Preparation Of Nickel / Cobalt Based Two-dimensional Nano Films And Their Catalytic Performances For Hydrogen Production From Borane Hydrolysis

With the increasing environment pollution and the depletion of fossil energy,hydrogen has considerable potential as a substitute fossil fuels due to its high energy density,wide sources,and clean combustion.Ammonia borane has become one of the most promising chemical hydrogen storage materials due to its excellent stability and high hydrogen content.However,the hydrogen production rate of ammonia borane is low at room temperature,which requires the participation of catalysts to achieve controllable and efficient hydrogen production.Thereby the development of catalysts with high activity and low cost is the focus of this thesis.The interfacial synthesis is a method for preparing nanomaterials at the liquid-liquid interface formed by two incompatible liquid phases,and has independent template,simple operation and low cost.In this thesis,nickel（cobalt）nanofilms were prepared at the interface of ionic liquid/water,and the effects of preparation conditions on the microstructure of mental nanofilms was studied by XRD,XPS,TEM and other characterization methods.And the catalytic performances of hydrogen production for hydrolysis of the ammonia borane were explored.The main research is the following two aspects:（1）The effects of the type of ionic liquid,the dropping time of the metal salt precursor,and the reaction temperature on the microstructure of nickel nanofilms were studied.And the performance of catalyzing the hydrolysis of ammonia borane for hydrogen production was explored.The results show that the nickel nanofilms（Ni/Ni O-NFs）prepared at the interface of 1-octyl-3-methylimidazolium hexafliorophosphate under the conditions of dropping time of 180 s and reaction temperature of 40°C has the most uniform membrane structure and high catalytic activity.At 25°C,its hydrogen production rate is 2917.50 m L min^-1g _Ni^-1and the TOF value is 7.0 min^-1,but its cycle stability was poor.After three hydrogen production tests,the catalytic activity of Ni/Ni O-NFs retains 24%of that of fresh catalyst.The characterization results of the microstructure of the catalyst after three hydrogen production tests show that in the process of catalytic ammonia borane hydrolysis,part of Ni²⁺in Ni/Ni O-NFs is reduced to Ni⁰,which leads the destruction of films structure and agglomeration,resulting in the decline of catalytic activity of Ni/Ni O-NFs.（2）The ruthenium doped cobalt nanofilms（Co-Ru-（0.02%）-NFs,Co-Ru-（1%）-NFs）were successfully prepared at the interface between1-octyl-3-methylimidazolium hexafluorophosphate and water.The effects of the doping amount of ruthenium on the microstructure of cobalt nanofilms were studied.And the catalytic performance of ruthenium doped cobalt nanofilms in catalyzing the hydrolysis of ammonia borane for hydrogen production was explored.The experimental results show that the cobalt nano films prepared with ruthenium doping of 0.02%have the most evenly dispersed film structure.The catalytic activity of ruthenium doped cobalt nanofilms is better than that of pure cobalt films,but the catalytic activity of Co-Ru-（0.02%）-NFs is slightly better due to the cobalt nanofilms with ruthenium doping of 1%.Co-Ru-（0.02%）-NFs showed excellent stability in the durability test.The activity retention rate of the catalyst after five hydrolysis hydrogen production tests retain 87%of the premier catalytic activity.