A Review on Physical Hydrogen Storage: Insights into Influencing Parameters, Energy Consumption, Global Outlook and Bibliographic Analysis.

The transition of the global energy market towards an environment-friendly, sustainable society requires a profound transformation from fossil fuel to zero carbon emission fuel. To cope with this goal production of renewable energy is accelerating worldwide. Hydrogen is a clean energy carrier, due to its clean combustion and abundance. Nonetheless, its storage is a critical challenge to its success. Hydrogen must be stored long after being produced and transported to a storage site. Physical hydrogen storage (PHS) is vital among hydrogen storage modes, and its shortcoming needs to overcome for its successful and economic benefits. This review intends to discuss the techniques and applications of physical hydrogen storage in the state of compressed gas, liquefied hydrogen gas, and cold/cryo compressed gas concerning their working principle, chemical and physical properties, influencing factors for physical hydrogen storage, and transportation, economics, and global outlook. In addition, insights of several probable PHS systems are highlighted. The outcomes of this review envisioned that the PHS still necessitates technological advancements despite having remarkable success. The limitation opens the door to further research, which would be helpful for efficient and long-term physical hydrogen storage.

High-Selectivity Hydrogen Gas Sensors based on Mesoporous PbOx -ZnO Nanocomposites.

Hydrogen heralded as a promising renewable and environmentally friendly energy carrier, carries inherent risks owing to its highly flammable nature. A mere 4 % concentration of hydrogen in the air can trigger an explosion. To counteract this peril, a composite material comprising PbOX -ZnO (2 : 1) was synthesized, characterized, and subsequently employed to fabricate a hydrogen sensing device. Various analytical tools were used to characterize as-deposited materials, including X-ray diffraction, Scanning electron microscopy /Energy Dispersive X-ray Spectroscopy, Transmission electron microscopy UV-Vis Reflectance Spectroscopy and Fourier-transform infrared spectroscopy. The device exhibited favorable properties, such as good selectivity, stability, and a low detection limit for hydrogen. At ambient room temperature, the device demonstrated a sensing signal reaching 468.7, with a response time (T90) of 155 seconds and a recovery time (Tr90) of 69 seconds when exposed to a hydrogen concentration of 5 ppm. This performance underscores the device's rapid and effective response to hydrogen exposure. Moreover, the PbOX-ZnO (2 : 1) composite-based device exhibited a detection limit of 2.4 ppm, functioning accurately within a linear range spanning from 5 ppm to 50 ppm. This capability confirms its precision in accurately detecting hydrogen concentrations within this designated range.

Nb2CTx MXene reinforcement stimulated microstructure and mechanical properties of magnesium.

In this study, Nb2CTx MXene reinforced commercially pure magnesium composite was processed using traditional blend-press-sinter technique. The added one volume percentage of Nb2CTx MXene was fairly dispersed around the magnesium particles despite having sporadic clustering. Nb2CTx MXene reinforcement was stable and developed defect free strong interfacial bonding with the magnesium matrix. The small amount of chemically compatible and thermally stable Nb2CTx MXene reinforcement was successful in enhancing the bulk hardness and compressive yield strength, compressive strength, ductility and fracture toughness of the commercially pure magnesium.

The Synergy of Lead Chalcogenide Nanocrystals in Polymeric Bulk Heterojunction Solar Cells.

Photoactive polymer and quantum dots (QDs)/nanocrystals (NCs)-based bulk heterojunction (BHJ) solar cells have the combined positivity of organic semiconductors and inorganic components, which can enable a high carrier mobility and absorption coefficient. Additionally, the NCs also provide the opportunity to tune the band gap to obtain enhanced absorption in a broad solar spectrum. Among the semiconductors, lead chalcogenide NCs are of particular interest due to their good photosensitivity in the near-infrared (NIR) region of the solar spectrum. These NCs have large exciton Bohr radii (18, 46, and 150 nm for PbS, PbSe, and PbTe, respectively) and tunable sizes depending on the optical bandgaps between 0.3 and 1.5 eV. Independently, lead chalcogenide NCs have been studied extensively for different applications; however, uses in polymer-NC-based bulk heterojunction solar cells are limited. This Review has been structured on the lead chalcogenide NCs incorporated in polymer composite-based bulk heterojunction solar cells covering the material, properties, and solar cell performance to find the issues and explore future opportunities.

Removal of lead ions (Pb2+) from water and wastewater: a review on the low-cost adsorbents.

The presence of lead compounds in the environment is an issue. In particular, supply water consumption has been reported to be a significant source of human exposure to lead compounds, which can pose an elevated risk to humans. Due to its toxicity, the International Agency for Research on Cancer and the US Environmental Protection Agency (USEPA) have classified lead (Pb) and its compounds as probable human carcinogens. The European Community Directive and World Health Organization have set the maximum acceptable lead limits in tap water as 10 µg/L. The USEPA has a guideline value of 15 µg/L in drinking water. Removal of lead ions from water and wastewater is of great importance from regulatory and health perspectives. To date, several hundred publications have been reported on the removal of lead ions from an aqueous solution. This study reviewed the research findings on the low-cost removal of lead ions using different types of adsorbents. The research achievements to date and the limitations were investigated. Different types of adsorbents were compared with respect to adsorption capacity, removal performances, sorbent dose, optimum pH, temperature, initial concentration, and contact time. The best adsorbents and the scopes of improvements were identified. The adsorption capacity of natural materials, industrial byproducts, agricultural waste, forest waste, and biotechnology-based adsorbents were in the ranges of 0.8-333.3 mg/g, 2.5-524.0 mg/g, 0.7-2079 mg/g, 0.4-769.2 mg/g, and 7.6-526.0 mg/g, respectively. The removal efficiency for these adsorbents was in the range of 13.6-100%. Future research to improve these adsorbents might assist in developing low-cost adsorbents for mass-scale applications.

Recent Development in Laminar Transition Metal Dichalcogenides-Based Membranes Towards Water Desalination: A Review.

Transition metal dichalcogenides (TMDCs)-based laminar membranes have gained significant interest in energy storage, fuel cell, gas separation, wastewater treatment, and desalination applications due to single layer structure, good functionality, high mechanical strength, and chemical resistivity. Herein, we review the recent efforts and development on TMDCs-based laminar membranes, and focus is given on their fabrication strategies. Further, TMDCs-based laminar membranes for water purification and seawater desalination are discussed in detail. Finally, present their merits, limits and future challenges needed in this area.

Removal of Pb2+ from water using the carbon nanotube-g-poly[(sodium methacrylate)-co- 2-(methacryloyloxy)ethyl acetoacetate]: experimental investigation and modeling.

A solid polymer, poly[(sodium methacrylate)-co-2-(methacryloyloxy)ethyl acetoacetate], p(MAA-co-MEAA) was synthesized and then grafted onto carbon nanotubes to prepare poly(MAA-co-MEAA)-grafted carbon nanotubes [CNT-g-p(MAA-co-MEAA)]. NMR, TGA, and FT-IR characterized the synthesized polymers and adsorbents. SEM-EDX was used to investigate the surface characteristics of the adsorbents. Pb2+ was removed from the aqueous solution using the CNT-g-p(MAA-co-MEAA). A batch adsorption experiment was performed at different Pb2+ concentrations (1, 10, 25, 50 mg/L), pH (4 and 6.75), temperature (25 and 35 °C), and contact periods (1, 5, 20, 60, and 1440 min) to study the adsorption kinetics and isotherm. The adsorbent dose of 2.5 g/L could effectively lower the initial Pb2+ concentration of 1000 to 2 ppb. The maximum adsorption capacity of the adsorbent was found to be 1178 mg/g. In addition, the adsorbents have been shown to effectively reduce the coexisting metal ion concentrations from industrial wastewater, which indicated the potential of the proposed adsorbent in removing metal ions from coexisting metals containing wastewater. To predict the adsorption efficiency of Pb2+, various linear, non-linear, and neural network models were established. An additional data set, not incorporated in model training, was used to validate the models. A number of models showed excellent performance with R2 in the range of 0.89-0.98. In model validation studies, the correlation coefficients (r) ranged from 0.94 to 0.99. The novel adsorbent and models will most likely aid in the development of a robust treatment technique for removing Pb2+ ions from water and wastewater.

Evaluating the Capacitive Response in Metal Halide Perovskite Solar Cells.

The perovskites solar cells (PSCs) is composed of multifaceted device architecture and involve complex charge extraction (both electronic and ionic), this makes the task demanding to unlock the origin of the different physical process that occurs in a PSC. The capacitance in PSCs depends on several external perturbations including frequency, illumination, temperature, applied bias, and importantly on the interface modification of perovskites/charge selective contact. Arguably, different features including interfacial and bulk; ionic, and electronic charge transport in PSCs occur at different time scales. Capacitance spectroscopy is a prevailing technique to unravel the various physical phenomenon that occurs in a PSC at different time scales. A deeper knowledge of the capacitive response of a PSCs is essential to understand the charge carrier kinetics and unlock the device physics. This work highlights the capacitive response of PSCs and its application to unlock the device physics which is essential for the further optimization and improvement of the device performance.

Thermal energy storage and thermal conductivity properties of fatty acid/fatty acid-grafted-CNTs and fatty acid/CNTs as novel composite phase change materials.

In recent year, fatty acids (FAs) are heavily studied for heat storage applications and they have shown promising advantages over other organic phase change materials (PCMs). Among the FAs; capric, palmitic and stearic acids are the most studied PCMs. Several researchers have investigated these FAs and tried to improve their thermal properties, mainly by adding different high conducting fillers, such as graphite, metal foams, CNTs, graphene etc. In most cases, these fillers improved the thermal conductivity and heat transfer property but reduce the heat storage capacity considerably. These composites also lose the mixing uniformity during the charging and discharging process. To overcome these issues, selected FAs were grafted on the functionalized CNT surfaces and used as conductive fillers to prepare FA based composite PCMs. This process significantly contributed to prevent the drastic reduction of the overall heat storage capacity and also showed better dispersion in both solid and liquid state. Thermal cycling test showed the variations in the thermal energy storage values of all composite PCMs, however, within the tolerable grade and they had appreciable phase change stability and good chemical stability even after 2,000 cycles.

Thermal energy storage and thermal conductivity properties of Octadecanol-MWCNT composite PCMs as promising organic heat storage materials.

Fatty alcohols have been identified as promising organic phase change materials (PCMs) for thermal energy storage, because of their suitable temperature range, nontoxicity and can be obtained from both natural and synthetic sources. Like all other organic PCMs, octadecanol (OD) as PCM suffers from low thermal conductivity (TC). In this work, to enhance its TC, it was grafted on the functionalized MWCNT and were used as a conductive filler to enhance overall thermal properties of OD in a composite PCM (CPCMs) structure. The OD/OD-g-MWCNT sample showed better dispersion within the composites and the presence of additional OD boosted the overall heat storage enthalpy compared to that of plane composite sample with OD/MWCNT. In a non-quantitative approach, it was observed that, any increase in grafting ratio of OD increases the heat storage enthalpy of the composites. The heat storage enthalpy of (267.7 J/g) OD/OD-g-MWCNT(4:1)-5wt% composite PCM had reached very close to the heat storage enthalpy value of pure OD (269.3 J/g), and much higher than that of OD/MWCNT-5wt% (234.5 J/g). Champion sample i.e. OD/OD-g-MWCNT (4:1)-5wt%, showed good heat storage enthalpy, cycling performance, thermal stability and TC enhancement by 262.5%.

Assessment of sulfonated homo and co-polyimides incorporated polysulfone ultrafiltration blend membranes for effective removal of heavy metals and proteins.

Sulfonated homo and co- polyimide (sPI) were synthesized with new compositional ratios, and used as additives (0.5 wt%, 0.75 wt%, and 1.0 wt%) to prepare blend membranes with polysulfone (PSf). Flat sheet membranes for ultrafiltration (UF) were casted using the phase inversion technique. Surface morphology of the prepared UF membranes were characterized by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Surface charge of the membranes were determined by zeta potential, and hydrophilicity was studied by contact angle measurement. The contact angle of the membrane decreased with increasing sPI additive indicates increasing the hydrophilicity of the blend membranes. Filtration studies were conducted for rejection of heavy metals (Pb2+ and Cd2+) and proteins (pepsin and BSA). Blend membranes showed better rejection than pure PSf membrane. Among the blend membranes it was observed that with increasing amount of sPIs enhance the membrane properties and finally, PSf-sPI5 membrane with 1 wt% of sPI5 showed the improved permeability (72.1 L m-2 h-1 bar-1), and the best rejection properties were found for both metal ions (≈98% of Pb2+; ≈92% of Cd2+) and proteins (>98% of BSA; > 86% of Pepsin). Over all, this membrane was having better hydrophilicity, porosity and higher number of sites to attach the metal ions. Its performance was even better than several-reported sulfonic acid based UF membranes. All these intriguing properties directed this new UF membrane for its potential application in wastewater treatment.

An Ultrasensitive and Selective Metal-Organic Framework Chemosensor for Palladium Detection in Water.

A new europium-based metal-organic framework, termed KFUPM-3, was constructed using an allyloxy-functionalized linker. As a result of coordinative interactions between the allyloxy moieties and Pd2+, highly selective changes in both the absorption and emission spectra of KFUPM-3 were observed. Accordingly, KFUPM-3 was demonstrated to have an ultrasensitive Pd2+ detection limit (44 ppb), regenerative properties without loss in performance, detection of palladium in different oxidation states and in the presence of other competitor metal ions, and fully functional sensing capabilities over a wide pH range.

Tuning the Interplay between Selectivity and Permeability of ZIF-7 Mixed Matrix Membranes.

Nanoparticles of zeolitic imidazolate framework-7 (nZIF-7) were blended with poly(ether imide) (PEI) to fabricate a new mixed-matrix membrane (nZIF-7/PEI). nZIF-7 was chosen in order to demonstrate the power of postsynthetic modification (PSM) by linker exchange of benzimidazolate to benzotriazolate for tuning the permeability and selectivity properties of a resulting membrane (PSM-nZIF-7/PEI). These two new membranes were subjected to constant volume, variable pressure gas permeation measurements (H2, N2, O2, CH4, CO2, C2H6, and C3H8), in which unique gas separation behavior was observed when compared to the pure PEI membrane. Specifically, the nZIF-7/PEI membrane exhibited the highest selectivities for CO2/CH4, CO2/C2H6, and CO2/C3H8 gas pairs. Furthermore, PSM-nZIF-7/PEI membrane displayed the highest permeabilities, which resulted in H2/CH4, N2/CH4, and H2/CO2 permselectivities that are remarkably well-positioned on the Robeson upper bound curves, thus, indicating its potential applicability for use in practical gas purifications.

Polyester sulphonic Acid interstitial nanocomposite platform for peroxide biosensor.

A novel enzyme immobilization platform was prepared on a platinum disk working electrode by polymerizing aniline inside the interstitial pores of polyester sulphonic acid sodium salt (PESA). Scanning electron microscopy study showed the formation of homogeneous sulphonated polyaniline (PANI) nanotubes (∼90 nm) and thermogravimetric analysis (TGA) confirmed that the nanotubes were stable up to 230 °C. The PANI:PESA nanocomposite showed a quasi-reversible redox behaviour in phosphate buffer saline. Horseradish peroxidase (HRP) was immobilized on to this modified electrode for hydrogen peroxide detection. The biosensor gave a sensitivity of 1.33 µA (µM)(-1) and a detection limit of 0.185 µM for H(2)O(2). Stability experiments showed that the biosensor retained more than 64% of its initial sensitivity over four days of storage at 4 °C.

Modelling of the impedimetric responses of an aflatoxin B(1) immunosensor prepared on an electrosynthetic polyaniline platform.

Aflatoxins are a group of mycotoxins that have deleterious effects on humans and are produced during fungal infection of plants or plant products. An electrochemical immunosensor for the determination of aflatoxin B(1) (AFB(1)) was developed with AFB(1)antibody (AFB(1)-Ab) immobilized on Pt electrodes modified with polyaniline (PANi) and polystyrene sulphonic acid (PSSA). Impedimetric analysis shows that the electron transfer resistances of the Pt/PANi-PSSA electrode, the Pt/PANi-PSSA/AFB(1)-Ab immunosensor and Pt/PANi-PSSA/AFB(1)-Ab incubated in bovine serum albumin (BSA) were 0.458, 720 and 1,066 kOmega, respectively. These results indicate that electrochemical impedance spectroscopy (EIS) is a suitable method for monitoring the change in electron transfer resistance associated with the immobilization of the antibody. Modelling of EIS data gave equivalent circuits which showed that the electron transfer resistance increased from 0.458 kOmega for the Pt/PANi-PSSA electrode to 1,066 kOmega for the Pt/PANi-PSSA/AFB(1)-Ab immunosensor, indicating that immobilization of the antibody and incubation in BSA introduced an electron transfer barrier. The AFB(1) immunosensor had a detection limit of 0.1 mg/L and a sensitivity of 869.6 kOmega L/mg.