Sunlight Research Articles

Multi-Person Localization Based on a Thermopile Array Sensor with Machine Learning and a Generative Data Model

Thermopile sensor arrays provide a sufficient counterbalance between person detection and localization while preserving privacy through low resolution. The latter is especially important in the context of smart building automation applications. Current research has shown that there are two machine learning-based algorithms that are particularly prominent for general object detection: You Only Look Once (YOLOv5) and Detection Transformer (DETR). Over the course of this paper, both algorithms are adapted to localize people in 32 × 32-pixel thermal array images. The drawbacks in precision due to the sparse amount of labeled data were counteracted with a novel generative image generator (IIG). This generator creates synthetic thermal frames from the sparse amount of available labeled data. Multiple robustness tests were performed during the evaluation process to determine the overall usability of the aforementioned algorithms as well as the advantage of the image generator. Both algorithms provide a high mean average precision (mAP) exceeding 98%. They also prove to be robust against disturbances of warm air streams, sun radiation, the replacement of the sensor with an equal type sensor, new persons, cold objects, movements along the image frame border and people standing still. However, the precision decreases for persons wearing thick layers of clothes, such as winter clothing, or in scenarios where the number of present persons exceeds the number of persons the algorithm was trained on. In summary, both algorithms are suitable for detection and localization purposes, although YOLOv5m has the advantage in real-time image processing capabilities, accompanied by a smaller model size and slightly higher precision.

Ultrafast Diamond Photodiodes for Vacuum Ultraviolet Imaging in Space‐Based Applications

AbstractMonitoring the vacuum ultraviolet (VUV) radiation from the Sun by spaceborne photodetectors is an indispensable and crucial approach in solar physics research and atmospheric photochemistry investigations. Diamond‐based photodetectors are emerging as ideal candidates to replace traditional silicon‐based detectors for high‐selectivity and radiation hardness. Here, a vertical Schottky photodiode based on p‐type high‐quality single‐crystal diamond is presented. By modulating the diamond surface band structure and band alignment, an ultra‐short response time of only 15 ns, and a photo‐to‐dark current ratio greater than 105 under the reverse bias are achieved. It is the first time to study the spectral response of the diamond photodiode in the range of 260 nm to as low as 120 nm under vacuum conditions, exhibiting an ideal selective responsivity and excellent imaging capability in the VUV range. This device holds promising prospects for coupling with optomechanical systems to enable a multidimensional detection of solar VUV radiation, including imaging and spectrum.

Solar-Driven Thermally Regenerative Electrochemical Cells for Continuous Power Generation with Coupled Optical and Thermal Integration.

This study presents the development of a solar-driven thermally regenerative electrochemical cell (STREC) for continuous power generation. Key innovations include dual-function carbon-based electrodes for efficient solar absorption and electrochemical reactions, a transparent and ultrainsulating silica aerogel to maximize solar spectrum transmission while minimizing heat loss, and a compact heat exchanger to recover heat from hot cell streams. Under 1 sun conditions, the STREC achieves a power density of 912.1 mW/m2, doubling the performance compared to a nonintegrated system. At higher solar concentrations (2 suns), the power density further increases to 1214.4 mW/m2. Our findings indicate that this combination holds significant promise for efficient and continuous solar power generation. The application of state-of-the-art redox couples with high-temperature coefficients suggests a potential solar electricity efficiency of 12.6%, comparable to that of industrial photovoltaic technologies, providing a viable pathway for enhancing the renewable energy share in the global energy mix.

Composites of YF3: Yb3+, Er3+, Tm3+@C3N4-Au with near-infrared light-driven ability for photocatalytic wastewater purification.

Photocatalytic technology for removing organic dye pollutants has gained considerable attention because of its ability to harness abundant solar energy without requiring additional chemical reagents. In this context, YF3 spheres doped with Yb3+, Er3+, Tm3+ (YF) are synthesized using a hydrothermal method and are subsequently coated with a layer of graphitic carbon nitride (g-C3N4) with Au nanoparticles (NPs) adsorbed onto the surface to create a core-shell structure, designated as YF3: Yb3+, Er3+, Tm3+@C3N4-Au (abbreviated as YF@CN-Au). The core-shell composites demonstrate remarkable stability, broadband absorption, and exceptional photocatalytic activity across the ultraviolet (UV) to near-infrared (NIR) spectral range. Notably, by optimizing the amount of Au loaded, excellent methyl orange (MO) degradation rates of 0.068 min-1 under UV light and 0.423 h-1 under light excitation with λ > 420 nm can be achieved. Even under low-energy NIR light (λ > 800 nm), a degradation rate of 0.087 h-1 was reached, indicating a significantly enhanced degradation effect compared to YF@CN without Au loading. The high performance of the core-shell composite is attributed to its unique structure, which enables efficient transfer of energy and charge carriers, thereby promoting charge separation and suppressing recombination. Furthermore, this article reveals and discusses three distinct photocatalytic mechanisms under UV, visible, and NIR light. This study underscores the considerable promise of core-shell composites in developing efficient g-C3N4-based broadband photocatalysts, focusing on comprehensive utilization of the solar spectrum through the synergistic effects of plasma and upconversion materials.

Partial Substitution of Copper with Silver in Cu2ZnSnS4: An Efficient Strategy to Boost the Performance of Self-Powered Broadband Photodetectors in Superstrate Configuration.

Self-powered broadband photodetectors (SPBPDs) hold great potential for next-generation optoelectronic applications, but their performance is often limited by interface defects that impair charge transport and increase recombination losses. In this work, we report the enhancement of the photodetection efficiency of SPBPDs by partially substituting copper (Cu) with silver (Ag) in kesterite Cu2ZnSnS4 (ACZTS) thin films. Varying Ag concentrations (0%, 2%, 4%, 6%) are incorporated into the CZTS layer, forming a TiO2/ACZTS heterojunction in superstrate configuration fabricated via a low-cost sol-gel spin-coating technique with low-temperature open air annealing avoiding conventional postdeposition sulfurization or selenization. Photodetection performance varied significantly with Ag content in CZTS layer, where optimal performance is observed for 4% Ag doping. Under the simulated solar spectrum (100 mW/cm2), the TiO2/4% ACZTS device demonstrates superior performance with an ON/OFF ratio of 6.0 × 102, a photoresponsivity of 0.42 mA/W, and a detectivity of about 2.5 × 109 Jones. In contrast, under 405 nm incident radiation, the device performance improves significantly, achieving an ON/OFF ratio of approximately 4.6 × 103, a photoresponsivity of around 63.9 mA/W, and a detectivity of about 4.8 × 1011 Jones which are the highest reported values observed for CZTS-based single-junction superstrate SPBPDs without a crystalline silicon wafer. Ag doping effectively reduces interface defects and enhances carrier dynamics, as evidenced by capacitance-voltage (C-V) and drive-level capacitance profiling (DLCP) measurements of the fabricated heterojunction. This approach offers a novel strategy for enhancing SPBPD performance through partial cation substitution, paving the way for advanced photodetectors in diverse optoelectronic applications.

Pengaruh Pengetahuan Tentang Manfaat Tabir Surya Terhadap Perilaku Penggunaan Tabir Surya pada Siswa Siswi SMA Dewi Sartika Jakarta

The negative impact caused by prolonged exposure to the sun's UV rays causes health problems and other skin losses. The skin has a layer of melanin that can protect the skin from the sun's UV rays, including the facial skin, which tends to be more sensitive than other parts of the skin. One way to protect facial skin is by using sunscreen. Dewi Sartika High School is located in Jakarta. The climate of Jakarta is a tropical climate with a rainy season and a dry season. Students of SMA Dewi Sartika Jakarta really need to protect their facial skin from exposure to the sun's UV rays, moreover students of SMA Dewi Sartika Jakarta do a lot of outdoor activities with examples of sports, ceremonies, and extracurricular activities. This study was conducted to determine the effect of knowledge of the benefits of sunscreen on sunscreen use behavior. Sampling on 19 questions about knowledge and 20 statements about behavior. The results showed that between the knowledge variable (X) and the behavior variable (Y) (P=0.0898) so it can be concluded that Ha is rejected and Ho is accepted. This states that there is no significant influence between knowledge on usage behavior.

Crucial impact of spectrum calculation on energy and daylighting performance of glazing windows

The rapid advancement of spectrally selective materials has enabled the development of smart windows that can regulate different bands of solar radiation. However, existing methods for calculating spectral properties vary, leading to inconsistent results when evaluating their light-electricity-heat-color performance. Therefore, this paper presents five methods for calculating window spectral properties, intending to compare and identify the most effective approach for assessing building thermal performance, energy efficiency, and daylighting. The methods focus primarily on the solar spectrum input and the glazing spectrum response. The solar spectrum inputs include the Beijing local solar spectrum, ASTM G173-03, and ISO 9845 (methods S1 to S3), and the glazing spectrum response methods differ based on whether they account for spectral selectivity and the choice of spectral weighting functions (methods S3 to S5). The findings reveal that variations in solar spectrum input have a minimal effect on window performance, while differences in glazing spectral response calculations significantly impact results. It is particularly evident in thermochromic windows, where discrepancies in energy efficiency, specifically in lighting load, can reach up to 67.21 %, and variations in dynamic daylighting performance, specifically in Useful Daylight Illuminance (UDI) below 500 lx, can be as high as 28.27 %. To provide more accurate assessment results of glazing windows, this study recommends using the spectral calculation method S1, which incorporates the local solar spectrum and applies the standard luminous efficiency function to the glazing spectrum response. This paper highlights that further refinement of spectral calculation methods will enhance their utility for performance evaluation and guide the reverse design of innovative window features.

A perfect ultra-wideband solar absorber with a multilayer stacked structure of Ti-SiO2-GaAs: structure and outstanding characteristics.

In this paper, we introduce an entirely new solar absorber design-a multi-layer periodic stacked structure. Through coupling effects, this design has perfect ultra-wideband absorption characteristics. The absorber structure is composed of four absorption units with varying cycle lengths, which are cyclically stacked on the surface of the refractory metal Cr. Each cycle encompasses three-layer nanosheets of Ti-SiO2-GaAs. We verify through finite difference time domain method (FDTD) simulations that the absorber achieves an absorption efficiency of 97.8% within the wavelength range of 280 nm to 3000 nm, with an average efficiency of 96.6% under the AM1.5 standard solar spectrum. The absorber can achieve such a remarkable absorption effect because of surface plasmon resonance (SPR) and Fabry-Pérot resonance effects. At 1500 K, this structure exhibits a thermal radiation efficiency of up to 97.83%. Furthermore, the design is not affected by polarization and it is less affected by the incident angle of the light source. These absorption spectra remain consistent regardless of whether it is in the TE or TM mode. Even when the angle of incidence is increased to 60 degrees, the absorption efficiency remains high. Its unique structure and excellent performance characteristics provide higher solar energy efficiency. These outstanding features enable solar absorbers to have broad application potential in improving solar energy efficiency.

Green sol–gel synthesis of biogenic B‐ZnO nanoparticles: Enhancing antibacterial activity and solar‐driven photocatalytic degradation of methylene blue dye

AbstractBiological techniques based on plant extracts have attracted significant interest in the sustainable development era, exceeding the popularity of conventional physical and chemical synthesis methods. Current research biogenic boron‐doped zinc oxide nanoparticles (B‐ZnONPs) synthesized employing leaf extract from Lantana camara via the green synthesis approach with their inherent characteristics and solar‐driven photocatalytic activity was evaluated with chemically generated B‐ZnONPs. Numerous analytical methods, including field emission scanning electron microscopy, Fourier transform infrared spectroscopy, X‐ray diffractometry and UV–visible spectroscopy, have been applied to characterize the B‐ZnONPs, revealing the formation of monoclinic crystalline phase B‐ZnONPs. Notably, under sunlight irradiation at pH 11, the B‐ZnONPs exhibited significantly higher efficacy in the photocatalytic breakdown of methylene blue dye induced by sun radiation, achieving 96.2% photodegradation within 60 min. These results highlight the potential of L. camara leaf extract‐mediated B‐ZnONPs in solar‐based photocatalytic applications. Additionally, the biogenic B‐ZnONPs have been examined for their efficacy against gram‐positive and gram‐negative bacteria, exhibiting significant antibacterial properties.

Potential development of thermally stable polycrystalline photovoltaic modules utilizing biocomposite materials

Abstract Solar energy has become a vital source for generating and harvesting electricity. Enhancing the efficiency of solar modules is an essential factor for successful transition to a sustainable and green energy production. Since natural fiber composites (NFCs) possess various outstanding properties, they can be used as an adequate alternative to synthetic fibers and environmentally harmful materials that are used in photovoltaic (PV) applications and module components. Solar modules are believed to undergo a decline in efficiency when exposed to excessive sun radiation, which eventually caused by a gradual escalation in temperature. Therefore, utilizing appropriate NFCs in the rear components and backsheets of solar modules could significantly contribute to the overall efficiency of these modules and enhance their thermal stability.

Conjugated Polyvinyl Alcohol Modified SnO2 for Efficient Visible Light Photocatalytic Reduction of Cr(VI)

The photocatalytic activity of tin dioxide (SnO2) is limited due to its inadequate response to the solar spectrum, wide band gap, and low visible light photocatalytic activity. Here, we synthesized conjugated polyvinyl alcohol (CPVA) modified tin dioxide (CPVA/SnO2) through in-situ hydrothermal synthesis and evaluated its performance for photocatalytic reduction of hexavalent chromium Cr(VI). A series of testing and characterization results revealed that CPVA was uniformly coated on the surface of SnO2, forming a mesoporous CPVA/SnO2 heterojunction with enhanced crystallinity and reduced oxygen defects, which resulted in an expanded light absorption range towards the red light region. The reaction rate constant of CPVA/SnO2-A for photocatalytic reduction of Cr(VI) under visible light (0.060 min-1) was 6 times higher than that of homemade CPVA/TiO2 and 2.87 times higher than that of SnO2 for the photocatalytic reduction of Cr(VI) under UV light (0.0209 min-1). The photocatalytic mechanism indicates that CPVA/SnO2 exhibited significantly enhanced performance under UV-light irradiation by forming a type II heterojunction. When CPVA/SnO2 was exposed to visible light, photogenerated electrons on the lowest unoccupied molecular orbital (LUMO) of CPVA were efficiently transferred to the surface of SnO2 through the CPVA/SnO2 heterojunction, reducing electron-hole recombination while also photosensitizing the photocatalyst and promoting efficient photocatalysis under visible light illumination. Ultimately, this process effectively reduces Cr(VI) to Cr(III). Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Characterization and Disinfection Performance of α-Fe2O3-TiO2 Based Polyester Membranes for Water Treatment

Water is essential for life; however, many people in developing countries, particularly in rural areas, lack access to clean and safe piped water. Lack of appropriate water treatment makes such people to consume untreated water containing biological and chemical pollutants, leading to diseases and even death. Hence, developing eco-friendly technologies using available resources can help address this critical issue. In this study α-Fe2O3-TiO2 coated polyester membranes were employed the disinfection of water containing Escherichia coli (E. coli) as an indicator microorganism. The coated and uncoated membranes were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD). Antibacterial studies were done through direct contact with bacteria (glass bottle test) and the flow test under sunlight irradiation at various initial bacterial concentrations (2.45 × 103 to 2.45 × 105 CFU/mL). SEM images revealed the presence of the photocatalyst within the membranes, and EDX confirmed the successful impregnation through component analysis. A clear inhibition zone was observed around the coated membranes, 19 and 17 mm for 2.45 × 103 and 2.45 × 105 CFU/mL, respectively, and no inhibition zone was observed around the uncoated membranes. The coated membranes achieved disinfection efficiency of 91.3% in the glass bottle test and 98.30% in the flow test under sun light irradiation. The novelty of the study is that α-Fe2O3-TiO2 impregnated photocatalytic membranes demonstrated excellent disinfection efficacy compared to the uncoated membranes and can readily be applied for water purification in areas that lack centralized water treatment systems.

Lead-Free Perovskite Cs2AgxNa1-xBiyIn1-yCl6 Microcrystals for Scattering-Fluorescent Luminescent Solar Concentrators.

In recent years, luminescent solar concentrators (LSCs) have gained a renaissance as a pivotal transparent photovoltaic (PV) for building-integrated photovoltaics (BIPVs). However, most of the studies focused on light-selective LSCs, and less attention was paid to the utilization of the full solar spectrum. In this study, a lead-free microcrystal Cs2AgxNa1-xBiyIn1-yCl6 (CANBIC) perovskite phosphor is demonstrated to have bifunctional effects of luminescent down-shifting (LDS) and light scattering for the fabrication of LSCs, realizing light response from ultraviolet (UV) to NIR regions by an edge-mounted Si solar cell. The optimized CANBIC content (30 mg) in an LSC realizes the best optical efficiency (ηopt) of 5.40% and an average visible transmission (AVT) of >50%. This contributes to the improvement in short circuit current density (JSC) up to 1.232 mA/cm2 for the LSC-PV system (one-edge mounted Si solar cell) as a result of the best power conversion efficiencies (PCEs) of 0.463% and 1.852% for the LSC-PV and LSC-4PV systems (four-edge mounted Si solar cells), respectively. An Al foil is applied as a reflection background in the LSC-4PV system, and a champion PCE of 3.14% is realized due to an improved JSC of up to 7.94 mA/cm2 in total. Furthermore, the LSC maintains superior stability under exposure to continuous ultraviolet illumination or in ambient air.

Light Absorption-Enhanced Ultra-Thin Perovskite Solar Cell Based on Cylindrical MAPbI3 Microstructure.

In order to promote power conversion efficiency and reduce energy loss, we propose a perovskite solar cell based on cylindrical MAPbI3 microstructure composed of a MAPbI3 perovskite layer and a hole transport layer (HTL) composed of PEDOT:PSS. According to the charge transport theory, which effectually increases the contact area of the HTL, promoting the electronic transmission capability, the local field enhancement and scattering effects of the surface plasmon polaritons help to couple the incident light to the solar cell, which can increase the absorption of light in the active layer of the solar cell and improve its light absorption efficiency (LAE). based on simulation results, a cylindrical microstructure of the perovskite layer increases the contact area of the hole transport layer, which could improve light absorption, quantum efficiency (QE), short-circuit current density (JSC), and electric power compared with the perovskite layer of other structures. In the AM 1.5 solar spectrum, the average light absorption efficiency is 93.86%, the QE is 80.7%, the JSC is 24.50 mA/cm2, and the power conversion efficiency (PCE) is 20.19%. By enhancing the efficiency and reducing material usage, this innovative design approach for perovskite solar cells is expected to play a significant role in advancing solar technology and positively impacting the development of renewable energy solutions.

Modeling and estimation of solar panel tilting angles and orientations in the Gambia: a case study of Brikama, West Coast Region

Propelled by worries about climate change and global warming Photovoltaic panels installation has gain prominence in recent times worldwide due to its affordability and cleaner nature when compared to other renewable energy sources. Many people have switched to solar PV installations as a result of this. A thorough understanding of the orientation and tilt angles of the solar panel in relation to the sun radiation it receives is essential for optimizing the design of any PV system for best performance. In Brikama, West Coast Region of The Gambia, this work ascertains the solar ideal tilt angle and panel orientation. This was accomplished by contrasting the outcomes of the mathematical model with experimental data gathered at the same location and during the same months of the year using a PV module (Model AP-120) made by Astro Power, Inc., Delaware, USA, using a single-axis tracker technology. While the mathematical model approach yielded a tilt angle within the range of 9.10°–22.30° with a mean value of 15.50°, the experimental tilt angles obtained varied from 5.10° to 28.20° with an average angle of 14.80°. According to the generated power study, the solar panel's maximum power was measured at a 30° South angle, and the PV panel's orientation resulted in a mean power gain of 3.6–48.1W. The mean power result indicates that the solar gathering efficiency is better at the ideal tilt angle compared to a horizontal position. To maximize solar energy collection from photovoltaic systems, these findings are vital. PV module systems should be installed carefully since they generate a lot of power when the sun's rays are at a 90° angle, with the PV module pointed directly toward the sun. Solar engineers or workers are advised to install PV panels at a 15° angle facing the south. The method and model described in this study can be used to predict the maximum solar radiation incidence on a PV panel and the ideal tilt angle deployed at another place.

Nature-inspired MPPT algorithms for solar PV and fault classification using deep learning techniques

In recent years, renewable energy attracts the researchers interest due to its environment free nature and abundant availability. Solar photovoltaic (PV) is widely used to generation power from the sun light. Major issue in solar PV power generation is tracking of the peak power from the available multiple power peaks in the operating points. A proper MPPT algorithm is required to capture the maximum power point (MPP) from the characteristic curves of a solar PV under partial shaded conditions (PSC). An optimized maximum power point tracking (MPPT) and fault classification in solar PV systems are presented in this research work. To select the best optimization model for MPPT under PSC, the nature-inspired dragonfly algorithm (DA), moth flame optimization algorithm (MFOA), grasshopper optimization algorithm (GOA), and salp swarm optimization algorithm (SSOA) are used in this work to evaluate the tracking efficiency (TE) of the solar PV systems. From the simulation results, SSOA exhibits a supreme TE of 98.38%, which is better than the other algorithms like DA, GOA, and MFOA. To further classify the faults in solar PV systems, random forest (RF), artificial neural network (ANN), support vector machine (SVM), and convolutional neural network (CNN) models are employed. Among all, CNN provides a maximum accuracy of 94.11% in fault classification. Simulation analysis demonstrates the proof-of-concept for maximum TE and classification accuracy for all the methods. Thus, the optimized MPPT and fault classification models can be combined to enhance the overall performance of solar PV systems.

Ultra-Broadband Perfect Absorbers Based on Biomimetic Metamaterials with Dual Coupling Gradient Resonators.

Ultra-broadband metamaterial absorbers can achieve near-perfect absorption of omnidirectional electromagnetic waves, crucial for light utilization and manipulation. Traditional ultra-broadband metamaterials rely on the superposition of different resonator units either in the plane or in perpendicular directions to broaden absorption peaks. However, this approach is subject to quantity restrictions and complicates the fabrication process. This study introduces a novel concept for broadband absorption metamaterial design-Metal-Insulator-Metal metamaterials with gradient resonators (GR-MIMs) to surpass limitations in quantity and fabrication. The GR-MIMs absorber features gradient resonant cavities in both nanoscale and microscale dimensions, each with continuous resonance points. By converting "resonance points" into "resonance bands" and perfectly coupling the two gradient resonators, the GR-MIMs absorber with a thickness of only 200nm demonstrates 93% ultra-broadband high absorption across the UV, visible, near-infrared, and mid-infrared spectra (0.2-5µm). Moreover, the solar spectrum absorption rate of the GR-MIMs absorber can reach 94.5%, offering broad prospects for applications in solar energy utilization. The design of gradient resonators provides a new approach for the development of ultra-broadband metamaterials and photothermal conversion metamaterials.

Intermolecular Interactions and their Implications in Solid-State Photon Interconversion.

Photon interconversion promises to alleviate thermalization losses for high energy photons and facilitates utilization of sub-bandgap photons - effectively enabling the optimal use of the entire solar spectrum. However, for solid-state device applications, the impact of intermolecular interactions on the energetic landscape underlying singlet fission and triplet-triplet annihilation upconversion cannot be neglected. In the following, the implications of molecular arrangement, intermolecular coupling strength and molecular orientation on the respective processes of solid-state singlet fission and triplet-triplet annihilation are discussed.

Design, Characterization, and Evaluation of Textile Systems and Coatings for Sports Use: Applications in the Design of High-Thermal Comfort Wearables.

Exposure to high temperatures during indoor and outdoor activities increases the risk of heat-related illness such as cramps, rashes, and heatstroke (HS). Fatal cases of HS are ten times more common than serious cardiac episodes in sporting scenarios, with untreated cases leading to mortality rates as high as 80%. Enhancing thermal comfort can be achieved through heat loss in enclosed spaces and the human body, utilizing heat transfer mechanisms such as radiation, conduction, convection, and evaporation, which do not require initial energy input. Among these, two primary mechanisms are commonly employed in the textile industry to enhance passive cooling: radiation and conduction. The radiation approach encompasses two aspects: (1) reflecting solar spectrum (SS) wavelengths and (2) transmitting and emitting in the atmospheric window (AW). Conduction involves dissipating heat through materials with a high thermal conductivity. Our study focuses on the combined effect of these radiative and conductive approaches to increase thermal energy loss, an area that has not been extensively studied to date. Therefore, the main objective of this project is to develop, characterize, and evaluate a nanocomposite polymeric textile system using electrospinning, incorporating graphene oxide (GO) nanosheets and titanium dioxide nanoparticles (TiO2 NPs) within a recycled polyethylene terephthalate (r-PET) matrix to improve thermal comfort through the dissipation of thermal energy by radiation and conduction. The textile system with a 5:1 molar ratio between TiO2 NPs and GO demonstrates 89.26% reflectance in the SS and 98.40% transmittance/emittance in the AW, correlating to superior cooling performance, with temperatures 20.06 and 1.27 °C lower than skin temperatures outdoors and indoors, respectively. Additionally, the textile exhibits a high thermal conductivity index of 0.66 W/m K, contact angles greater than 120°, and cell viability exceeding 80%. These findings highlight the potential of the engineered textiles in developing high-performance sports cooling fabrics, providing significant advancements in thermal comfort and safety for athletes.

Biomimetic Alumina Film for Passive Daytime Radiative Cooling.

Passive daytime radiative cooling is receiving more and more attention as a cooling method that does not consume energy to cool objects. However, most radiative cooling materials require the mixing of multiple particles, which increases the manufacturing process requirements. Most radiative cooling materials are susceptible to outdoor abrasion, pollution, and UV exposure, which leads to decreased performance. In this paper, the biomimetic film with both radiative cooling and self-cleaning functions was prepared by a simple evaporation-induced self-assembly process and spraying process using Al2O3 as the main radiatively cooling raw material, poly(vinylidene fluoride-co-hexafluoropropylene) [P(VDF-HFP)] as the additive, and polydimethylsiloxane as the binder. Therefore, we can get a biomimetic-Al2O3-P(VDF-HFP)-PDMS film (BAPPF). The BAPPF was spectrally selective. Specifically, the reflectance of BAPPF in the solar spectrum (0.45-0.89 μm) exceeded 100%, and the average reflectance in the main thermal effect of the solar spectrum (0.78-1.10 μm) was 99.92%. In addition, the BAPPF had 96.97% reflectance in the solar spectrum (0.3-2.5 μm) and 90.55% mid-infrared emissivity in the atmospheric window (8-13 μm). The combined performance enabled BAPPF to reduce temperature by up to 8.4 °C over air temperature in outdoor tests. What's more, BAPPF had excellent superhydrophobic properties, with a water contact angle of up to 159°. The self-cleaning of the BAPPF prevented contamination and maintained cooling even when working outdoors for long periods of time. Furthermore, the BAPPF maintained high performance after mechanical friction, chemical corrosion, UV aging, and water impact, which has broad reference value and application prospects.