The Ni−25%X(X=Fe,Co,Cu,molar fraction)solid solutions were prepared and then doped into MgH_(2) through high-energy ball milling.The initial dehydrogenation temperatures of MgH_(2)/Ni−25%X composites are all decreased...The Ni−25%X(X=Fe,Co,Cu,molar fraction)solid solutions were prepared and then doped into MgH_(2) through high-energy ball milling.The initial dehydrogenation temperatures of MgH_(2)/Ni−25%X composites are all decreased by about 90℃relative to the as-milled pristine MgH_(2).The Ni−25%Co solid solution exhibits the most excellent catalytic effect,and the milled MgH_(2)/Ni−25%Co composite can release 5.19 wt.%hydrogen within 10 min at 300℃,while the as-milled pristine MgH_(2) can only release 1.78 wt.%hydrogen.More importantly,the dehydrogenated MgH_(2)/Ni−25%Co composite can absorb 5.39 wt.%hydrogen at 275℃within 3 min.The superior hydrogen sorption kinetics of MgH_(2)/Ni−25%Co can be ascribed to the actual catalytic effect of in-situ formed Mg_(2)Ni(Co)compounds.First-principles calculations show that the hydrogen absorption/desorption energy barriers of Mg/MgH_(2) systems decrease significantly after doping with transition metal atoms,which interprets well the improved hydrogen sorption properties of MgH_(2) catalyzed by Ni-based solid solutions.展开更多
基金the National Natural Science Foundation of China(Nos.51874049,51904036)the Science Research Project of Hunan Province Office of Education,China(No.20A024)+2 种基金the Changsha Science and Technology Program Project(No.kq1907092)the Hunan Provincial Key Laboratory of Materials Protection for Electric Power and Transportation,China(No.2019CL03)the Research and Innovation Project of Graduate Students in Changsha University of Science and Technology,China(No.CX2020SS35).
文摘The Ni−25%X(X=Fe,Co,Cu,molar fraction)solid solutions were prepared and then doped into MgH_(2) through high-energy ball milling.The initial dehydrogenation temperatures of MgH_(2)/Ni−25%X composites are all decreased by about 90℃relative to the as-milled pristine MgH_(2).The Ni−25%Co solid solution exhibits the most excellent catalytic effect,and the milled MgH_(2)/Ni−25%Co composite can release 5.19 wt.%hydrogen within 10 min at 300℃,while the as-milled pristine MgH_(2) can only release 1.78 wt.%hydrogen.More importantly,the dehydrogenated MgH_(2)/Ni−25%Co composite can absorb 5.39 wt.%hydrogen at 275℃within 3 min.The superior hydrogen sorption kinetics of MgH_(2)/Ni−25%Co can be ascribed to the actual catalytic effect of in-situ formed Mg_(2)Ni(Co)compounds.First-principles calculations show that the hydrogen absorption/desorption energy barriers of Mg/MgH_(2) systems decrease significantly after doping with transition metal atoms,which interprets well the improved hydrogen sorption properties of MgH_(2) catalyzed by Ni-based solid solutions.
