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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.)

Developing efficient catalysts to degrade pollutants in water is a very important way to alleviate water pollution. However, it is crucial but challenging to broaden the functions of conventional photocatalysts and improve their environmental adaptability. In this paper, Bi(Er 3+ /Yb 3+ )OBr/polyacrylonitrile (BOB-EY/PAN) composite fibers with a swallowed-embedded structure assembled with nanopetal-rich microflowers were designed and fabricated, integrating photocatalytic and temperature-monitoring functions simultaneously. Their unique structure brings a large specific surface area, and the doping of rare earth ions improves the separation efficiency of electron-hole pairs, which enhances the photocatalytic efficiency and endows the fibers with a temperature-monitoring function at the same time. Under simulated sunlight irradiation, the nanofibers show a maximum degradation efficiency of 99.2% for tetracycline hydrochloride (TC) with a degradation constant of K as high as 0.078 min -1 . Based on the fluorescence intensity ratio (FIR), the two thermally coupled levels of Er 3+ in the nanofibers, 2 H 11/2 and 4 S 3/2 , provide real-time temperature feedback, displaying a maximum relative sensitivity as high as 0.0215 K -1 at 303 K. Dual-functional BOB-EY/PAN composite nanofibers show great potential for industrial wastewater disposition, providing solutions for wastewater purification in special scenarios.

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 Ho 3+ /Yb 3+ co-doped BiOBr/g-C 3 N 4 (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 ( 5 F 4 , 5 S 2 ) →  5 I 8 and 5 F 5  →  5 I 8 radiation transitions of Ho 3+ with excellent sensitivity. More importantly, the nanofiber luminescence performance is enhanced by the doping of g-C 3 N 4 , 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., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Bi 2 WO 6 :Ho 3+ , Yb 3+ /g-C 3 N 4 (BHY/CN) photocatalysts are successfully loaded on polyacrylonitrile (PAN) nanofibers by electrospinning technology, which combines an upconversion effect and heterojunctions to achieve dual-functional characteristics. Polymer-modified photocatalytic materials offer a large specific surface area of 24.1 m 2 /g and a pore volume of 0.1 cm 3 /g, promoting the utility of solar energy. The introduction of rare earth ions and g-C 3 N 4 optimizes the structural band gap, which broadens the light absorption range and promotes electron transfer. Moreover, the heterojunction between Bi 2 WO 6 and g-C 3 N 4 has suppressed the complexation of photoinduced carriers, further improving catalytic performance. The optimized photocatalysts have higher photocatalytic activity with degrading 92.6% tetracycline-hydrochloride (120 min) under simulated sunlight irradiation. The optical thermometry has also been achieved based on the fluorescence intensity ratio technique, where the maximum absolute and relative sensitivity values of BHY/CN-1:6@PAN are 3.322% K -1 and 0.842% K -1 , respectively. This dual-functional nanofibers with excellent mechanical properties provide noncontact temperature feedback and efficient catalytic performance for better wastewater treatment and ecological restoration in extreme harsh environments.

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.

Sr 2 (La 1- x Er x )F 7 /polyacrylonitrile composite fibers with special pliability and excellent crystal dispersibility have been fabricated, which provide smaller size and appropriate temperature sensitivity. Up-conversion emission shows quadratic dependence of the photoluminescence intensity on pump power, confirming the participation of two photons during the excitation processes. The composite fibers, combining main and auxiliary sensing derived from green and red emissions, give fibers the ability to obtain accurate results and better reproducibility. Among them, assigning the green emission as the main indicator of non-contact temperature sensing, the absolute and relative sensitivities are 0.514% K -1 and 0.654% K -1 at 373 K, respectively. Furthermore, the ratio of green and red emission serves as an auxiliary monitoring parameter to calibrate the deviation, where the absolute and relative sensitivities reach 7.208% K -1 and 0.901% K -1 at 373 K. In general, composite fibers with excellent dual-ratiometric temperature sensing are expected to be applied in biological probes, miniature devices and accurate temperature sensors.

All-inorganic dual-phase CsPbBr 3 -Cs 4 PbBr 6 quantum dots (CPB QDs)-based polyacrylonitrile (PAN) fiber synthesized by supersaturated recrystallization and electrospinning technique possesses characteristics of homogeneous morphology, high crystallinity and solution sensitivity. Under 365 nm laser excitation, CPB@PAN fiber exhibits surprising trace-recording capability attributing to the splash-enhanced fluorescence (FL) performance with a narrow-band emission at 477-515 nm. In the process of ethanol anhydrous (EA) and water splashing, the CPB@PAN fiber presents conspicuous blue and green emission when contacting with EA and water, and maintains intense blue and green FL for more than 4 months. These experimental and theoretical findings provide a facile technology for the development of biological protection display, biotic detection and moisture-proof forewarning based on the trace-recording performance of CPB@PAN fiber., (© 2021 IOP Publishing Ltd.)

Miscible-order fluoride-phosphate blocky phosphor (FBP), composed with ordered-phase of NaYF 4 crystals and unordered phase of tin-fluorophosphate glass, is prepared by a two-step process and luminescent properties of FBPs embedded with different particle sizes of NaYF 4 crystals are presented. High-frequency fluorescence from higher metastable 5 D J ( J  = 1, 2 and 3) energy levels are effectively released in Eu 3+ doped fluoride crystals. Taking the blue emission of Sn 2+ as the framework, multi-peak emissions from metastable energy levels are controlled to adjust the color coordinates of the FBP to the white-light region, which the color rendering index (CRI) reaches 89. Tunable color FBP with high CRI retains splendid luminescence property of fluoride, providing a potential candidate for the development of white LED., (© 2021 IOP Publishing Ltd.)

Na(Y 1- x - y Ho x Yb y )F 4 /PAN (NYF-HY/PAN) composite fibers were synthesized using an electrospinning method, and the sub-micron crystals embedded in the fibers had complete hexagonal crystal structures. Under 977 nm laser excitation, strong green and red up-conversion (UC) emission that originated from flexible fibers were due to the radiative transitions ( 5 F 4 , 5 S 2 ) → 5 I 8 and 5 F 5 → 5 I 8 of Ho 3+ , respectively. The effective green fluorescence emission (539 and 548 nm) can be applied to micro-domain non-contact temperature measurements, realizing rapid and dynamic temperature acquisition in a complex environment without destroying the temperature field. In the temperature range of 313-393 K, the absolute and relative sensitivity of the fibers are 0.00373 K -1 and 0.723% K -1 , respectively, which indicates that the NYF-HY/PAN composite fibers have good thermal sensitivity. Composite fibers in which crystallites are embedded have superior properties, with great stability, high sensitivity, and excellent flexibility, providing a reliable reference for developing temperature-sensing materials for the biomedical field., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

C e 3+ doped M 3 A l 5 O 12 (MAG, M = L u , Y) glass ceramics (GCs) have been proved to be shapeable phosphors for white lighting driven by a 453 nm laser. Quantitative characterization reflects that the net emission powers of 4 wt% LuAG-doped GC and 4 wt% YAG-doped GC are 59.99 mW and 66.22 mW at the pump power of 117.63 mW, and the quantum yields reach up to 71.1% and 78.0%, respectively. Miniaturization of devices can be achieved for LuAG/YAG-GCs by optimizing sample size and phosphor concentration with maintaining fluorescence intensity of the samples. Presupposed color coordinate trace reveals that the high-brightness white fluorescence can be realized when the appropriate intensity ratio is determined between residual laser and sample emission. The tunable white fluorescence and the efficient radiation releasing illustrate that LuAG/YAG-GCs are potential candidates for application in solid-state laser illumination.

Multi-photon-excited thermal-correlated green and red upconversion (UC) emissions have been quantified in H o 3+ / Y b 3+ co-doped fluotellurite (BZLFT) glass phosphor under the 978 nm laser excitation. The temperature dependence of the fluorescence intensity ratio (FIR) originated from UC emissions bands centered at 550 nm and 661 nm has been verified in the range of 303-543 K. The net emission photon numbers of 5 F 4 + 5 S 2 → 5 I 8 and 5 F 5 → 5 I 8 transition emissions are up to 40.08×10 12 and 68.51×10 12 c p s in the 0.4 w t . % H o 2 O 3 -0.4 w t . % Y b 2 O 3 co-doped BZLFT case under the 6.95 W / m m 2 laser power density. Furthermore, the quantum yield (QY) and luminous flux are determined to be dependent on pumping power. When the excitation power increases 874 mW, the QY values for 550 nm and 661 nm emissions are as high as 0.94×10 -5 and 1.60×10 -5 . In addition, the high photon producing efficiency is conducive to ensuring high feedback to thermosensitive performance. The temperature thermal sensor can be manipulated steadily in medium temperature range, and the relative sensitivity reaches 0.4 % K -1 at 303 K, which is 1 order of magnitude larger than those in several rare-earth-doped materials. Efficient photon conversion ability and high temperature sensitivity indicate that the rare-earth-ion-doped fluotellurite material has a prospective application in the construction of optical temperature sensors based on the FIR technique allowing for self-referenced temperature determination.

In recent years, surface-enhanced Raman scattering (SERS) of a molecule/metal-semiconductor hybrid system has attracted considerable interest and regarded as the synergetic contribution of the electromagnetic and chemical enhancements from the incorporation of noble metal into semiconductor nanomaterials. However, the underlying mechanism is still to be revealed in detail. Herein, we report an irreversible accumulated SERS behavior induced by near-infrared (NIR) light irradiating on a 4-mercaptobenzoic acid linked with silver and silver-doped titanium dioxide (4MBA/Ag/Ag-doped TiO 2 ) hybrid system. With increasing irradiation time, the SERS intensity of 4MBA shows an irreversible exponential increase, and the Raman signal of the Ag/Ag-doped TiO 2 substrate displays an exponential decrease. A microscopic understanding of the time-dependent SERS behavior is derived based on the microanalysis of the Ag/Ag-doped TiO 2 nanostructure and the molecular dynamics, which is attributed to three factors: (1) higher crystallinity of Ag/Ag-doped TiO 2 substrate; (2) photo-induced charge transfer; (3) charge-induced molecular reorientation.

Multivariate terbium-complexes were incorporated into polyacrylonitrile (PAN) and electrospun into flexible multifunctional nanofibers with a uniform diameter of ~200 nm. Fluorescence comparison in multi-ligand-binding nanofibers under ultraviolet (UV) radiation verifies that the differentiated β-diketone ligands with dual functions are the primary cause of the spectral fluctuation, adequately illustrating the available methods for the quantification of intermolecular reciprocities between organic ligands and central Tb 3+ ions. Especially under 308 nm UVB-LED pumping, the total emission spectral power of supramolecular Tb-complexes/PAN nanofibers are identified to be 2.88 µW and the total emission photon number reaches to 7.94 × 10 12  cps which are nearly six times higher than those of the binary complex ones in the visible region, respectively. By modifying the sorts of organic ligands, the luminous flux and luminous efficacy of multi-ligand Tb-complexes/PAN nanofibers are up to 1553.42 μlm and 13.72 mlm/W, respectively. Efficient photon-releasing and intense green-emission demonstrate that the polymer-capped multi-component terbium-complexes fibers have potential prospects for making designable flexible optoelectronic devices.

Adaptive fluoride ceramic with glass forming layer (GC ZBL -Er) used in laser anti-escaping has been prepared by one-step synthesis, and the thickness of glass layer is identified as ~0.41 mm. Blue, green and red emissions of Er 3+ /Yb 3+ codoped fluoride ceramic (C ZBL -Er) and glass layer (G ZBL -Er) have been investigated under ~980 nm laser pumping. With the forming of thin glass layer on ceramic surface, the absorption intensities on diffuse reflection of GC ZBL -Er at 974 nm and 1.53 μm increase by 48% and 53% than those of C ZBL -Er. Excited by a 979 nm laser, the presence of the glass layer increases the absolute absorption rate in spectral power from 75% in C ZBL -Er to 83% in GC ZBL -Er, which is consistent with the improvement in the absorbed photon number. In addition, the quantum yield of GC ZBL -Er complex is raised by 28.4% compared to the case of ceramic substrate by photon quantification. Intense absorption-conversion ability and efficient macroscopical anti-escaping effect confirm the superiority of ingenious structure in the fluoride ceramics with glass forming layer, which provides a new approach for developing the absorption-conversion materials of anti-NIR laser detection.

Intense multi-peak red fluorescence and effective near-infrared (NIR) ultra-broadband emission have been observed in Pr 3+ doped ion-exchangeable aluminum germanate (NMAG) glasses. The maximum emission cross section for P 0 3→F 2 3 red emission is up to 100.58×10 -21   cm 2 , and the NIR emission corresponding to D 2 1→G 4 1 transition possesses a full-width at half-maximum (FWHM) of 210 nm. Although the obvious cross-relaxation (CR) process at high concentration causes a decrease of the quantum efficiency, the CR broadens the spectral FWHM effectively from another perspective. The admirable red fluorescence trace and the NIR single-mode transmission confirm that Pr 3+ doped NMAG glass planar waveguides can support the generation of visible fluorescence and the amplification of infrared signal. For a waveguide channel ion-exchanged in molten KNO 3 for 2 h, the single-mode field diameters at 1.55 μm are identified to be 10.4 μm in the horizontal direction and 6.5 μm in the vertical direction, implying an acceptable overlap with a standard single-mode fiber. Effective red fluorescence and broad NIR emission demonstrate that Pr 3+ doped NMAG glasses are a promising substrate in developing irradiative luminescence sources and ultra-broadband waveguide amplifiers, especially operating at the entire S-, C-, and L- bands.

The spin and orbital angular momentum (SAM and OAM) of light is providing a new gateway toward high capacity and robust optical communications. While the generation of light with angular momentum is well studied in linear optics, its further integration into nonlinear optical devices will open new avenues for increasing the capacity of optical communications through additional information channels at new frequencies. However, it has been challenging to manipulate the both SAM and OAM of nonlinear signals in harmonic generation processes with conventional nonlinear materials. Here, we report the generation of spin-controlled OAM of light in harmonic generations by using ultrathin photonic metasurfaces. The spin manipulation of OAM mode of harmonic waves is experimentally verified by using second harmonic generation (SHG) from gold meta-atom with 3-fold rotational symmetry. By introducing nonlinear phase singularity into the metasurface devices, we successfully generate and measure the topological charges of spin-controlled OAM mode of SHG through an on-chip metasurface interferometer. The nonlinear photonic metasurface proposed in this work not only opens new avenues for manipulating the OAM of nonlinear optical signals but also benefits the understanding of the nonlinear spin-orbit interaction of light in nanoscale devices.