The continuous discharge of synthetic dyes into aquatic environments poses serious ecological and human health risks, highlighting the urgent need for efficient remediation strategies. In this study, a natural Moroccan aluminosilicate clay was purified and magnetically modified with Fe₃O₄ nanoparticles (5–20 wt
Perovskite-based tandem solar cells offer a promising route for efficient solar energy conversion across a broad spectrum. In this study, we explore the development of perovskite-based tandem solar cells, focusing on Cs3Bi2I9 and La2NiMnO6 (LNMO) as absorber layers, in conjunction with FTO as the transparent conducting oxide. Initial investigations utilizing only LNMO and Cs3Bi2I9 with FTO yielded an efficiency of 22.4%, which was subsequently optimized to achieve an efficiency of 31.17% through the integration of electron transport layers (ETLs) and hole transport layers (HTLs). Notably, the incorporation of titanium dioxide (TiO2) as the ETL, in conjunction with various HTLs such as poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), resulted in the highest efficiency. Further investigations into interlayers revealed their significant impact on device performance, with certain combinations enhancing efficiency while others exhibited a decrease. Additionally, suitable back contacts were compared, and the performance of the configured tandem solar cell was analyzed under diverse conditions. This work presents a comprehensive one-dimensional solar cell capacitance simulator (SCAPS-1D) simulation study focused on optimizing a fully lead-free tandem solar cell that combines Cs3Bi2I9 and La2NiMnO6 absorber layers. The theoretical predictions derived from this study represent the upper efficiency limits achievable under idealized simulation conditions, providing valuable insights and guidance for future experimental design and optimization of sustainable, lead-free perovskite-based tandem solar cell devices. Meticulous simulations using SCAPS-1D affirmed the viability of the Cs3Bi2I9/LNMO-based tandem solar cells, reaching optimal efficiency. This research contributes valuable insights into the optimization of device architecture and interface engineering, paving the way for the development of efficient and cost-effective solar energy harvesting systems.
The gas sensing response of semiconducting chemiresistors is governed by changes in electronic properties caused by molecular adsorption. These changes, such as in the band gap, work function, and density of states near the Fermi level, are often small when molecules are adsorbed on pristine materials, leading to low sensitivities. The decoration with single atoms is an effective strategy to enhance the sensitivity of the sensing material toward target molecules. Moreover, decoration-induced magnetism can lead to spin-dependent transport behavior that influences the sensing signal. In this work, by using density functional theory calculations, we investigate the adsorption behavior and sensing properties of selected volatile organic compounds, namely isopropanol (C3H8O), acetonitrile (C2H3N), toluene (C7H8), and formaldehyde (CH2O), onto Ti2CO2 MXene decorated with Mn and Ru single atoms. Our results show that these molecules preferentially adsorb on the single-atom sites, with adsorption energies ranging from adsorption energies ranging from -1.32 to -3.01 eV, ensuring strong immobilization essential for reliable detection. Electronic structure analysis reveals that Ru-decorated Ti2CO2 maintains a semiconducting character with spin-dependent band gaps of 0.30/0.44 eV, which are slightly modified upon molecular adsorption. In contrast, Mn-decorated Ti2CO2 shows half-metallic behavior with a spin-up gap of 0.34 eV and a metallic spin-down channel, while adsorption of toluene leads to a quenching of its magnetization and induces a transition to a semiconducting state with a band gap of 0.38 eV. Such a transition causes a significant drop in conductivity, which translates into a highly selective sensing response. These results demonstrate the superior sensing performance of the Mn-decorated MXene, which guarantees high sensitivity and selectivity along with reasonable recovery times, unlike the Ru-decorated MXene. This work also highlights the crucial role of magnetism in tuning the selectivity of semiconducting chemiresistors and provides valuable insights into designing efficient gas sensing platforms.
Drought is an increasing concern in Morocco’s semi-arid regions, where water resources are under growing pressure from climate variability and land degradation. Most previous studies on drought monitoring in Morocco have examined meteorological or hydrological dimensions separately, overlooking vegetation dynamics. This fragmented approach limits the ability to capture the full spectrum of drought impacts across natural and managed ecosystems. This study assesses drought dynamics in the Ahmed El Hansali Dam basin, located in the Upper Oum Er-Rbia watershed, during 1975–2023. The novelty of this research lies in the long-term, combined assessment of meteorological, hydrological, and remote sensing indices at the basin scale, providing one of the most comprehensive drought evaluations for Morocco’s inland watersheds. A multi-index approach combining Standardized Precipitation Index (SPI), Streamflow Drought Index (SDI), and Normalized Difference Vegetation Index (NDVI) was applied to assess meteorological, hydrological, and vegetation responses to drought. Meteorological data from five stations, hydrological inflows at the dam, and Landsat-derived NDVI composites were utilized. The SPI and SDI revealed a marked increase in drought frequency and severity beginning in the early 1990s, with the most critical period between 2020 and 2023. SPI values below − 1.5 and SDI near − 1.6 confirmed intensifying precipitation deficits and declining inflows. The NDVI showed moderate interannual variability with lower values during drought years, though weak correlation with SPI and SDI suggests that vegetation response is influenced by altitude, land cover, and soil water retention, and agricultural practices including irrigation. Spatial analyses highlighted the greater resilience of forested highlands compared to lower-elevation agricultural areas. Overall, the combined use of these three indices offers a robust picture of drought evolution in the basin. By bridging the gap between single-dimension studies and proposing a comprehensive multi-source monitoring framework, this work provides a more holistic understanding of drought impacts and delivers actionable insights for water resource managers and policymakers.
Electroactive polymer composites, which exhibit a combination of functional properties, hold promise for applications ranging from chemical sensing and biosensing to energy harvesting and environmental remediation, thereby contributing to the advancement of sustainable and efficient technologies. Polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP), zinc oxide (ZnO), and several loadings of graphene oxide (GO) were utilized to produce composite films. The obtained films were widely characterized by analyzing morphological, spectroscopic, and thermal properties. The analysis of the specimens revealed a homogeneous distribution of ZnO and GO. Notably, the GO in the ZnO/PVDF-HFP induced an increase in the beta-phase ratio (up to 65% for PVDF-HFP/ZnO/GO1), calculated by using FTIR techniques. Dielectric analysis confirms that the incorporation of GO fillers (1%) leads to a great enhancement of the dielectric properties compared to the neat polymer. These observed improvements give valuable understandings into the features of the composite films and highlight their capability for use in piezoelectric energy harvesting purposes.
