(1. 長(zhǎng)沙理工大學(xué)工程車(chē)輛輕量化與可靠性技術(shù)湖南省高校重點(diǎn)實(shí)驗(yàn)室，長(zhǎng)沙 410114；
2. 長(zhǎng)沙理工大學(xué)能源高效清潔利用湖南省高校重點(diǎn)實(shí)驗(yàn)室，長(zhǎng)沙 410114；
3. 湖南大學(xué)汽車(chē)車(chē)身先進(jìn)設(shè)計(jì)制造國(guó)家重點(diǎn)實(shí)驗(yàn)室，長(zhǎng)沙410082)
摘 要: 選取石墨與石墨烯兩種碳材料作為摻雜劑，采用機(jī)械球磨方法分別制備純MgH2、MgH2-10%石墨(質(zhì)量分?jǐn)?shù))及MgH2-10%石墨烯3種儲(chǔ)氫體系，并結(jié)合XRD、SEM、DSC-TG實(shí)驗(yàn)表征手段與具有原子尺度模擬能力的第一性原理計(jì)算方法，研究碳材料摻雜對(duì)MgH2釋氫性能的影響及其微觀(guān)機(jī)理。結(jié)果表明：微量石墨與石墨烯的摻雜使得MgH2釋氫溫度得到降低，相比之下，石墨烯摻雜效果較為明顯，其摻雜致使MgH2初始釋氫溫度降低近33℃。此外，石墨與石墨烯摻雜均有助于抑制球磨過(guò)程中顆粒的團(tuán)聚，起到結(jié)構(gòu)限域的作用，促進(jìn)MgH2快速釋氫。第一性原理計(jì)算表明，碳材料摻雜改善MgH2釋氫性能的內(nèi)在原因在于其摻雜削弱了Mg—H間的鍵強(qiáng)，降低了H原子從MgH2基體中釋放時(shí)的解離能。
關(guān)鍵字: MgH2；碳材料；摻雜；釋氫性能；第一性原理
（1. Key Laboratory of Lightweight and Reliability Technology for Engineering Vehicle, Education Department of Hunan Province, Changsha University of Science and Technology, Changsha 410114, China;
2. Key Laboratory of Efficient and Clean Energy Utilization, Education Department of Hunan Province,
Changsha University of Science and Technology, Changsha 410114, China;
3. State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body,
Hunan University, Changsha 410082, China）
Abstract:The pure MgH2, MgH2-10% graphite (mass fraction) and MgH2-10% graphene hydrogen storage systems were prepared by mechanical ball-milling technology with two kinds of carbon materials such as graphite and graphene as the dopants. Using the XRD, SEM, DSC-TG experimental testing methods in combination with the first-principle calculations with the atomic scale simulation ability, the influence of carbon materials doping on the dehydrogenation properties of MgH2 and the micro-mechanism were investigated. The results show that the doping of a little graphite or graphene lowers the dehydrogenation temperature of MgH2. By contrast, the doping effect of graphene is relatively better and it lowers the initial dehydrogenation temperature of MgH2 by about 33 ℃. Besides, graphite and graphene play the role of structural confinement since they inhibit powder agglomeration during ball-milling, which is beneficial toaccelerating hydrogen desorption. The first-principle calculations show that the doping of carbon materials weakens the bonding strength between Mg and H, which results in the reduced dissociation energy of H atoms from MgH2 matrix. This may be the intrinsic reason for improving dehydrogenation properties of MgH2 with carbon materials doping.
Key words: MgH2;carbon material; doping; dehydrogenation property; first-principle
