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Metal organic framework supported niobium pentoxide nanoparticles with exceptional catalytic effect on hydrogen storage behavior of MgH_(2)

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Green Energy & Environment 2023年第2期8卷 589-600页

作者： Liuting Zhang farai michael nyahuma Haoyu Zhang Changshan Cheng Jiaguang Zheng Fuying Wu Lixin Chen School of Energy and Power Jiangsu University of Science and TechnologyZhenjiang 212003China Analysis and Testing Center Jiangsu University of Science and TechnologyZhenjiang 212003China State Key Laboratory of Silicon Materials Department of Materials Science andEngineeringZhejiang UniversityHangzhou 310027China

Nb_(2)O_(5)nanoparticles with an average particle size of 10 nm supported on a rhombic dodecahedral metal organic framework(MOF)were successfully synthesized by a facile one-pot hydrothermal reaction and subsequent calcination *** results demonstrated that the prepared catalyst drastically improved the hydrogen storage behavior of MgH_(2).7 wt%Nb_(2)O_(5)@MOF doped MgH_(2)started to desorb hydrogen at 181.9℃and 6.2 wt%hydrogen could be released within 2.6 min and 6.3 min at 275℃and 250℃,*** fully dehydrogenated composite also displayed excellent hydrogenation by decreasing the onset absorption temperature to 25℃and taking up4.9 wt%and 6.5 wt%hydrogen within 6 min at 1750C and 1500C,***,the corresponding activation energy was calculated to be 75.57±4.16 kJ mol^(-1)for desorption reaction and 51.38±1.09 kJ mol^(-1)for absorption *** 20 cycles,0.5 wt%hydrogen capacity was lost for the MgH_(2)+7 wt%Nb_(2)O_(5)@MOF composite,much lower than 1.5 wt%of the MgH_(2)+7 wt%Nb_(2)O_(5)***,the addition of Nb_(2)O_(5)@MOF had limited effect on reducing the dehydrogenation enthalpy of MgH_(2).Microstructure analysis revealed that Nb_(2)O_(5)particles were uniformly distributed on surface of the MgH_(2)matrix and synergistically improved the hydrogen storage property of MgH_(2)with MOF.

关键词： Hydrogen storage MgH_(2) Nb_(2)O_(5)@MOF Reversibility Catalytic mechanism

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Significantly improved hydrogen storage behaviors in MgH_(2) with Nb nanocatalyst

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International Journal of Minerals,Metallurgy and Materials 2022年第9期29卷 1788-1797页

作者： farai michael nyahuma Liuting Zhang Mengchen Song Xiong Lu Beibei Xiao Jiaguang Zheng Fuying Wu School of Energy and Power Jiangsu University of Science and TechnologyZhenjiang 212003China Analysis and Testing Center Jiangsu University of Science and TechnologyZhenjiang 212003China

The study explores the excellent modification effect of Nb nanocatalyst prepared via surfactant assisted ball milling technique(SABM)on the hydrogen storage properties of MgH_(2).Optimal catalyst doping concentration was determined by comparing onset decomposition temperature,released hydrogen capacity,and reaction rate for different MgH_(2)-ywt%Nb(y=0,3,5,7,9)*** MgH_(2)-5wt%Nb composite started releasing hydrogen at 186.7℃ and a total of 7.0wt%hydrogen was released in the dehydrogenation *** addition,5wt%Nb doped MgH_(2) also managed to release 4.2wt%H_(2) within 14 min at 250℃ and had the ability to absorb 4.0wt%hydrogen in 30 min at 100℃.Cycling tests revealed that MgH_(2)-5wt%Nb could retain 6.3wt%H_(2) storage capacity(89.2%)after 20 *** and hydrogenation activation energy values were decreased from 140.51±4.74 and 70.67±2.07 kJ·mol^(−1) to 90.04±2.83 and 53.46±3.33 kJ·mol^(−1) after doping MgH_(2) with Nb,*** analysis proved that homogeneously distributed NbH acted as active catalytic unit for improving the hydrogen storage performance of MgH_(2).These results indicate SABM can be considered as an option to develop other nanocatalysts for energy related areas.

关键词： hydrogen storage magnesium hydride surfactant assisted ball milling Nb nanosheets

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Natural Radionuclide Concentrations and Radiological Impact Assessment of River Sediments of the Coastal Areas of Nigeria

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Journal of Environmental Protection 2011年第4期2卷 418-423页

作者： Olatunde michael Oni Idowu Peter farai Ayodeji Oladiran Awodugba Department of Physics University of Ibadan Nigeria Department of Pure and Applied Physics Ladoke Akintola University of Technology Ogbomoso Nigeria

This work was carried out to measure the radioactivity level in the coastal areas of Nigeria by gamma counting of river sediment samples and assess the radiological impact associated with the use of the river sediments as building material. The method of gamma spectrometry with a 7.6 cm by 7.6 cm NaI(Tl) detector was employed in determining 40K, 238U and 232Th levels in 95 and 38 sediment samples respectively collected from representative sites in the oil producing and non oil producing coastal areas of Nigeria. Results of the samples assayed showed that the radioactivity concentrations of 40K, 226Ra and 228Ra in the sediment samples of oil producing areas range from 95.4 to 160.0;7.6 to 31.0 and 9.5 to 41.6 Bq kg–1, respectively. The respective means were calculated as 122.39 ± 47.49;18.93 ± 12.53 and 29.31 ± 18.67 Bq kg–1. In the sediment samples from the non oil producing areas, the respective mean values are 88.48 ± 8.22, 14.87 ± 3.51 and 16.37 ± 3.87 Bq kg–1. Statistical analysis of the results showed that there is no significant difference between the radionuclide concentration of the sediment samples from different rivers in the oil producing and non oil producing coastal areas, except for 40K. The values of the natural radionuclide concentrations however translate to the determina-tion of the radiological impact assessment values. The values of the radiological assessment indices obtained were ob-served to be lower than limits internationally reported and recommended for building materials. It could therefore be reported that the operations of the oil companies in the coastline, involving use of radioactive materials have not contributed adversely to the radioactivity level of the river sediments and that the use of river sediments as building mate-rial in the coastal areas of Nigeria poses no radiological risk.

关键词： Radiological Risk Indices River Sediments In Coastal Area Gamma Spectrometery

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