Transparent Lu3Al5O12:Dy3+ ceramics were fabricated for UV-pumped white light-emitting diodes (WLEDs) via solid-state sintering under vacuum. The color chromaticity of the ceramic-based phosphors were tuned by tailoring the Dy3+ concentration and incorporating Yb into the crystal lattice to form (Lu, Yb)3Al5O12:Dy3+ solid solutions. Phase composition, microstructure, optical and photoluminescence properties of the ceramics were investigated in detail by X-ray diffraction (XRD), Scanning electron microscopy (SEM), UV–vis-NIR spectrometer and fluorescence spectrophotometer, respectively. White light can be obtained by combining the UV-chip and the structure/property-optimized ceramic phosphors. The color hue was tuned from (0.4107, 0.4037) to (0.3647, 0.3299) with the increasing Yb content from 0 to 0.5 substituting Lu sites in the garnet structure. The (Lu0.5Yb0.5)3Al5O12: 0.01Dy3+ ceramic-based phosphor showed a relative low correlated color temperature of 4137 K. The decrease in PL intensities with Yb incorporation was also discussed via microstructure and fluorescence lifetime characterizations.

•LuF3 mesocrystals were successfully synthesized for the first time.•The UC luminescence properties of LuF3:Yb3+/Er3+/Tm3+ were investigated in detail.•The fluorescent intensity ratio (IEr/ITm) decreases with increased temperature.•The phosphor exhibits a high sensitivity of 20.6% K−1.Yb3+/Er3+/Tm3+ triply doped LuF3 mesocrystals have been successfully synthesized to explore their possible application in optical temperature sensors. Especially, owing to the non-resonant energy match between the 4F9/2 (Er3+) and 3F2 (Tm3+) states and thus the occurrence of multiphonon assisted energy transfer process (Er3+→ Tm3+), two upconversion (UC) emission bands corresponding to F9/24→I15/24 (Er3+) transition and F23 → H63 (Tm3+) one exhibit distinct temperature-dependent behaviors, which result in monotonous decrease of the related fluorescent intensity ratio (IEr/ITm) with increased temperature. Consequently, the high sensitivity of 20.6% per K for LuF3:Yb3+/Er3+/Tm3+ mesocrystals may make them very promising candidate as optical temperature sensor.

•A inner-motile photocatalyst film is designed by citing magnetic cilia.•The light absorption, charge separation and transport are improved simultaneously.•The photocatalyst film can boost mass transfer through mimicking ciliary motion.An active inner-motile photocatalytic film has been explored, which integrates three functional modules, i.e. magnetic cilia, ZnO nanorod arrays and TiO2 nanoparticles. This new design strategy is a multifunctional key to improving light absorption, interior mass transfer, charge separation and transport simultaneously. When the magnetic photocatalyst cilia mimic ciliary motion like natural beating cilia, the photocatalytic activity can be enhanced because the inner mass transfer is accelerated. Besides, ZnO nanorod arrays is applied in the inner-motile photocatalytic system because that the micro-nano structure can effectively trap the light via multiple reflections. Furthermore, through constructing ZnO@TiO2 heterojunction, the electron−hole recombination is reduced and the charge transport is improved.

•Sm0.5Sr0.5CoO3-δ ceramic was modified with CuO by magnetron sputtering and subsequent annealing treatments.•Surface morphologies and spectra properties were adjusted by the temperatures and atmospheres of annealing treatments.•Modified Sm0.5Sr0.5CoO3-δ annealed at 400 °C in an oxygen atmosphere for 1 h exhibits a high solar selectivity of 2.58.We investigated the optical properties of CuO-modified Sm0.5Sr0.5CoO3-δ ceramics as possible candidate materials for solar absorbing applications. Bulk composite materials were successfully prepared by a facile and cost-effective solid-state reaction method and subsequent magnetron sputtering. The solar absorbance and spectral selectivity properties were evaluated using room-temperature hemispherical reflectance spectra measured from the ultraviolet to the mid-infrared region for samples with different composition, thickness, and surface roughness. The effect of annealing at different temperatures in air or oxygen was also investigated. The experimental results showed that a composite of Sm0.5Sr0.5CoO3 and Cu (100 nm) ceramic annealed at 600 °C in air for 1 h had a solar absorbance comparable to that of the most advanced solar absorber materials, such as silicon carbide, with a higher spectral selectivity. Our material also exhibits better solar-selective absorption properties and higher solar selectivity (2.69) than that of smooth, unmodified Sm0.5Sr0.5CoO3 (2.07) and could potentially be used as an alternative material for spectrally selective absorber applications.Download high-res image (139KB)Download full-size image

•A strategy to achieve 808 nm excited single-band red UC emission has been provided.•Nd3+/Yb3+/Er3+ tri-doped KMnF3 nanocrystals are synthesized by solvothermal method.•The corresponding energy transfer mechanism have been discussed in detail.•A new type of UCNPs is developed as attractive alternative for deep-tissue imaging.A new type of upconversion nanoparticles (UCNPs) whose excitation and emission peaks are both located in the biological window has been developed based on the combination of Nd3+ sensitization and efficient energy transfer between Mn2+ and Er3+ ions. In our design, Nd3+ ions act as sensitizers for efficient absorption of 808 nm NIR photons, while the usage of Yb3+ ions as energy migrators facilitates the efficient energy transfer from Nd3+ to Er3+ ions. More importantly, the introduction of Mn2+ ions plays a key role in the realization of single-band red UC emission of Er3+ ions via the efficient energy transfer process between Mn2+ and Er3+. Consequently, upon 808 nm laser excitation, single-band red UC emission can be obtained in the as-synthesized Nd3+/Yb3+/Er3+ tri-doped KMnF3 nanocrystals, which could be considered as attractive alternative to conventionally used UCNPs for deep-tissue imaging with mitigation of the attenuation effect associated with the emission peaks outside biological window and the overheating constraints imposed by the conventional 980 nm laser excitation.

Efficient charge separation accelerated by a spatial electric field is a vital factor for semiconductor photocatalysts to achieve high photocatalytic activity. In this work, poly(vinylidene fluoride) (PVDF) with piezoelectric effects was first introduced into a photocatalyst system to highly improve the photocatalytic efficiency. The results indicate that, in the presence of organic piezoelectric PVDF, the photocatalytic efficiency of a PVDF–TiO2 film is improved by about 55%. The corresponding first-order reaction rate constant (k) value is increased 5.42 times. Moreover, photocatalytic activity enhancement is ascribed to the promotion effect of the spatial electric field on charge separation, which has been demonstrated by hydroxyl radical analysis. Furthermore, the results indicate that the spatial electric field of PVDF plays a generic enhancement role in the photocatalysis of both ultraviolet (UV)-light-responsive and visible-light-responsive photocatalysts. In a wider perspective, this work provides an efficient strategy, coupling solar energy and electric energy induced by organic flexible piezoelectric PVDF, to greatly enhance the photocatalytic performance.

For practical applications, the stability of perovskite-like oxides in various environments should be evaluated. In this work, samples of Gd0.8Ca0.2BaCo2O5+δ (GCBC2)were annealed in different atmospheres and at different temperatures, and changes in their spectral reflective properties, infrared radiative properties, and electrical conductivity properties under solar irradiation were investigated using thermogravimetric analyses, reflection spectra measurements, electrical conductivity measurements, and X-ray photoelectron spectroscopy. The results of the study show that oxygen non-stoichiometry is dependent on the temperature and atmosphere used during the annealing process. In an oxygen atmosphere, an increase in oxygen non-stoichiometry was observed up to temperatures of 500 °C, and then a decrease at 800 °C. In a nitrogen atmosphere, oxygen stoichiometry always decreased at temperature above 400 °C. Although an increase in oxygen content had no effect on the ceramic’s electrical and optical properties, a decrease in oxygen content affected its properties significantly. Therefore, because GCBC2 has a typical insulator–metal transition under solar irradiation below 500 °C, and a low infrared emissivity in oxidized atmospheres, it can be used as a solar thermal conversion material, or for spacecraft thermal control devices in an oxidized environment.

The incorporation of thermally-induced shape-memory polymer (SMP) with photothermal fillers has been widely used in creating photoresponsive SMP composites (SMPCs). Near-infrared (NIR) light, which is safer for human tissues and naked eyes, has been widely used to trigger such intelligent SMPCs containing carbon nanomaterials, metal nanoparticles, or rare earth organic complexes. There is still a need to aim invisible NIR light beam remotely onto SMPCs to realize the precise shape recovery of their featured areas. Here, NaYF4:99.5%Yb3+, 0.5%Tm3+ particles presenting both upconversion and photothermal capabilities were utilized as multifunctional fillers in a crosslinked copolymer of methyl methacrylate and butyl acrylate, enabling the prepared SMPCs to transfer the NIR light at 980 nm simultaneously into both visible light and heat. The particles with a low content up to 1 phr did not vary the crosslinking level and glass transition temperature of the SMPC. With the aid of upconversion at a relatively low power density, the position of laser beam on SMPC surface was detected easily, facilitating the aim towards the area anticipated to be triggered without inducing a shape deformation. The subsequent increase in power density successfully resulted in the precise shape recovery with the recovery ratio higher than 90%. The concept of precise location before stimulation was demonstrated in the cases of multiple shape deformations, remote activation in the darkness, and microscale structured surfaces. The reported multifunctional nanoparticles truly executed the remote and precise trigger of SMPCs using invisible NIR light, which can be further exploited in other thermally-induced smart polymer composites.

•Organic complexes Yb0.2Er0.4Tm0.4(TTA)3Phen which can transfer infrared light to visible light were successfully prepared.•Photonic crystal films with controllable layers were fabricated by controlling concentrations of self-assembly solutions.•The emission color of photonic crystal materials can be adjusted from green to blue as the periodic size increases.•Finite-different time-domain calculation was used to analyze electric field properties of photonic crystal structures.Novel photonic crystal materials (PCMs) with adjustable fluorescence were fabricated by distributing organic fluorescent powders of Yb0.2Er0.4Tm0.4(TTA)3Phen into the opal structures of self-assembled silica photonic crystals (PCs). Via removing the silica solution in a constant speed, PCs with controllable thicknesses and different periodic sizes were obtained on glass slides. Yb0.2Er0.4Tm0.4(TTA)3Phen powders were subsequently distributed into the opal structures. The structures and optical properties of the prepared PCMs were investigated. Finite-difference-time-domain (FDTD) calculation was used to further analyze the electric field distributions in PCs with different periodic sizes while the relation between periodic sizes and fluorescent spectra of PCMs was discussed. The results showed that the emission color of the PCMs under irradiation of 980 nm laser can be easily adjusted from green to blue by increasing the periodic size from 250 to 450 nm.Download high-res image (252KB)Download full-size image

•The TTA-UCL clusters possesses a core–shell structure which is of crucial importance for enhancing the mobility of core liquid.•The core-shell structure provides a solid surface for coupling with CdS which absorbs the converted high energy photons from TTA-UCL.•Pt as co-catalyst is deposited on CdS surface to facilitate the separation of photo-generated electrons and holes.•The CdS/Pt system based on TTA-UCL has a preferable photocatalytic activity in decomposing tetracycline and photoinduced hydrogen evolution.•This work opens a distinctive perspective for building a kind of TTA-based upconversion–photocatalysis system.We herein report the triplet–triplet annihilation upconversion luminescence (TTA-UCL) clusters achieved by loading the platinum(II)-octaethylporphyrin (PtOEP) and 9,10-diphenylanthracene (DPA) into silica shells. This aqueous-based system possesses a core–shell structure which is of crucial importance for enhancing the mobility of core liquid. The encapsulated clusters with efficient green-to-blue upconversion without deoxygenation are conjoined with cadmium sulfide (CdS) as the photocatalyst. Platinum (Pt) is used to improve the separation of electron−hole pairs on the photocatalytic system. Given the band gap of photocatalysts, tetracycline (TC) degradation and photoinduced hydrogen evolution are used to perform the photocatalytic activity. CdS loaded with Pt has higher Pseudo-first-order rate constant (kpfo) in decomposing tetracycline than pure CdS. Moreover, the excellent hydrogen evolution property appears when the converted high energy photons from TTA-UCL-based clusters are introduced to the photocatalytic system. The quantum efficiency of hydrogen evolution increases further after the cocatalyst Pt deposition. This work not only fabricates an encapsulated structure for TTA-UCL clusters, but also provides an effective TTA-supported upconversion-photocatalysis system.Download high-res image (154KB)Download full-size imageSchematic illustration of the photocatalysis mechanism of PtDPA@SiO2@CdS/Pt based on TTA-UCL process. The core–shell structure to encapsulate the inert organic medium containing triplet–triplet annihilation upconversion chromophores (PtOEP as the sensitizer and DPA as the emitter) in a rigid silica shell. The green excited light with lower energy photons (2.23 eV < E < 2.38 eV) can’t acitve the catalyst CdS that has a band-gap width of 2.4 eV, while obtained higher energy photons (3.06 eV > E > 2.91 eV) through triplet–triplet annihilation upconversion process can sensitize effectively CdS. The sensitized CdS further makes the photogenerated electron transfer to the noble metal Pt. This upconversion–photocatalysis system opens a distinctive perspective for improving photocatalytic activity.

•Transparent Er3Al5O12 ceramic with excellent optical quality has been fabricated.•The ceramic is pore-free and the density was measured to be 6.38 g/cm3.•Upconversion luminescence of the Er3+:YAG and ErAG ceramics were studied and compared.•Luminescence of ErAG under the excitation of LD with various pump power were investigated.Highly transparent Er3Al5O12 (ErAG) ceramic was fabricated by a solid-state reactive sintering method under vacuum. The optical property, microstructure and up-conversion luminescence of the ErAG ceramic were investigated. For the 3 mm thick sample, the in-line transmittance at the wavelength of 3000 nm and 425 nm were about 84% and 81%, respectively, which was very close to the theoretical transmittance of the Er3Al5O12 single crystal. Micrograph of the ErAG transparent ceramic exhibited a pore-free structure and the density of the ceramic was measured to be 6.38 g/cm3. Average grain size of the ceramic was about 9 μm. When pumped by a 980 nm laser diodes (LD), strong green and red emission in the ErAG ceramic was observed from the photoluminescence (PL) spectrum. The luminescent properties of the ceramic under the excitation of LD with various pumping power were investigated.

•Fe powders replacing Cu powders is first proposed.•The optimal results are gained when the content of Fe powders substitution is 10 wt%.•Fe powders replacing Cu powders is more effective especially at high temperature.Cost-effective thermal energy storage materials are vital to the application of solar thermal power plants. One focus of this paper is improving thermal and mechanical properties of the thermal energy storage materials; the second focus lies in reducing the investment cost. On the basis of aluminate cementitious composites with 1 wt% nano-SiO2, 1 wt% nano-Cu and 15 wt% Cu powders, we introduced different wt% (0, 5, 10, and 15) of Fe powders to gradually replace 15 wt% Cu powders. The samples were heated at 105, 350, and 900 °C, respectively. As a result, when the content of Fe powders substitution was 10 wt%, volume heat capacity, thermal conductivity and compressive strength of the composites after heat-treatment at 900 °C were up to 2.38 MJ m−3 K−1, 1.45 W m−1 K−1, and 73.8 MPa respectively, which were 26.6%, 26.1%, and 24.0% higher than those of the composites with 15 wt% Cu powders. At the same time, the investment of the composites with 10 wt% Fe powders substitution was reduced almost 62.0%, compared with that of the composites with 15 wt% Cu powders. In addition, XRD and MIP were employed to characteristic the mineral phases and the pore structures of the aluminate cementitious composites, respectively.

•The optical properties of La1−xSrxCoO3−δ (0.2 ⩽ x ⩽ 0.8) ceramics were studied.•The investigated samples showed low thermal emittance at high temperatures.•La0.5Sr0.5CoO3−δ solar absorber was thermally stable in air up to 800 °C for 10 cycles (90 h).Perovskite-type La1−xSrxCoO3−δ (0.2 ⩽ x ⩽ 0.8) ceramics were prepared by tape casting and solid state reaction method. The room temperature optical properties of these samples were studied in detail. The temperature dependent emittance measurements and high-temperature durability tests were carried out. Results showed that these materials exhibited low reflectance at the solar spectrum wavelengths and high reflectance in the infrared region, with an optimal spectral selectivity of 3.2. The investigated samples showed low thermal emittance at high temperatures. More importantly, the sample was highly stable in air at 800 °C, as the performance criterion value was lower than 0.05 after 10 cycles (90 h) heat treatment. Our results demonstrate that the La1−xSrxCoO3−δ ceramics have the potential to emerge as high temperature (∼800 °C) solar absorbers for the future solar power systems.

A well-designed, efficient, one-step assembly strategy is implemented in this work by constructing a confined nanospace to manufacture an approximately 120 nm thick inorganic upconversion (UC) nanofilm with highly (101) oriented and morphology-controllable crystal grains, as well as transparent and robust characteristics. The morphology and distribution density of crystal grains of the film can be tuned by varying space heights and precursor concentrations. The confined space incubates a stable growing environment for crystal grains to decrease crystal defects and grow bigger. Therefore, there are high populations of doped Tm ions and high efficiencies of radiation transitions to realize multiphotons ultraviolet (UV) (monitoring range: 300–400 nm) emissions under laser excitation with a wide power range. Quantum yields of the film in the UV region are 4.7 and 16.1 times higher than those of UC nanoparticles synthesized by the typical thermal decomposition method and hydrothermal method, respectively. The UV-enhanced UC film is demonstrated to have the ability to serve as a medium to realize near-infrared induced undersurface photochemical reactions, which may inspire broad applications, such as UC three-dimensional printing.

•Y2O3: Dy3+ particles were prepared by urea homogeneous precipitation.•Doping concentration effect on the particle growth of Y2O3: Dy3+ was discovered.•A possible controlled-growth mechanism of particles induced by Ln3+ was proposed.•The luminescence color hue can be tuned to (0.31, 0.33) under UV-light excitation.Submicron-sized Dy3+: Y2O3 particles were successfully prepared via an urea homogeneous precipitation method, followed by a calcination at 800 °C. TG-DSC, FT-IR, X-ray diffraction (XRD), Field emission scanning electron microscope (FE-SEM), scanning electron microscope (SEM), photoluminescence (PL), and photoluminescence excitation (PLE) spectra were used to characterize the prepared samples. The particles were spherical shape and monodispersed. More importantly, the spherical Y2O3 particles were found to have significant changes in size with varying dopant concentration of the Dy3+ ions, ranging approximately from 550 to 840 nm. The possible growth mechanism of the particles was proposed. Under 349 nm excitation, the crystalline powders exhibited blue and yellow emissions due to the 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 transitions of Dy3+ ions, respectively. It was further found that with proper Dy3+ doping concentration, the luminescence color hue was tuned close to the ideal white light with color coordinates of (0.33, 0.33). The submicron-sized Dy3+: Y2O3 phosphor is a promising candidate for the white light emitting diodes (WLEDs).

•The ratio of diamine and monoamine was varied to tailor the structure and property of epoxy coatings, offering good thermally-induced self-healing effect.•Carbon black (0.20 phr) acted as photothermal filler to achieve the NIR light induced healing in 3 min under the power density of 1.2 W cm−2.•The recoveries of filler distribution on healed regions and anti-corrosion property demonstrated the well healing efficiency.Light responsive self-healing capability offers polymer coatings the opportunity to heal surface scratches in a localized, non-contact, and remote manner. A near-infrared (NIR) light (808 nm) responsive self-healing coating is reported here, using epoxy and carbon black as coating matrix and photothermal filler, respectively. The chemical structure and property of the prepared epoxy coatings are tailored by changing the ratio of m-xylylenediamine as diamine and 3,5-bis(trifluoromethyl) benzylamine as monoamine. Carbon black is subsequently incorporated into the coating with the optimized thermally induced self-healing ability to achieve good photothermal effect, correspondingly transferring the thermally triggered healing to the light responsive repairing. The results indicate that with the gradual replacement of diamine with monoamine, the epoxy network having lower crosslink density and glass transition temperature (Tg) is achieved, offering sufficient chain mobility for thermally induced healing. A small amount of CB (up to 1.0 phr) provides the coating good photothermal effect under NIR light. Upon exposed to NIR light of 1.2 W cm−2 for only 3 min, efficient healing is achieved. The recovery of the filler distribution on the healed region and the restoration of the anti-corrosion property are finally demonstrated. The combination of photothermal filler into tailored epoxy network via changing the ratio of diamine and monoamine provides a convenient approach to heal scratches of coatings via NIR light.

•The solar absorption properties of GdBaCo2O5+δ can be improved by Ca doping.•Gd0.8Ca0.2BaCo2O5 shows ultrafast conductivity transition induced by solar energy.•Gd0.8Ca0.2BaCo2O5 exhibits low thermal radiative properties at high temperature.This study reveals that the use of a Ca dopant can increase the solar absorption of GdBaCo2O5+δ, with an optimal composition of Gd0.8Ca0.2BaCo2O5 achieving 85% solar absorptance. Electrical conductivity measurements revealed that this composition allows for faster insulator-metal transition and higher conductivity, with the observed variation in conductivity with 0.8 W/cm2 of solar illumination explained in terms of a first-order spin-state transition. Thermal radiation imaging confirmed that regions of different radiative temperature are related to a change in free carriers that promote scattering, and therefore, cause an increase in infrared reflection. This rapid electrical conductivity transition and the low infrared radiation properties at high temperatures strongly suggest that Gd0.8Ca0.2BaCo2O5 could be used in a variety of potential fields, such as high-temperature thermosensitive or thermal storage materials.

•A novel Sr2MgSi2O7/g-C3N4 photocatalyst was prepared for the first time.•The best mass ratio of Sr2MgSi2O7 in the composite was confirmed.•The new-type photocatalyst can still remain photocatalytic activity for about 6 h in the darkness.•The photocatalytic activity of new-type photocatalyst is enhanced.A stable round-the-clock photocatalyst was prepared for the first time by combining Sr2MgSi2O7: (Eu, Dy) (SMSO) and g-C3N4. When the external light source was removed, the new-type photocatalyst still remained photocatalytic activity for about 6 h. Furthermore, the photocatalytic activity was enhanced by combined with SMSO, possibly due to the higher visible-light utilization efficiency and the reduced recombination rate of the photo-generated carriers. The repeated photocatalysis experiment showed that the photocatalytic activity was stable.

•Spectrally selective absorbing properties of Ti3SiC2 and Zr3[Al(Si)]4C6 are investigated.•The spectral selectivity of Ti3SiC2 and Zr3[Al(Si)]4C6 are 3.7 and 2.8, respectively.•Ti3SiC2 and Zr3[Al(Si)]4C6 exhibit a low emissivity in the investigated temperature range.•Suitability of Ti3SiC2 and Zr3[Al(Si)]4C6 as high-temperature solar absorbers is discussed.Layered Ti3SiC2 and Zr3[Al(Si)]4C6 ceramics were prepared by hot-pressed sintering. The spectrally selective absorption properties of these layered carbides have been investigated and compared with those of TiC and ZrC. It is found that the Ti3SiC2 ceramic exhibits a solar absorbance of 0.70 and a thermal emissivity of 0.19, yielding spectral selectivity (absorbance divide by emissivity) of 3.7, while the spectral selectivity of Zr3[Al(Si)]4C6 is 2.8 (0.71/0.25). To evaluate the suitability of these ceramics as high-temperature absorbers for solar radiation, the investigation on the thermal stability and temperature dependent emittance was performed in air. Compared with TiC and ZrC, both Ti3SiC2 and Zr3[Al(Si)]4C6 show better thermal stability. Meanwhile, Ti3SiC2 and Zr3[Al(Si)]4C6 exhibit a low emissivity in the investigated temperature range, benefiting from their metal-like electrical conductivity.

•A new strategy was adopted to enhance luminescence intensity of UCNPs.•The mechanism for the luminescence intensity enhancement of UCNPs was discussed.•Significant enhancement of UC emission in β-NaGdF4:Ln3+ nanocrystals was observed.Currently, enhancing luminescence efficiency of upconversion nanoparticles (UCNPs) has still been a challenging topic in despite of many efforts to improve UC luminescence. In this paper, a new strategy to enhance UC emission has been described based on coupling of Li+ ions doping with growth an inert shell. Significant enhancement of upconversion (UC) luminescence intensity of lanthanide-doped nanoparticles was observed under synergistic effect of internal adjustment and external approach. In addition, the mechanism for the luminescence enhancement of UCNPs has been discussed. Our results suggest that this UC enhancement strategy, proven here in NaGdF4 nanoparticles, could be extended to other lanthanide-doped nanocrystal systems for applications ranging from luminescent biological labels to volumetric three-dimensional displays.

Surface textured Sm0.5Sr0.5CoO3−δ oxide ceramics were prepared by means of compression molding followed by high temperature sintering. The effects of surface texture on the optical and photo-thermal conversion performances of Sm0.5Sr0.5CoO3−δ were investigated. Results showed that the solar absorptance of Sm0.5Sr0.5CoO3−δ increased from 0.69 to 0.85 because of surface texturization. Besides, textured Sm0.5Sr0.5CoO3−δ exhibited better photo-thermal conversion ability than the planar ones, with almost no selectivity to the incident irradiation, normal or oblique. Optimized samples were tested as sunlight absorber for concentrating solar thermoelectric generator. It is anticipated that the textured Sm0.5Sr0.5CoO3−δ ceramic absorber can be extended to design non-tracking concentrating solar thermoelectric generators.

Calcium-doped lanthanum chromite, La1−xCaxCrO3, was prepared using a solid-state reaction method, and the effect of varying the Ca content (0 ≤ x ≤ 0.5) was investigated in relation to its crystalline structure, surface morphology, solar absorption and thermal radiation. This found that the crystalline structure is slightly distorted by Ca2+ doping, with an accompanying increase in the valence state of Cr ions and oxygen vacancies enhancing both the solar absorption and thermal emittance. Overall, the La1−xCaxCrO3 system displays relatively high thermal radiation properties, with an optimal composition of La0.5Ca0.5CrO3 exhibiting a solar absorption of 95% and a thermal emittance of 0.94. When used as a light absorber coupled to a thermoelectric module this proved capable of generating electricity and hot water, thereby demonstrating the suitability of this energy-saving material for use in solar thermal radiation applications.

A new type of inner-motile photocatalyst film is explored to enhance photocatalytic performance using magnetically actuated artificial cilia. The inner-motile photocatalyst film is capable of generating flow and mixing on the microscale because it produces a motion similar to that of natural cilia when it is subjected to a rotational magnetic field. Compared with traditional photocatalyst films, the inner-motile photocatalyst film exhibits the unique ability of microfluidic manipulation. It uses an impactful and self-contained design to accelerate interior mass transfer and desorption of degradation species. Moreover, the special cilia-like structures increase the surface area and light absorption. Consequently, the photocatalytic activity of the inner-motile photocatalyst film is dramatically improved to approximately 3.0 times that of the traditional planar film. The inner-motile photocatalyst film also exhibits high photocatalytic durability and can be reused several times with ease. Furthermore, this feasible yet versatile platform can be extended to other photocatalyst systems, such as TiO2, P25, ZnO, and Co3O4 systems, to improve their photocatalytic performance.

•Sm0.5Sr0.5Co1−xCrxO3 can be used as a controlled near-infrared reflective inorganic oxide.•Sm0.5Sr0.5Co1−xCrxO3 was prepared by solid-state reaction.•Effects of Cr3+ doping on crystal structure and electrical conductivity were found.•Solar absorbance, infrared emittance can be controlled by Cr3+ dopant concentration to meet various demands.A new application of Sm0.5Sr0.5Co1−xCrxO3 as a controlled near-infrared reflective inorganic oxide has been developed. Samples were prepared by a solid-state reaction to form a perovskite solid solution with an orthorhombic structure. Then, the effect of Cr3+ cation doping on the crystal structure, electrical conductivity, solar absorbance, and thermal emittance properties of the Sm0.5Sr0.5Co1−xCrxO3 was investigated. The electrical conductivity decreases upon the substitution of Cr3+ ions for Co3+/Co4+ because of the appearance of Cr3+–O2−–Cr3+ and Co3+–O2−–Cr3+ units, reducing the amount of the Co3+–O–Co4+ network. The Cr3+ ions doped into Co3+ sites were found to enhance the solar absorbance from 68.2% to 91.6% and to simultaneously increase the infrared emittance from 0.25 to 0.93. The mobility of infrared optical phonons from free electrons decreases upon Cr3+ doping, which weakens the scattering effect and enhances the absorption. Based on these properties, we can control the Cr3+ dopant concentration of Sm0.5Sr0.5Co1−xCrxO3 to meet our demands.

The mutual ultraviolet (UV) degradation protection and optical conversion mechanism of ethylene-vinyl acetate copolymer (EVA) rare earth organic complex (REOC) composite were investigated. The uniform Sm(TTA)3Phen (MSTP) particles were successfully synthesized via microwave ultrasonic technique, and were uniformly embedded into the EVA long chain cross-linked structure with excellent dispersion. The MSTP doped EVA film provides an excellent active optical conversion and highly visible transmission performance, the properties of which are strongly dependent on the size and concentration of the doped particle, and its absorption and emission properties. MSTP was effective as a UV light resistant agent and was a highly active optical conversion additive for EVA rare earth organic complex composites with perfect network structure and excellent adhesion properties, which through the destruction of the structure can transform the heat energy into the form of light energy release via hydrogen bonding.

•Spectrally selective absorbing properties of Ti3SiC2 and Zr3[Al(Si)]4C6 are investigated.•The spectral selectivity of Ti3SiC2 and Zr3[Al(Si)]4C6 are 3.7 and 2.8, respectively.•Ti3SiC2 and Zr3[Al(Si)]4C6 exhibit a low emissivity in the investigated temperature range.•Suitability of Ti3SiC2 and Zr3[Al(Si)]4C6 as high-temperature solar absorbers is discussed.Layered Ti3SiC2 and Zr3[Al(Si)]4C6 ceramics were prepared by hot-pressed sintering. The spectrally selective absorption properties of these layered carbides have been investigated and compared with those of TiC and ZrC. It is found that the Ti3SiC2 ceramic exhibits a solar absorbance of 0.70 and a thermal emissivity of 0.19, yielding spectral selectivity (absorbance divide by emissivity) of 3.7, while the spectral selectivity of Zr3[Al(Si)]4C6 is 2.8 (0.71/0.25). To evaluate the suitability of these ceramics as high-temperature absorbers for solar radiation, the investigation on the thermal stability and temperature dependent emittance was performed in air. Compared with TiC and ZrC, both Ti3SiC2 and Zr3[Al(Si)]4C6 show better thermal stability. Meanwhile, Ti3SiC2 and Zr3[Al(Si)]4C6 exhibit a low emissivity in the investigated temperature range, benefiting from their metal-like electrical conductivity.

In this study, Ce3+, Gd3+ and Sm3+ co-doped β-NaLuF4 micro-prisms with prominently uniform shape and size have been successfully prepared by a facile and efficient hydrothermal strategy. By modifying the dopant concentration of migrator (Ce3+) and activator (Sm3+), the luminescent properties of β-NaLuF4:Ce3+/Gd3+/Sm3+ samples are systematically studied and the corresponding energy transfer (ET) mechanism can be discussed in detail. Impressively, upon the excitation into the electric-dipole-allowed 4f→4f→5d5d transition of CeCe3+ ions at 250 nmnm, the efficient ET from CeCe3+ ions (sensitizer) to SmSm3+ ions (activator) can be realized through the Ce3+→(Gd3+)n→Sm3+Ce3+→(Gd3+)n→Sm3+ energy migration process, in which the Gd3+ (migrator) acts as a bridge center to yield intense orange emission from Sm3+ ions. The above results not only enrich the knowledge of the synthetic chemistry and optical spectroscopy of luminescent materials, but also endow such materials with potential applications in a diversity of fields.

Cobalt-based perovskite oxides, LnBaCo2O5+δ (Ln=La to Lu), were investigated as potential variable electrical and thermal radiative materials under solar irradiation. The particular Ln3+ dopant has a significant effect on the oxide's phase structure, spectral reflectivity, electrical conductivity, and thermal radiative properties. Stable, cation-ordered oxides with layered lattice structures were obtained with medium-size Ln3+ ions. The general features of the electrical and spectral reflective properties of LnBaCo2O5+δ (Ln=La, Nd, Sm to Ho) are discussed. It is shown that LnBaCo2O5+δ (Ln=Sm to Ho) has a significant insulator–metal transition under solar irradiation, whereas LnBaCo2O5+δ (Ln=La, Nd) has a lower infrared emissivity at high temperatures due to the metal-like optical behavior.

•The spatial electric field of PMN-PT was constructed into photocatalytic system to enhance photocatalytic activity.•Spatial electric field greatly improves the photocatalytic efficiency of PDMS-PMN-PT@TiO2filmbyabout55(*)%.•The preparation of photocatalyst film avoids introducing secondary pollution into environment in the practical application.•PDMS-PMN-PT@TiO2 film exhibits brilliant stability even after five runs.Efficient charge separation is quite significant to obtain high photocatalytic performance. In this work, piezoelectric-based composite photocatalyst film PDMS-PMN-PT@TiO2 possessing high recoverability was prepared. The spatial electric field of PMN-PT was introduced into photocatalyst system by ultrasonic wave vibration to accelerate charge separation. Compared with magnetic stirring, ultrasonic wave vibration greatly improved the photocatalytic degradation efficiency of rhodamine B (RhB) over PDMS-PMN-PT@TiO2 film by about 55%. A possible improvement mechanism that spatial electric field promotes charge separation was presented herein. The piezoelectric potential output demonstrated the piezoelectricity of composite film. The durability experiments of PDMS-PMN-PT@TiO2 film indicated its great stability over several runs.