Search Results (738)

In this article, we present density functional theory (DFT) calculations for $Z{n}_{(1-x)}{M}_{x}O$, where M represents one of the following substitutional metallic impurities: Ga, Cd, Cu, Pd, Ag, In, or Sn. Our study is based on the wurtzite structure of pristine ZnO. We employ the Quantum Espresso package, using a fully unconstrained implementation of the generalized gradient approximation (GGA) with an additional U correction for exchange and correlation effects. We analyze the density of states, energy gaps, and absorption spectra for these doped systems, considering the limitations of a finite-size cell approximation. Rather than focusing on precise numerical values, we highlight the following two key aspects: the location of impurity-induced electronic states and the overall trends in optical properties across the eight systems, including pristine ZnO. Our results indicate that certain dopants introduce electronic levels within the band gap, which enhance optical absorption in the visible, near-infrared, and near-ultraviolet regions. For instance, Sn-doped ZnO shows a pronounced absorption peak at ∼2.5 eV, which is in the middle of the visible spectrum. In the case of Ag and Pd impurities, they lead to increased electromagnetic radiation absorption at the near ultra-violet spectrum. This represents a promising performance for efficient solar radiation absorption, both at the Earth’s surface and in outer space. Furthermore, Ga- and In-doped ZnO present bandgaps of ∼0.9 eV, promising an interesting performance in the near infrared region. These findings suggest potential applications in solar energy harvesting and selective sensors. Full article

All inorganic CsPbBr₃ possesses ideal stability in halide perovskites, but its wide bandgap and relatively poor film quality seriously limit the performance enhancement and possible applications of perovskite solar cells (PSCs). In this work, a triple-functional poly(3-Hexylthiophene) (P3HT) modifier was introduced to realize color-tunable semi-transparent CsPbBr₃ PSCs. From the optical perspective, the P3HT acted as the assistant photoactive layer, enhanced the light absorption capacity of the CsPbBr₃ film, and broadened the spectrum response range of devices. In view of the hole transport layer, P3HT modified the energy level matching between the CsPbBr₃/anode interface and facilitated the hole transport. Simultaneously, the S⁻ in P3HT formed a more stable Pb-S bond with the uncoordinated Pb²⁺ on the surface of CsPbBr₃ and played the role of a defect passivator. As the P3HT concentration increased from 0 to 15 mg/mL, the color of CsPbBr₃ devices gradually changed from light yellow to reddish brown. The PSC treated by an optimal P3HT concentration of 10 mg/mL achieved a champion power conversion efficiency (PCE) of 8.71%, with a V_OC of 1.30 V and a J_SC of 8.54 mA/cm², which are remarkably higher than those of control devices (6.86%, 1.22 V, and 8.21 mA/cm²), as well its non-degrading stability and repeatability. Here, the constructed CsPbBr₃/P3HT heterostructure revealed effective paths for enhancing the photovoltaic performance of CsPbBr₃ PSCs and boosted their semi-transparent applications in building integrated photovoltaics (BIPVs). Full article

In recent years, advanced CO₂ cycles, including supercritical CO₂ power cycles, transcritical CO₂ power cycles and refrigeration cycles, have demonstrated significant potential for application across a broad spectrum of energy conversion processes, owing to their high efficiency and compact components that are environmentally benign and non-polluting. This study presents a comprehensive review of the dynamic performance and control strategies of these advanced CO₂ cycles. It details the selection of system configurations and various control strategies, detailing the principles behind different control strategies, their applicable scopes, and their respective advantages. Furthermore, this study conducts a comparison between the joint control strategy and single control strategies for CO₂ cycles, demonstrating the superiority of the joint control strategy in CO₂ cycles. It then delves into the potential of novel control technologies for CO₂ cycles, using model-based control technology powered by artificial intelligence as a case study. This study also offers an extensive overview of control theory, methodology, scope of application, and the pros and cons of various control strategies, with examples including extreme value-seeking control, model predictive control (MPC) based on an artificial neural network model, and MPC based on particle swarm optimization. Finally, it explores the application of AI-controlled CO₂ cycles in new energy vehicles, solar power generation, aerospace, and other fields. It also provides an outlook on the development direction of CO₂ cycle control strategies in light of the evolving trends in the energy sector and advancements in AI methodologies. Full article

Using the results of numerical simulations and solar observations, this study shows that the transition from deterministic chaos to hard turbulence in the magnetic field generated by the emerging small-scale, near-surface (within the Sun’s outer 5–10% convection zone) solar MHD dynamos occurs through a randomization process. This randomization process has been described using the concept of distributed chaos, and the main parameter of distributed chaos $\beta$ has been employed to quantify the degree of randomization (the wavenumber spectrum characterising distributed chaos has a stretched exponential form $E\left(k\right)\propto exp-{(k/k_{\beta })}^{\beta }$). The dissipative (Loitsianskii and Birkhoff–Saffman integrals) and ideal (magnetic helicity) magnetohydrodynamic invariants govern the randomization process and determine the degree of randomization $0<\beta \le 1$ at various stages of the emerging MHD dynamos, directly or through Kolmogorov–Iroshnikov phenomenology (the magnetoinertial range of scales as a precursor of hard turbulence). Despite the considerable differences in the scales and physical parameters, the results of numerical simulations are in quantitative agreement with solar observations (magnetograms) within this framework. The Hall magnetohydrodynamic dynamo is also briefly discussed in this context. Full article

YVO₄ based phosphors have aroused extensive interest in the field of optoelectronics due to their good chemical stability and unique luminescence properties. However, commercialization of YVO₄ phosphors requires high luminescence intensity, enhanced conversion efficiency, and a wide excitation spectrum. In this work, Eu³⁺, Ba²⁺, Bi³⁺ co-doped YVO₄ was prepared by the sol–gel method. The XRD of YVO₄: 5%Eu³⁺, 5%Ba²⁺, 0.5%Bi³⁺ phosphor analysis confirms the pure tetragonal phase, with a fairly large size of approximately 100 nm for the optimal composition. And the SEM and TEM revealed well-dispersed spherical nanoparticles with sizes of 100–120 nm. The introduction of Ba²⁺ ions enhanced the luminescence intensity, while the incorporation of Bi³⁺ ions improved the excitation width of the phosphor. The resulting YVO₄: 5%Eu³⁺, 5%Ba²⁺, 0.5%Bi³⁺ phosphor exhibited a 1.39-times broader excitation bandwidth and a 2.72-times greater luminescence intensity at 618 nm compared to the benchmark YVO₄: 5% Eu³⁺ sample. Additionally, the transmittance of the films in the 350 nm to 800 nm region exceeded 85%. The YVO₄: 5%Eu³⁺, 5%Ba²⁺, 0.5%Bi³⁺ film effectively absorbed ultraviolet light and converted it to red emission, enabling potential applications in solar cell window layers, dye-sensitized cell luminescence layers, and solar cell packaging glass. Full article

High-precision measurements of direct solar radiation spectra are crucial for the development of solar resources, climate change research, and agricultural applications. However, the current measurement systems all rely on a moving two-axis tracking system with a complex structure and many error transmission links. In response to the above problems, a polar-axis rotating solar direct radiation spectroscopic measurement method is proposed, and an overall architecture consisting of a rotating reflector and a spectroradiometric measurement system is constructed, which simplifies the system’s structural form and enables year-round, full-latitude solar direct radiation spectroscopic measurements without requiring moving tracking. The paper focuses on the study of its optical system, optimizes the design of a polar-axis rotating solar direct radiation spectroscopy measurement optical system with a spectral range of 380–780 nm and a spectral resolution better than 2 nm, and carries out spectral reconstruction of the solar direct radiation spectra as well as the assessment of measurement accuracy. The results show that the point error distribution of the AM0 spectral curve ranges from −9.05% to 13.35%, and the area error distribution ranges from −0.04% to 0.09%; the point error distribution of the AM1.5G spectral curve ranges from −9.19% to 13.66%, and the area error distribution ranges from −0.03% to 0.11%. Both exhibit spatial and temporal uniformity exceeding 99.92%, ensuring excellent measurement performance throughout the year. The measurement method proposed in this study enhances the solar direct radiation spectral measurement system. Compared to the existing dual-axis moving tracking measurement method, the system composition is simplified, enabling direct solar radiation spectrum measurement at all latitudes throughout the year without the need for tracking, providing technical support for the development and application of new technologies for solar direct radiation measurement. It is expected to promote future theoretical research and technological breakthroughs in this field. Full article

Most commercially available InGaP/InGaAs/Ge triple-junction solar cells suffer from current mismatch due to the excess current generated by the Ge sub-cell. Combining epitaxial germanium with III–V materials would enable the realization of lattice-matched four- or five-junction solar cells, where the near-infrared spectrum could be split between two Ge sub-cells instead of one, thereby eliminating current mismatch in these devices and achieving higher conversion efficiency. In this work, we present the first demonstration of a quadruple-junction (4J) InGaP/InGaAs/Ge/Ge device, with all layers sequentially deposited in the same MOVPE growth chamber. The 4J device also features a novel architecture that exploits the “transistor effect” between the two Ge junctions to eliminate the current mismatch in the upper 3J InGaP/GaAs/Ge part. We describe the growth and the cell structure realization strategy developed to overcome—and, where beneficial, to exploit—the cross-contamination between III–V and group IV elements, thus avoiding the need for two separate deposition systems. The structural and electrical characterizations performed to ascertain the 4J device quality are presented. This result represents a key step toward the realization of highly efficient, all-MOVPE-grown, lattice-matched MJ solar structures that combine III–V and group IV alloys. Full article

Emerging organic contaminants (EOCs), including polychlorinated bisphenyls (PCBs), pharmaceuticals, personal care products, pesticides, polycyclic aromatic hydrocarbons (PAH), and dyes, are among the most hazardous pollutants found in water bodies and sediments. These substances pose serious threats to the environment and human health due to their high toxicity, long-range mobility, and bioaccumulation potential. Although various methods for degradation of organic pollutants exist, photocatalysis using ultraviolet (UV) and visible light (VIS) has emerged as a promising approach. However, its practical applications remain limited due to challenges such as the use of powdered photocatalysts, which complicates their removal and recycling in industrial settings, and the restricted solar availability of UV light (~4% of the solar spectrum). This review investigates the effectiveness of hybrid electrospun conductive polymer nanofibers on metal oxide photocatalysts such as TiO₂ and ZnO (including doped and co-doped forms) and fabricated via mono- or coaxial electrospinning, in the degradation of EOCs in water under visible light. Furthermore, strategies to enhance the fabrication of these hybrid electrospun conductive nanofibers as visible-light-responsive photocatalysts, such as the inclusion of dopants and/or plasmonic materials, are discussed. Finally, the current challenges and future research directions related to electrospun nanofibers combined with photocatalysts for the degradation of EOCs in water treatment applications are outlined. Full article

Aiming at the insufficient broad-spectrum absorption and high carrier complexation rate in the photocatalytic antimicrobial application of TiO₂, Ag/TiO₂ composite materials were prepared by co-precipitation method in this study. The material characterization showed that Ag was uniformly dispersed on the TiO₂ surface in the form of nanoparticles, and the specific surface area of Ag/TiO₂ composite materials was enhanced by 59.6% compared with that of pure TiO₂, and the mesoporous structure was significantly optimized. Visible photocatalytic tests showed that the degradation rate of Ag/TiO₂ composite materials for Rh B and M O was more than two times higher than that of pure TiO₂. Under dark conditions, the material showed a minimum inhibitory concentration (MIC) of 62.5 μg/mL against Escherichia coli and Staphylococcus aureus, with an antimicrobial rate of 99.8% for 8 h, confirming its non-light-dependent antimicrobial activity. Mechanistic studies revealed that photogenerated electrons were efficiently captured by Ag nanoparticles, which inhibited e-h⁺ complexation; meanwhile, the photothermal effect (ΔT > 15 °C) promoted the sustained release of Ag⁺, which realized the triple synergistic antimicrobial activity by disrupting the bacterial membrane and interfering with metabolism. This study provides a new strategy for the development of efficient solar-powered water treatment materials. Full article

The g-C₃N₄/ZnO nanocomposite materials were applied to degrade methylene blue (MB). The samples were characterized and evaluated to study the adsorption and photocatalytic degradation under visible light. The g-C₃N₄ was incorporated at percentages of 5%, 10%, 20%, and 40% relative to the ZnO weight. These composite materials were prepared using a solvothermal microwave technique. The structural, textural, morphological, and optical properties were investigated using XRD, FTIR, SEM, EDS, STEM, BET, UV-Vis, and XPS techniques. The XRD patterns of the samples showed the coexistence of crystalline phases of g-C₃N₄ and ZnO, while images and elemental composition analysis confirmed the formation of nanocomposite samples. The UV-Vis spectrum revealed a redshift in the absorption edge of the nanocomposites, indicating improved light-harvesting capability. The synthesized material g-C₃N₄/ZnO (20/80), with a surface area of 25 m²/g, exhibited higher photocatalytic performance, achieving 85% degradation of MB after 100 min under visible light, which corresponds to nearly three times the degradation efficiency of commercial P25-TiO₂ (31%) under the same conditions. The reusability and stability tests were conducted up to the fifth cycle, and this material showed 77% degradation, indicating good stability. This nanocomposite material has good potential as a photocatalyst for solar-driven MB. Full article

In this work, a unique approach was used to synthesise black coatings on aluminium alloys (AA) 6061 and 7075 for applications in the aerospace field. In detail, plasma electrolytic oxidation (PEO) technology was used, maintaining the voltage constant at a relatively low value (V_max ≤ 292 V) during the process. NaVO₃ additive was used in the silicate-based electrolyte to obtain a black colour. The coatings were characterised by SEM-EDS, XPS, XRD, VIS-NIR spectroscopy, and EIS. The presence of vanadium oxides in the PEO coatings was detected by EDS, XPS, and XRD analyses. PEO coatings on AA7075 produced with 10 g/L of NaVO₃ exhibited exceptional optical characteristics, with a solar absorptance value of 95.3% in the VIS-NIR spectrum (wavelength range of 400–2000 nm). All the coatings improved the corrosion performances of the tested AA6061 and AA7075 by two or three orders of magnitude in 3.5 wt. % aqueous NaCl. Moreover, there was no sign of delamination, cracks, or any visible changes on coatings after thermal shock, performed by cycling samples between two extreme temperatures, −196 °C and 150 °C, respectively. Full article

The tension in the relationship between water and energy seriously restricts the harmonious coexistence between man and the ecological environment. The solar-powered interface evaporation technology emerging in recent years has shown good application prospects in high-salt wastewater treatment for achieving the zero-discharge treatment of wastewater. In this review, advanced solar-driven interfacial evaporation is primarily focused on its mechanisms, photothermal materials optimization, and the structure of solar evaporators for salt removal. The high wide-spectrum solar absorption rate of photothermal materials determines the total energy that can be utilized in the evaporation system. The light-to-heat conversion capacity of photothermal materials directly affects the efficiency and performance of solar interface evaporators. We highlight the microstructures enabled by the nanophotonic designs of photothermal material-based solar absorbers, which can achieve highly efficient light harvesting across the entire solar irradiance spectral range with weighted solar absorptivity. Finally, based on current research, existing problems, and future development directions for high-salt wastewater evaporation research are proposed. The review provides insights into the effective treatment of high-salt wastewater. Full article

Soil fertility is the essential attribute of soil quality. Large-scale coal mining has led to the continuous deterioration of the fragile ecosystems in arid and semi-arid mining areas. As one of the key indicators for land ecological restoration in these coal mining regions, rapidly and accurately monitoring topsoil fertility and its spatial variation information holds significant importance for ecological restoration evaluation. This study takes Wuhai City in the Inner Mongolia Autonomous Region of China as a case study. It establishes and evaluates various soil indicator inversion models using multi-temporal Landsat8 OLI multispectral imagery and measured soil sample nutrient content data. The research constructs a comprehensive evaluation method for surface soil fertility based on multispectral remote sensing monitoring and achieves spatiotemporal variation analysis of soil fertility characteristics. The results show that: (1) The 6SV (Second Simulation of the Satellite Signal in the Solar Spectrum Vector version)-SVM (Support Vector Machine) prediction model for surface soil indicators based on Landsat8 OLI imagery achieved prediction accuracy with R² values above 0.85 for all six soil nutrient contents in the study area, thereby establishing for the first time a rapid assessment method for comprehensive topsoil fertility using multispectral remote sensing monitoring. (2) Long-term spatiotemporal evaluation of soil indicators was achieved: From 2015 to 2025, the spatial distribution of soil indicators showed certain variability, with soil organic matter, total phosphorus, available phosphorus, and available potassium contents demonstrating varying degrees of increase within different ranges, though the increases were generally modest. (3) Long-term spatiotemporal evaluation of comprehensive soil fertility was accomplished: Over the 10 years, Grade IV remained the dominant soil fertility level in the study area, accounting for about 32% of the total area. While the overall soil fertility level showed an increasing trend, the differences in soil fertility levels decreased, indicating a trend toward homogenization. Full article

We investigated a metasurface broadband absorber composed entirely of iron and featuring a simple bilayer structure: a metallic iron substrate topped with an iron nanodisk-patterned layer. This absorber structure achieved over 90% absorption across the visible spectrum, with an average absorption of 97%. The designed metasurface structure had an aspect ratio of less than 1, which facilitated high-quality sample fabrication. In contrast to precious or rare metals typically utilized in visible broadband metasurface absorbers, this absorber offers a significant cost advantage. Furthermore, it exhibits polarization insensitivity and maintains a stable performance under oblique incidence over a wide angular range, making it suitable for practical applications. Additionally, the high melting point and favorable thermal conductivity of iron satisfy the requirements for solar harvesting and photothermal conversion devices. Therefore, this paper presents a highly efficient, low-cost, easy-to-fabricate, and operationally stable solution that is amenable to large-scale deployment in solar energy-harvesting devices. Full article

Thermal insulation materials used in power and industrial systems must maintain high performance under extreme environmental conditions. Among such materials, aerogel and basalt fiber are widely applied due to their low thermal conductivity and ease of installation. However, over time, these materials are susceptible to degradation, which can significantly impair their insulating efficiency and increase energy losses. Despite their importance, the long-term behavior of these materials under realistic climatic stressors has not been analyzed enough. This study investigates the degradation of thermal insulation performance in aerogel and basalt fiber materials subjected to complex atmospheric stressors, simulating long-term outdoor exposure. Aerogel and basalt fiber mats were tested under accelerated aging conditions using an artificial weather chamber equipped with xenon lamps to replicate full-spectrum solar radiation, high humidity, and elevated temperatures. The results show that the thermal conductivity of aerogel remained stable, indicating excellent durability under environmental stress. In contrast, basalt fiber insulation exhibited a deterioration in thermal performance, with a 9–11% increase in thermal conductivity, corresponding to reduced thermal resistance. Computational modeling using COMSOL Multiphysics confirmed that aerogel insulation outperforms basalt fiber, especially at temperatures exceeding 200 °C, offering better heat retention with thinner layers. These findings suggest aerogel-based materials are more suitable for long-term thermal insulation of high-temperature pipelines and industrial equipment. Full article