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PublicationArticle Synthesis, characterization and hydrogen storage characteristics of ambient pressure dried carbon aerogel(Elsevier Ltd, 2016) Sweta Singh; Ashish Bhatnagar; Viney Dixit; Vivek Shukla; M.A. Shaz; A.S.K. Sinha; O.N. Srivastava; V. SekkarThe present communication deals with the hydrogen storage performance of ambient pressure dried pristine as well as platinum doped carbon aerogel (CA-0.10 Pt). These carbon aerogels (CAs) have been prepared from resorcinol-formaldehyde (R-F) through sol-gel synthesis route with sodium carbonate as a catalyst (C). The synthesis parameters adapted led to the formation of CA having preponderance of submicropores. Structural and microstructural characteristics of these carbon aerogels have been investigated through XRD, SEM, TEM, nitrogen adsorption and Raman spectroscopic techniques. Nitrogen adsorption and TEM studies confirm the large density of micropores with the majority of pores having sizes between 0.30 and 1.46 nm (submicropores). The hydrogen storage characteristics of as synthesized carbon aerogels have been investigated by monitoring the hydrogen ad/desorption curves. At room temperature and at pressure upto 22 atm the CA and CA-0.1 Pt have hydrogen storage capacity of 0.40 wt.% and 0.33 wt.% respectively. However, under the same pressure but at liquid nitrogen temperature CA and CA-0.10 Pt have hydrogen storage capacity of 5.65 wt.% and 5.15 wt.%. Feasible reasons for the high hydrogen storage capacities at liquid nitrogen temperature for the present CAs have been put forward. Copyright © 2016 Hydrogen Energy Publications, LLC.PublicationConference Paper Structural and hydrogenation studies of ZnO and Mg doped ZnO nanowires(2012) Jai Singh; M.S.L. Hudson; S.K. Pandey; R.S. Tiwari; O.N. SrivastavaIn this work, Mg doped zinc oxide (Mg xZn 1-xO, x = 5, 10 and 20 at. %) nanowires were successfully prepared by two step process. Initially, ZnO nanowires were grown by thermal evaporation of Zn powder under oxygen atmosphere. Mg powder was doped in as grown ZnO through solid state diffusion at low temperature. Energy dispersive x-ray spectroscopy (EDAX), transmission electron microscopy (TEM), X-ray diffraction (XRD) and UV-Visible absorption spectra analysis reveals that the Mg doping on ZnO nanowires induces lattice strain in ZnO. Rietveld analysis of XRD data confirms the wurtzite structure and a continuous compaction of the lattice (in particular, the c-axis parameter) as x increases. The hydrogenation properties of ZnO nanowires and Mg doped ZnO (Mg xZn 1-xO, x = 0, 5, 10 and 20 at. %) nanowires were studied. The hydrogenated samples were further investigated through XRD and Fourier transform infrared spectroscopy (FTIR). The hydrogen storage capacity of as grown ZnO nanowires has been estimated to be 0.57 wt. % H 2 at room temperature. However, the hydrogen storage capacity gets increased to ∼1 wt. % upon doping ZnO with 10 at. % Mg. Further increase in Mg concentration decreases the hydrogen storage capacity of ZnO nanowires. Thus for 20 at. % Mg doped ZnO; the hydrogen absorption capacity gets decreased from ∼1 wt. % to 0.74 wt. %. The mechanism of hydrogen storage in ZnO nanowires and Mg doped samples of ZnO has been discussed. © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.PublicationBook Chapter Catalytic Application of Carbon-based Nanostructured Materials on Hydrogen Sorption Behavior of Light Metal Hydrides(wiley, 2013) Rohit R. Shahi; O.N. SrivastavaThe development of hydrogen storage materials with favorable thermodynamics (e.g., kinetics, desorption/adsorption temperature) has attracted considerable attention in recent years. Alanates, amide-hydride mixtures and magnesium hydride are the candidates with the most potential storage material due to their high hydrogen storage capacity and good reversibility, but each has its own limitations (e.g., high desorption temperature and sluggish kinetics). Carbon has many allotropes such as graphite, activated carbon, fullerenes, carbon nanotubes, and the most recent, graphene, etc. These have novel properties which are useful in many new innovative applications. Several recent investigations have also demonstrated the benefi cial effect of carbon materials as catalyst for enhancing sorption behavior of different light hydrogen storage materials. Carbon with a small curvature radius exhibits prominent "catalytic" effect for light metal and complex hydrides. The reduction in curvature radius of carbon nanostructures enhances the electron affi nity and interaction of carbon with hydrogen because the hydrogen release/combination energy has been changed, and consequently, the de-/rehydrogenation kinetics of the material is improved. In this chapter, we will highlight the current advances (including our recent works) in the hydrogen sorption enhancement of metal and complex hydrides by incorporating carbon nanomaterials as a catalyst. There will be a particular emphasis on carbon nanotubes, carbon nanofi bers and graphene employed as a catalyst for the aforesaid hydrogen storage materials. © 2014 Scrivener Publishing LLC. All rights reserved.PublicationArticle Physically activated resorcinol-formaldehyde derived carbon aerogels for enhanced hydrogen storage(Elsevier Ltd, 2025) Pargai Neema; Satish Kumar Verma; Mohammad Abu ShazCarbon aerogels have great potential as hydrogen storage materials owing to their exceptional specific surface area, low weight, and high porosity. These characteristics improve the ability to increase hydrogen adsorption capacity, making them promising candidates for hydrogen storage materials. Nevertheless, the implementation encounters obstacles such as limited storage capacity under ambient temperature and pressure. The present study reports the improved hydrogen storage capacity of carbon aerogels synthesized by Pekala's sol-gel method and optimized by physical activation. This study aims to optimize specific surface area and micropore volumes by physical activation to enhance hydrogen adsorption via the physisorption mechanism. The as-synthesized carbon aerogel has a specific surface area of 579.53 m2/g with a pore volume of 0.34 cm3/g whereas this surface area and pore volume have been tuned using its physical activation. The physically activated carbon aerogel shows a significantly higher specific surface area of 799.68 m2/g with a pore volume of 0.47 cm3/g as compared to the pristine carbon aerogel. This optimization in the specific surface area has enhanced the hydrogen storage capacity of carbon aerogel. The activated carbon aerogel exhibits a promising hydrogen storage capacity of 5.28 wt% at liquid nitrogen temperature under a hydrogen pressure of 22 atm whereas 3.39 wt% of hydrogen storage capacity has been seen in the unactivated carbon aerogel under the same conditions. In addition, activated carbon aerogel showed good hydrogen adsorption and desorption kinetics up to 30 cycles at room temperature (27 °C) under 22 atm hydrogen pressure. The reason behind enhanced hydrogen adsorption capacity in activated carbon aerogel has been put forward using various characterization techniques like XRD, TEM, SEM, and BET and discussed in the mechanism section. © 2024 Hydrogen Energy Publications LLCPublicationArticle Improved de/re-hydrogenation properties of MgH2 catalyzed by graphene templated Ti–Ni–Fe nanoparticles(Elsevier Ltd, 2022) Pawan K. Soni; A. Bhatnagar; V. Shukla; M.A. ShazThe present investigation deals with the excellent catalytic effect of graphene templated Ti–Ni–Fe nanoparticles (Ti–Ni–Fe@Gr) on de/re-hydrogenation characteristics of MgH2. The catalytic effect of Ti–Ni–Fe@Gr on MgH2 has also been compared with Ti@Gr, Ni@Gr, and Fe@Gr. It has been found that Ti–Ni–Fe@Gr lowers the onset desorption temperature up to 252 °C with improved kinetics and cyclability for the hydrogen release and absorption from MgH2. The presence of a multivalence environment around Mg/MgH2 has been analyzed by XPS analysis which gives the evidence of possible electronic exchange between the catalyst and Mg/MgH2 during de-/rehydrogenation. Since Mg/MgH2 and Ti–Ni–Fe are both anchored on graphene template, agglomeration detrimental to cycling is not possible. Thus negligible degradation of 0.22 wt% has been observed even after 24 cycles of de/re-hydrogenation. © 2022PublicationArticle Effect of graphene templated fluorides of Ce and La on the de/rehydrogenation behavior of MgH2(Elsevier Ltd, 2017) Pawan K. Soni; Ashish Bhatnagar; M.A. Shaz; O.N. SrivastavaThe present investigation describes the hydrogen storage properties of MgH2 ball milled with different additives i.e. graphene templated rare earth metal (La and Ce) fluorides, CeF4 and LaF3. MgH2 ball milled with graphene templated CeF4 (MgH2:CeF4@Gr) has onset desorption temperature of 245 °C, which is 50 °C, 52 °C and 75 °C lower than MgH2 ball milled with LaF3 templated graphene, CeF4 and LaF3 respectively. CeF4@Gr also shows the superior effect amongst all additives during rehydrogenation where MgH2:CeF4@Gr absorbs 5.50 wt% within 2.50 min at 300 °C under 15 atm H2 pressure. Dual tuning effect, i.e. lowering of thermodynamic (62.77 kJ/mol H2: lower from 74 kJ/mol for pristine MgH2) and kinetics barrier (93.01 kJ/mol) has been observed for MgH2:CeF4@Gr. Additionally, MgH2 ball milled with CeF4@Gr shows good reversibility up to 24 cycles of de/rehydrogenation. The feasible working mechanism of CeF4@Gr as additive for MgH2 has been studied in detail with the help of Transmission Electron Microscope (TEM), Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Diffraction characterizations (XRD). © 2017 Hydrogen Energy Publications LLCPublicationArticle Notable catalytic activity of Al–Cu–Fe–Ni–Cr high entropy alloy nanoparticles for hydrogen sorption in MgH2(Elsevier Ltd, 2025) Yogesh Kumar Yadav; Mohammad Abu Shaz; Thakur Prasad YadavMagnesium hydride (MgH2) is a promising material for hydrogen storage because of its abundance and beneficial properties, such as high storage capacity and cost-effectiveness under mild conditions. Despite of these benefits, MgH2 unfavorable thermodynamics and kinetics make it difficult to use in real applications. In this work, the hydrogen storage properties of MgH2 have been improved using Al–Cu–Fe–Ni–Cr high entropy alloy (HEA) based catalysts, which has been synthesized via mechanical alloying. The experimental findings show that the beginning desorption temperature of MgH2 significantly lowered from 425 °C to 180 °C by adding 5 wt. % Al–Cu–Fe–Ni–Cr HEA in MgH2. Moreover, the catalyst shows enhanced kinetics, attaining 7.3 wt. % hydrogen absorption in 3 min at 320 °C with 15 atm hydrogen pressure, and ∼5 wt. % desorption in 6 min at 320 °C. These findings emphasize how significantly lower its desorption temperature is than those of other well-known catalysts. Over a span of 25 cycles, MgH2 catalyzed by Al–Cu–Fe–Ni–Cr HEA exhibits remarkable cyclic stability with negligible fluctuations (∼0.05 wt. %). After a thorough characterization of the materials, a workable catalytic mechanism for HEA was proposed considering the results. © 2025 Hydrogen Energy Publications LLCPublicationArticle Recent developments in state-of-the-art hydrogen energy technologies – Review of hydrogen storage materials(Elsevier Ltd, 2023) Rupali Nagar; Sumita Srivastava; Sterlin Leo Hudson; Sandra L. Amaya; Ashish Tanna; Meenu Sharma; Ramesh Achayalingam; Sanjiv Sonkaria; Varsha Khare; Sesha S. SrinivasanHydrogen energy has been assessed as a clean and renewable energy source for future energy demand. For harnessing hydrogen energy to its fullest potential, storage is a key parameter. It is well known that important hydrogen storage characteristics are operating pressure-temperature of hydrogen, hydrogen storage capacity, hydrogen absorption-desorption kinetics and heat transfer in the hydride bed. Each application needs specific properties. Every class of hydrogen storage materials has a different set of hydrogenation characteristics. Hence, it is required to understand the properties of all hydrogen storage materials. The present review is focused on the state-of–the–art hydrogen storage materials including metal hydrides, magnesium-based materials, complex hydride systems, carbonaceous materials, metal organic frameworks, perovskites and materials and processes based on artificial intelligence. In each category of materials’ discovery, hydrogen storage mechanism and reaction, crystal structure and recent progress have been discussed in detail. Together with the fundamental synthesis process, latest techniques of material tailoring like nanostructuring, nanoconfinement, catalyzing, alloying and functionalization have also been discussed. Hydrogen energy research has a promising potential to replace fossil fuels from energy uses, especially from automobile sector. In this context, efforts initiated worldwide for clean hydrogen production and its use via fuel cell in vehicles is much awaiting steps towards sustainable energy demand. © 2023 The Author(s)PublicationArticle Physically activated resorcinol-formaldehyde derived carbon aerogels for enhanced hydrogen storage(Elsevier Ltd, 2024) Pargai Neema; Satish Kumar Verma; Mohammad Abu ShazCarbon aerogels have great potential as hydrogen storage materials owing to their exceptional specific surface area, low weight, and high porosity. These characteristics improve the ability to increase hydrogen adsorption capacity, making them promising candidates for hydrogen storage materials. Nevertheless, the implementation encounters obstacles such as limited storage capacity under ambient temperature and pressure. The present study reports the improved hydrogen storage capacity of carbon aerogels synthesized by Pekala's sol-gel method and optimized by physical activation. This study aims to optimize specific surface area and micropore volumes by physical activation to enhance hydrogen adsorption via the physisorption mechanism. The as-synthesized carbon aerogel has a specific surface area of 579.53 m2/g with a pore volume of 0.34 cm3/g whereas this surface area and pore volume have been tuned using its physical activation. The physically activated carbon aerogel shows a significantly higher specific surface area of 799.68 m2/g with a pore volume of 0.47 cm3/g as compared to the pristine carbon aerogel. This optimization in the specific surface area has enhanced the hydrogen storage capacity of carbon aerogel. The activated carbon aerogel exhibits a promising hydrogen storage capacity of 5.28 wt% at liquid nitrogen temperature under a hydrogen pressure of 22 atm whereas 3.39 wt% of hydrogen storage capacity has been seen in the unactivated carbon aerogel under the same conditions. In addition, activated carbon aerogel showed good hydrogen adsorption and desorption kinetics up to 30 cycles at room temperature (27 °C) under 22 atm hydrogen pressure. The reason behind enhanced hydrogen adsorption capacity in activated carbon aerogel has been put forward using various characterization techniques like XRD, TEM, SEM, and BET and discussed in the mechanism section. © 2024 Hydrogen Energy Publications LLCPublicationArticle On the synthesis, characterization and hydrogen storage behavior of ZrFe2 catalyzed Li-Mg-N-H hydrogen storage material(Elsevier Ltd, 2015) Vivek Shukla; Ashish Bhatnagar; Sunita K. Pandey; Rohit R. Shahi; T.P. Yadav; M.A. Shaz; O.N. SrivastavaThe present study deals with the use of ZrFe2 for the formation of pure phase of hydrogen storage material Mg(NH2)2/LiH. Since ZrFe2 is harder than the starting material LiNH2 and MgH2, pulverization effect produced by ZrFe2 assists in the synthesis of pure phase. The formation of pure Mg(NH2)2/LiH has been examined by XRD and confirmed by FTIR. The catalytic effect of ZrFe2 has been found to improve significantly the de/rehydrogenation characteristic of Mg(NH2)2/LiH. The ZrFe2 catalyzed Mg(NH2)2/LiH shows good recyclability. The activation energy of ZrFe2 catalyzed Mg(NH2)2/LiH was found to be 74.80 kJ/mol which is better than several other reported studies using different catalysts. Based on experimental results, a viable mechanism for dehydrogenation of Mg(NH2)2 in the presence of ZrFe2 has also been proposed. © 2015 Hydrogen Energy Publications, LLC.