Browsing by Author "M. Sterlin Leo Hudson"

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Ab initio insight into graphene nanofibers to destabilize hydrazine borane for hydrogen release
(Elsevier B.V., 2017) Zhao Qian; Himanshu Raghubanshi; M. Sterlin Leo Hudson; O.N. Srivastava; Xiangfa Liu; Rajeev Ahuja
We report the potential destabilizing effects of graphene nanofibers on the hydrogen release property of hydrazine borane via state-of-the-art ab initio calculations for the first time. Interactions of a hydrazine borane cluster with two types of graphene patch edges which exist abundantly in our synthesized graphene nanofibers have been investigated. It is found that both zigzag and armchair edges can greatly weaken the H-host bonds (especially the middle N[sbnd]H bond) of hydrazine borane. The dramatic decrease in hydrogen removal energy is caused by the strong interaction between hydrazine borane and the graphene patch edges concerning the electronic charge density redistribution. © 2016 Elsevier B.V.
Carbon nanostructures as catalyst for improving the hydrogen storage behavior of sodium aluminum hydride
(2012) M. Sterlin Leo Hudson; Himanshu Raghubanshi; D. Pukazhselvan; O.N. Srivastava
The present paper reports the catalytic effect of carbon nanomaterials, particularly carbon nanotubes (CNTs) and graphitic nanofibres (GNFs) with two different structure morphology, namely planar GNFs (PGNFs) and helical GNFs (HGNFs) as the catalyst for improving the dehydrogenation and rehydrogenation behavior of sodium aluminum hydride (NaAlH 4). It has been observed that HGNFs posses superior catalytic activity than other carbon nanoforms in improving the desorption kinetics and decreasing the desorption temperature of NaAlH 4. Temperature programmed desorption (TPD) reveals that HGNFs admixed NaAlH 4 undergo hydrogen desorption at a much lower temperature than PGNFs and CNTs (SWCNTs and MWCNTs) admixed NaAlH 4. Thus for the heating rate of 2 °C/min, the peak desorption temperature corresponds to initial step decomposition of NaAlH 4 admixed with 2 wt.% HGNFs and 2 wt.% PGNFs has been lowered to 143.6 °C and 152.6 °C, respectively (for pristine NaAlH 4, it is ∼170 °C). In addition to the enhancement in desorption kinetics, the HGNFs admixed NaAlH 4 undergoes fast rehydrogenation at the moderate condition. Microstructural investigation reveals that the HGNFs were present on the surface of NaAlH 4 grains, whereas CNTs were tunneled into the grains of NaAlH 4 suggesting a distinct catalytic behavior of different carbon nanovariants. © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
Carbon nanostructures as catalyst for improving the hydrogen storage behaviour of complex aluminium hydride
(2010) M. Sterlin Leo Hudson; Himanshu Raghubanshi; D. Pukazhselvan; O.N. Srivastava
The present paper reports the catalytic effect of carbon nanostructures, particularly graphitic nanofibres (GNFs) with different structure morphology, namely helical GNFs (HGNFs) and planar GNFs (PGNFs) as the catalyst for complex aluminium hydride. HGNFs and PGNFs were synthesized by catalytic thermal decomposition of acetylene (C2H2). The growth of HGNFs was achieved by employing faceted Ni nanoparticles, whereas spherical Ni nanoparticles produce PGNFs. It has been observed that HGNFs posses superior catalytic activity than PGNFs in improving the desorption kinetics and decreasing the desorption temperature of complex aluminium hydride (NaAlH 4, LiAlH4 and LiMg(AlH4)3). Temperature programmed desorption (TPD) reveals that HGNFs admixed alanates undergo hydrogen desorption at a much lower temperature than PGNFs admixed material. Thus for the heating rate of 2°C/min, the peak desorption temperature corresponds to initial step desorption of NaAlH4 admixed with 8 mol% HGNFs and 8 mol% PGNFs has been lowered to 143.6°C and 152.6°C, respectively. In addition to the enhancement in desorption kinetics, the GNFs admixed NaAlH4 also undergoes rehydrogenation at the moderate condition. In order to get supportive evidence for our experiment, we have carried out abinitio studies by calculating hydrogen removal energy from alanates with planar and helical model of GNF. It becomes clear that from both experiment and ab-initio calculations, that catalytic effect of GNFs is curvature dependent. Thus HGNF with higher helicity helps to lower the energy needed to remove hydrogen from alanates.
Comparative evaluation of liquid-liquid extraction and nanosorbent extraction for HPLC-PDA analysis of cabazitaxel from rat plasma
(Elsevier B.V., 2024) Medapati Nikitha Lakshmi Suseela; Abhishesh Kumar Mehata; Bhaskar Vallamkonda; Pathraj Gokul; Aditi Pradhan; Jyotsana Pandey; Joseph Selvin; M. Sterlin Leo Hudson; Madaswamy S. Muthu
A precise, sensitive, accurate, and validated reverse-phase high-performance liquid chromatography (RP-HPLC) method with a bioanalytical approach was utilized to analyze Cabazitaxel (CBZ) in rat plasma. Comparative research on extraction recoveries was performed between traditional liquid-liquid extraction (LLE) and synthesized graphene oxide (GO) based magnetic solid phase extraction (GO@MSPE). The superparamagnetic hybrid nanosorbent was synthesized using the combination of iron oxide and GO and subsequently applied for extraction and bioanalytical quantification of CBZ from plasma by (HPLC-PDA) analysis. Fourier- transform infrared spectroscopy (FT-IR), particle size, scanning electron microscopy (SEM), and x-ray diffraction (XRD) analysis were employed in the characterization of synthesized GO@MSPE nanosorbent. The investigation was accomplished using a shim pack C18 column (150 mm×4.6 mm, 5 µm) with a binary gradient mobile phase consisting of formic acid: acetonitrile: water (0.1:75:25, v/v/v) at a 0.8 mL/min flow rate, and a λmax of 229 nm. The limits of detection (LOD) and quantitation (LOQ) have been determined to be 50 and 100 ng/mL for both LLE and SPE techniques. The linearity range of the approach encompassed from 100 to 5000 ng/mL and was found to be linear (coefficient of determination > 0.99) for CBZ. The proposed method showed extraction recovery of 76.8–88.4% for the synthesized GO@MSPE and 69.3–77.4% for LLE, suggesting that the proposed bioanalytical approach was robust and qualified for all validation parameters within the acceptable criteria. Furthermore, the developed hybrid GO@MSPE nanosorbent with the help of the proposed RP-HPLC method, showed a significant potential for the extraction of CBZ in bioanalysis. © 2024 Elsevier B.V.
Economical synthesis of highly efficient and tunable carbon aerogels for enhanced storage of CO2 emitted from energy sources
(John Wiley and Sons Ltd, 2021) Ashish Bhatnagar; Anant Prakash Pandey; M. Sterlin Leo Hudson; Pawan K. Soni; Satish K. Verma; Vivek Shukla; V. Sekkar; Manoj Tripathi; O.N. Srivastava
The present investigation reports the synthesis of Carbon Aerogel (CA) with varying pore size and surface area by changing the initial precursor that is, Resorcinol (R) and novel Catalyst (triethyl amine [TEA]) (C) ratio (R/C). The catalyst, TEA allows the gel to dry with negligible shrinkage. The R/C ratio has been kept 1000, 2000 and 3000. The CA with R/C = 1000 has the lowest pore size 1.93 nm, the highest surface area (369.14 m2/g) and the highest CO2 uptake of 24.40 wt.% (5.54 mmol/) at 40 atm CO2 pressure. The activated version of optimum CA (R/C = 1000) has been found to have an average pore diameter ~ 1.91 nm and CO2 uptake capacity of 29.56 wt% (6.71 mmol/g) at 25°C which is one of the highest CO2 storage capacity of CAs reported so far. Thus, the present manuscript put forward highly efficient and tunable CAs for enhanced CO2 storage. © 2020 John Wiley & Sons Ltd
Effect of TiO2 nanoparticles on the hydrogen sorption characteristics of magnesium hydride
(2013) Sunita K. Pandey; Ashish Bhatnagar; Rohit R. Shahi; M. Sterlin Leo Hudson; Milind K. Singh; O.N. Srivastava
The present paper explores the enhancement in hydrogen sorption behavior of MgH2 with TiO2 nanoparticles. The catalytic effect of TiO2 nanoparticles with different sizes (7, 25, 50, 100 and 250 nm) were used for improving the sorption characteristics of MgH2. The MgH2 catalyzed with 50 nm of TiO2 exhibited the optimum catalytic effect for hydrogen sorption behavior. The desorption temperature of MgH2 catalyzed through 50 nm TiO2 was found to be 310 )C. This is 80 )C lower as compared to MgH2 having a desorption temperature of 390 )C. It was noticed that the dehydrogenated MgH2 catalyzed with 50 nm TiO2 reabsorbed 5.1 wt% of H2 within 6 minutes at temperature and pressure of 250 )C and 50 atm, respectively. The 50 nm TiO2 catalyst lowered the absorption activation energy of MgH2 from ̃92 to ̃52.7 kJ mol-1. Copyright © 2013 American Scientific Publishers All rights reserved.
Effects of helical GNF on improving the dehydrogenation behavior of LiMg(AlH4)3 and LiAlH4
(2010) M. Sterlin Leo Hudson; Himanshu Raghubanshi; D. Pukazhselvan; O.N. Srivastava
The present paper reports the effect of graphitic nanofibres (GNFs) for improving the desorption kinetics of LiMg(AlH4)3 and LiAlH4. LiMg(AlH4)3 has been synthesized by mechano-chemical metathesis reaction involving LiAlH4 and MgCl2. The enhancement in dehydrogenation characteristics of LiMg(AlH4)3 has been shown to be higher when graphitic nanofibres (GNFs) were used as catalyst. Out of two different types of nanofibres namely planar graphitic nanofibre (PGNF) and helical graphitic nanofibre (HGNF), the latter has been found to act as better catalyst. We observed that helical morphology of fibres improves the desorption kinetics and decreases the desorption temperature of both LiMg(AlH4)3 and LiAlH4. The desorption temperature for 8 mol% HGNF admixed LiAlH4 gets lowered from 159 °C to 128 °C with significantly faster kinetics. In 8 mol% HGNF admixed LiMg(AlH4)3 sample, the desorption temperature gets lowered from 105 °C to ∼70 °C. The activation energy calculated for the first step decomposition of LiAlH4 admixed with 8 mol% HGNF is ∼68 kJ/mol, where as that for pristine LiAlH4 it is 107 kJ/mol. The activation energy calculated for as synthesized LiMg(AlH4)3 is ∼66 kJ/mol. Since the first step decomposition of LiMg(AlH4)3 occurs during GNF admixing, the activation energy for initial step decomposition of GNF admixed LiMg(AlH4)3 could not be estimated. © 2009 Professor T. Nejat Veziroglu.
Effects of nano size mischmetal and its oxide on improving the hydrogen sorption behaviour of MgH2
(2013) T. Sadhasivam; M. Sterlin Leo Hudson; Sunita K. Pandey; Ashish Bhatnagar; Milind K. Singh; K. Gurunathan; O.N. Srivastava
This paper reports the catalytic effects of mischmetal (Mm) and mischmetal oxide (Mm-oxide) on improving the dehydrogenation and rehydrogenation behaviour of magnesium hydride (MgH2). It has been found that 5 wt.% is the optimum catalyst (Mm/Mm-oxide) concentration for MgH2. The Mm and Mm-oxide catalyzed MgH2 exhibits hydrogen desorption at significantly lower temperature and also fast rehydrogenation kinetics compared to ball-milled MgH2 under identical conditions of temperature and pressure. The onset desorption temperature for MgH2 catalyzed with Mm and Mm-oxide are 323 C and 305 C, respectively. Whereas the onset desorption temperature for the ball-milled MgH2 is 381 C. Thus, there is a lowering of onset desorption temperature by 58 C for Mm and by 76 C for Mm-oxide. The dehydrogenation activation energy of Mm-oxide catalyzed MgH 2 is 66 kJ/mol. It is 35 kJ/mol lower than ball-milled MgH 2. Additionally, the Mm-oxide catalyzed dehydrogenated Mg exhibits faster rehydrogenation kinetics. It has been noticed that in the first 10 min, the Mm-oxide catalyzed Mg (dehydrogenated MgH2) has absorbed up to 4.75 wt.% H2 at 315 C under 15 atmosphere hydrogen pressure. The activation energy determined for the rehydrogenation of Mm-oxide catalyzed Mg is ∼62 kJ/mol, whereas that for the ball-milled Mg alone is ∼91 kJ/mol. Thus, there is a decrease in absorption activation energy by ∼29 kJ/mol for the Mm-oxide catalyzed Mg. In addition, Mm-oxide is the native mixture of CeO2 and La2O3 which makes the duo a better catalyst than CeO2, which is known to be an effective catalyst for MgH2. This takes place due to the synergistic effect of CeO 2 and La2O3. It can thus be said that Mm-oxide is an effective catalyst for improving the hydrogen sorption behaviour of MgH2. © 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights.
Electrochemical capacitance and hydrogen adsorption behavior of activated carbon derived from cattail fiber
(John Wiley and Sons Inc, 2024) Ramesh Achayalingam; Sourabh Basu; Prins Kumar Rao; Jyotsana Pandey; Nivetha Selvaraj; Jayachitra Selvam; M. Sterlin Leo Hudson
In this paper, we have reported the synthesis of activated carbon (AC) from biomass cattail fiber through hydrothermal carbonization, followed by chemical activation, and its electrochemical capacitance and hydrogen storage properties. The AC exhibits a Brunauer-Emmett-Teller (BET) surface area (SBET) of 1597.5 m2g−1, determined from the low-pressure N2 adsorption isotherm at 77 K using a BET-multipoint plot. The AC sample shows a reversible hydrogen adsorption capacity of 0.25 wt.% H2 (1.25 mmol H2 g−1) at 293 K and 74 atm. The capacitance performance of AC was investigated with various conductive additives such as carbon nanotubes (CNTs), carbon black (CB), and reduced graphene-oxide (rGO). From galvanostatic charge discharge (GCD) and cyclic voltammetry (CV) measurements, the as-derived AC with polymer binder exhibits a specific capacitance (Cs) of 245.2 F g−1 at 0.2 A g−1 and 158.1 F g−1 at 5 mV s−1. Among the investigated conductive additives, AC with CNTs in KOH electrolyte exhibit highest Cs of 326 F g−1 at 0.2 A g−1 and 173 F g−1 at 5 mV s−1. Furthermore, the symmetrical two-electrode device fabricated using AC with CNTs (as a conductive additive) in 1 M aq. Na2SO4 electrolyte shows a Cs of 97.2 F g−1 at 0.1 A g−1. The energy and power densities of the two-electrode device were observed to be 28 kW kg−1 and 2.64 Wh kg−1, respectively. © 2024 John Wiley & Sons Ltd.
Enhancement in hydrogen sorption behaviour of MgH2 catalyzed by graphene quantum dots
(Elsevier Ltd, 2024) Rashmi Kesarwani; Ashish Bhatnagar; Satish K. Verma; M. Sterlin Leo Hudson; M.A. Shaz
The present investigation reports the synthesis of graphene quantum dots (GQDs) by the microwave-assisted green synthesis method, and its catalytic effect in improving the hydrogen storage behaviour of magnesium hydride (MgH2). Transmission electron microscopy, UV–Vis, Raman, FTIR and XRD analysis was done to characterize the samples. It has been observed that the as-synthesized GQDs are in the size range of 3–12 nm. The catalytic activity of GQDs on improving the de/re-hydrogenation kinetics of MgH2 has been investigated with different additive concentrations. It has been observed that there is an improvement in the hydrogen sorption characteristics of ball-milled MgH2 when 7 wt.% GQDs was employed. The onset dehydrogenation temperature of 7 wt.% GQDs admixed ball milled MgH2 (7 % GQDs-MgH2) was observed at 300 ᵒC, which is 60 ᵒC lower than that of additive free ball-milled MgH2 under identical condition. Furthermore, the 7 % GQDs-MgH2 sample reabsorbs nearly 5 wt.% hydrogen in 2.5 min at 300 ᵒC and 15 atm hydrogen pressure. The GQDs catalyzed MgH2 sample exhibit good de/re-hydrogenation cyclic stability. No significant loss in hydrogen capacity was noticed even after 25 de-/re-hydrogenation cycles. From the Van't Hoff plot, the formation enthalpy of 7 % GQDs-MgH2 was estimated to be 58 kJmol-1. © 2024 Hydrogen Energy Publications LLC
Excellent catalytic effects of graphene nanofibers on hydrogen release of sodium alanate
(2012) Zhao Qian; M. Sterlin Leo Hudson; Himanshu Raghubanshi; Ralph H. Scheicher; Biswarup Pathak; C. Moysés Araújo; Andreas Blomqvist; Börje Johansson; O.N. Srivastava; Rajeev Ahuja
One of the most technically challenging barriers to the widespread commercialization of hydrogen-fueled devices and vehicles remains hydrogen storage. More environmentally friendly and effective nonmetal catalysts are required to improve hydrogen sorption. In this paper, through a combination of experiment and theory, we evaluate and explore the catalytic effects of layered graphene nanofibers toward hydrogen release of light metal hydrides such as sodium alanate. Graphene nanofibers, especially the helical kind, are found to considerably improve hydrogen release from NaAlH 4, which is of significance for the further enhancement of this practical material for environmentally friendly and effective hydrogen storage applications. Using density functional theory, we find that carbon sheet edges, regardless of whether they are of zigzag or armchair type, can weaken Al-H bonds in sodium alanate, which is believed to be due to a combination of NaAlH 4 destabilization and dissociation product stabilization. The helical form of graphene nanofibers, with larger surface area and curved configuration, appears to benefit the functionalization of carbon sheet edges. We believe that our combined experimental and theoretical study will stimulate more explorations of other microporous or mesoporous nanomaterials with an abundance of exposed carbon edges in the application of practical complex light metal hydride systems. © 2012 American Chemical Society.
Graphene decorated with Fe nanoclusters for improving the hydrogen sorption kinetics of MgH 2 - Experimental and theoretical evidence
(Royal Society of Chemistry, 2016) M. Sterlin Leo Hudson; Keisuke Takahashi; A. Ramesh; Seema Awasthi; Ashish Kumar Ghosh; Ponniah Ravindran; Onkar Nath Srivastava
Graphene decorated with Fe clusters is proposed to be a possible alternative catalyst for the hydrogenation and dehydrogenation reactions of MgH 2 . In particular, graphene decorated with Fe clusters is effective for both hydrogenation and dehydrogenation processes of MgH 2 . The change in enthalpy and entropy values of hydrogen absorption determined for MgH 2 with 5 wt% graphene decorated with Fe clusters is -50.4 ± 2.9 kJ per mole of H 2 and 99.8 ± 5.2 J K -1 per mole of H 2 , respectively. This is significantly lower than those for well-established metal catalysts and nano-interfacial confined MgH 2 . Moreover, the graphene decorated with Fe clusters facilitates the fast rehydrogenation kinetics of MgH 2 , which reabsorbed 90% of the total reabsorption capacity in less than 4 minutes at 300 °C and 20 atm. In addition, TEM analysis reveals that MgH 2 particles are covered by graphene with Fe clusters, resulting in the reduction of grain growth. Density functional theory shows that the defects in graphene act as the active sites for the dehydrogenation of MgH 2 , while the Fe clusters reduce the adsorption of dissociated H atoms, resulting in low-temperature dehydrogenation. Thus, graphene decorated with metal clusters could open up a new way of designing a new type of catalyst which could replace transition metal catalysts. © The Royal Society of Chemistry 2016.
Graphitic Nanofibres as Catalyst for Improving the Dehydrogenation Behavior of Complex Aluminium Hydrides
(Forschungszentrum Julich GmbH, 2010) M. Sterlin Leo Hudson; Himanshu Raghubanshi; D. Pukazhselvan; O.N. Srivastava
In the present work, we explored the catalytic effect of graphitic nanofibres (GNF) particularly of two different morphology, namely planar graphitic nanofibre (PGNF) and helical graphitic nanofibre (HGNF) for enhancement of hydrogen desorption from complex aluminium hydrides such as LiAlH4 and LiMg(AlH4)3. We found that the catalytic activity of fibres depends mainly on its morphology. Hence helical morphology fibres possess superior catalytic activity than planar graphitic nanofibres. The desorption temperature for 8 mol% HGNF admixed LiAlH4 gets lowered from 159°C to 128°C with significantly faster kinetics. In 8 mol% HGNF admixed LiMg(AlH4)3 sample, the desorption temperature gets lowered from 105°C to ~70°C. The activation energy calculated for the first step decomposition of LiAlH4 admixed with 8 mol% HGNF is ~68 kJmol-1, whereas that for pristine LiAlH4 it is 107 kJ/mol. The activation energy calculated for as synthesized LiMg(AlH4)3 is ~66 kJ/mol. Since the first step decomposition of LiMg(AlH4)3 occurs during GNF admixing, the activation energy for initial step decomposition of GNF admixed LiMg(AlH4)3 could not be estimated. © 2010 18th World Hydrogen Energy Conference 2010, WHEC 2010, Proceedings. All Rights Reserved.
Highly sensitive organic electrochemical transistor for detection of stress-induced cation leakage from plant cells
(Elsevier Ltd, 2022) Jeyavelan M; Farheen Khurshid; M. Akhil; R. Rathes Kannan; A. Ramesh; S. Nagarajan; Mario Hofmann; M. Sterlin Leo Hudson
Stress-induced ionic leakage plays a key role in understanding plant physiology. The ability of the plant cell membrane to withstand environmental stress factors can be gauged through monitoring of cation (especially K+) leakage. In this study, we have developed a PEDOT:PSS polymer-based organic electrochemical transistor (OECT) for detecting the discharged cations from Tephrosia purpurea leaf samples under hyperthermal stress. The test leaf samples were exposed to different heat stress environments and the discharged ions from the stress-treated leaf samples were collected in DI water through incubation. The cation detection was then performed via depletion mode operation of OECTs. Our analysis revealed that the OECTs are highly sensitive toward cation detection under low operating voltage (<1 V). In addition, OECTs are sensitive even at cation concentrations below 5 ppm. The present approach of cation detection through OECT provides a new way of understanding plant physiology. © 2022 The Author(s)
Hydrogen energy in changing environmental scenario: Indian context
(2009) M. Sterlin Leo Hudson; P.K. Dubey; D. Pukazhselvan; Sunil Kumar Pandey; Rajesh Kumar Singh; Himanshu Raghubanshi; Rohit. R. Shahi; O.N. Srivastava
This paper deals with how the Hydrogen Energy may play a crucial role in taking care of the environmental scenario/climate change. The R&D efforts, at the Hydrogen Energy Center, Banaras Hindu University have been described and discussed to elucidate that hydrogen is the best option for taking care of the environmental/climate changes. All three important ingredients for hydrogen economy, i.e., production, storage and application of hydrogen have been dealt with. As regards hydrogen production, solar routes consisting of photoelectrochemical electrolysis of water have been described and discussed. Nanostructured TiO2 films used as photoanodes have been synthesized through hydrolysis of Ti[OCH(CH3)2]4. Modular designs of TiO2 photoelectrode-based PEC cells have been fabricated to get high hydrogen production rate (∼10.35 lh-1 m-2). However, hydrogen storage is a key issue in the success and realization of hydrogen technology and economy. Metal hydrides are the promising candidates due to their safety advantage with high volume efficient storage capacity for on-board applications. As regards storage, we have discussed the storage of hydrogen in intermetallics as well as lightweight complex hydride systems. For intermetallic systems, we have dealt with material tailoring of LaNi5 through Fe substitution. The La(Nil - xFex)5 (x = 0.16) has been found to yield a high storage capacity of ∼2.40 wt%. We have also discussed how CNT admixing helps to improve the hydrogen desorption rate of NaAlH4. CNT (8 mol%) admixed NaAlH4 is found to be optimum for faster desorption (∼3.3 wt% H2 within 2 h). From an applications point of view, we have focused on the use of hydrogen (stored in intermetallic La-Ni-Fe system) as fuel for Internal Combustion (IC) engine-based vehicular transport, particularly two and three-wheelers. It is shown that hydrogen used as a fuel is the most effective alternative fuel for circumventing climate change. © 2009 International Association for Hydrogen Energy.
Hydrogen energy in Indian context and R&D efforts at Banaras Hindu University
(2007) P.R. Mishra; D. Pukazhselvan; M. Sterlin Leo Hudson; Sunil Kumar Pandey; O.N. Srivastava
This paper describes Hydrogen energy in India and R&D efforts at Banaras Hindu University. All the three important ingredients i.e. production, storage and application of hydrogen have been dealt with. As regards hydrogen production, we have described and discussed the solar route consisting of photoelectrochemical electrolysis of water. Nanostructured TiO2 films have been synthesized through hydrolysis of Ti[OCH(CH3)2]4. This has been used as photoanode. Modular designs of TiO2 photoelectrode based PEC cells have been fabricated to get high rate of hydrogen production (∼10.35 Lh-1m-2). Regarding storage which appears to be most crucial issue at present, we have discussed the intermetallic as well as complex hydride systems. For intermetallic we have dealt with materials tailoring of LaNi5 through Fe substituion. The La(Ni1-xFex)5 (x=0.16) has been found to yield to high storage capacity of ∼2.40wt%. We have also described and discussed the hydrogen storage in carbon nanofibres. Here storage capacity in excess of ∼10wt% has been obtained. We have shown that CNT admixing in NaAlH4 helps to circumvent the low desorption rate of hydrogen in NaAlH4. For 8 mol % CNT admixing, we have found the desorption rate to increase from ∼3.3 in more than 50 hrs to within 2 hrs. Relating to applications, we have focused on use of hydrogen (stored in intermetallic La-Ni-Fe system) as fuel for IC engine based vehicular transport particularly 2 and 3-wheelers (and small car). The 2 and 3-wheeler have nearly the same performance as the petrol fueled vehicles. At present we have vehicle range of ∼60-80 kms for 2-wheelers and ∼60 kms for 3-wheelers (at top speed of ∼50 kms/hr). Commercialization efforts on hydrogen fueled vehicular transport is being done by BHU:HEC with the help of Indian auto industries. © 2007 Taylor & Francis.
Hydrogen storage by reduced graphene oxide and graphene-like nanosheets decorated with Fe nanoclusters
(Nano Science and Technology Institute, 2014) M. Sterlin Leo Hudson; O.N. Srivastava; Satoru Simizu; S.G. Sankar
Here, we present the high pressure hydrogen sorption isotherm up to 50 bar of graphene oxide (GO) reduced by thermal reduction (TR-GO), chemical reduction (CR-GO) and graphene like nanosheets decorated with Fe nanoclusters (Fe-GS). GO was first derived by thermal exfoliation of graphite oxide, prepared by modified Standermiur method; further reduction at 623K under high vacuum yields TR-GO. CR-GO has been produced by reduction of GO using hydrazine. Fe-GS has been synthesized through arc discharge between the ends of two graphite rods with one rod carrying Fe nanoparticles. The surface area calculated from nitrogen adsorption isotherm at 77 K using BET method for GO, TR-GO, CR-GO and Fe-GS are 304, 357, 90 and 185 m2g-1, respectively. The skeletal density of TR-GO, CR-GO and Fe-GS determined through He gas probing are 1.8, 2.0 and 1.05 gcm-3, respectively. High pressure hydrogen PCT isotherm of TR-GO, CR-GO and Fe-GS has been determined at 300 K and 77 K. The volume of hydrogen adsorbed by TR-GO, CR-GO and Fe-GS at 77 K and 50 bar is 230 ccstp/gram (2.07 wt.% H2), 60 ccstp/gram (0.54 wt.% H2) and 240 ccstp/gram (2.16 wt.% H2), respectively.
Hydrogen storage characteristics of CNT doped NaAlH4
(2006) D. Pukazhselvan; M. Sterlin Leo Hudson; Bipin Kumar Gupta; O.N. Srivastava
The current Hydrogen based energy infrastructure required a high energy density consumer friendly hydrogen storage media. Although the desired goals for the hydrogen fueled vehicular transport has not yet met by any hydrogen storage material, complex Sodium Alanate is said to be a promising candidate under this demand due to its high hydrogen storage capacity and the thermodynamically permissible reversible hydrogen storage capacity. However its poor sorption behavior under moderate conditions (NaAlH4→ Na 3AlH6; 3.7 wt % vs 50 hrs at ∼170°C and Na 3AlH6→ NaH; 1.85 wt % vs 30 hrs at ∼220°C) urges their limited uses in ages. But these limitations can be removed by using catalysts particularly transition elements but the location of catalyst in NaAlH4 matrix and the possible mechanism is not yet clearly understood. The aim of the present investigation is to improve the overall sorption characteristics of NaAlH4 by a new light weighted high surface area (1315 sq mtr/gm) material (CNT) admixing and to obtain a best doping level to NaAlH4. So far only Ti has been attempted as a suitable catalyst. It is believed that the high surface area of CNT can provide an additional solid-gas (H2) surface/interface and it can produce thermal contact between grains (thermal conductivity Kth of MWCNT: 3000 w/k and Kth of NaAlH4: 0.32 w/k) for stimulating their thermally activated dissociation in NaAlH4. In parallel with this approach XRD of NaAlH4 reveals that there was no change in lattice structure after doping by CNT, SEM picture depicts that CNT precipitation in grain surfaces. Catalytic concentration of various mole % of x values finds that x = 8 is the best doping level as it gives 3.3 wt % of hydrogen within 2 hrs. The comparative sorption behavior with Ti:NaAlH 4 also shows CNTs as an optimum alternative catalyst to NaAlH 4 and besides this CNT doped desorbed ingredients shown good rehydrogenation behavior(3.7 wt % at 8th cycle & 4.2 wt % maximum at elevated temperatures). We are trying for catalyzing NaAlH4 with some new transition m metal catalysts which leads better desorption rate and recyclability.
Hydrogen uptake of reduced graphene oxide and graphene sheets decorated with Fe nanoclusters
(Elsevier Ltd, 2014) M. Sterlin Leo Hudson; Himanshu Raghubanshi; Seema Awasthi; T. Sadhasivam; Ashish Bhatnager; Satoru Simizu; S.G. Sankar; O.N. Srivastava
Graphene oxide (GO) has been prepared by employing modified Staudenmaier's method through thermal exfoliation of graphite oxide. High pressure hydrogen sorption isotherms up to 50 bar of GO, reduced by thermal reduction (TR-GO), chemical reduction (CR-GO) and graphene sheets decorated with Fe nanoclusters (Fe-GS) have been investigated. Thermal reduction of GO at 623 K under high vacuum yields TR-GO. Chemical reduction of GO using hydrazine forms CR-GO. Fe-GS was synthesized through arc-discharge between the ends of two graphite rods with one rod carrying Fe nanoparticles. The surface areas of these graphene samples were determined from the nitrogen adsorption isotherm employing Brunauer, Emmett and Teller (BET) method. Kelvin's equation was used to determine the pore size distribution of all graphene based samples. Hydrogen pressure-composition isotherms (PCI) were determined at 300 K and at 77 K, between 0.1 and 50 bar. Further, in this paper, we present a comparative adsorption isotherm analysis of hydrogen and helium on TR-GO. This reveals that the volume of hydrogen and helium adsorbed by TR-GO is nearly equal. The similar uptake volume determined for both hydrogen and helium indicates the possibility of monolayer adsorption of hydrogen and also nearly similar binding energy between TR-GO and H2/He. © 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
Improved electrocatalytic performance of delaminated-MXene and cobalt ferrite nanocomposite for hydrogen evolution in acidic medium
(Elsevier Ltd, 2025) Jyotsana Pandey; Sourabh Basu; Shalinee Dubey; Vellaichamy Ganesan; Mohammad Abu Shaz; M. Sterlin Leo Hudson
Recently, the electrochemical hydrogen evolution reaction (HER) for hydrogen generation has garnered research attention due to growing environmental concerns over fossil fuels usage. This paper discusses HER activity of cobalt ferrite and delaminated-MXene (D-MX) nanocomposites at different mass ratios. The electrochemical performance of the nanocomposites was evaluated based on their structural, microstructural, and spectroscopic features. D-MX was successfully synthesized from the MAX phase by the chemical etching route, followed by a chemical delamination process. CoFe2O4 nanoparticles (CF) were synthesized using the sol-gel auto-combustion method. It has been observed that the D-MX and CF nanocomposite with the mass ratio of 5:1 (CMX51) exhibits superior electrocatalytic behavior for HER. When compared to other mass ratios, the composite CMX51 has the lowest overpotential of 681 mV in a 0.5 M acidic solution. The CMX51 composite demonstrated a Tafel slope of 112 mV/dec for the hydrogen evolution reaction (HER), which is lower compared to that of CF. This indicates that the presence of D-MX in the nanocomposite improved the sluggish kinetic behavior of the CF nanoparticles. This may be attributed to the enhancement in ionic conductivity of CF with improved charge transfer kinetics resulting from the addition of D-MX. The Electrochemical impedance spectroscopy analysis reveals that the nanocomposite CMX51 shows improved ionic conductivity with a low charge transfer resistance. © 2025