In this study, the hydrogen storage properties of MgH-X wt% KNiF（X = 5, 10, 15, 20, and 50） were investigated for the first time. From the analysis of the onset desorption temperature and isothermal de/absorption ki...In this study, the hydrogen storage properties of MgH-X wt% KNiF（X = 5, 10, 15, 20, and 50） were investigated for the first time. From the analysis of the onset desorption temperature and isothermal de/absorption kinetics, it was shown that MgH+ 5 wt% KNiFsample has the best performance. The 5wt% doped sample started to release hydrogen at about 260 °C, which was a reduction of about 95 °C and 157 oC compared with the as-milled and as-received MgH. In addition, the de/absorption kinetics of the MgH+ 5 wt% KNiFwere also improved significantly compared to the un-doped MgH. The apparent activation energy for hydrogen desorption exhibited the decrement from 167.0 k J/mol for as-milled MgHto 111.0 k J/mol with the addition of 5 wt% KNiF. Moreover, the X-ray diffraction spectra displayed the formation of new phases of KF, KH, MgNi and MgNiHby doping the KNiFwith MgHafter the dehydrogenation and rehydrogenation processes. The scanning electron microscope results revealed that MgHdoped with 5 wt% KNiFdemonstrated the smallest particle size compared to the as-received and as-milled MgH. It is believed that the formation of in situ active species of KF, KH, and MgNi could provide a synergetic catalytic effect in enhancing the hydrogen sorption properties of MgH.展开更多
Mg-based metal hydrides are promising as hydrogen storage materials for fuel ce ll application. In this work,Mg2FeH6 complex hydride phase was synthesized by controlled reactive ball milling of 2Mg-Fe （atomic ratio）...Mg-based metal hydrides are promising as hydrogen storage materials for fuel ce ll application. In this work,Mg2FeH6 complex hydride phase was synthesized by controlled reactive ball milling of 2Mg-Fe （atomic ratio） powder mixture in H2. Mg2FeH6 is confirmed to be formed via the following three stages: form ation of MgH2 via the reaction of Mg with H2,incubation stage and formation of Mg2FeH6 by reaction of fully refined MgH2 and Fe. The incubation stage is characterized by no traces of Mg or hydride crystalline phase by XRD. On the other hand,Mg is observed uniformly distributed in the milled powder by SEM-E DS. Also,almost the same amount of H2 as the first stage is detected stored i n the powders of the second stage by DSC and TGA.展开更多
Lithium element has attracted remarkable attraction for energy storage devices, over the past 30 years. Lithium is a light element and exhibits the low atomic number 3, just after hydrogen and helium in the periodic t...Lithium element has attracted remarkable attraction for energy storage devices, over the past 30 years. Lithium is a light element and exhibits the low atomic number 3, just after hydrogen and helium in the periodic table. The lithium atom has a strong tendency to release one electron and constitute a positive charge, as Li<sup> </sup>. Initially, lithium metal was employed as a negative electrode, which released electrons. However, it was observed that its structure changed after the repetition of charge-discharge cycles. To remedy this, the cathode mainly consisted of layer metal oxide and olive, e.g., cobalt oxide, LiFePO<sub>4</sub>, etc., along with some contents of lithium, while the anode was assembled by graphite and silicon, etc. Moreover, the electrolyte was prepared using the lithium salt in a suitable solvent to attain a greater concentration of lithium ions. Owing to the lithium ions’ role, the battery’s name was mentioned as a lithium-ion battery. Herein, the presented work describes the working and operational mechanism of the lithium-ion battery. Further, the lithium-ion batteries’ general view and future prospects have also been elaborated.展开更多
The feasibility of using liquid nitrogen cold trap （LNCT） for the removal of water vapour and alkaline mist from the hydrogen gas stream which is generated from the catalytic and acidic decomposition of sodium boroh...The feasibility of using liquid nitrogen cold trap （LNCT） for the removal of water vapour and alkaline mist from the hydrogen gas stream which is generated from the catalytic and acidic decomposition of sodium borohydride is investigated. Practically, the target application is mobile fuel cells based on hydrogen production from storage in chemical hydrides. The LNCT would be used as a one step purification method with less cost and space requirements instead of applying the conventional purification techniques. Two catalysts were investigated for the production of hydrogen from the aqueous solution of NaBH4 in a small scale packed bed reaction column. The hydrogen generated from the catalytic decomposition of NaBH4 was accompanied by limited quantity of water vapour and alkaline mist. Nonetheless, higher quantities were generated when applying the acidic decomposition of NaBH4 and consequently the utilization of LNCT for H2 purification has proved useful and lead to a reduction in the content of these impurities; thereby the concentration of hydrogen in the outlet stream has increased.展开更多
基金supported by Ministry of Higher Education Malaysia Fundamental Research Grant Scheme(FRGS 59362)
文摘In this study, the hydrogen storage properties of MgH-X wt% KNiF（X = 5, 10, 15, 20, and 50） were investigated for the first time. From the analysis of the onset desorption temperature and isothermal de/absorption kinetics, it was shown that MgH+ 5 wt% KNiFsample has the best performance. The 5wt% doped sample started to release hydrogen at about 260 °C, which was a reduction of about 95 °C and 157 oC compared with the as-milled and as-received MgH. In addition, the de/absorption kinetics of the MgH+ 5 wt% KNiFwere also improved significantly compared to the un-doped MgH. The apparent activation energy for hydrogen desorption exhibited the decrement from 167.0 k J/mol for as-milled MgHto 111.0 k J/mol with the addition of 5 wt% KNiF. Moreover, the X-ray diffraction spectra displayed the formation of new phases of KF, KH, MgNi and MgNiHby doping the KNiFwith MgHafter the dehydrogenation and rehydrogenation processes. The scanning electron microscope results revealed that MgHdoped with 5 wt% KNiFdemonstrated the smallest particle size compared to the as-received and as-milled MgH. It is believed that the formation of in situ active species of KF, KH, and MgNi could provide a synergetic catalytic effect in enhancing the hydrogen sorption properties of MgH.
文摘Mg-based metal hydrides are promising as hydrogen storage materials for fuel ce ll application. In this work,Mg2FeH6 complex hydride phase was synthesized by controlled reactive ball milling of 2Mg-Fe （atomic ratio） powder mixture in H2. Mg2FeH6 is confirmed to be formed via the following three stages: form ation of MgH2 via the reaction of Mg with H2,incubation stage and formation of Mg2FeH6 by reaction of fully refined MgH2 and Fe. The incubation stage is characterized by no traces of Mg or hydride crystalline phase by XRD. On the other hand,Mg is observed uniformly distributed in the milled powder by SEM-E DS. Also,almost the same amount of H2 as the first stage is detected stored i n the powders of the second stage by DSC and TGA.
文摘Lithium element has attracted remarkable attraction for energy storage devices, over the past 30 years. Lithium is a light element and exhibits the low atomic number 3, just after hydrogen and helium in the periodic table. The lithium atom has a strong tendency to release one electron and constitute a positive charge, as Li<sup> </sup>. Initially, lithium metal was employed as a negative electrode, which released electrons. However, it was observed that its structure changed after the repetition of charge-discharge cycles. To remedy this, the cathode mainly consisted of layer metal oxide and olive, e.g., cobalt oxide, LiFePO<sub>4</sub>, etc., along with some contents of lithium, while the anode was assembled by graphite and silicon, etc. Moreover, the electrolyte was prepared using the lithium salt in a suitable solvent to attain a greater concentration of lithium ions. Owing to the lithium ions’ role, the battery’s name was mentioned as a lithium-ion battery. Herein, the presented work describes the working and operational mechanism of the lithium-ion battery. Further, the lithium-ion batteries’ general view and future prospects have also been elaborated.
文摘The feasibility of using liquid nitrogen cold trap （LNCT） for the removal of water vapour and alkaline mist from the hydrogen gas stream which is generated from the catalytic and acidic decomposition of sodium borohydride is investigated. Practically, the target application is mobile fuel cells based on hydrogen production from storage in chemical hydrides. The LNCT would be used as a one step purification method with less cost and space requirements instead of applying the conventional purification techniques. Two catalysts were investigated for the production of hydrogen from the aqueous solution of NaBH4 in a small scale packed bed reaction column. The hydrogen generated from the catalytic decomposition of NaBH4 was accompanied by limited quantity of water vapour and alkaline mist. Nonetheless, higher quantities were generated when applying the acidic decomposition of NaBH4 and consequently the utilization of LNCT for H2 purification has proved useful and lead to a reduction in the content of these impurities; thereby the concentration of hydrogen in the outlet stream has increased.
