Efficient Hydrogen Storage Research Articles

Efficient electrochemical hydrogenation and dehydrogenation of quinoxaline over a dendritic structure P-WO3/NF electrode

Liquid organic hydrogen carrier (LOHC) has been recognized as a highly promising candidate for hydrogen storage materials in addressing hydrogen utilization issues. However, the hydrogenation and dehydrogenation of LOHC typically require noble metal catalysts and harsh reaction conditions. In this paper, we proposed an efficient reversible electrochemical hydrogen storage system based on a nitrogen heterocyclic organic hydrogen carrier, quinoxaline, in which water was used as the solvent and hydrogen source for quinoxaline hydrogenation, and a self-supporting dendritic P-WO3/NF electrode was employed as the electrocatalyst. The catalytic properties of P-WO3/NF for electrochemical hydrogenation of quinoxaline and dehydrogenation of 1,2,3,4-tetrahydroquinoxaline were studied in 1 M KOH solution under mild conditions. The results showed that the hydrogenation conversion of quinoxaline was 90%, the selectivity was 99%, and the dehydrogenation conversion of 1,2,3,4-tetrahydroquinoxaline was 100%, the selectivity was 100%. This indicates that the system has high conversion efficiency, outstanding selectivity, and good reversibility. Meanwhile, the P-WO3/NF electrode adapted to the system exhibited good catalytic stability. In addition, no pre-prepared external hydrogen was required in the electrochemical hydrogenation reaction involving water, which gave the system an excellent safety profile. The reversible electrochemical hydrogen storage system established by this work broadens the vision of LOHC in hydrogen storage applications.

Micro-scale “top-down” construction of N/O Co-doped carbon aerogel particles for efficient hydrogen storage at ambient pressure

High specific surface area carbon aerogel is a kind of adsorption material with excellent comprehensive performance, while its large-scale application is faced with the bottleneck problems including high material cost and complex manufacturing process. Herein, the controllable stripping of the surface micro-scale macropore structure is realized by the control of the activation degree for polyacrylonitrile fiber, the activated fibers with micro-scale macropore structure is completely etched and stripped into three-dimensional frame structured carbon aerogel particles. The prepared carbon aerogel particles have ultra-high surface area (2732.18 m2·g−1) and pore volume (1.13 cm3·g−1) arising almost entirely from micropores (near 90 %), along with abundant surface heterogeneous elements composed by N (10.97 at%) and O (29.67 at%). Attributed to the synergistic effect of physisorption by micropore structure and chemisorption by O/N-containing surface groups, the carbon aerogel particles exhibit excellent hydrogen storage density of 3.17 wt% under ambient pressure. The facile construction strategy for carbon aerogel is proposed from ameliorative activation technology that has been industrialized, which avoids the time-consuming drying process and strict drying conditions in traditional preparation process.

RETRACTED: Nanoscale silicon porous materials for efficient hydrogen storage application

The increasing energy demand and the worldwide energy crisis must be met in large part via the sustainable growth of hydrogen energy, since this economy is relied upon to provide clean and carbon-free energy carriers. It is anticipated that the growing demand for light and heavy fuel cell cars would stimulate the development of onboard solid-state hydrogen technology. The research here concentrates on the importance of various permeable substances such as polymers in general, metallic substances, and complex metal hydrides, even if Si nanostructures (SiNSs) have become known as the obvious contender for solid-state hydrogen storage systems. SiNSs have gained prominence as a leading candidate for solid-state hydrogen storage systems. Renowned for their high storage capacity, SiNSs, including silicon nanowires and quantum dots, exhibit promising potential in addressing challenges associated with traditional hydrogen storage methods, positioning them as a key player in advancing clean and efficient energy storage technologies. SiNSs play a crucial role in advancing solid-state hydrogen storage technology. SiNSs, including silicon nanowires and quantum dots, exhibit high storage capacity. Despite challenges like surface oxidation, SiNS holds promise for efficient hydrogen storage, contributing to the development of sustainable energy solutions and mitigating the environmental impact associated with conventional automotive technologies. We focus on the processes that result in permeable silicon, nanowires made of porous silicon, and Si quantum dots. This investigation elucidates the characteristics and patterns of hydrogen's aid, the value of hydrogen power in automobiles for reducing global warming occurrences, and the potential of using SiNSs for hydrogen storage in tandem with other forms of transition and alkali earth materials to meet these difficulties. It demonstrates how catalysts are critical to fixing the current reversibility and desorption problems with hydrogen energy storage. As a result of the analysis, energy suppliers and Si-based fuel cells may be better able to tailor their services to individual customers' needs, which might boost the growth of the hydrogen energy industry.

N/S co-doped Nb2CTx MXene as the effective catalyst for improving the hydrogen storage performance of MgH2

While MgH2 has high hydrogen storage capacity, its high dehydrogenation temperature and sluggish de-/hydrogenation rate have hindered practical application. In the present work, a non-metallic element (N, S) co-doped Nb2CTx MXene catalyst (N/S-Nb2CTx) is employed to improve the hydrogen storage property of MgH2. The dehydrogenation activation energy of MgH2+N/S-Nb2CTx composite is reduced to 70.00 kJ mol–1 H2, which is much lower than that of MgH2+Nb2CTx (99.44 kJ mol–1 H2) and Milled-MgH2 (133.19 kJ mol–1 H2). The composite can release about 4.78 wt% of H2 within 30 min at 225 °C and uptake about 4.00 wt% of H2 within 80 min even at 30 °C under 30 bar H2, which is significantly better than most of the reported MgH2+Nb-based-catalyst composites. The mechanism analysis reveals that the stable layered structure of the N/S-Nb2CTx catalyst provides enough nucleation sites for MgH2/Mg, and the in-situ formed substances (Nb, NbO2) play the role of elongating Mg–H bond. Besides, the N, S co-doped effectively enhances the ability of multivalent Nb elements to promote the electron transfer between Mg2+ and H–, and it promotes the diffusion of hydrogen through weakening the interaction between Nb and H atoms, thus the de-/hydrogenation kinetics and cyclic stability of MgH2 is significantly improved. This work not only proves that Nb2CTx can effectively enhance its catalytic activity by N and S co-doping, but also provides a MXene-based catalyst design concept for highly efficient hydrogen storage catalysts.

Fine Gas Purification Approaches for High Purity Hydrogen Production from Ammonia

This review aims to evaluate the state‐of‐the‐art in purifying hydrogen from green ammonia. Green ammonia contains 17.8% of H2 and enables efficient liquid storage and transport of hydrogen produced from renewable electricity. Back‐conversion of ammonia to hydrogen may be carried out by several routes, whereby thermal ammonia cracking is one of the most efficient approaches. In the conversion of ammonia at high pressures, it is only possible to achieve complete conversion at very high temperatures (≈ 800 °C). Therefore, the separation of ammonia in the low percentage range (e.g., <0.001%) is an important task. For mobility applications wherein, polymer electrolyte membrane fuel cells are to be fed with cracked H2 (from NH3), fine purity must be achieved, in agreement with ISO 14687‐2. In such a context, ammonia is particularly important, with a permissible concentration of 0.100 ppm. The main feasible routes for ultrafine purification are presented, namely, 1) permeation membranes and 2) absorbents, as well as a third route via 3) biological scrubber, and discussed with regard to efficiency, availability, and cost. Current technology gaps are also identified and an outlook is given toward new innovative approaches.

Stochastic Cyclic Inventory Routing with Supply Uncertainty: A Case in Green-Hydrogen Logistics

Hydrogen can be produced from water, using electricity. The hydrogen can subsequently be kept in inventory in large quantities, unlike the electricity itself. This enables solar and wind energy generation to occur asynchronously from its usage. For this reason, hydrogen is expected to be a key ingredient for reaching a climate-neutral economy. However, the logistics for hydrogen are complex. Inventory policies must be determined for multiple locations in the network, and transportation of hydrogen from the production location to customers must be scheduled. At the same time, production patterns of hydrogen are intermittent, which affects the possibilities to realize the planned transportation and inventory levels. To provide policies for efficient transportation and storage of hydrogen, this paper proposes a parameterized cost function approximation approach to the stochastic cyclic inventory routing problem. Firstly, our approach includes a parameterized mixed integer programming (MIP) model which yields fixed and repetitive schedules for vehicle transportation of hydrogen. Secondly, buying and selling decisions in case of underproduction or overproduction are optimized further via a Markov decision process (MDP) model, taking into account the uncertainties in production and demand quantities. To jointly optimize the parameterized MIP and the MDP model, our approach includes an algorithm that searches the parameter space by iteratively solving the MIP and MDP models. We conduct computational experiments to validate our model in various problem settings and show that it provides near-optimal solutions. Moreover, we test our approach on an expert-reviewed case study at two hydrogen production locations in the Netherlands. We offer insights for the stakeholders in the region and analyze the impact of various problem elements in these case studies. Funding: This project received funding from the Fuel Cells and Hydrogen 2 Joint Undertaking (now Clean Hydrogen Partnership) under [Grant Agreement 875090]. The Joint Undertaking receives support from the European Union’s Horizon 2020 research and innovation programme, Hydrogen Europe and Hydrogen Europe Research. A. H. Schrotenboer received support from the Dutch Science Foundation (Nederlandse Organisatie voor Wetenschappelijk Onderzoek; NWO) through [Grant VI.Veni.211E.043].

Highly dispersed Pd-based pseudo-single atoms in zeolites for hydrogen generation and pollutant disposal.

Atomically dispersed metal catalysts with excellent activity and stability are highly desired in heterogeneous catalysis. Herein, we synthesized zeolite-encaged Pd-based pseudo-single atoms via a facile and energy-efficient ligand-protected direct H2 reduction method. Cs-corrected scanning transmission electron microscopy, extended X-ray absorption, and pair distribution function measurements reveal that the metal species are close to atomic-level dispersion and completely confined within the intersectional channels of silicalite-1 (S-1) zeolite with the MFI framework. The Pd@S-1-H exhibits excellent activity and stability in methane combustion reactions with a complete combustion temperature of 390 °C, and no deactivation is observed even after 100 h on stream. The optimized bimetallic 0.8Pd0.2Ni(OH)2@S-1-H catalyst exhibits an excellent H2 generation rate from FA decomposition without any additives, affording a superhigh turnover frequency up to 9308 h-1 at 333 K, which represents the top activity among all of the best heterogeneous catalysts under similar conditions. Significantly, zeolite-encaged metal catalysts are first used for Cr(vi) reduction coupled with formic acid (FA) dehydrogenation and show a superhigh turnover number of 2980 mol(Cr2O72-) mol(Pd)-1 at 323 K, surpassing all of the previously reported catalysts. This work demonstrates that zeolite-encaged pseudo-single atom catalysts are promising in efficient hydrogen storage and pollutant disposal applications.

Catalytic dehydrogenative coupling and reversal of methanol-amines: advances and prospects.

The development of efficient hydrogen release and storage processes to provide environmentally friendly hydrogen solutions for mobile energy storage systems (MESS) stands as one of the most challenging tasks in addressing the energy crisis and environmental degradation. The catalytic dehydrogenative coupling of methanol and amines (DCMA) and its reverse are featured by high capacity for hydrogen release and storage, enhanced capability to purify the produced hydrogen, avoidance of carbon emissions and singular product composition, offering the environmentally and operationally benign strategy of overcoming the challenges associated with MESS. Particularly, the cycle between these two processes within the same catalytic system eliminates the need for collecting and transporting spent fuel back to a central facility, significantly facilitating easy recharging. Despite the promising attributes of the above strategy for environmentally friendly hydrogen solutions, challenges persist, primarily due to the high thermodynamic barriers encountered in methanol dehydrogenation and amide hydrogenation. By systematically summarizing various reaction mechanisms and pathways involving Ru-, Mn-, Fe-, and Mo-based catalytic systems in the development of catalytic DCMA and its reverse and the cycling between the two, this review highlights the current research landscape, identifies gaps, and suggests directions for future investigations to overcome these challenges. Additionally, the critical importance of developing efficient catalytic systems that operate under milder conditions, thereby facilitating the practical application of DCMA in MESS, is also underscored.

Porous carbons: a class of nanomaterials for efficient adsorption-based hydrogen storage

This review provides an overview of porous carbon materials and their hydrogen storage properties with insight on strategic improvement by structural and chemical modifications and current trends of using machine learning and lifecycle assessment.

Lithium-grafted Si-doped γ-graphyne as a reversible hydrogen storage host material.

In recent years, hydrogen (H2) has become the most sought-after sustainable energy carrier by virtue of its high energy content and carbon-free emission. The practical implementation of hydrogen as an alternative fuel calls for an efficient and secure storage medium. Within this framework, we have investigated Li-grafted Si-doped γ-graphyne for H2 storage applications by implementing the cutting-edge density functional theory (DFT). A dynamically and thermally stable Si-doped γ-graphyne (SiG) monolayer is functionalized with Li metal atoms that augmented the hydrogen binding strength of the nanolayer by almost three times, owing to the polarization effect of the Li atoms. The Li metal atoms get adsorbed over the monolayer, allowing a binding energy of -2.73 eV that is greater than the Li cohesive energy (-1.63 eV), which eliminates the metal-metal clustering probability. The reliability of the Li-functionalized SiG monolayer (Li8SiG) at elevated temperature has been further substantiated by performing and analyzing ab initio molecular dynamics (AIMD) simulations at 400 K. It is noteworthy that a total of four H2 molecules are held up by each Li atom with an average adsorption energy of -0.32 eV and a maximum gravimetric capacity of 8.48 wt%, which remarkably follows the US-DOE parameters. Partial density of states and Hirshfeld charge analysis are utilized to recognize the interaction channel which reveals the Kubas and Niu-Rao-Jena-like bonding among the metal atoms and loaded hydrogen molecules. The hydrogen occupancy calculated at different temperatures and pressures indicates that hydrogen molecules can be reversibly stored over the Li8SiG system, and it is noted that adsorbed H2 begins to desorb at 280 K, with complete desorption at 400 K and 20 atm (or lower). AIMD simulations are further performed to authenticate the H2 desorption at various temperatures, which agrees well with the occupation number analysis. All the outcomes advocate for efficient reversible hydrogen storage over the proposed host material.

Recent progress of MXene as an energy storage material.

Thanks to its adjustable interlayer distance, large specific surface area, abundant active sites, and diverse surface functional groups, MXene has always been regarded as an excellent candidate for energy storage materials, including supercapacitors and ion batteries. Recent studies have also shown that MXene can serve as an efficient hydrogen storage catalyst. This review aims to summarize the latest research achievements in the field of MXene, especially its performance and application in energy storage. Different synthesis techniques have different effects on the energy storage performance of MXene. In this review, various common synthesis methods and the latest innovations in synthesis methods are discussed. MXene is prone to oxidation, and how to resist oxidation is also an important topic in MXene research. This article introduces the research results on improving the chemical stability of MXene through annealing. In addition, it aims to gain a deeper understanding of the future development and potential of MXene.

Two-dimensional TiO2 quantum dots for efficient hydrogen storage: Effect of doping and vacancies

The electronic and optical properties and hydrogen storage capacity of doped two-dimensional TiO2 quantum dots are studied using density functional theory computations. The considered dopants are C, S, N, Fe, Ni, and Zn. Temperature stability is confirmed at 500 K according to ab initio molecular dynamics simulations. Doping and vacancy formation increase the energy gap due to the relaxation of Ti-atoms by additional electrons from the dopants or surface reconstruction after removing O or Ti atoms. The UV–Vis absorption spectra imply that the dominant absorption peak experiences a blue shift after doping and vacancies. The pristine TiO2 is promising for hydrogen storage with suitable adsorption energy that can be enhanced by doping. We obtained a gravimetric adsorption capacity of 6.23 wt% which is higher than the 6.0 wt% issued by the US Department of Energy. Therefore, the high adsorption capacity/energy and thermal stability render TiO2 nanodots promising for efficient H2-storage devices.

Geochemical interactions in geological hydrogen Storage: The role of sandstone clay content

Hydrogen holds promise as a clean energy alternative, crucial for achieving global decarbonization goals and net-zero carbon emissions. Its low volumetric energy density necessitates underground storage in sandstone formations to maintain year-round supply. The efficacy of such storage hinges on the geochemical interplay between hydrogen and the host sandstone. Despite the slow reaction rates in sandstone, the influence of its clay composition on hydrogen interaction remains underexplored. In this study, we specifically investigate the geochemical interactions of hydrogen with clay-bearing sandstone formations under controlled conditions, simulating storage scenarios. This study evaluates the impact of clay on hydrogen-sandstone geochemistry after 75 days of injection at 1500 psi and 75 °C into Berea and Bandera gray sandstone cores, utilizing microcomputed tomography to assess changes in pore structure. Our results reveal that, even in sandstones with high clay content, there is negligible alteration in porosity and mineral content, as well as minimal clay and quartz dissolution or expansion over storage time, indicating stability in these formations. These findings provide crucial insights for selecting suitable geological formations for hydrogen storage, supporting the global shift towards sustainable energy systems Our study contributes to the global efforts in decarbonization by providing essential guidance on the feasibility of using clay-bearing sandstone formations for efficient and sustainable hydrogen storage.

First principle studies on triphenylene-hexathiol-based metal-organic framework for hydrogen storage application

We have studied the hydrogen storage capability of the recently synthesized triphenylene-hexathiol based metal-organic framework (MOF) with Fe and Cu metal atoms by using density functional theory and Ab Initio Molecular Dynamics (AIMD) simulations. We found that up to 12 hydrogen molecules were spontaneously adsorbed on the six Fe atoms of the MOF (FeMOF) with adsorption energy of −0.18 eV per H2 molecule, whereas only six H2 molecules were adsorbed on the six Cu atoms of the MOF (CuMOF) with an adsorption energy of −0.17 eV per H2 molecule. Hydrogen molecules were adsorbed on the Fe atom in the FeMOF surface by Kubas interaction. It is observed that the H2 storage capacity of FeMOF did not change due to the substitution of electron donating group, OCH3 on triphenylene molecules. The charge transfer from H2 molecules to the MOF through metal atoms has been confirmed through the density of states and Bader charge analysis. The gravimetric weight percentage of the FeMOF is found to be 1 wt% at room temperature and 1 atm pressure which is considerably higher than that of the studied CuMOF (0.5 wt%). Further, the AIMD results confirmed the structural stability of the studied MOFs. Therefore, the studied FeMOF surface is a suitable material for efficient and reversible hydrogen storage application.

Pristine [formula omitted] monolayer as highly efficient reversible hydrogen storage material under ambient temperature and pressure

The advent of 2D materials has made physisorption-based H2 storage a promising alternative to conventional techniques involving high pressure and cryogenic temperature. However, most of the reported 2D materials require the addition of metal atoms or the application of an electric field to meet the U.S. Department of Energy (DoE) target of 6.5% gravimetric storage capacity for practical usage. Based on density functional theory (DFT), we show 2D BC6N, in its pristine form, demonstrates a storage capacity of 11.11 wt% with a binding energy of 0.139 eV per H2. At 1 atm pressure, the desorption occurs at temperatures above 118.23 °C, making the storage fully reversible at experimentally conceivable temperatures. The study of the desorption temperatures at varied external pressures indicates a broad operational range for commercial usage. Such high uptake capacity at ambient conditions makes pristine 2D BC6N an ideal candidate for metal-free, reversible hydrogen storage.

Enhanced Hydrogen Storage Capacity in Two-Dimensional Fullerene Networks.

In contrast to isolated C60 molecular dispersion in solvents, the monolayer C60 networks synthesized by Hou et al. (Nature 2022, 606, 507-510) feature compact nanocages, serving as natural containers for hydrogen storage. The anisotropic lattice and intrinsic local strains induce delocalization of conjugated π orbitals within C60, enabling hydrogen chemisorption without an additional chemical modification. Through first-principles calculations and molecular dynamics simulations, we reveal the correspondence between chemisorption sites and orbital distributions, determining the orientation of polyhedrons formed by physiosorbed hydrogen molecules. The combination of chemisorption and physisorption processes significantly enhances hydrogen storage capacity in monolayer C60 networks while maintaining the thermodynamic stability of the nanocage structures. Numerical results indicate a maximum internal hydrogen pressure exceeding 116 GPa at room temperature and atmospheric pressure. These findings suggest that monolayer C60 networks are promising solid-state candidates for highly efficient hydrogen storage.

Metal hydrides in hydrogen storage: optimization of dynamic control strategies

Metal hydrides have emerged as a promising solution for efficient hydrogen storage in solid matter. While the charging and discharging kinetics of these systems are well-known, dynamic control strategies from a system’s perspective still need a detailed analysis by the scientific community. In this research work, a metal hydrides system and its dynamic controls have been numerically studied. AB2-type metals (ZrMn2) are involved as a storage medium, which is coupled to a conditioning system via a heat pump and a hydrogen compressor; therefore, both operating temperature and pressure can be controlled. Results showed that hydrogen pressure is a fundamental component in accelerating reaction dynamics and increasing stored mass. However, it is also the most energy-intensive component. The use of a conditioning system, which works at a proper set temperature, can reduce the hydrogen compressor energy to achieve the same performance, although requiring higher power input from the heat pump’s compressor. Furthermore, the operational strategy must be chosen based on either the minimization of charging/discharging time or energy expenses.

Can endohedral transition metals enhance hydrogen storage in carbon nanotubes?

The safe and efficient use of hydrogen energy, which is in high demand worldwide today, requires efficient hydrogen storage. Despite significant advances in hydrogen storage using carbon-based nanomaterials, including carbon nanotubes (CNTs), efforts to substantially increase the storage capacity remain less effective. In this work, we demonstrate the effect of endohedral transition metal atoms on the hydrogen storage capacity of CNTs using reactive molecular dynamics simulations. We find that an increase in the volume fraction of endohedral nickel atoms leads to an increase in the concentration of physisorbed hydrogen molecules around single-walled CNTs (SWNTs) by approximately 1.6 times compared to pure SWNTs. The obtained results provide insight into the underlying mechanisms of how endohedral transition metal atoms enhance the hydrogen storage ability of SWNTs under nearly ambient conditions.

Metal-decorated Tri-graphene as a high-performance reversible hydrogen storage medium: A first-principles study

Due to a series of problems caused by the energy crisis, the development of safe and efficient new hydrogen storage materials has become the top priority of current research. In this work, based on the experimental preparation of T‑carbon (Zhang et al. Nat Commun 8, 683 (2017)) material, the [110] surface Tri-graphene (Tri-G) was intercepted. The first-principles method was used to study the hydrogen storage properties of Tri-G and metal-decorated Tri-G. The basic structure and stability of Tri-G are studied systematically, and the electronic properties of Tri-G and metal-decorated Tri-G are calculated respectively. Next, Tri-G is decorated with lithium (Li), sodium (Na), potassium (K), and calcium (Ca). Finally, H2 molecules are attached to each of these bases. The results showed that Tri-G and K@Tri-G could not stably adsorb hydrogen, while Li@Tri-G, Na@Tri-G and Ca@Tri-G could adsorb 24, 14 and 24 hydrogen molecules, and their hydrogen storage rates reached 13.99 wt%, 8.26 wt% and 12.77 wt%, respectively. Moreover, it can be seen that the desorption temperature of H2 is in the range of 255.55 K–281.11 K under the actual conditions of simulated temperature and pressure by Van't Hoff equation, which proves that Li/Na/Ca@Tri-G is an efficient and reversible hydrogen storage material. This study provides theoretical guidance for further expanding the application of carbon-based materials in the field of hydrogen storage.

Tailoring TiO2 finite nanotubes: Doping-induced modulation of electronic, optical, and hydrogen storage properties

In this study, we employ density functional theory calculations to investigate the properties of finite single walled TiO2 finite nanotubes (TiO2NTs). The constructed nanotubes demonstrate geometric stability, as evidenced by positive binding energy and real positive vibrational frequencies obtained from the infrared spectra. Substitutional doping with various atoms (B, N, C, Si, Li, Sc, Fe, and Cu) introduces intriguing effects on the electronic and optical properties of TiO2NTs. Doping with Fe slightly reduces the wide energy gap (∼5 eV) of unmodified TiO2NTs to 4.2 eV, while Si doping significantly decreases the energy gap by half. Furthermore, we investigate the impact of doping TiO2NTs with boron, carbon, nitrogen, iron, cesium, and silicon on their UV–Vis absorption spectra. The introduction of these dopants induces significant redshifts in the absorption peaks, indicating alterations in the electronic energy gap and transitions between specific states. These findings provide valuable insights into the structural and electronic modifications of TiO2NTs. Moreover, we explore the adsorption properties of TiO2NTs for H2 molecules. While unmodified TiO2NTs exhibit low adsorption energy, doping with a small number of C or Si atoms leads to a substantial enhancement in the adsorption energy. Specifically, Si doping achieves adsorption energy of approximately 0.2 eV, accompanied by a hydrogen storage capacity of 6.1 wt%, exceeding the standard capacity of 6.0 wt%. Importantly, the desorption temperature remains comparable to room temperature, ensuring long-term recyclability. These results highlight the potential of doped single-walled TiO2 nanotubes as efficient hydrogen storage devices.