石墨烯含量对Mg/MgH_(2)体系储氢性能的影响

Effect of Graphene Content on Hydrogen Storage Properties of Mg/MgH_(2) System

MgH_(2)因具有高达7.6wt%的理论氢容量而被认为是一种很有前景的储氢材料,但其较差的动力学和热力学性能,限制了其实际应用。在MgH_(2)中加入催化剂是改善其吸放氢动力学的有效策略。利用机械球磨法制备Mg-xwt%石墨烯(x=0,1,2,3,5)复合储氢材料,采用XRD、SEM、TG-DSC和PCT对复合材料的物相组成、形貌结构和储氢性能进行了研究。结果表明:随石墨烯含量的增加,Mg/MgH_(2)储氢性能呈先增大后减小趋势。当石墨烯的含量达到2wt%时,Mg-2wt%G复合材料具有最佳的吸放氢性能、更快的吸放氢速率和更低的放氢温度;在350℃,300min下Mg-2wt%G吸氢量达4.07wt%,相同温度下,400min内放氢量为3.82wt%;放氢峰值温度较未添加石墨烯降低了11.4℃。

MgH_(2) is considered as a promising material for hydrogen storage due to its high theoretical hydrogen capacity of 7.6wt%,but poor kinetic and thermodynamic properties limit its practical application.The addition of catalysts to MgH_(2) is an effective strategy to improve the kinetics of hydrogen absorption and release.Mg-xwt% graphene(x=0,1,2,3,5)composite hydrogen storage materials were prepared by mechanical ball milling method,and the material phase composition,morphological structure and hydrogen storage properties were investigated by XRD,SEM,TG-DSC and PCT.According to the findings,with the increasing of graphene content,the hydrogen storage performance of Mg/MgH_(2) rises and then decreases.The best hydrogen absorption and desorption performance of Mg-2wt%G composites was achieved when the amount of graphene reached 2wt%,with faster hydrogen absorption and release,and lower hydrogen release temperature;at 350℃,the mass fraction of hydrogen absorbed by Mg-2wt%G reached 4.07wt% at 300 min,and the hydrogen release was 3.82wt%at the same temperature and 400 min;the peak hydrogen release temperature was 11.4℃ lower than that without graphene.