Hydrogen energy, economy and storage: Review and recommendation

A review on the current progress of metal hydrides material for solid-state hydrogen storage applications

Review of hydrogen storage techniques for on board vehicle applications

Materials, technological status, and fundamentals of PEM fuel cells – A review

Hydrogen is a promising alternative energy carrier that can potentially facilitate the transition from fossil fuels to sources of clean energy because of its prominent advantages such as high energy density (142 MJ kg(-1); ref. 1), great variety of potential sources (for example water, biomass, organic matter), light weight, and low environmental impact (water is the sole combustion product). However, there remains a challenge to produce a material capable of simultaneously optimizing two conflicting criteria--absorbing hydrogen strongly enough to form a stable thermodynamic state, but weakly enough to release it on-demand with a small temperature rise. Many materials under development, including metal-organic frameworks, nanoporous polymers, and other carbon-based materials, physisorb only a small amount of hydrogen (typically 1-2 wt%) at room temperature. Metal hydrides were traditionally thought to be unsuitable materials because of their high bond formation enthalpies (for example MgH(2) has a ΔHf~75 kJ mol(-1)), thus requiring unacceptably high release temperatures resulting in low energy efficiency. However, recent theoretical calculations and metal-catalysed thin-film studies have shown that microstructuring of these materials can enhance the kinetics by decreasing diffusion path lengths for hydrogen and decreasing the required thickness of the poorly permeable hydride layer that forms during absorption. Here, we report the synthesis of an air-stable composite material that consists of metallic Mg nanocrystals (NCs) in a gas-barrier polymer matrix that enables both the storage of a high density of hydrogen (up to 6 wt% of Mg, 4 wt% for the composite) and rapid kinetics (loading in <30 min at 200 °C). Moreover, nanostructuring of the Mg provides rapid storage kinetics without using expensive heavy-metal catalysts.

/pdf/air-stable-magnesium-nanocomposites-provide-rapid-and-high-46jxslft3m.pdf

Air-stable magnesium nanocomposites provide rapid and high-capacity hydrogen storage without using heavy-metal catalysts

The effect of thickness on the optical and electrical properties of CdSe thin films is investigated in this paper. The films of thickness 445 nm, 631 nm and 810 nm were deposited on glass and ITO coated glass substrates using thermal evaporation technique. The deposited thin films were thermally annealed in air atmosphere at temperature 100°C and were subjected to UV-Vis spectrophotometer and source meter for optical and electrical analysis respectively. The absorption coefficient is observed to increase with photon energy and found maximum in higher photon energy region. The extinction coefficient and refractive index are also calculated. The electrical analysis shows that the electrical resistivity is observed to be decreased with thickness.

Thickness dependent optical and electrical properties of CdSe thin films

Materials behave in a different way when they are in their nano sizes. Nanomaterials encompass a high surface-to-volume ratio, a high adsorption capacity, high sensitivity, and reactivity, hence these can be efficiently used for textile wastewater treatment. Numerous studies have shown that nanoparticles can effectively eliminate various pollutants of domestic and industrial effluent. Nanoparticles are conventionally synthesized by physical and chemical methods but these methods use toxic chemicals, complicated procedures, and expensive materials. Presently, enzymatic processes are the most preferred method as they are economically cheap and environmentally sustainable. Microorganisms, break down the metal salts into metal nanoparticles, which can be isolated and used for textile dye degradation. This review epitomizes the various biosynthesized metal and metal oxide nanoparticles by different microorganisms and if they are efficient to degrade diverse textile dyes.

Biosynthesis of Nanoparticles using Microorganisms and their Applications

Revealing the photophysics of N719 dye based dye-sensitized solar cell

Magnesium oxide has long been intriguing due to several significant phenomena, including wide laser emission, spin electron reflectivity, and defect-induced magnetism. MgO nanostructures have a variety of applications, from spintronics to wastewater treatment, depending on their size and shape. Mg is sensitive material for hydrogen and forms MgH2, so we used Mg/MgO as a sensor to sense hydrogen gas in the present work. Magnesium oxide thin films were synthesized by electrodeposition technique using magnesium nitrate salt. XRD results suggested that the deposited thin films have a face-centered cubic structure. X-ray photoelectron spectroscopy was used to detect the elemental composition and chemical state with the general electronic structure of the sample. The morphology and growth of deposited nanostructure with elemental mapping of the thin film were investigated by SEM-EDS. The UV-visible analysis shows the calculated band gap for MgO thin filmwas 4.16 eV which is in the ultraviolet region. The I-V characteristics have been studied to find out the effect of hydrogenation on the synthesized MgO nanostructure and the sensitivity responseof about 31%. It is quiteevident that MgO nanostructure may be used for gas sensing applications (such as H2 gas).
Bangladesh J. Sci. Ind. Res. 58(2), 119-128, 2023

/pdf/synthesis-of-mgo-nanostructure-thin-films-via-13uzw9g6.pdf

Synthesis of MgO nanostructure thin films via electrodeposition method for gas sensing applications

The effects of 1.75 MeV N5+ ion beams of varying fluences, ranging from 1x1011 to 5x1014 ions/cm2 on structural, optical, and chemical properties of polyethylene terephthalate (PET) polymer, have been investigated by x-ray diffraction (XRD), UV–Visible spectroscopy, and Fourier transform infrared (FTIR) spectroscopy. The XRD patterns of PET samples show that the crystallinity increases with ion irradiation of fluences 4x1011 and 5x1012 ions/cm2. Optical bandgap energy decreases more at the ion fluences of 5x1014 ions/cm2. Absorption maxima shifted towards a higher wavelength value due to the formation of extended conjugation. Acetylenic (-C≡C-) group formation and free CO2 group are confirmed by FTIR spectroscopy. The reaction mechanism of the degradation product formation chemistry is discussed.

/pdf/modification-of-optical-bandgap-and-formation-of-2217ltyj.pdf

Modification of Optical Bandgap and Formation of Carbonaceous Clusters Due to 1.75 MeV N5+ Ion Irradiation in PET Polymers and Search for Chemical Reaction Mechanisms

Chhagan Lal

Papers

Thickness dependent optical and electrical properties of CdSe thin films

Biosynthesis of Nanoparticles using Microorganisms and their Applications

Revealing the photophysics of N719 dye based dye-sensitized solar cell

Synthesis of MgO nanostructure thin films via electrodeposition method for gas sensing applications

Modification of Optical Bandgap and Formation of Carbonaceous Clusters Due to 1.75 MeV N5+ Ion Irradiation in PET Polymers and Search for Chemical Reaction Mechanisms