Search Results (25)

Cesium tungsten bronzes (Cs_xWO₃), as functional materials with excellent near-infrared shielding properties, demonstrate significant potential for applications in smart windows. However, traditional synthesis methods, such as solid-state reactions and solvothermal/hydrothermal approaches, typically require harsh conditions, including high temperatures (above 200 °C), high pressure, inert atmospheres, or prolonged reaction times. In this study, we propose an optimized microwave-assisted solvothermal synthesis strategy that significantly reduces the severity of reaction conditions through precise parameter control. When benzyl alcohol was employed as the solvent, Cs_xWO₃ nanoparticles could be rapidly synthesized within a relatively short duration of 15 min at 180 °C, or alternatively obtained through 2 h at a low temperature of 140 °C. However, when anhydrous ethanol, which is cost-effective and environmentally friendly, was substituted for benzyl alcohol, successful synthesis was also achieved at 140 °C in 2 h. This method overcomes the limitations of traditional high-pressure reaction systems, achieving efficient crystallization under low-temperature and ambient-pressure conditions while eliminating safety hazards and significantly improving energy efficiency. The resulting materials retain excellent near-infrared shielding performance and visible-light transparency, providing an innovative solution for the safe, rapid, and controllable synthesis of functional nanomaterials. Full article

Far infrared radiation (FIR) within the wavelength range of 4–14 μm can offer human health benefits, such as improving blood flow. Therefore, additives that emit far infrared radiation have the potential to be incorporated into polymer/fabric matrices to develop textiles that could promote health. In this study, biochar derived from candlenuts and pyrolyzed with activated carbon (AC) was incorporated into polypropylene (PP) films and investigated for its potential as a health-promoting textile additive. The properties of biochar were compared with other far infrared (FIR) emitting additives such as hematite, Indian red ochre, and graphene. The addition of biochar increased FIR emissivity to 0.90, which is 9% higher than that of pristine PP. Additionally, biochar enhanced UV and near-infrared (NIR) blocking capabilities, achieving an ultra-protection factor (UPF) of 91.41 and NIR shielding of 95.85%. Incorporating 2 wt% biochar resulted in a 3.3-fold higher temperature increase compared to pristine PP after 30 s of exposure to an FIR source, demonstrating improved heat retention. Furthermore, the ability to achieve the lowest thermal effusivity among other additives supports the potential use of biochar-incorporated fabric as a warming material in cold climates. The tensile properties of PP films with biochar were superior to those with other additives, potentially contributing to a longer product lifespan. Additionally, samples with red ochre exhibited the highest FIR emissivity, while samples with hematite showed the highest capacity for UV shielding. Full article

Cs_0.33WO₃ (CWO) is a widely used inorganic material in window films and glass coatings, known for its excellent near-infrared radiation (NIR) blocking property and high visible light transmittance (T_vis). However, the stability of NIR blocking and the optical properties of CWO in the process of application is an urgent and important problem, because significant changes in optical results can impact the related products, such as window films, glass coatings, and so on. In this paper, the particle sizes and optical properties of CWO are tested to study the light stability and their relative relations. The results indicate that CWO particle sizes between 130 nm and 100 nm (D90, the point where 90% of the particles have a diameter smaller than the specified value) exhibit high stability in terms of NIR blocking and visible light transmittance (Tvis). CWO particles with D90 < 100 nm experience a greater reduction in NIR blocking, though this ability significantly recovers upon exposure to sunlight, making these coatings particularly suitable for use in tropical and subtropical climates. Full article

This research aims to enhance the near-infrared (NIR) shielding ability of cesium tungsten bronze (CsWO₃) by increasing the spectral absorption in this region through the incorporation of gold nanorods (Au_NR). Two approaches were used to prepare the composite materials: physical mixing and solvothermal process. The effects of gold nanorods content on the crystalline size, particle size, shape, and optical properties of the composite were investigated systematically using DLS, TEM, XRD, and UV–Vis spectroscopy techniques, respectively. The physical mixing process synergizes Au_NR and CsWO₃ into a composite which has better NIR absorption than that of neat Au_NR and CsWO₃ nanorods. A composite with 10 mol% of Au_NR shows the highest NIR absorption ability due to the surface plasmon resonance and energy coupling between Au and CsWO₃. With the solvothermal process, the CsWO₃ nanorods grow up to 4–7 microns when the Au_NR content increases to 0.8 mol% due to the incorporation of the Au atoms. The microsized CsWO₃ rods have superior NIR shielding property compared to other conditions, including the Au_NR+CsWO₃ nanocomposite with 10 mol% of Au_NR from the physical mixing process. Full article

The global antibiotic resistance crisis has drawn attention to the development of treatment methods less prone to inducing drug resistance, such as antimicrobial photodynamic therapy (aPDT). However, there is an increasing demand for new photosensitizers capable of efficiently absorbing in the near-infrared (NIR) region, enabling antibacterial treatment in deeper sites. Additionally, advanced strategies need to be developed to avert drug resistance stemming from prolonged exposure. Herein, we have designed a conjugated oligoelectrolyte, namely TTQAd, with a donor-acceptor-donor (D-A-D) backbone, enabling the generation of reactive oxygen species (ROS) under NIR light irradiation, and cationic adamantaneammonium groups on the side chains, enabling the host-guest interaction with curcubit[7]uril (CB7). Due to the amphiphilic nature of TTQAd, it could spontaneously form nanoassemblies in aqueous solution. Upon CB7 treatment, the positive charge of the cationic adamantaneammonium group was largely shielded by CB7, leading to a further aggregation of the nanoassemblies and a reduced antibacterial efficacy of TTQAd. Subsequent treatment with competitor guests enables the release of TTQAd and restores its antibacterial effect. The reversible supramolecular switch for regulating the antibacterial effect offers the potential for the controlled release of active photosensitizers, thereby showing promise in preventing the emergence of drug-resistant bacteria. Full article

The necessity for reliable and efficient multifunctional optical and optoelectronic devices is always calling for the exploration of new fertile materials for this purpose. This study leverages the exploitation of dyed environmentally friendly biopolymeric thin films as a potential optical absorber in the development of multifunctional opto-(electronic) and solar cell applications. Uniform, stable thin films of dyed chitosan were prepared using a spin-coating approach. The molecular interactivity between the chitosan matrix and all the additive organic dyes was evaluated using FTIR measurements. The color variations were assessed using chromaticity (CIE) measurements. The optical properties of films were inspected using the measured UV-vis-NIR transmission and reflection spectra. The values of the energy gap and Urbach energy as well as the electronic parameters and nonlinear optical parameters of films were estimated. The prepared films were exploited for laser shielding as an attenuated laser cut-off material. In addition, the performance of the prepared thin films as an absorbing organic layer with silicon in an organic/inorganic heterojunction architecture for photosensing and solar energy conversion applicability was studied. The current-voltage relation under dark and illumination declared the suitability of this architecture in terms of responsivity and specific detectivity values for efficient light sensing applications. The suitability of such films for solar cell fabrications is due to some dyed films achieving open-circuit voltage and short-circuit current values, where Saf-dyed films achieved the highest V_oc (302 mV) while MV-dyed films achieved the highest J_sc (0.005 mA/cm²). Finally, based on all the obtained characterization results, the engineered natural cost-effective dyed films are considered potential active materials for a wide range of optical and optoelectronic applications. Full article

The shielding and spectroscopic properties of Pr⁺³ and Pr³⁺/Ho³⁺-codoped tellurite glass were investigated. The intensity parameters (Ω2 = 3.24-, Ω4 = 1.64-, Ω6 = 1.10 × 10⁻²⁰ cm²) as well as the radiative lifetimes of ³F₄ + ⁵S₂ and ⁵I₆ excited states of Ho³⁺ ions were equal to 301 μs and 3.0 μs, respectively. The former value appears to be much higher than that obtained from the lifetime measurement, indicating the presence of various energy transfer processes. The NIR spectrum of Pr³⁺/Ho³⁺-co-doped tellurite glass is dominated by strong Ho³⁺: ⁵I₆ emission at around 1200 nm, being the result of the energy transfer from Pr³⁺ to Ho³⁺ ions. The shielding effectiveness of the prepared glasses showed good performance against high-energy photons. These findings suggest that the prepared glasses could be used in laser technology such as photodynamic therapy (PDT) treatment procedures and as shielding for radiation protection. Full article

Window−film−integrated, near−infrared (NIR) absorption−based nanomaterials are of great interest in terms of numerous demands to reduce energy consumption, especially in buildings and vehicles. However, the question of how to effectively manage thermal energy generated from NIR harvesting in light−absorbing materials, rather than being wasted or causing negative effects, remains challenging. Herein, hollow copper sulfide (Cu_2−xS) on colorless polyimide (PI) films, enabling them to be well−dispersed and robustly adhered, underwent in situ growth fabrication and were utilized as NIR−thermal−shielding and organic−pollutant−removal dual−function window films. Due to strong NIR absorbance, arising from the heavy hole−doping (copper cation deficiency), the Cu_2−xS/PI composite film exhibited great promise for use in the filtration of the NIR spectrum. By monitoring Cu_2−xS densities, its NIR−shielding efficiency reached 69.4%, with hundred−percent UV blocking and consistent performance within the reliability (85 °C/85%RH) tests over one week as well as 5000 bending cycles. The integration of the films into model cars and building windows exhibited excellent thermal−shielding performance upon exposure to direct sunlight. Moreover, benefiting from the distinctive distribution of Cu_2−xS, the additional thermal energy (holes) generated in NIR absorption was successfully utilized. The densely surface−confined hollow structure of Cu_2−xS on PI significantly endowed good formaldehyde catalytic capacity, with removal efficiency reaching approximately 72% within 60 min and a negligible decline after quartic reuse. These integration methodologies enable the promising fabrication of a high−performance, bifunctional window film combining thermal shielding and indoor organic pollutant removal. Full article

The melt-quenching approach was used to prepare phosphate–titanite glasses with the composition P₂O₅-Na₂O-CaO-8KF-CaCl₂-xTiO₂ (where x = 2, 4, and 6) in a mol %. The optical, physical, and shielding properties, such as the mass attenuation coefficient (MAC), half-value layer (HVL), effective electron density (N_eff), and effective atomic number (Z_eff), of the glasses were investigated at energies ranging between 15 and 200 keV. The shielding parameters were investigated using recently developed software (MIKE). The optical properties were examined using devices such as UV-Vis-NIR spectroscopy over wavelengths ranging between 190 and 2500 nm. The reported results showed that increasing the concentration of TiO₂ led to an increase in the density from 2.657 to 2.682 g/cm³ and an increase in the OPD from 66.055 to 67.262 mol/L, while the molar volume (V_M) and oxygen molar volume (V_O) decreased from 39.21 to 39.101 cm³/mol and from 15.139 to 14.867 cm³/mol, respectively. The energy gap was found to decrease from 3.403 to 3.279 eV when the TiO₂ concentration increased. Furthermore, as the surface plasmon resonance of TiO₂ increases, so does its third-order susceptibility, non-linear refractive indices, linear attenuation, and mass attenuation. The shielding performance evaluation indicates that the most suitable energy range is between 15 and 50 keV. Based on the results, the PCKNT3 glass sample exhibits the highest attenuation performance of all of the samples tested. Full article

Understanding the photophysical properties and stability of near-infrared fluorescent proteins (NIR FPs) based on bacterial phytochromes is of great importance for the design of efficient fluorescent probes for use in cells and in vivo. Previously, the natural ligand of NIR FPs biliverdin (BV) has been revealed to be capable of covalent binding to the inherent cysteine residue in the PAS domain (Cys15), and to the cysteine residue introduced into the GAF domain (Cys256), as well as simultaneously with these two residues. Here, based on the spectroscopic analysis of several NIR FPs with both cysteine residues in PAS and GAF domains, we show that the covalent binding of BV simultaneously with two domains is the reason for the higher quantum yield of BV fluorescence in these proteins as a result of rigid fixation of the chromophore in their chromophore-binding pocket. We demonstrate that since the attachment sites are located in different regions of the polypeptide chain forming a figure-of-eight knot, their binding to BV leads to shielding of many sites of proteolytic degradation due to additional stabilization of the entire protein structure. This makes NIR FPs with both cysteine residues in PAS and GAF domains less susceptible to cleavage by intracellular proteases. Full article

Aramid nonwoven (AN), with lightweight and flexible features, is highly attractive as a thermal insulation material to prevent or minimize skin burn damage. However, it has a finite protective effect due to the restriction of the polymer material and the surface hairiness of nonwoven fabrics. This study aimed to introduce different shapes of TiO₂ particles coated with Sn(Sb)O₂ (ATO) so as to promote protective performance by taking advantage of the high refraction of TiO₂@ATO in the visible light (Vis) and near-infrared (NIR) range. It is demonstrated that, compared with AN, the thermal protection effect of the obtained TiO₂@ATO-coated AN (TiO₂@ATO/AN) was significantly improved owing to the excellent radiation and conduction heat-shielding performance of the TiO₂@ATO coating. The micro-morphology, Vis–NIR spectral features, heat-shielding performances, and thermal protective performance (TPP) values of different composite nonwovens were measured to explore their thermal insulation mechanisms and performances. Compared with pristine AN and AN coated with commercial nano-ATO (ATO/AN), the heating rate of TiO₂@ATO/AN heated using an alcohol lamp was much lower. The maximum TPP values of TiO₂@ATO/AN were enhanced to 1457.874 kW·s/m², while the values for AN and ATO/AN were only 432.23 kW·s/m² and 945.054 kW·s/m², respectively. This study proposes an attractive solution for protecting fabrics against heat damage and opens up tremendous possibilities for heat-resistant nonwoven materials applied in the thermal protection field. Full article

Due to the extraordinary optoelectronic properties and surface-rich functional groups, MXene has shown great promise in many applications, such as electromagnetic shielding, catalysis, sensors, ultrafast photons, etc. In this work, we propose a wide-angle absorber based on a metal-insulator-metal (MIM) metamaterial consisting of MXene. By optimizing the design, the absorption efficiency can be further improved throughout the entire wavelength range. More importantly, the absorber exhibits high-efficiency broadband and wide-angle (20–80°) absorption in the near-infrared range (NIR: 1.1–1.7 μm) by numerical calculation. It is foreseeable that the excellent absorption characteristics and easy-to-manufacture structure of the designed absorber will bring some inspiration to the absorption device in the NIR and its practical application. Full article

The synthesized glass system with a composition of (80-x) TeO₂-10P₂O₅-10Nb₂O₅-xKCl mol% (where x = 5, 10, 15, 20, and 25) was successfully fabricated. The density (ρ) and molar volume (V_m) have been calculated. The investigated glasses were characterized using different analysis methods (differential thermal analysis (DTA) and UV-VIS-NIR spectroscopy). The radiation shielding effectiveness of the synthesized glass system was evaluated using different shielding parameters, such as mass and linear attenuation coefficients (MAC, LAC), half-value layer (HVL), mean free path (MFP), effective atomic number (Z_eff), and effective electron number (N_eff). The results showed that with the increasing potassium chloride (KCl) concentration and decreasing tellurium oxide (TeO₂) concentration, the density, refractive index, Urbach energy (E_u), and glass transition temperature (T_g) decreased, while the optical energy gap (E_opt) and thermal stability increased. As the KCl concentration increases, the values of MAC, LAC, and Z_eff increase in the following order: TPNK5 % > TPNK10 % > TPNK15 % > TPNK20 % > TPNK25 %. Additionally, the shielding effectiveness of TPNK glass system showed good performance compared with some standard materials. The synthesized glass with a minimum KCl content has both good shielding effectiveness and good optical properties, in addition to reasonable thermal stability, which makes it suitable for shielding and optical applications. Full article

The synthesis of ZnO comprising different ratios of zinc acetate (ZA) and zinc nitrate (ZN) from the respective zinc precursor solutions was successfully completed via a simple precipitation method. Zinc oxide powders with different mole ratios of ZA/ZN were produced—80/1, 40/1, and 20/1. The crystallinity, microstructure, and optical properties of all produced ZnO powders were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-Vis-NIR spectrophotometry. The average agglomerated particle sizes of ZnO-80/1, ZnO-40/1, and ZnO-20/1 were measured at 655, 640, and 620 nm, respectively, using dynamic light scattering (DLS). The optical properties of ZnO were significantly affected by the extreme ratio differences in the zinc precursors. ZnO-80/1 was found to have a unique coral-sheet structure morphology, which resulted in its superior ability to reflect near-infrared (NIR) radiation compared to ZnO-40/1 and ZnO-20/1. The NIR-shielding performances of ZnO were assessed using a thermal insulation test, where coating with ZnO-80/1 could lower the inner temperature by 5.2 °C compared with the neat glass substrate. Due to the synergistic effects on morphology, ZnO-80/1 exhibited the property of enhanced NIR shielding in curtailing the internal building temperature, which allows for its utilization as an NIR-reflective pigment coating in the construction of building envelopes. Full article

Polymer coatings containing thermal blocking and near-infrared (NIR)-reflective pigments have received much attention for their potential applications in energy-saving fields. A drawback of these coatings is sustainability providing similar long-term performance. Surface cleaning is mandatory to remove contaminants that decrease reflectance. In this study, synthesized hollow titania as photocatalyst was used to impart anti-contamination to infrared (IR)-reflective coatings. A TiO₂ shell was selectively formed on an anionic polystyrene core, modified by methacrylic acid. According to sintering temperature, the enhancement of light absorption ability and photocatalytic activity as methyl orange decomposition was observed with phase composition change. The methylene blue decomposition reaction, reflectance measurement, and measuring thermal profiling of coated steel confirmed the manifestation of hollow particles to dust degradation characteristics and the enhancement of reflection and thermal shielding. Full article