio approach. A ratiometric strategy for the excitation of Er3+ ions by a special upconversion (UC) process is proposed. The green and red UC emissions of Er3+ single doping are confirmed to be unusual three-photon excitation processes attributed to cross-relaxation (CR) of Er3+ ion pairs. When Yb3+ is introduced, the CR process is forced to interrupt and energy is absorbed monopolistically by Yb3+ due to the huge absorption cross section of Yb3+ compared to that of Er3+; therefore, energy transfer from Yb3+ to Er3+ plays a dominant role, and the excitation process is transformed into a conventional two-photon process. With the rearrangement of the excitation mechanism, the overall increase in Er3+ emission is accompanied by an enhancement in the total quantum yield from 8.31 × 10–5 to 1.23 × 10–3. Significant fluorescence sensitization improves the signal-to-noise ratio in practical applications and keeps the relative sensitivity at a high level of 1.29% K–1, further demonstrating the excellent self-feedback nano-temperature sensing function of LOS-EY/PAN fibers promising as a flexible sensing element in fabrics and biomedical devices. [ABSTRACT FROM AUTHOR]

The effective double-site metal ion replacement strategy was adopted to optimize the crystal field environment of a Mn4+-activated fluoride phosphor. In this study, a series of K2yBa1−ySi1−xGexF6:Mn4+ phosphors with optimized fluorescence intensity, excellent water resistance, and outstanding thermal stability was synthesized. The composition adjustment includes two different types of ion substitution based on the BaSiF6:Mn4+ red phosphor: [Ge4+ → Si4+] and [K+ → Ba2+]. X-ray diffraction and theoretical analysis revealed that Ge4+ and K+ could be successfully introduced into BaSiF6:Mn4+ to form new solid solution K2yBa1−ySi1−xGexF6:Mn4+ phosphors. The emission intensity enhancement and slight wavelength shift were detected in different cation replacement procedures. Furthermore, K0.6Ba0.7Si0.5Ge0.5F6:Mn4+ with superior color stability performance possessed a negative thermal quenching phenomenon. Excellent water resistance was also found, which was more reliable than K2SiF6:Mn4+ commercial phosphor. A warm WLED with low correlated color temperature (CCT = 4000 K) and high color rendering index (Ra = 90.6) was successfully packaged by using K0.6Ba0.7Si0.5Ge0.5F6:Mn4+ as the red light component, and it also exhibited high stability for different currents. These findings demonstrate that the effective double-site metal ion replacement strategy can open up a new avenue for designing new Mn4+-doped fluoride phosphors to improve the optical properties of WLEDs. [ABSTRACT FROM AUTHOR]

Medium‐temperature molten Dy3+‐doped silicate (LNKBAS) glass phosphors can be excited efficiently in the low‐energy ultraviolet region (UVA). To this end, the addition of sensitizers Sb3+ and Ce3+ expands the validly excitable wavelength of Dy3+ from 348 to 248 nm. Fluorescence spectra demonstrate the superposition effect of the sensitization in the high‐energy ultraviolet region (UVC), and the multiplicative effect of sensitization in the UVA and medium‐energy ultraviolet region (UVB) for Sb3+–Ce3+–Dy3+ tri‐doped LNKBAS glass phosphors. The chromaticity coordinate of LNKBASCe0.04Sb0.1Dy1.0 is (0.2725, 0.3031) at 248 nm excitation, and the sensitization coefficient of LNKBASCe0.04Sb0.2Dy1.0 reaches at 19.85 under 309 nm excitation. Static fluorescence photographs and dynamic fluorescence video reveal the excitation expansion and the multiplicative effect of sensitization to Dy3+ by adding sensitizers at a macroscopic level. In general, the ideal rare‐earth energy conversion in medium‐temperature molten silicate glass phosphors offers promising prospects for saving energy and manufacturing high‐quality optoelectronic devices. [ABSTRACT FROM AUTHOR]

In this work, combining the advantages of upconversion materials, nanofibers, and TiO2 semiconductors, the composite fibers embedded with NaGdF4: Tm3+, Yb3+@TiO2 nanocrystals (NGF‐TY@TiO2 NCs) are prepared as wide‐spectral (UV‐NIR) response photocatalysts and temperature sensing materials. Based on the FIR technique, both the thermally (3F2,3 and 3H4) and nonthermally (1G4 and 3F2,3) coupled levels of Tm3+ are confirmed to be applicable as temperature probes for real‐time monitoring and feedback of the working temperature of the catalytic degradation process, and the maximum relative sensitivity values of SR1 and SR2 are as high as 2.760%K−1 and 3.019%K−1 at 304 K, respectively. Under 977 nm laser excitation, the energy migration from NGF‐T0.4Y6 to TiO2 is demonstrated to a fluorescence resonance energy transfer process. The degradation ratio of rhodamine B (RhB) is 19.3% in the presence of NGF‐T0.4Y6@TiO2/PAN fibers and the degradation constant K reaches 0.00117 min−1 after 3 h irradiating from Xe lamp with a UV cutoff filter. Accordingly, this study suggests a new perspective to utilize the NIR energy of sunlight for photocatalytic application based on TiO2, and the addition of dual temperature feedback provides a reliable reference for the development of safer and more efficient catalytic materials. [ABSTRACT FROM AUTHOR]

Exploration of multifunctional integrated catalysts is of great significance for photocatalysis toward practical application. Herein, a 1D confined nanoreactor with a heterogeneous core-shell structure is designed for synergies of efficient catalysis and temperature monitoring by custom encapsulation of Z-scheme heterojunction CuS quantum dots/BiVO 4 (CuS QDs/BiVO 4 ) and Y 2 O 2 S-Er, Yb. The dispersed active sites created by the QDs with high surface energy improve the mass transfer efficiency, and the efficient electron transport channels at the heterogeneous interface extend the carrier lifetime, which endows the nanoreactor with excellent catalytic performance. Meanwhile, real-time temperature monitoring is realized based on the thermally coupled levels 2 H 11/2 / 4 S 3/2 → 4 I 15/2 of Er 3+ using fluorescence intensity ratio, which enables the monitorable photocatalysis. Furthermore, the nanoreactor with a multidimensional structure increases effective intermolecular collisions to facilitate the catalytic process by restricting the reaction within distinct enclosed spaces and circumvents potential unknown interaction effects. The design of multi-space nanoconfined reactors opens up a new avenue to modulate catalyst function, providing a unique perspective for photocatalytic applications in the mineralization of organic pollutants, hydrogen production, and nitrogen fixation., (© 2024 Wiley‐VCH GmbH.)

The effective double-site metal ion replacement strategy was adopted to optimize the crystal field environment of a Mn 4+ -activated fluoride phosphor. In this study, a series of K 2 y Ba 1- y Si 1- x Ge x F 6 :Mn 4+ phosphors with optimized fluorescence intensity, excellent water resistance, and outstanding thermal stability was synthesized. The composition adjustment includes two different types of ion substitution based on the BaSiF 6 :Mn 4+ red phosphor: [Ge 4+ → Si 4+ ] and [K + → Ba 2+ ]. X-ray diffraction and theoretical analysis revealed that Ge 4+ and K + could be successfully introduced into BaSiF 6 :Mn 4+ to form new solid solution K 2 y Ba 1- y Si 1- x Ge x F 6 :Mn 4+ phosphors. The emission intensity enhancement and slight wavelength shift were detected in different cation replacement procedures. Furthermore, K 0.6 Ba 0.7 Si 0.5 Ge 0.5 F 6 :Mn 4+ with superior color stability performance possessed a negative thermal quenching phenomenon. Excellent water resistance was also found, which was more reliable than K 2 SiF 6 :Mn 4+ commercial phosphor. A warm WLED with low correlated color temperature (CCT = 4000 K) and high color rendering index ( R a = 90.6) was successfully packaged by using K 0.6 Ba 0.7 Si 0.5 Ge 0.5 F 6 :Mn 4+ as the red light component, and it also exhibited high stability for different currents. These findings demonstrate that the effective double-site metal ion replacement strategy can open up a new avenue for designing new Mn 4+ -doped fluoride phosphors to improve the optical properties of WLEDs.