Centre de Recherche en Technologie des Semi-conducteurs pour l’Energétique

This study investigates the enhancement of the thermal, structural, and optical properties of elastomeric polyolefin (POE)/phase change material (PCM(C25H52)) composite polymers through the incorporation of zinc oxide (ZnO) nanoparticles, targeting applications in thermal energy storage, photovoltaics, and encapsulation. Composites were prepared with varying ZnO doping levels (0%, 10%, and 30%) and characterized using differential scanning calorimetry, thermogravimetric analysis, X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and photoluminescence spectroscopy. The results demonstrate that the addition of ZnO nanoparticles significantly improves thermal stability, energy storage capacity, and heat transfer efficiency. The 30% ZnO-doped composite exhibited the highest melting temperature (90.5°C), no mass loss up to 180°C, and the greatest thermal conductivity, making it a promising candidate for thermal energy storage and encapsulation. X-ray diffraction analysis confirmed the successful incorporation of ZnO nanoparticles and an increase in crystallinity with doping, while photoluminescence spectra revealed enhanced optical properties due to defect passivation. The POE/PCM(C25H52) matrix provides a stable environment that preserves the intrinsic properties of ZnO nanoparticles, enabling their effective integration into the composite. These findings highlight the potential of ZnO-doped POE/PCM(C25H52) composites for advanced applications in thermal energy storage, heat management, optoelectronics, and encapsulation — particularly in photovoltaic systems, where uniform dispersion of ZnO nanoparticles can enhance light absorption, charge transport, and device durability.

This study evaluates the dual role of dune sand (DS), used both as a fine aggregate and, after mechanical activation by grinding, as a supplementary cementitious material (SCM) in cement mortars.The experimental program involved the preparation of mortars with raw DS at various replacement levels of crushed sand (0–30 %) and the production of ground dune sand (GDS) by ball milling with different ball-to-sand ratios (7, 10, 12) for partial cement replacement (10–30 %). Before incorporation, GDS reactivity was assessed using laser granulometry, X-ray diffraction (XRD), the Chapelle test, and scanning electron microscopy (SEM). The workability, physical and mechanical properties and microstructural characteristics of the mortars were then evaluated. At a 30 % replacement level, the incorporation of raw DS improved both the density and compactness of the mortars, leading to enhanced mechanical performance compared to the control mix. Similarly, GDS, produced by ball milling with different ball-to-sand ratios, showed significantly increased fineness and reactivity, confirming its partial pozzolanic activation through XRD, FTIR and TGA analyses. The intermediate ball-to-sand ratio provided the most effective activation, promoting additional C–S–H formation while limiting particle agglomeration. At moderate cement replacement levels, GDS improved the mechanical properties due to the combined effects of pozzolanic reactions and filler-induced densification, whereas higher substitution levels resulted in reduced strength attributed to the clinker dilution. In conclusion, the study results demonstrated that DS and GDS can represent sustainable alternatives to natural sand and cement, enabling the formulation of high-performance mortars while contributing to resource preservation and reducing environmental impact. • Dune sand (DS) is an alternative to the use of common sand. • Replacing 30 % of crushed sand with DS improved workability, density, and mechanical strength. • Ground dune sand (GDS) is a pozzolanic additive. • Grinding of dune sand (ball/sand = 10) promoted partial amorphization of quartz and pozzolanic reactivity. • Optimal GDS addition (10 % cement replacement) enhanced compressive strength up to 58 MPa.

Advanced energy storage technologies, such as rechargeable Batteries and Micro-supercapacitors (μSCs) play a pivotal role in addressing the growing global energy demand. Improving their energy and power densities requires the development of electrode materials with well-engineered, hierarchical porous architectures. In this work, we report a facile hydrothermal synthesis of WO₃-MnO₂ composite nanostructures directly integrated onto silicon nanowires (SiNWs), which serve as a highly conductive and high-surface-area scaffold. The influence of annealing temperature on the structural, morphological, and electrochemical properties of the WO₃-MnO₂@SiNWs composite was systematically investigated. Structural characterization through X-ray diffraction (XRD) and surface analysis via X-ray photoelectron spectroscopy (XPS) confirmed the successful formation of the hybrid oxide network. Furthermore, scanning electron microscopy (SEM) revealed a homogeneous distribution of the nanostructured composite coating over the vertically aligned SiNWs, forming a porous, interconnected network favorable for ion diffusion. Energy-dispersive X-ray spectroscopy (EDX) mapping confirmed the uniform presence of W, Mn, O, and Si elements throughout the electrode, indicating successful and consistent deposition of the WO₃-MnO₂ layers. The optimized electrode exhibited excellent capacitive performance, delivering a specific capacitance (Csp) of 16.56 mF·cm −2 , an energy density (Ed) of 0.0001 Wh·cm −2 , and a power density (Pd) of 0.024 W·cm −2 , along with long-term cycling stability retaining 84 % of its initial capacitance over 4000 charge–discharge cycles. Additionally, electrochemical impedance spectroscopy revealed a consistent Csp of 14.23 mF·cm −2 over a wide frequency range (0.01 Hz–1 MHz), indicating efficient charge transfer and low internal resistance. A solid-state symmetric μSC device constructed using WO₃-MnO₂@SiNWs electrodes further demonstrated impressive performance, achieving a maximum specific capacitance of 96 mF·cm −2 at a scan rate of 2 mV·s −1 , with 85 % capacitance retention over 2300 cycles and an energy density of 0.0028 Wh·cm −2 at a power density of 0.4 W·cm −2 . These remarkable electrochemical properties are attributed to the synergistic effects of multivalent WO₃ and MnO₂ species combined with the high conductivity and mechanical stability of the SiNWs framework, highlighting the potential of this composite architecture for next-generation on-chip energy storage devices.

Lithium titanate (Li4Ti5O12) materials are ideally suited for use in lithium-ion batteries (LIBs) due to their numerous exceptional characteristics. In this work,Li4Ti5O12 based nanocomposites were synthesized by hydrothermal method followed by ball mill technique .The structure and morphology of these materials : Li4Ti5O12 / Si , Li4Ti5O12 / V2O5 ,and Li4Ti5O12 /SnO2 were examined by XRD, SEM-EDX, and XPS.The following results demonstrate that composites based on Li4Ti5O12 of different nano sizes were successfully made. For the battery electrochemical performances, EIS, CV, and CD tests are performed

Abstract During long-term operation, solar cell cover glasses are exposed to harsh environmental conditions, potentially causing significant surface damage and modification. Against this background, the main objective of the present study is to investigate and characterise the chemical and physical alterations occurring on solar cell cover glass surfaces after prolonged exposure to desert climates. For this purpose, complementary spectroscopic techniques, namely laser-induced breakdown spectroscopy (LIBS) and X-ray photoelectron spectroscopy (XPS), were employed to provide detailed insights into surface modifications and contaminations. Specifically, cover glasses installed for 25 years in the Southern Algerian desert were examined using scanning electron microscopy (SEM), LIBS, and XPS. Apart from mechanical damage such as chipping, adhesion of (hydro) carbonaceous dirt and sand grains, and accumulation of organic herbaceous structures at the outermost surface, significant changes in the chemical composition of the near-surface glass layer were observed. These changes include carbon penetration into the surface and noticeable leaching of key glass constituents such as calcium and magnesium, both effects attributable to prolonged exposure to desert climate. Additionally, notable surface contamination by tin and lead was identified, likely resulting from impurities introduced via the liquid metal bath used during the float glass manufacturing process. It turns out that both influencing factors, manufacturing and exposure, cause an accumulated modification of the investigated glass surfaces, subsequently affecting their optical properties. Such modifications ultimately have implications for the overall efficiency of the embedded actual photovoltaic cell.