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With the development of new materials and technology, high entropy alloy (HEA) nitride films have attracted much attention of researchers due to their excellent optical properties and mechanical properties. Herein, a novel SS/NbMoTaWN (HEAN)/NbMoTaWON (HEAON)/SiO2 coatings are prepared, which shows a high spectral selectivity of α/e = 0.944/0.12. The preparation and optimization of the coating are studied by combining experiments with ellipsometric program and CODE software. High temperature thermal stability test is performed in depth, which proves that the coating could bear 400 °C in air for 2 h, and 600 °C for 2 h in vacuum. Long-term thermal stability researches indicate that the SSACs still keep good optical properties (α = 0.902, e = 0.106) even after annealing at 600 °C for 100 h. The failure mechanism is analyzed by XRD and Raman spectra. In addition, neutral salt spray test is performed to investigate the anti-corrosion ability, which indicates the coating has a good optical performance after soaking in 3.5 wt% NaCl solution for 30 days. Obviously, this work provides a new strategy to construct solar absorber coatings based on NbMoTaW high entropy alloy.

High entropy alloys (HEAs), which is at the expense of high cost compared to traditional alloy, should not be confined to the mechanical properties, but should be employed to devise a novel combination with unique functional and mechanical performances. In this work, high entropy alloy nitride (HEAN) is utilized as a novel double absorption layer to improve solar absorption in the high temperature solar selective absorbing coatings (SSACs). Our primary motivation is to lower thermal emittance (e) and enhance solar absorptance (α). In order to realize this goal, coating design (CODE) software is employed to design and optimize the proposed HEAN based SSACs using appropriate dielectric function model. The ultimate as-deposited coating shows good optical properties with a high α value of 0.965 and a low e value of 0.086 (at 82 °C). The estimate of thermal stability tests indicates that HEAN based SSACs has the ability to resist instability in high working temperature, which keeps good optical properties (α = 0.925, e = 0.070) after annealing at 600 °C for 10 h.

Solar selective absorber coatings (SSACs), with the characteristics of efficient harvesting and conversion of solar energy into the heat work fluid, are considered to be one of the key components f...

Recent advances in high-entropy alloys have spurred many breakthroughs in the fields of high-temperature materials and optical materials and they provide incredible application potentialities for photothermal conversion systems. Solar-selective absorbers (SSAs), as key components, play a vital role in photothermal conversion efficiency and service life. The most pressing problem with SSAs is their inconsistent optical performance, an instability constraint induced by thermal stress. A feasible method of improving performance stability is the introduction of high-entropy materials, such as high-entropy alloy nitrides. In this study, enabled by an intrinsic MoTaTiCrN absorption layer, the solar configuration achieves greatly enhanced, exceptional thermotolerance and optical properties, leading to the formation of a scalable, highly efficient, and cost-effective structure. Computational and experimental approaches are employed to achieve optimum preparation parameters for thicknesses and constituents. The crystal structure of high-entropy ceramic MoTaTiCrN is fully investigated, including thickness-dependent crystal nucleation. High-temperature and long-term thermal stability tests demonstrate that our proposed SSA is mechanically robust and chemically stable. Moreover, a low thermal emittance (15.86%) at 500 °C promotes the photothermal conversion efficiency. In addition, due to the exceptional spectral selectivity (α/ε = 92.3/6.5%), thermal robustness (550 °C for 168 h), and photothermal conversion efficiency (86.9% at 550 °C under 100 sun), it is possible for our proposed SSA to enhance the practical realization of large-area photothermal conversion applications, especially for concentrated solar power systems.

The most recent advances in high-entropy materials provide impetus for the development of high-performance materials, simultaneously providing high-temperature robustness and excellent functional properties owing to the high configurational entropy and distorted lattices. Thus, in this work, double-layer high-entropy alloy nitride HfNbTaTiZrN with a well-designed metal content gradient is employed to fabricate a solar selective absorber coating (SSAC). We extensively investigated whether the coating meets the definition of a high-entropy material from the points of elemental analysis and phase structure, combined with thermodynamic calculation. Remarkably, the new, tailored SSAC exhibits an exceptionally high solar absorptance (α = 96%) and a suppressed thermal emittance (e = 8.2%) at 82 °C and omnidirectional absorption. Investigations of the long-term thermal stability indicate that the HfNbTaTiZrN-based SSAC due to the entropy-driven structural stabilization could endure heat treatment at 600 °C for 168 h, retaining a performance criterion (PC) value less than 0.05, which implies the feasibility of practical applications. More importantly, the photothermal conversion efficiency (η), which is utilized to quantitatively evaluate the performance at elevated temperatures, reaches 90.1% at a working temperature of 550 °C under 100 suns, and even after annealing at 600 °C for 168 h, the efficiency drop is still less than 5%. Overall, the combination of thermal robustness and photothermal conversion efficiency at working temperatures less than 600 °C provides significant potential to maximize solar energy harvesting and pioneers an opportunity to explore simultaneous multifunctional applications of high-entropy alloys.

The functional application of high entropy alloys, which emerge as a novel multi-principal component alloy, has been constantly expanding in the field of solar photothermal harvesting from optical materials to high temperature materials due to their excellent properties. A solar spectrally selective absorbing coating requires such materials that show not only outstanding optical properties but also prominent thermal stability. It is desirable but challenging to fabricate high performance solar absorbing coatings. A prospective strategy for the preparation of solar absorbing coatings is the introduction of high entropy alloys. In this work, we have developed a simple, cost-conscious, scalable and highly efficient solar selective absorbing coating using a single layer high entropy nitride AlCrTaTiZrN by choosing appropriate elemental compositions. The as-deposited coatings show an outstanding spectral selectivity of α/e = 92.8%/5.1% or 91.6%/5.1%. High temperature thermal stability tests are performed in depth, indicating that the coating could endure annealing treatment at 800 °C for 2 h with insignificant reflectance spectrum variation. A prolonged period of thermal stability characterization presents that this coating could maintain good optical performance after annealing at 650 °C for 300 h. Furthermore, high temperature thermal emittance can be suppressed to as low as 15.4% at 600 °C, which contributes to the state-of-the-art photothermal conversion efficiency under 100 suns (87.7% at 600 °C, and 84.6% at 650 °C). Overall, the high entropy nitride AlCrTaTiZrN based coating contributes to good thermal stability and optical properties, showing great potential for extensive applications in solar energy harvesting.

The newly increasing development of abruptly high entropy alloy nitride (HEAN), especially the refractory HEAN, manifests excellent mechanical, corrosion resistance , and optical properties, which exhibits a wide application prospect in the field of coatings. Herein, we develop a high entropy nitride NbMoTaWN-based solar selective absorber coatings (SSACs), providing a potential to strengthen structural and optical advance through component selection and structure design. The coating exhibits a high solar absorptance (α) of 0.936 and a low thermal emittance ( e ) of 0.126 at 82 °C. Investigation on structural and optical robustness demonstrates that the NbMoTaW HEAN-based SSAC could endure heat treatment at 500 °C for 10 h in vacuum environment. In addition, through the evolution of XRD and Raman spectra after annealing, the failure mechanism of coatings annealed in vacuum at 500 °C for 10 h and 400 °C in air for 5 h are obtained. Obviously, the advantages such as low-cost preparation, easily scalable production, convenient technology process, and repeatability in this work promise potentially valuable applications for photothermal conversion techniques.

With the rapid advance of science and technology, it is essential to research and develop new intrinsic solar absorber coatings with the simple production process and excellent photo-thermal conversion efficiency. Herein, we have developed a novel AlCrMoTaTiN intrinsic absorber layer by radio frequency (RF) reactive sputtering method via adjusting the deposition time and the flow rate of N2. The AlCrMoTaTiN intrinsic absorber layer exhibits a high absorptance of 0.752 and a low emittance of 0.074 at 82 °C. The AlCrMoTaTiN/Al2O3 solar absorber coating is deposited by using Al2O3 works as an anti-reflective layer and the spectral selectivity (α/e) is 0.929/0.082. This coating also possesses a good thermal stability, which can be stabilized at 300 °C in air and 500 °C in vacuum for 2 h, respectively. In addition, a prolonged period of thermal stability characterization is carried out, which indicates that this coating could keep good optical performance after annealing at 600 °C for 100 h. The corresponding failure mechanism is obtained by analyzing the Raman spectroscopy and XRD. Obviously, the AlCrMoTaTiN/Al2O3 solar absorber coating has a broad application prospect in large-scale and efficient industrial production.

A novel TiC-TiN/Al2O3 tandem solar selective absorbing coating was successfully deposited on Si (1 0 0) and stainless steel (SS) substrates by reactive RF magnetron sputtering deposition. The spectral characteristics, microstructure, thermal stability and solar-thermal conversion efficiency of the coating before and after a long annealing in vacuum were investigated systematically. The optical constants of the coating are measured by an Ultraviolet–visible-near-infrared (UV/Vis/NIR) spectrometer, and the chemical composition analysis, structure information and surface morphology are investigated using XRD, XPS and FESEM. An excellent absorptance (α = 0.92) and a low emittance (e = 0.11) at 82 °C are obtained by the as-prepared coatings. After annealed at 500 °C for 100 h in vacuum, there is no significant change in micromorphology and optical properties of the coating, which produces a good solar-thermal conversion efficiency. These results indicate that it can be applied as a potential coating material to a high temperature concentrated solar power (CSP) system.

Bio-synthesis of nano-metal oxide particles is gaining lot of significance and recommended as promising substitute not only physical methods but also chemical methods. Here in, we demonstrate the nano-zinc oxide (nano-ZnO) particles were successfully prepared by an eco-friendly process using plant Barleria gibsoni (B. gibsoni) aqueous leaf extract. The water leaf extract of B. gibsoni responsible for not only reducing source but also protective agent. The prepared nano-ZnO particles were studied by UV–Vis diffuse reflectance (UV-DRS), Photoluminescence (PL), Fourier transform (FT-IR) infrared spectroscopy, X-ray diffraction spectroscopy (X-RD), transmission electron microscopy (TEM), thermal stability was studied by thermogravimetric and differential thermal (TG-DTA) analysis and particle size by zeta sizer, dynamic light scattering (DLS). UV-DRS spectrum of nano-ZnO particles showed below at wave length 400 nm. FT-IR spectra showed that plant metabolites like polyphenols, flavonoids and amino acids etc., are act as reducing and protective agent. X-RD studies revealed the formed nano-ZnO particles have hexagonal (wurtzite) structure. TEM analysis confirmed the range of nanoparticles between 30 and 80 nm, which is supported by DLS analysis. The antibacterial property of synthesized nano-ZnO particles was tested with bacterial pathogens showed good results. The developed nano-ZnO gel act as an efficient and superior another tropical antimicrobial formulations for healing of burn infections. Moreover, the formulated nano-ZnO gel exhibited a remarkable wound healing potential in rats.