Solar Absorption Research Articles

Wideband, polarization-insensitive rectangular-shaped with thin wire MXene-based resonator solar absorber for solar energy harvesting application

Solar absorbers are used in many different applications to collect solar energy. The Rectangular-Shaped with Thin Wire MXene-based resonator (RSWTWMR) is a unique solar absorber design that is proposed in this study. Aluminium and MXene are the materials used in the substrate and resonator layers of the RSWTWMR, respectively. MXene allows for the absorption of a large amount of solar light because of its remarkable absorption qualities and unique optical properties. The MXene-based resonator has a unique design with a thin wire and a rectangular box that makes it insensitive to polarization. RSWTWMR shows an astounding 95.67 % average absorption over three different wide bands. It is noteworthy that the absorption values in the 920 nm and 720 nm bandwidths exceed 90 % and 94 %, respectively. In addition, the absorption is more than 96 % at wavelengths of 550 nm. Additional research examined how well the system performs in air mass (AM1.5) conditions and examined how different factors, such as substrate and resonator thickness, affect absorption properties. Furthermore, the research looks at the impact of an angle of incidence, which is unaffected between 0 and 70°. This study suggests the RSWTWMR solar absorber has great promise for applications in solar energy harvesting.

Efficient solar-driven interfacial evaporation and desalination using simple, salt-resistant, carbon nanotube-based Janus evaporators

Desalination technology is an effective solution for global freshwater crisis, but conventional methods usually consume fossil energy. Solar-driven interfacial evaporation desalination offers a promising solution to address freshwater scarcity and energy crisis. Its key feature is that the solar absorber is at interface between seawater and air above, where localized heating generates vapor. However, there remains crucial challenges in designing evaporators that are simple to prepare, salt-resistant, stable, and highly efficient in evaporation. Janus evaporators in this study demonstrates superior performance compared to other carbon nanotube-based evaporators reported in current literature, particularly in terms of evaporation and salt resistance. In-laboratory experimental results showed the evaporation rate of deionized water was 2.49 kg m−2 h−1 and the energy conversion efficiency was 91 % under 1 kW m−2. Furthermore, evaporators exhibited excellent salt resistance performance, with evaporation rates of 2.0 and 1.9 kg m−2 h−1 in Bohai seawater and 3.5 wt% NaCl solution, respectively. Additionally, salt crystals formed during the evaporation with salinity higher than 15 wt% for continuous 12 h could be self-cleaned in absence of light. In outdoor environments, a simple device based Janus evaporator also exhibited good desalination performance. Overall, this study indicates great potential of Janus evaporators for future sustainable energy applications in solar desalination.

Investigation on hourly characteristics of solar absorption refrigeration cycle integrated with a dual-cooling grade-compression cycle

Solar absorption refrigeration cycle consumes almost no electricity, but its low refrigeration efficiency and intermittent operation issues need addressing. Based on the viewpoint of cold energy grade production matching air-conditioning cooling load grade, a solar absorption refrigeration cycle integrated with a dual-cooling grade-compression cycle (SARC-DGC) is proposed to boost the solar utilization and achieve all-weather cooling, which includes solar absorption refrigeration (SAR) subsystem, subcooled water circulating (SWC) subsystem and dual-cooling grade-compression refrigeration (DGR) subsystem. The simulation models of proposed cycle are developed by lumped-parameter and distributed-parameter methods, and the simulation results are validated with experimental results. The hourly characteristics of SARC-DGC cycle on a typical day are evaluated and compared with those of the conventional solar absorption refrigeration (SAR) cycle and air-cooled compression refrigeration (ACR) cycle. The results show that the hourly cooling performance of SARC-DGC cycle is well matched with the building cooling load demand, so as to realize the cold energy grade production and utilization. The working hours of SAR subsystem are 42.86 % longer than that of conventional SAR cycle, with a 31.92 % increase in daily cooling capacity, while the daily power consumption of the proposed cycle is on average 27.31 % lower than that of conventional ACR cycle.

Selective double-layer on black Ni-P enhances solar absorption and reduces corrosion

This work investigates a double-layer configuration for the black Ni-P layers used in solar adsorption technology, aiming to increase the absorption of a broader range of solar wavelengths. This multilayer configuration has a surface with increased roughness and absorption area. The valleys were porous materials, which were connected to an underlying metallic sub-layer that is susceptible to corrosion. In turn, this corrosion induced changes to the top layer. The Ni-P layer was deposited by the electroless technique using an acid nickel sulfate bath as a source of metal ions and a reducing agent of sodium hypophosphite. Etching initiated an oxidation process on the surface, forming a layer of amorphous black nickel oxide for absorption. The surface features of the black Ni-P double layer consist of an uneven surface that aids sunlight adsorption. Carbon steel (AISI 1018) with different surface finishes was used for depositing Ni-P and black Ni-P, aiming to establish correlations with solar adsorption. The sample with an increased surface roughness obtained a higher absorption percentage than a single layer. The corrosion rate was calculated as 7 mmpy for the black Ni-P layer by applying polarization curves. A 6 µm-thick Ni-P double layer was obtained, achieving 96% absorption within the 300–2,000 nm range.

Carbonized sawdust based solar absorber in a solar still for seawater desalination

AbstractCurrent industrial technologies for seawater desalination involve high cost and energy consumption, that is, distillation and reverse osmosis, where these technologies are difficult to implement especially in developing countries. A cost‐effective, environmental‐friendly, and sustainable technology is essential in providing alternative methods for generation of clean water. Solar vapor generation is one of the potential green technologies in generating clean water, where the production and collection of clean water is made possible by using a solar absorber in a solar still. The practicality and performance of the carbonized sawdust based solar absorber in a solar still for the seawater desalination towards clean water generation was conducted outdoors with gradual enhancement on the solar still setup. The enhanced solar still with reflective surface and external thermal insulator improved the solar absorber performance, in contrast to the evaporation of the bulk seawater only and using solar absorber in the solar still without any enhancement. The average efficiency and evaporation rate of the solar absorber in the enhanced solar still was recorded at 61.5% and 0.98 kg m−2 h−1, respectively. The pH (7.52) and salinity (10 ppm) of the collected clean water meets the standard of safe water by the World Health Organization.

PdS-ZnS-Doped Electrospun Polymer Nanofibers as Effective Photocatalyst for Hydrogen Evolution

Poly(vinyl acetate) nanofibers doped with PdS-ZnS nanoparticles (PdS-ZnS/PVAc nanofibers) were fabricated via an electrospinning technique. PdS-ZnS nanoparticles were in situ synthesized by adding (NH4)2S solution to poly(vinyl acetate)/zinc acetate/palladium acetate solution. Electrospinning of the formed colloidal solution led to the formation of poly(vinyl acetate) nanofibers containing uniformly distributed PdS-ZnS nanoparticles. The prepared samples were characterized by field emission scanning electron microscopy, X-ray diffraction, transmission electron microscopy and Fourier transform infrared spectroscopy. In photocatalytic activity investigation, the PdS-ZnS/PVAc nanofibers showed remarkably enhanced performance towards water photosplitting under solar irradiation compared to the ZnS/PVAc nanofibers. This enhanced performance is attributed to the synergistic effects of heterostructured PdS-ZnS nanoparticles, which can improve photogenerated charge migration and solar light absorption.

Preparation and Thermal Stability of AlMoON Based Solar Selective Absorption Coating

Preparation and Thermal Stability of AlMoON Based Solar Selective Absorption Coating

Chemical structure modification of Brazilin-based natural dye with TiO2 nanostructure improves photovoltaic properties for maximum simulated PCE for DSSCs application

Brazilin has been explored as a photosensitizer in dye-sensitized solar cells (DSSCs) owing to its easy extraction, abundance, and environmental friendliness. However, its narrow solar spectrum absorption and weak interaction with the semiconductor hamper its wide application, highlighting the need for developing novel dyes for enhanced DSSC performance. This study reports eight designed dyes (Braz 01 ‒ Braz 02tb) obtained via introducing the π-bridges such as benzene, thiophene, and benzene-thiophene linked to thieno[3,2-b]thiophene, alongside a cyanoacrylic acceptor into the sites of two hydroxyl (OH) groups of brazilin dye. The density functional theory (DFT) and time-dependent density functional theory (TD- DFT) methods were employed to examine the free dyes' photoelectrical, optoelectronic and structural properties. The results show that the absorption spectra of the designed dyes redshifted by 183.22 nm 239.43 nm regarding the brazilin dye. The energy gap was reduced from 5.074 to 2.46 eV. The reorganization energy decreased from 0.951 eV to 0.528 eV, indicating that the designed dyes exhibited better intramolecular charge transfer (ICT). Notably, the electron affinity, electron accepting power, and maximum charge transfer increased from 1.021 3.472 eV, 1.024 8.387 eV and 1.447 4.780, respectively, signifying improved ICT. The exciton binding energy was lowered from 0.591 0.137 eV, implying that all designed dyes possess minimum charge recombination. The amount of charge transfer of the designed dyes (0.286219.051 au) was observed to be greater than brazilin, signifying enhanced ICT. Moreover, the theoretical DSSCs sensitized with designed dyes demonstrated higher PCE than brazilin dye. The greatest PCE of 13.1 % was attained by Braz 01tb dye. Generally, the improved optoelectronic and photovoltaic characteristics observed in all the designed dyes indicate that modifying the hydroxyl group on the brazilin's R1 or R2 location enhances its photoelectrical properties. Therefore, the designed dyes are regarded as superior candidates for utilization as photosensitizers in DSSCs.

Clothing color effect as a target of the smallest scale climate change adaptation.

The purpose of this study is to understand a physical mechanism to determine the surface temperature of clothes in calm and fine conditions of outdoors. We observed surface temperatures of polo shirts of the same material and design but different colors. The shirts were placed in unshaded and well-ventilated outdoor, open spaces on sunny summer days. The maximum difference between dark green or black and white was more than 15°C during calm, fine weather and was greatest when the solar radiation was strong. If the transmission of solar radiation energy through a shirt is ignored to calculate the absorption by the shirt, the difference in solar radiation absorption due to different colors is as much as 24% in the maximum, and if considered, we concluded that an absorption difference of 34% led to a temperature difference of 15℃. When we compared the brightness of the colors, we found that the albedo of both the visible and NIR bands explained why the red and green colors were so different with respect to the surface temperatures we observed. The reflection in the NIR bands was also an important determinant of the surface temperature. An additional experiment using masks showed that the temperature difference between white and black was almost eliminated at a wind speed of ~ 3m/s. The color of clothing is therefore a target for small-scale adaptation to climate change.

Solar-driven salt-free deposition evaporation for simultaneous desalination and electricity generation based on tip-effect and siphon-effect

Solar-driven desalination is a promising way to alleviate the freshwater shortage, while is facing challenges posed by low evaporation rates and severe salt accumulation. Herein, a high-performance two-dimensional (2D) solar absorber with Co3O4 nanoneedle arrays (Co3O4-NN) grown on the surface of reduced graphene oxide-coated pyrolyzed silk cloth (Co3O4-NN/rGO/PSC) was prepared, and a salt-free evaporator system was assembled based on the composite material and siphonage-the flowing water delivery. It is revealed that the evaporation enthalpy of water can be reduced over the 2D solar absorber grown with Co3O4-NN, enabling an evaporation rate of up to 2.35 kg m−2 h−1 in DI water under one solar irradiation. The desalination process can be carried out continuously even with salt concentration up to 20 wt%, due to the timely removal of concentrated brine from the interface with the assistance of directed flowing water. Moreover, the 2D structure and the flowing water also provide an opportunity to convert waste solar heat into electricity in the evaporator based on the seebeck effect, ensuring simultaneous freshwater production and power generation. It is believed that this work provides insights into designing hybrid systems with high evaporation rate, salt resistance, and electricity generation.

A Colored Temperature‐Adaptive Cloak for Year‐Round Building Energy Saving

AbstractAchieving year‐round energy savings in buildings holds great significance toward reaching carbon neutrality and sustainability. Switchable thermal‐management materials offer an energy‐free solution to dynamically regulating internal building temperatures, by passively emitting heat into cold outer space in summer, and absorbing heat from hot sunlight in winter. In addition to dynamic thermal regulation, color display is another pursuit for addressing aesthetic considerations; however, most current dynamically switchable materials lack color options, due to an optical conflict between adaptive solar reflection and selective visible absorption, limiting their wide adoption in aesthetic scenarios such as commercial exterior walls. Herein, a colored temperature‐adaptive cloak (CTAC) that achieves dynamically switchable thermal management in an energy‐neutral way without sacrificing year‐round vibrant color display is reported. This is realized by decoupling solar reflectivity modulation and color display through the choice of two individual constituent components, including thermochromic microcapsules, and fluorescent dyes. Moreover, compared to single‐mode samples with similar colors, the CTAC with dual modes stays 5.6–3.4 °C warmer during cold winter and 14.9–7.9 °C cooler during hot summer (peak solar irradiance: ≈735 and 1030 W m−2, respectively), exhibiting a remarkable potential to achieve year‐round building energy savings.

2D/2D Heterojunctions of Layered TiO2 and (NH4)2V3O8 for Sunlight-Driven Methylene Blue Degradation

Photocatalysis based on titanium dioxide (TiO2) has become a promising method to remediate industrial and municipal effluents in an environmentally friendly manner. However, the efficiency of TiO2 is hampered by problems such as rapid electron–hole recombination and limited solar spectrum absorption. Furthermore, the sensitization of TiO2 through heterojunctions with other materials has gained attention. Vanadium, specifically in the form of ammonium vanadate ((NH4)2V3O8), has shown promise as a photocatalyst due to its ability to effectively absorb visible light. However, its use in photocatalysis remains limited. Herein, we present a novel synthesis method to produce lamellar (NH4)2V3O8 as a sensitizer in a supramolecular hybrid photocatalyst of TiO2–stearic acid (SA), contributing to a deeper understanding of its structural and magnetic characteristics, expanding the range of visible light absorption, and improving the efficiency of photogenerated electron–hole separation. Materials, such as TiO2–SA and (NH4)2V3O8, were synthesized and characterized. EPR studies of (NH4)2V3O8 demonstrated their orientation-dependent magnetic properties and, from measurements of the angular variation of g-values, suggest that the VO2+ complexes are in axially distorted octahedral sites. The photocatalytic results indicate that the 2D/2D heterojunction layered TiO2/vanadate at a ratio (1:0.050) removed 100% of the methylene blue, used as a model contaminant in this study. The study of the degradation mechanism of methylene blue emphasizes the role of reactive species such as hydroxyl radicals (•OH) and superoxide ions (O2•−). These species are crucial for breaking down contaminant molecules, leading to their degradation. The band alignment between ammonium vanadate ((NH4)2V3O8) and TiO2–SA, shows effective separation and charge transfer processes at their interface. Furthermore, the study confirms the chemical stability and recyclability of the TiO2–SA/(NH4)2V3O8 photocatalyst, demonstrated that it could be used for multiple photocatalytic cycles without a significant loss of activity. This stability, combined with its ability to degrade organic pollutants under solar irradiation, means that the TiO2–SA/(NH4)2V3O8 photocatalyst is a promising candidate for practical environmental remediation applications.

Study of the photo-stability of ceramic thermal control coating based on aluminium oxide

The study examined the photo-stability of the thermal control coating (TCC), a class of “Optical Solar Reflectors”, used in spacecrafts. This TCC is achieved by applying a layer of dielectric ceramic paste (DCP) onto the substrate using a printer (PCB printing). The DCP was prepared from filler (ground Al2O3 ceramic) and solvent with thickener (terpineol with ethylcellulose). The coating obtained by high-temperature firing (T = 850 оC, 2 h) has high reflectivity in the solar range of the spectrum (0.2–2.5 μm) with the solar absorptance (αs) of DCP equal to 0.143. It has high adhesion and photo-stability that exceeds photo-stability parameters of ZnO, TiO2, BaSO4, and CaSiO3 pigments. The developed coating can be recommended not only as a TCC for spacecrafts, but also as a protective or dielectric layer in manufacturing of printed circuit boards in various fields of technology, where increased resistance to solar radiation or its ultraviolet region is required.

Reinforcing the photocatalytic removal of ibuprofen antibiotic over S-scheme 2D/1D Bi12O17Cl2/V2O5 heterojunction under solar light illumination

In our work, the Bi12O17Cl2/V2O5 hybrid with a favorable S-scheme mechanism was prepared via a simple self-assembly procedure for ibuprofen (IBF) oxidation under solar light energy. The 2D Bi12O17Cl2 provides abundant active sites to immobilize 1D V2O5 nanorods, enhancing the interaction between two semiconductors. The establishment of the 2D/1D structure reflected a positive effect on the surface area of Bi12O17Cl2/V2O5-10 %, which was linked to the reduction in the aggregation rate of V2O5 nanorods. Amazingly, optimal Bi12O17Cl2/V2O5 photocatalysts achieved exceptional IBF degradation capacities of 88.6 % and 71.3 % under LED and direct solar light irradiation, respectively. Among the samples, the optimized Bi12O17Cl2/V2O5-10 % reflected the best IBF oxidation kinetic with a reaction constant of 0.03894 min− 1, which is stronger than pristine Bi12O17Cl2 (0.00885 min− 1) and V2O5 (0.0119 min− 1) by 4.4 and 3.27 times, respectively. The promoted catalytic activity was correlated to the S-scheme heterojunction between Bi12O17Cl2 and V2O5 that could upgrade the solar light absorbance, facilitate the separation and transportation of charge carriers, and strengthen the redox potential of Bi12O17Cl2/V2O5. Furthermore, the parameters revealed the best IBF treatment at a catalyst dosage of 0.6 g/L and a pH value of 7. Besides, Bi12O17Cl2/V2O5-10 % recorded outstanding catalytic stability in six cycles without notable alteration in its structure, morphology, or optical properties. On the other hand, the radical quenching tests declared that •O2− and •OH play major contributions in IBF photooxidation over Bi12O17Cl2/V2O5-10 %. Finally, our work offers vital guidance towards designing robust bismuth-based heterojunctions for efficient degradation of IBF antibiotics in a sustainable and cost-effective strategy.

Luminescent boron carbon oxynitride phosphors: a cost-efficient strategy to boost solar cell spectral responsiveness

The incorporation of a Luminescent down-shifting (LDS) layer has emerged as a compelling approach for augmenting the light absorption sensitivity and power conversion efficiency of solar cells, particularly in the short-wavelength light spectrum. In this investigation, we propose the utilization of low-cost, environmentally benign Boron carbon oxynitride (BCNO) phosphors as a viable material for the enhancement of solar radiation absorption in the ultraviolet-blue range. We synthesized BCNO phosphors through a combustion method and conducted a comprehensive analysis of the structural and spectral attributes concerning the impact of temperature. The synthesized boron carbon oxynitride phosphors exhibit a hexagonal boron nitride structure, with an irregular shape and an average particle size of 2447.9 nm. The analysis of photoluminescence spectra reveals that BCNO phosphors effectively capture photons within the 300–500 nm wavelength range and subsequently re-emit them at longer wavelengths. This phenomenon aligns with the overarching goal of optimizing solar cell performance, as it is in the longer wavelength range that solar cells exhibit enhanced efficiency. These findings support the promising potential of BCNO phosphors as a compelling choice for deployment as an LDS layer material on the periphery of solar cells. By facilitating increased photon absorption in the short-wavelength region, BCNO phosphors have the capacity to significantly enhance device performance.

Boosting quantum-structured solar cell light absorption through compressively strained superlattices

The escalating demand for improved energy conversion efficiency in vehicular applications of solar cells underscores the need for innovative solutions. This study focuses on enhancing the current density of GaAs middle cells within conventional Ge-based triple-junction solar cells to realize unprecedented levels of energy conversion efficiency. We introduced a novel superlattice configuration termed a compressively strained superlattice (CSSL) and demonstrated its integration into a p-i-n junction GaAs solar cell, achieving a current density increase of 1.03 mA cm−2 over conventional GaAs solar cells. Prior investigations have explored a strain-balanced superlattice (SBSL) to enhance GaAs middle cell current density. However, our findings establish the superiority of the CSSL over the SBSL in terms of current density improvement, with the CSSL featuring 1.59 times more quantum wells per unit length than the SBSL. This increase in quantum well quantity significantly enhances light absorption efficiency and consequently, the current density.

Influences of Space Weather Forecasting Uncertainty on Satellite Conjunction Assessment

AbstractA significant increase in the number of anthropogenic objects in Earth orbit has necessitated the development of satellite conjunction assessment and collision avoidance capabilities for new spacecraft. Neutral mass density variability in the thermosphere, driven by enhanced geomagnetic activity and solar EUV absorption, is a major source of satellite propagation error. This work investigates the impacts of space weather driver forecasting uncertainty on satellite drag and collision avoidance maneuver decision‐making. Since most operational space weather driver forecasts do not offer an uncertainty assessment, the satellite operator community is left to make dangerous assumptions about the trustworthiness of the forecast models they use to perform satellite state propagation. Climatological persistence‐based forecast models are developed for F10.7 and Kp. These models accurately capture the heteroscedastic and, at times, highly non‐Gaussian uncertainty distribution on forecasts of the drivers of interest. A set of realistic satellite conjunction scenarios is simulated to demonstrate the contributions of space weather driver forecast uncertainty on the probability of collision and maneuver decisions. Improved driver forecasts, especially forecasts of F10.7, are demonstrated to be very useful for enabling durable maneuver decisions with additional lead time (up to 24 hr for the period examined), though the improvement depends on the specific conjunction scenario of interest.

Evaluation of Constructive Parameters to Minimize the Effects of Solar Radiation in Households with Tropical Climate

In tropical climates, the energy consumption of buildings is strongly influenced by solar radiation. However, more research needs to be done on how specific design parameters can mitigate the effects of solar radiation in tropical homes. This study uses simulations in EnergyPlus to evaluate how orientation, roof solar absorptance, overhang depth, glass type, and wall type affect energy consumption in a typical middle-income home in a tropical climate. The results highlight the benefits of adequate solar absorbance and correct orientation. Incorporating insulation into exterior walls does not offer significant improvements in the energy performance of the building. Key words. Building energy simulation, Tropical climate, parametric analysis.

Controllable preparation of graphene glass fiber fabric towards mass production and its application in self-adaptive thermal management

Direct synthesis of graphene on nonmetallic substrates via chemical vapor deposition (CVD) has become a frontier research realm targeting transfer-free applications of CVD graphene. However, the stable mass production of graphene with a favorable growth rate and quality remains a grand challenge. Herein, graphene glass fiber fabric (GGFF) was successfully developed through the controllable growth of graphene on non-catalytic glass fiber fabric, employing a synergistic binary-precursor CVD strategy to alleviate the dilemma between growth rate and quality. The binary precursors consisted of acetylene and acetone, where acetylene with high decomposition efficiency fed rapid graphene growth while oxygen-containing acetone was adopted for improving the layer uniformity and quality. Notably, the bifurcating introducing-confluent premixing (BI-CP) system was self-built for the controllable introduction of gas and liquid precursors, enabling the stable production of GGFF. GGFF features solar absorption and infrared emission properties, based on which the self-adaptive dual-mode thermal management film was developed. This film can automatically switch between heating and cooling modes by spontaneously perceiving the temperature, achieving excellent thermal management performances with heating and cooling power of ∼501.2 and ∼108.6 W m−2, respectively. These findings unlock a new strategy for the large-scale batch production of graphene materials and inspire advanced possibilities for further applications.

A review on solar air conditioning systems

In order to meet the growing need for cooling in buildings, solar air conditioning systems are a creative and environmentally friendly alternative. Solar energy is the primary energy source for producing chilled air, which can be used to maintain comforting inside temperatures. The working theories and components of several solar air conditioning systems, including hybrid, adsorption, and absorption systems, are thoroughly reviewed in this research. It also discusses the performance, efficiency, and economic feasibility of these systems and their environmental impact. The review highlights the potential benefits of solar air conditioning, such as plummeting greenhouse gas emissions, reducing energy usage, and enhancing indoor air quality. However, the paper also recognizes the limitations and challenges that need to be addressed to increase the widespread adoption of solar air conditioning systems. During our analysis, we found that solar air conditioning systems require consideration in terms of design and technological aspects. Ensuring these systems perform optimally in different climates and are economically viable is crucial. While there are challenges involved such as addressing the variations in resources and the initial setup costs. However, we are witnessing progress through advancements in materials, components, and control strategies. This continuous improvement inspires and reinforces the belief that solar air conditioning can become an accessible cooling solution for applications. This review provides a valuable resource for researchers, engineers, and policymakers interested in promoting sustainable and energy-efficient cooling technologies.