Metal Oxide Nanowire-Based Sensor Array for Hydrogen Detection

Accurate hydrogen leakage detection is a major requirement for the safe and widespread integration of this fuel in modern energy production devices, such as fuel cells. Quasi-1D nanowires of seven different metal oxides (CuO, WO3, Nb-added WO3, SnO2, ZnO, α-Bi2O3, NiO) were integrated into a conductometric sensor array to evaluate the hydrogen-sensing performances in the presence of interfering gaseous compounds, namely carbon monoxide, nitrogen dioxide, methane, acetone, and ethanol, at different operating temperatures (200–400 °C). Principal component analysis (PCA) was applied to data extracted from the array, demonstrating the ability to discriminate hydrogen over other interferent compounds. Moreover, a reduced array formed by only five sensors is proposed. This compact array may be easily implementable into artificial olfaction systems used in real hydrogen detection applications

P-Type Metal Oxide Semiconductor Thin Films: Synthesis and Chemical Sensor Applications

This review focuses on the synthesis of p-type metal-oxide (p-type MOX) semiconductor thin films, such as CuO, NiO, Co3O4, and Cr2O3, used for chemical-sensing applications. P-type MOX thin films exhibit several advantages over n-type MOX, including a higher catalytic effect, low humidity dependence, and improved recovery speed. However, the sensing performance of CuO, NiO, Co3O4, and Cr2O3 thin films is strongly related to the intrinsic physicochemical properties of the material and the thickness of these MOX thin films. The latter is heavily dependent on synthesis techniques. Many techniques used for growing p-MOX thin films are reviewed herein. Physical vapor-deposition techniques (PVD), such as magnetron sputtering, thermal evaporation, thermal oxidation, and molecular-beam epitaxial (MBE) growth were investigated, along with chemical vapor deposition (CVD). Liquid-phase routes, including sol–gel-assisted dip-and-spin coating, spray pyrolysis, and electrodeposition, are also discussed. A review of each technique, as well as factors that affect the physicochemical properties of p-type MOX thin films, such as morphology, crystallinity, defects, and grain size, is presented. The sensing mechanism describing the surface reaction of gases with MOX is also discussed. The sensing characteristics of CuO, NiO, Co3O4, and Cr2O3 thin films, including their response, sensor kinetics, stability, selectivity, and repeatability are reviewed. Different chemical compounds, including reducing gases (such as volatile organic compounds (VOCs), H2, and NH3) and oxidizing gases, such as CO2, NO2, and O3, were analyzed. Bulk doping, surface decoration, and heterostructures are some of the strategies for improving the sensing capabilities of the suggested pristine p-type MOX thin films. Future trends to overcome the challenges of p-type MOX thin-film chemical sensors are also presented

le crowdfunding comme levier de développement de l’entrepreneuriat : cas du maroc

Le crowdfunding consiste à financer un projet par le grand public via une plateforme sur internet, il constitue un système de financement collectif. Ce nouveau mode de financement offre d’importantes possibilités face à la récurrente problématique de sous-financement des TPE, PME, et des start-up au Maroc. En effet cette catégorie d’entreprises fait face à des contraintes financières importantes qui rendent l’accès au crédit difficile et à des coûts relativement élevés. L’objet de cette communication est de présenter l’expérience marocaine en matière du crowdfunding en visant trois objectifs fondamentaux. Tout d’abord, nous analysons l’évolution du crowdfunding au Maroc et son cadre réglementaire qui vient d’être instauré en février 2021. Ensuite nous présentons une analyse SWOT de ce nouveau mode de financement. Finalement, nous essaierons de dévoiler la contribution du crowdfunding comme un levier de l’entreprenariat au Maroc. Ces objectifs seront étayés par une recherche documentaire approfondie

Synthesis and characterization of CuO thin films grown by chemical spray pyrolysis

International audienceIn this study, nanostructured cupric oxide (CuO) thin films were deposited using simple spray pyrolysis technique on glass substrates with a fixed temperature at 375 ∘C. The films were deposited at different precursor molarities 0.035, 0.05 and 0.1 M using (CuCl2· 2 H2O) as precursor. The characterizations used such as X-ray diffraction (XRD) shows the formation of pure polycrystalline CuO with tenorite phase which belongs to a monoclinic structure. Raman spectroscopy confirms what we obtained in XRD. The films deposited with 0.1 M show high absorbance. The gap energy decreased from 1.58 to 1.53 eV with increasing precursor concentration from 0.035 to 0.1 M. Other optical parameters such as refractive index, extinction coefficient and dielectric constants were calculated through absorbance/transmittance data extracted from spectrophotometry. © 2017, Springer Science+Business Media New York

Growth and characterization of CuO thin films prepared by spray pyrolysis with various precursors

International audiencein In this work, we study the effect or the different copper precursors on the structural optical and electrical properties of CuO thin films deposited on glass substrates using spray pyrolysis technique, the phase of tenorite (CuO) are identified using X-Ray diffraction. A single phase without impurities is observed for the three precursors. The band gap energy and others optical parameters are calculated using absorbance/transmittance data giving by spectrophotometry. The semiconductor aspect of our films are showed by four probes method. © 2016 IEEE

1D Titanium Dioxide: Achievements in Chemical Sensing

For the last two decades, titanium dioxide (TiO2) has received wide attention in several areas such as in medicine, sensor technology and solar cell industries. TiO2-based gas sensors have attracted significant attention in past decades due to their excellent physical/chemical properties, low cost and high abundance on Earth. In recent years, more and more efforts have been invested for the further improvement in sensing properties of TiO2 by implementing new strategies such as growth of TiO2 in different morphologies. Indeed, in the last five to seven years, 1D nanostructures and heterostructures of TiO2 have been synthesized using different growth techniques and integrated in chemical/gas sensing. Thus, in this review article, we briefly summarize the most important contributions by different researchers within the last five to seven years in fabrication of 1D nanostructures of TiO2-based chemical/gas sensors and the different strategies applied for the improvements of their performances. Moreover, the crystal structure of TiO2, different fabrication techniques used for the growth of TiO2-based 1D nanostructures, their chemical sensing mechanism and sensing performances towards reducing and oxidizing gases have been discussed in detail

Water security and sustainable development

International audienceIn the realms of Climate change impact, economic and population growth, and pollution, Water security, and sustainable development are paramount, for addressing the food-water-energy nexus and mitigating the impact of the cited drawbacks. The presented paper in the first part, emphasizes water security and sustainable development notions. In 2015 s the 2030 agenda were approved by 193 members of the United Nation, it consists of 17 goals (SDG) for environmental sustainability, social inclusion, economic development, peace, justice, good governance, and partnership. The 6th target of SDG is dedicated to clean water and sanitation since it is considered as one of the central focuses of Sustainable Development Goals. The second part is focused on Moroccan's water management plans. This latter elaborate a legal framework for water use, the law n° 36-15 that comprises the protection of human health through the regulation of exploitation, and provision of sanction. The green Morocco Plan (PMV) which aims first to develop modern agriculture aligned with the world global market requirement, and second to eliminate poverty by helping smallholder farming. The 140 dam's that Morocco counts provide strong support to economic growth. However, under the actual uncontrollable changing rate, Morocco is still threatened by low "water security", the access of drinkable water and sanitation services are improved but not totally covered, Moreover, the climate chang