A focused review of the hydrogen storage tank embrittlement mechanism process

Hydrogen embrittlement is a widely known phenomenon in high-strength and storage materials. Hydrogen embrittlement is responsible for subcritical crack growth in material, fracture initiation, subsequent loss in mechanical properties, and catastrophic failure. Hydrogen is induced in the material during an electrochemical reaction between the hydrogen, storage materials, and high-pressure gaseous hydrogen environment. Various mechanisms which are responsible for crack development, growth, and fracture have been deliberated and reported. However, the fundamental mechanism of hydrogen embrittlement remains unclear. Several techniques such as linearly increasing stress test techniques (LIST), constant extension rate test (CERT) and slow strain rate testing (SSRT), thermal desorption spectroscopy (TDS), permeation testing (PT), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) have been utilized to determine the amount of hydrogen diffused and available in the hydrogen storage material. The review intends to categorize and provide a clear understanding of the degradation mechanism that occurs during hydrogen embrittlement. The improvement in mitigating the hydrogen embrittlement degradation as a function of modifying the structure and surfaces of the material is established. Prospects for addressing hydrogen embrittlement degradation through further experimental and numerical research are suggested. Lastly, this paper through recommendation endeavors to prevent hydrogen storage tank degradation and reduces high costs associated with the replacement of the component in renewable energy applications.     

Controlled synthesis of W–Co3S4@Co3O4 as an environmentally friendly and low cost electrocatalyst for overall water splitting

Electrochemistry splitting of water is considered to be one of the most fascinating methods to replace traditional chemical fuels. Here, we design a new method to exploit W–Co₃S₄@Co₃O₄ heterostructures. The W–Co₃S₄@Co₃O₄ material was first prepared and grown in situ on nickel foam by a typical hydrothermal and calcination approach. Based on the principle of electronic regulation, the synergistic effect of W and Co metal ions can increase the charge transfer of the electrode, thus significantly prompting the catalytic activity of the electrode. The W–Co₃S₄@Co₃O₄ material present superior catalytic performance for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), and the overpotential at 10 mA cm⁻² is 260 mV and 140 mV, respectively. Notably, W–Co₃S₄@Co₃O₄ catalyst showed excellent water splitting performance under alkaline conditions (cell voltage of 1.63V @10 mA cm⁻²). Density functional theory calculation shows that the existence of the Co₃O₄ material accelerates the rate of hydrogen production reaction, and the existence of the W–Co₃S₄ material promotes the conductivity of the W–Co₃S₄@Co₃O₄ electrode. The synergistic effect of W–Co₃S₄ and Co₃O₄ materials is beneficial to the improvement of the catalytic activity of the electrode. This study provides a novel view for the development of electrodes synthesis and a novel paradigm for the development of robust, better and relatively non-toxic bifunctional catalysts.     

The characteristics of waste-cooking palm biodiesel-fueled CRDI diesel engines: Effect hydrogen enrichment and nanoparticle addition

The influence of iron nanoparticle (INP) addition (75 ppm) and hydrogen enrichment (10 lpm) with waste cooking palm biodiesel blend (WCB) on a CRDI diesel engine is evaluated. A blend of 20% WCB and 80% diesel is used, and the dosing level of INP has been kept at 75 ppm, which has been decided based on the oxygen content of biodiesel. Results indicate that the combination of H₂ enrichment and INP addition improves the BTE and BSFC of biodiesel blends as that of diesel. A maximum improvement of BTE of 7.1% than that of diesel is obtained at 90% loading. The combined impact of better hydrogen combustion characteristics and improved air-fuel mixing with nanoparticles reduces CO and HC emissions by 37.5% and 41.8%, respectively, for the WCB fuel sample. However, NO_X emission shows an elevation of 27.4% compared to diesel. Combustion parameters, namely ICP (80.1 bar) and HRR (89.5 J/˚CA) indicate an improvement of 5.3% and 6.7% compared to diesel for WCB + INP + H₂. This is owing to the combination of hydrogen's rapid flame speed and INP-added biodiesel's increased thermal conductivity.     

Correlative high-resolution imaging of hydrogen in Mg2Ni hydrogen storage thin films

Nanometer scale imaging of hydrogen in solid materials remains an important challenge for the characterization of advanced materials, such as semiconductors, high-strength metallic alloys, and hydrogen storage materials. Within this work, we demonstrate high-resolution imaging of hydrogen and deuterium within Mg₂Ni/Mg₂NiH₄ hydrogen storage thin films using an in-house developed secondary ion mass spectrometer (SIMS) system attached to a commercially available dual-beam focused ion beam - scanning electron microscope (FIB-SEM) instrument. We further demonstrate a novel approach to measure the size, shape, and distribution of the hydride phase in partially transformed films using laser scanning confocal microscopy (LSCM) to measure surface topography changes from the hydride phase volume expansion. Combining these techniques provides new insights on hydride nucleation and growth within the Mg₂NiH_x system. Finally, we demonstrate the efficacy of tracking deuterium as a hydrogen analog to reduce the background for SIMS imaging of hydrogen in high-vacuum chambers (∼10⁻⁶ mbar).     

The economic analysis for hydrogen production cost towards electrolyzer technologies: Current and future competitiveness

Hydrogen production by electrolysis technology spurs as extensive investigation toward new clear energy acquisition. The mainstream hydrogen production electrolyzers, including alkaline electrolyzer (ALK), anion exchange membrane electrolyzer (AEM), and proton exchange membrane electrolyzer (PEM), are traced to compare their current and future hydrogen production cost regarding technology development. Technologies' characteristics are originally described as the polarization curve parameters such as current density, overpotential, and polarization curve slope. The feature of crucial materials such as catalysts and membranes are also taken into consideration. Then, a bottom-up hydrogen production cost prediction model stemming from technical factors is established with a combination of manufacturing and operating considerations. According to model predictions, the cost of hydrogen production of ALK will be 23.85% and 51.59% lower than AEM and PEM technologies in the short term. However, under technological advancement or breakthrough, the hydrogen production cost of AEM and PEM is expected to be 24% and 56.5% lower in the medium-term and long-term, respectively. The lifetime of the electrolyzers is significantly vital to affect the cost of hydrogen production. The cost reduction space brought about by various technical factors is also explored for the blueprint planning of the hydrogen economy.     

Metal doped black phosphorus/molybdenum disulfide (BP/MoS2–Y (Y: Ni,Co)) heterojunctions for the photocatalytic hydrogen evolution and electrochemical nitrite sensing applications

Recently, 2D semiconductor-based heterojunctions emerge as a focal point of intensive research owing to their unique properties, including efficient charge separation and large interface areas. Herein, Ni or Co-doped black phosphorus/molybdenum disulfide (BP/MoS₂–Y (Y: Ni, Co)) heterojunctions fabricate for photocatalytic H₂ evolution and electrochemical nitrite sensor. Compared to the BP/MoS₂, the BP/MoS₂–Ni and BP/MoS₂–Co exhibit enhanced H₂ performance, as 6.4139 mmol h⁻¹ g⁻¹ and 7.4282 mmol h⁻¹ g⁻¹, respectively, in the presence of Eosin-Y (λ ≥ 420 nm). Furthermore, BP/MoS₂–Co applies as an electrocatalyst on a GCE for the electrochemical detection of nitrite. To optimize the nitrite sensing performance of BP/MoS₂–Co, the effect of the pH, amount of material, scan rates, and other conditions study in detail. The BP/MoS₂–Co displays a linear response within the range of 100–2000 μM with a detection limit of 4.1 μM for DPV. This work can offer an opportunity for hydrogen systems as well as electrochemical sensor applications.     

An overview of hydrogen generation by hydrolysis of Al and its alloys with the addition of carbon-based materials

Al and its alloys are studied extensively for hydrogen generation through water splitting. Alloying Al with metal activators such as bismuth, indium, gallium, etc., leads to the formation of micro galvanic cells during hydrolysis reaction, resulting in an improved hydrogen generation rate. Activation of Al by adding carbon-based materials such as graphite, carbon nanotubes (CNTs), graphene, etc., can instantaneously generate hydrogen at room temperature. When carbon particles are desorbed from the Al matrix during hydrolysis, new Al is exposed, resulting in an increased reaction rate. In Al-Graphite composites which form core-shell structures, H₂O molecules penetrate through the graphite layers and break down the core-shell structure during hydrolysis, and the new Al surfaces are exposed to water. It was found that Al with nano bismuth and graphene nanosheets showed better hydrogen generation rate and hydrogen yield. Graphene nanosheets control the agglomeration of Al and enhance the specific surface area for hydrolysis. During the hydrolysis of Al-CNTs composites, CNTs act as a cathode, resulting in galvanic corrosion between CNTs and the Al matrix. CNTs can also effectively control the agglomeration of Al during ball milling. Spark plasma sintered Al–Bi-CNT composites showed an enhanced hydrogen generation rate during hydrolysis. This paper presents an overview of hydrogen generation by hydrolysis of Al and its alloys, emphasising the addition of carbon-based materials such as graphite, graphene, CNTs, etc.     

Numerical investigation on the wave transformation in the ionic liquid compressor for the application in hydrogen refuelling stations

The ionic liquid compressor exhibits excellent advantages in hydrogen refuelling stations due to the specific design based on the hydraulic system and the ionic liquid piston. The application of the ionic liquid column results in a complex two-phase flow issue inside the compression chamber. This two-phase flow behaviour is critical for the compressor design as it influences the wave dynamics during the compression, but it is absent in the open literature. In this paper, transit numerical simulations were carried out to investigate the wave transformation during a compression cycle by the volume of fluid (VOF) method under different heights of the ionic liquid piston. The effect of liquid height on the wave transformation, discharged quantity of ionic liquid and hydrogen gas, and the turbulence kinetic energy was analysed. The minimum crest value of the turbulent kinetic energy was observed as 0.54 kJ in the cases of 30 and 40 mm. The optimal height of the ionic liquid piston was recommended 40 mm under the presented design condition based on the simulation results.     

Effects of hydrogen addition on combustion and flame propagation characteristics of laser ignited methane/air mixtures

In this study, effects of hydrogen addition on combustion and flame propagation characteristics of methane/air mixtures were investigated in a constant volume combustion chamber. Tested gas mixtures are 100% CH₄, 05% H₂ – 95% CH₄, 10% H₂ – 90% CH₄ and 15% H₂ – 85% CH₄, and such mixtures were ignited using a passively Q-switched Nd:YAG laser ignitor which has a pulse energy of 12.3 mJ, pulse duration of 2.4 ns and wave length of 1064 nm. A Schlieren setup coupled with a high-speed camera enabled evaluating flame propagation behavior, while pressure curve analysis provided necessary data for characterization of combustion properties. Additionally, lean flammability limits of gas mixtures were also determined at the test conditions. The unique properties of hydrogen (such as low density, high reactivity, high diffusivity etc) widened lean flammability limit. Rate of pressure rise and measured pressure values increased with hydrogen addition, regardless of the air-fuel equivalence ratio (λ). Lastly, hydrogen addition uniformly affected flame propagation characteristics and flame luminosity. Combustion process became more stable with hydrogen addition.     

Energy,exergy, economic and environmental (4-E) analyses of plasma gasification steam cycle integrated molten carbonate fuel cell for hydrogen and power co-generation based on residual waste feedstocks

Two newly emerging technologies: (a) plasma gasification and (b) molten carbonate fuel cell (MCFC) are integrated for hydrogen and power production for various system configurations. Due to the emission concerns of fossil fuels, wastes such as refused derived fuel (RDF) is chosen as feedstock. The simulation of the power plants is performed using Aspen plus and consequently, 4-E (energy, exergy, economic and environmental) analyses are executed. The highest energy and exergy efficiencies attained are 54.12% and 52.02% for the system Syngas:CH₄ [PSA: MCFC], respectively. Moreover, the cost of electricity considering all the configurations is ranged between 77.48 and 107.93 $/MWh while the LCOH is between 1.01 and 3.94 $/kg. Likewise, introduction of MCFC for 0:100 [PSA: MCFC] case reduced the annual CO₂ emissions ∼5 times than of 100:0. Therefore, the 4-E analyses reported that integrated plasma gasification with MCFC introducing waste as feed could possibly favour H₂ and power co-generation and a cleaner environment.