Hydrogen Storage Capacity Research Articles

Electrochemical hydrogen storage using SrFe12O19 surface-immobilized polyoxometalate

A tri-nickel substituted Keggin-type polyoxometalate (PMo9Ni3O37) was synthesized and subsequently immobilized on the surface of the M-type strontium hexaferrite (SrFe12O19) via the sol-gel method. The investigation of hydrogen storage capacity for the synthesized PMo9Ni3O37@SrFe12O19 nanocomposite was conducted through electrochemical methodologies employing chronopotentiometry (CP). A conventional three-electrode configuration employing copper foam coated with PMo9Ni3O37@SrFe12O19 served as the working electrode and was examined across a current range of ±1.5 mA. The charge and discharge of the experimental procedure indicated the substantial potential of the PMo9Ni3O37@SrFe12O19 nanocomposite in the hydrogen storage process, which was determined 3125 mAh/g during the discharge phase. The successful synthesis was corroborated thorough FT-IR, UV-vis, XRD, SEM, EDX, and BET surface area analysis techniques by examining the characteristic absorption wavelengths or reflection patterns. The size of the nanoparticles was determined through SEM analysis yielding a diameter of 36.76 nm, and using the Scherrer equation, a diameter of 29.22 nm was obtained.

The structural, elastic, optoelectronic properties and hydrogen storage capability of lead-free hydrides XZrH3 (X: Mg/Ca/Sr/Ba) for hydrogen storage application: A DFT study

Perovskite hydrides are promising materials for hydrogen capacity application to achieve the US DOE on-board criteria. We have investigated novel perovskite hydrides XZrH3 (X: Mg/Ca/Sr/Ba) for H2 storage and transportation applications. In this study we investigates the physical properties of XZrH3 light materials for solid-state hydrogen storage application by incorporating the DFT framework with the CASTEP code. We have theoretically examined the structural, mechanical, electronic, optical, and hydrogen storage properties of these materials. The selected compounds were fully relaxed and optimized in the cubic phase space group Pm-3 m. Structural phase stability was confirmed through thermodynamic, and mechanical analyses. Mechanical properties, evaluated based on Poisson’s ratio, the Puagh’s ratio, and Cauchy pressure, indicate the ductile behavior with a preference for ionic bonding. The electronic structure analysis reveals the metallic behavior of these materials. Optical calculations were also performed to provide additional insights into the physical properties of H2 compounds. The gravimetric hydrogen storage capacities were calculated as 2.55, 2.25, 1.66, and 1.31 wt% for MgZrH3, CaZrH3, SrZrH3, And BaZrH3 hydrides respectively. The identified properties of XZrH3 suggest that these materials could significantly enhance hydrogen storage systems, with potential integration into existing energy technologies, offering a pathway toward more efficient and sustainable hydrogen-based solutions.

Computational study of the mechanical stability, hydrogen storage and optoelectronic properties of new perovskite hydrides CsXH3 (X = Ca, Sr and Ba)

In this study, the physical properties of the perovskite hydrides CsXH3 (X = Ca, Sr and Ba) were explored using density functional theory (DFT) to assess their suitability for optoelectronic and hydrogen storage applications. The properties analyzed for these materials included hydrogen storage capacity, as well as structural, mechanical, electronic, and optical characteristics. These investigations were conducted using the GGA-PBE method within the ABINIT simulation code. Initially, the structural properties revealed that the lattice constants of the optimized unit cell structures of CsCaH3, CsSrH3 and CsBaH3 are 4.66, 4.80 and 5.25 Å, respectively. Additionally, the formation energy calculations proved that the selected materials are thermodynamically stable and can be synthesized. The mechanical stability of such hydrides has been confirmed by the results of the elastic constants that met the necessary stability criteria. Moreover, the hydrogen storage properties of the considered compounds revealed capacities of 1.71 wt%, 1.35 wt%, and 1.11 wt% for CsCaH3, CsSrH3 and CsBaH3, respectively, indicating their considerable potential as candidates for hydrogen storage applications. The electronic properties revealed that the three investigated materials exhibit semiconducting behavior with band gaps of 3.16, 2.84 and 2.18 eV for CsCaH3, CsSrH3 and CsBaH3, respectively. Additionally, various optical features including real ε1(ω) and imaginary ε2(ω) dielectric components, refractive index n(ω), absorption factor α(ω) were also investigated and implied that CsCaH3, CsSrH3 and CsBaH3 are suitable for optoelectronic devices. This study is the first to highlight the relevance of new materials CsCaH3, CsSrH3 and CsBaH3 for hydrogen storage and optoelectronic applications.

Research on the modification of magnesium hydride by two-dimensional layered Mo2Ti2C3 MXene

One of the most important technologies for the sustainable development of energy in the future is solid-state hydrogen storage. This study employed etching methods to fabricate two-dimensional layered catalyst Mo2Ti2C3 MXene, which was compared with unetched MAX phases Mo2Ti2AlC3 and Ti3C2, as well as Mo2C. Through mechanical ball milling, these materials were mixed with MgH2 to prepare composite materials, including MgH2 + Ti2C3, MgH2 + Mo2C, MgH2 + Mo2Ti2AlC3, and MgH2 + Mo2Ti2C3. According to the study, Mo2Ti2C3 demonstrates the synergistic catalytic actions of Ti and Mo in contrast to Ti2C3 and Mo2C. The composite material MgH2 + Mo2Ti2C3 lowers the initial dehydrogenation temperature of MgH2 to 180 °C, which is 165 °C lower than pure MgH2. After 30 min at 250 °C, the dehydrogenation amount is approximately 5.85 wt%. Hydrogen absorption begins at 40 °C and reaches approximately 5.75 wt% at 150 °C. Additionally, it maintains a reversible hydrogen storage capacity of up to 96 % even after 20th cycles at 300 °C. This is because Mo2Ti2C3 has one less layer of Al than Mo2Ti2AlC3, which results in a wider interlayer spacing, more active sites for MgH2, and facilitates hydrogen molecule dissociation and recombination.

Advanced computational screening of X2CaH4 (X = Rb and Cs) for hydrogen storage applications

Utilizing cutting-edge computational screening methods, this study explores the hydrogen storage capacity of two complex metal hydrides, Cs2CaH4 and Rb2CaH4. We perform a thorough analysis of their structural, electrical, optical, and hydrogen storage properties using density functional theory (DFT). Within the I4/mmm space group, both compounds display stable tetragonal crystal structures, and their thermodynamic stability is confirmed by their formation energies. Notably, compared to Rb2CaH4, Cs2CaH4 is more stable. With band gaps of 2.99 eV for Cs2CaH4 and 3.28 eV for Rb2CaH4, the electronic properties show insulating behavior, which is beneficial for reducing electronic interference during hydrogen absorption and desorption. A comparative research reveals that the potential gravimetric hydrogen storage capacities of Cs2CaH4 (1.28%) and Rb2CaH4 (1.86%) are comparable to, albeit marginally less than, those of materials that are frequently explored, such as lithium borohydride. With their individual absorption and reflectivity peaks, the optical characteristics offer more information about how they interact with electromagnetic radiation, information that may be useful for improving their performance in real-world applications. Our results imply that Cs2CaH4and Rb2CaH4 have considerable potential for use in practical hydrogen storage systems, especially in situations where stability and minimal electronic interference are essential. Subsequent research endeavors may concentrate on enhancing the hydrogen storage capacity of these materials, so rendering their incorporation into existing hydrogen storage methods more feasible.

Intriguing phenomenon of hydrogen molecules occupancy in clathrate hydrate cages: Implications for hydrogen storage

The occupancy of hydrogen in hydrate cages plays a significant role in the hydrogen storage capacity of hydrate-based. Here, we have found two intriguing phenomena of multiple hydrogen molecules occupancy in hydrate cages under relatively mild conditions. We observed the double hydrogen molecule occupancies in the small cages with large-molecule guest substance (1,2-Epoxycyclopentan (ECP)) as the thermodynamic promoter. The discovery illustrates that the stereotypical idea that light guest molecules are always necessary for double hydrogen occupancy in the 512 cages needs to be reconsidered. And we also observed the coexistence of double hydrogen molecules occupancy in the 51264 cages, which is the prerequisite of high hydrogen storage capacity in clathrate hydrates. The discovery obtained in this study can also provide further insight into the mechanism of hydrate formation and significant advances in hydrate-based hydrogen storage technology.

Agarose derived carbon based nanocomposite for hydrogen storage at near-ambient conditions

Nanocomposites of high surface area adsorption materials and nanosized transition metals have emerged as a promising strategy for hydrogen storage applications. However, their potential use in both transport and stationary applications depends on reaching the ultimate storage capacity at near-ambient conditions along with scalable synthesis protocols. Herein, a direct and simple thermal decomposition technique is reported to synthesize carbon-based nanocomposite, where nickel nanoparticles are dispersed in a porous carbon matrix. It is also demonstrated that the storage capacity can be enhanced at near-ambient conditions by effectively engineering the microstructure and synergistically combining the ‘physisorption’ and ‘spillover’ mechanism. The structure, composition and morphology of the samples were investigated using X-ray diffraction, energy dispersive spectroscopy, transmission and scanning electron microscopy. Sorption-desorption isotherms were obtained to study the hydrogen storage capacity at a moderate H2 pressure of 20 bar. The nanocomposite showed a promising storage capacity of 0.73 wt% at 298 K with reversible cyclability. It is shown that the uniform dispersion of catalytic nanoparticles leads to an increase in the spillover efficiency, which further helps in the enhancement of hydrogen storage capacity by a factor of 6.5 over pure carbon.

Etching physicochemical adsorption sites of biochar by steam for enhanced hydrogen storage

Enhancing the hydrogen storage capacity of carbon-based materials requires the precise synthesis of strong hydrogen adsorption sites. Consequently, this work suggests improving hydrogen storage capacity by employing H2O low-temperature etching technology. First, the simulation methods investigated the pore structure and oxygen-containing groups’ adsorption properties on hydrogen. The results showed that the oxygen-containing group could increase the adsorption energy of biochar on hydrogen, and the carboxyl group had the greatest effect. A suitable coupling of pores and oxygen-containing groups can improve the microporous region’s hydrogen storage capacity. Moreover, biochar may form a new ultra-microporous region (less than 0.5 nm) by etching it at 700 °C and 30 vol% H2O. After etching 90 min, the surface oxygen concentration remained stable at 14 at.%. In conjunction with results from mass spectrometry, we discovered that the process influencing pore growth was the heterogeneous interaction between CO and H2 to create CH4. At 25 ℃ and −196 ℃, the KSBC-30–60 showed superior hydrogen storage capacity compared to KSB. Its total adsorption capacity was 0.49 wt% and 5.28 wt%, respectively, and increased by 1.32 and 1.2 times. This study proposes a novel approach to improving hydrogen storage by etching porous carbon structures with H2O. The strategy has the potential for large-scale application and can be further utilized in the design and optimization of related carbon adsorbents.

Investigation of microstructure, hydrogen storage performance of Re-Mg-based alloy modified by RE2O3 (RE = Dy, Er, Yb)

In order to further study the hydrogen storage mechanism of Mg-based hydrogen storage materials, Mg90Ce5Y5 alloy was used as the basis, and three kinds of heavy rare earth oxides were doped into the alloy by ball milling technology. The microstructure and hydrogen storage properties were characterized by XRD, SEM, TEM and PCI. The results show that the hydrogen absorption rate and discharge rate of modified Mg90Ce5Y5 alloy are significantly increased, and the performance is Er2O3 > Dy2O3 > Yb2O3. The hydrogen storage capacity of Er2O3 catalyzed samples is 5.02 wt%, which is higher than 4.82 wt% and 4.80 wt% of Dy2O3 and Yb2O3 catalyzed samples. The hydrogen absorption saturation rate of the sample catalyzed by Er2O3 for 2 min is ∼90 %, the complete release of hydrogen only takes 50 min at 573 K, and the dehydrogenation activation energy is 76.9 kJ/mol. The hydrogen absorption and emission rate is fast, and the dehydrogenation activation energy is slightly lower than that of the other two catalysts. In the process of hydrogen absorption and desorption, the three catalysts exhibit different phase transitions, namely DyH2↔DyH3, ErH2↔ErH3 and irreversible YbH2. DyH2↔DyH3, ErH2↔ErH3 phase transitions have the "hydrogen pump" effect, which can effectively improve the hydrogen absorption and desorption kinetic rate of Mg90Ce5Y5 alloy. Some nano-rare earth compounds and phase transformation significantly improve the kinetic properties of the alloy. However, the enthalpy change of all three catalytic alloys is around 76 kJ/mol H2, which is considered only a slight improvement in thermodynamic properties.

Design of air-stabilized Mg-Sc alloy with enhanced hydrogen storage properties via in-situ formation of Sc-hydride in Sc dissolved phase

Severe surface oxidation and slow kinetic rates are the main obstacles which limit the industrial application of Mg-based hydrogen storage alloys. In this work, an attempt is carried out to design and develop the highly active and air-stabilized Mg-Scx (x = 1, 2 and 3 at.%) alloys via an inexpensive and efficient method. The Sc atoms are completely dissolved in the Mg matrix to form single-phase solid solution alloy. At 325 °C and 2.0 MPa hydrogen pressure, Mg-Sc2 alloy exhibits the rapidest absorption rate with the hydrogen capacity of 6.25 wt%. The synergism of lattice distortion induced by Sc-doping and the in-situ formed ScH2 nanoparticles enhance the de/hydrogenation kinetics. After exposed to air for 800 h, almost no MgO can be detected and the hydrogen storage capacity is only reduced by 0.11 wt%, maintaining the initial total capacity more than 98 %. Sc can protect Mg-based alloys from O2 and H2O pollution, which is ascribed to the formation of an oxygen atoms exclusion zone around the solute atoms caused by valence electrons transfer.

The design of Mg–Ti–V–Nb–Cr lightweight high entropy alloys for hydrogen storage

In this study, body-centered-cubic Ti24V18Nb6Cr12 high entropy alloy (HEA) is selected as the matrix to design Mg–Ti–V–Nb–Cr lightweight HEAs. Based on first-principles calculations, the hydrogen storage properties of a series of Mg–Ti–V–Nb–Cr HEAs are systematically investigated. The designed Mg-based HEAs are found to be stable after hydrogenation and exhibit high gravimetric hydrogen storage capacities (HSCs). Particularly, the gravimetric HSC of Mg6Ti24V18Cr12 HEA is as high as 4.091 wt%. Besides, the dehydrogenation temperature of the Mg–Ti–V–Nb–Cr HEAs decreases obviously with increasing Mg content, which results from the weakened bonding strength of <M-H> pairs. This study demonstrates that the Mg6Ti24V18Cr12 HEA is a potential candidate for hydrogen storage.

Evaluation and screening of multivariate metal-organic frameworks for hydrogen storage

Multivariate metal-organic frameworks (MTV-MOFs) are characterized by their unique structural feature of incorporating multiple organic linkers and metal ions into a unified framework. This composite construction bestows MTV-MOFs with a broader spectrum of diverse and intricate properties compared to traditional single-component MOFs. In this study, the performance of 560 MTV-MOFs as hydrogen storage adsorbents has been thoroughly investigated. Firstly, the key structural parameters of materials, including density, pore occupied accessible volume, accessible surface area, and porosity were computed. Then, high-throughput Grand Canonical Monte Carlo (GCMC) simulations were employed to calculate hydrogen adsorption capacity of MTV-MOFs under hydrogen pressures of 100 bar at both 77 K and 298 K. Based on simulated results, the deliverable hydrogen capacity of these MTV-MOFs were deduced under both room temperature conditions (298 K, 97.2 bar → 298 K, 5 bar) and low-temperature conditions (77 K, 100 bar → 160 K, 5 bar). Through high-throughput screening, we identified top ten promising MTV-MOFs with the highest hydrogen storage capacity and conducted in-depth studies on their hydrogen adsorption properties. Furthermore, we developed a multivariate linear regression model to quantitatively predict the relationship between hydrogen adsorption capacity and their structural parameters for these MTV-MOFs. The predictions of this model align closely with the outcomes derived from GCMC simulations. The present study highlights the potential of MTV-MOFs as promising candidates for hydrogen storage applications, thereby providing valuable theoretical insights into the exploration of high-capacity hydrogen storage materials.

Hydrogen storage and refueling options: A performance evaluation

This study focuses on the comparative modeling and refueling simulations of hydrogen refueling stations for hydrogen-powered vehicles and high-pressure hydrogen storage options in tanks. The study further aims to simulate these under actual conditions in Ontario, Canada for better assessment which can be treated as a case study as well. The specific tests explore the modeling of hydrogen flow between the recharging station to the car's tank, as well as the optimization of transient variations in temperature, pressure and mass flow rate of hydrogen throughout the process of refueling a fuel cell electric vehicle. The H2FILLS program is utilized to assist for the simulation studies. The primary objective is to replicate various practical weather conditions, tank pressures, flow rates, and refueling periods for different categories of high-pressure hydrogen storage tanks and analyze their storage efficiency. The three different commercially available high-pressure type-IV hydrogen storage tanks were considered in the study as tank-I, tank-II and tank-III with working pressures of 500 bar, 700 bar, 700 bar, and hydrogen storage capacity of 9.5 kg, 4.6 kg, and 5 kg, respectively. Seven different ambient temperatures were selected to mimic seasonal effects. When the power output is constant, with temperature increases, flow rate decreases, and therefore time required to refuel also increases. There is a linear relationship between the final mass flow rate and the ambient temperature, where the mass flow rate drops by approximately 1.8 kg/h for every 10 °C rise in temperature. The variation in ultimate mass flow rate between the highest and lowest ambient temperatures is roughly 5.4 kg/h. Based on the refueling time and docking, undocking, downtime it’s been found that approximately five minutes is wasted between each vehicle. This can help reduce average of 230.02 kt, 231.70 kt, and 235.06 kt CO2 emission per year for vehicle-III, vehicle-II, and vehicle-I, respectively. Lastly, yearly CO2 reduction forecast shows that it may reach 0.9 Mt, 1.6 Mt, 2.7Mt, 3.76 Mt, and 4.73 Mt in the year 2030, 2035, 2040, 2045, and 2050, respectively corresponding to the Global Net-Zero scenario.

WO2–N co-doped 2D Carbon nanosheets as multifunctional additives for enhancing the electrochemical hydrogen storage performance of Co2B

Co2B, with its high theoretical hydrogen storage capacity, is a potential solid-state hydrogen storage material. However, its poor cycling life limits its practical application. In this work, in order to improve the cycling stability and reversibility of hydrogen absorption and desorption of Co2B, we propose to use WO2–N–C nanosheets as dopants to mix with Co2B, thereby enhancing its practical performance. Two-dimensional tungsten oxide-nitrogen-carbon (WO2–N–C) nanosheets was syntheized via a liquid-phase approach, using a tungstenate-polydopamine precursor followed by thermal treatment. Subsequently, these WO2–N–C nanosheets were compounded with cobalt boride (Co2B) particles through ball milling at various ratios of 1%, 3%, and 5%, which were confirmed by XRD (X-ray diffraction) and SEM (Scanning Electron Microscope) methods. Employing a comprehensive suite of electrochemical analyses, including corrosion potential measurements, polarization curves, step voltammetry, and electrochemical impedance spectroscopy (EIS), we found that the incorporation of WO2–N–C significantly enhances the corrosion resistance and electrochemical activity of Co2B. Furthermore, cyclic life tests revealed that the WO2–N–C-doped Co2B composites exhibit superior discharge capacities and capacity retention rates compared to pristine Co2B. Notably, the 3% WO2–N–C-doped Co2B composite demonstrated the optimal electrochemical performance, achieving a maximum discharge specific capacity of 555 mAh g−1 and maintaining 82% of its initial capacity after 50 cycles. Our findings underscore the dual role of WO2–N–C in not only augmenting the surface electrochemical activity of Co2B but also providing a protective surface layer, thereby enhancing its overall electrochemical performance.

Sc/Y/Ti functionalized N-substituted defective C24 as promising materials for hydrogen storage

Incorporating transition metal atoms and creating porphorin-like N4 cavity are effective strategies for improving the hydrogen storage capability of carbon materials. In this view, we designed and addressed the hydrogen uptake properties of TM4C8N8 (TM = Sc, Y, Ti) cages originating from C24 to overcome TM clustering. The stabilities of three clusters were confirmed by molecular dynamic simulation. Sc4C8N8/Y4C8N8/Ti4C8N8 can bind up to 20/20/36H2 molecules with a higher gravimetric density of 9.35/6.67/15.27 wt%, compared to the goal of 5.5 wt% proposed by the US-DOE. The interaction between H2 molecules and the hosts can be identified as van der Waals attractions. The average binding energies of Sc4C8N8(H2)20/Y4C8N8(H2)20/Ti4C8N8(H2)36 at M06(D3) and PBE(D3) functional are 0.159/0.173/0.128 eV/H2 and 0.139/0.141/0.102 eV/H2, respectively, meeting the desirable range of reversible hydrogen storage. Furthermore, an investigation was conducted on the impact of pressure and temperature on the hydrogen storage capabilities of TM4C8N8 (TM = Sc, Y, Ti). The desorption temperature exhibits a positive correlation with increasing pressure. The realization of hydrogen release at near mild conditions and the reversibility of hydrogen adsorption/desorption cycles were demonstrated using the van't Hoff equation and ADMP-MD simulations, respectively. Compared with the monomer, the hydrogen storage capacities of (TM4C8N8)2 (TM = Sc, Y, Ti) dimers are slightly reduced.

Investigation on the hydrogen storage properties, electronic, elastic, and thermodynamic of Zintl Phase Hydrides XGaSiH (X = sr, ca, ba)

This study presents a comprehensive investigation of the electronic, mechanical, and thermodynamic properties of Zintl phase hydrides XGaSiH (X = Sr, Ca, Ba) using Density Functional Theory (DFT) and the FP-LAPW method within the WIEN2k package. Our analysis covers the structural stability, electronic properties, and hydrogen interaction mechanisms in these compounds. The hydrides exhibit narrow band gaps, with values ranging from 0.1 to 0.5 eV using GGA and LDA functionals, and 0.6–1.0 eV with mBJ-GGA and mBJ-LDA. The hydrogen storage capacities are determined to be 0.34 wt %, 0.47 wt %, and 0.40 wt % for SrGaSiH, CaGaSiH, and BaGaSiH, respectively, highlighting their potential for energy storage applications. Thermodynamic properties, evaluated through the quasi-harmonic Debye model, provide insights into the Grüneisen parameter, heat capacity, and thermal expansion coefficient over a range of pressures (0–50 GPa) and temperatures (up to 1000 K). Elastic constants reveal that these compounds are mechanically stable, with a notable anisotropy in the {100} plane and varying degrees of compressibility among the different hydrides. Our study further highlights the slightly ordered hexagonal Ga and Si layers, which contribute to the enhanced hydrogen storage capabilities of these materials. The compounds demonstrate high structural stability, facilitating effective hydrogen retention and release at practical temperatures, making them promising candidates for hydrogen storage applications. Additionally, the analysis of electronic band structures and density of states suggests significant conductivity potential, with band gaps ranging from 0.1 to 1.0 eV, depending on the computational method used. The unique combination of structural, electronic, thermodynamic, and mechanical properties in XGaSiH compounds positions them as valuable materials for renewable energy applications. These findings lay the groundwork for future research focused on optimizing these materials through structural modifications or doping to enhance performance metrics such as hydrogen storage capacity and electrical conductivity.

Introducing 2D layered WS2 and MoS2 as an active catalyst to enhance the hydrogen storage properties of MgH2

The current work describes how 2D layered materials, such as MoS2 and WS2, might improve the de/re-hydrogenation kinetics of MgH2. In the presence of WS2 catalyst, desorption of MgH2 begins at 277 °C, with a hydrogen storage capacity of 5.95 wt%, while the onset desorption temperature of MgH2 catalyzed by MoS2 is 330 °C. In just 1.3 min at 300 °C under 13 atm hydrogen pressure, the MgH2-WS2 absorbed approximately 3.72 wt% of hydrogen, and in 20 min at 300 °C under 1 atm hydrogen pressure, it desorbed around ∼5.57 wt% of hydrogen. To ensure the cyclic stability up to 25 cycles of de/re-hydrogenation of the catalyzed MgH2, a continuously 25 cycles of dehydrogenation (under 1 atm hydrogen pressure at 300 °C) and rehydrogenation (under 13 atm hydrogen pressure at 300 °C) were carried out. As a result, MgH2-WS2 exhibits superior cyclic stability than MgH2–MoS2. In addition, with the de/re-hydrogenation kinetics, MgH2-WS2 has a lower reaction activation energy (∼117 kJ/mol) than to other catalyzed and pristine samples. Conversely, the thermodynamical parameters, specifically the change in enthalpy of MgH2, are unaffected by addition of these layered WS2 and MoS2 catalysts.

Extensive screening of novel BaXH3 (X = V, Cr, Co, Ni, Cu, and Zn) perovskites for physical properties and hydrogen storage application: A DFT study

A successful transition to a sustainable economy depends on effective hydrogen storage. To achieve this, we investigate novel inorganic transition metal-based BaXH3 (X = V, Cr, Co, Ni, Cu, Zn) perovskites using Density Functional Theory (DFT). We compute key properties such as structural, electrical, magnetic, optical, mechanical, and hydrogen storage using the GGA-PBE functional. We calculate lattice constants and unit cell volume, indicate thermochemical stability with the negative formation energy of all compounds, and confirm thermodynamic stability with phonon calculations. Investigations into the band structure and density of states (DOS) show that all compounds are metallic, with BaVH3 and BaCrH3 exhibiting magnetic characteristics. We calculate the optical properties, including refractive index, dielectric function, reflectivity, loss function, conductivity, and absorption. We verified mechanical stability using the Born stability criteria. We calculated the hydrogen storage capacities and desorption temperatures. These results indicate that the studied compounds are potential candidates for hydrogen storage in a green economy.

Hydrogen storage potential of XNiH3 (X= Sr and Ba) compounds: A comprehensive DFT analysis

The increasing need for sustainable energy solutions emphasizes the significance of effective hydrogen storage materials. This work provides a thorough analysis using density functional theory (DFT) to assess the capacity of XNiH3 (X = Sr and Ba) compounds, where X denotes strontium (Sr) and barium (Ba), for storing hydrogen. We employed the Cambridge Serial Total Energy Package (CASTEP) approach to optimize the geometries and determine the structural, electrical, optical, and mechanical properties of SrNiH3 and BaNiH3. The findings indicate that SrNiH3 demonstrates a higher gravimetric hydrogen storage capacity (2.03 %) in comparison to BaNiH3 (1.52 %). Both compounds exhibit metallic behavior, characterized by the absence of band gaps, which indicates a high level of electrical conductivity. The optical investigations reveal prominent absorption peaks at 25.32 eV for SrNiH3 and 18.82 eV for BaNiH3, accompanied by substantial energy loss functions and refractive behaviors. Based on mechanical studies, it has been determined that both compounds are mechanically stable. However, SrNiH3 exhibits a larger bulk modulus and Young's modulus compared to BaNiH3. The results highlight the potential of SrNiH3 and BaNiH3 as suitable options for storing hydrogen, which can contribute to the progress of clean energy technology.

Synergistic Enhancements of Zn-ZIF with Nano Zinc Oxide for Hydrogen adsorption, energy storage, and photocatalytic technologies

Creating the porous Zinc-Zeolitic Imidazolate Framework (Zn-ZIF) using a solvothermal technique addresses the need for advanced materials with distinctive properties and cost-effectiveness in modern applications. The PXRD, SEM, UV-DRS, TEM, and TGA/DTG are used to characterize different concentrations of Zn-ZIF. Zn-ZIF's crystalline structure and phase purity have been verified by PXRD. Using diffuse reflectance spectra, the Kubelka-Monk function determined the band gaps of the Zn-ZIF samples, and scanning electron microscopy revealed a more porous structure. At 77 K and 1 bar, the Zn-ZIF solution with a 2:1 ratio had the highest hydrogen storage capacity (1.71 wt%). The electrochemical behavior of several Zn-ZIF electrodes in a 6 M KOH electrolyte was evaluated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) experiments. The Zn-ZIF electrode with a 2:1 ratio exhibits a low charge transfer resistance and a high proton diffusion coefficient (D) of 1.687 × 10−4 cm2 s−1. The characteristics of the 2:1 synthesized Zn-ZIF electrode as a supercapacitor were investigated. Our analysis of the generated Zn-ZIF material's specific capacitance values after 2000 cycles revealed an impressive retention rate of nearly 89 %, with values of 296.6 Fg-1. In addition, we examined the photocatalytic activities of the as-synthesized material by exposing it to ultraviolet light and seeing how it degraded organic dyes such as Cango-Red (CR) dye. With a photocatalytic efficacy of 95.06 % for CR dye, Zn-ZIF (2:1 ratio) is the most effective. These findings should provide new knowledge for researchers interested in developing novel Zn-ZIF materials for photocatalytic, energy storage, and hydrogen storage applications.