Synthesis Of Co,Mo-Based Carbide Nanomaterials And Their Catalytic Performance In Hydrogen Production From Ammonia Borane

Energy depletion and environmental pollution problems have become more serious,the development of environmentally friendly sustainable energy is becoming increasingly urgent.Hydrogen energy,as an excellent secondary energy source,has large reserves,high calorific value,and clean products,can effectively solve the energy and environmental problems.Ammonia borane（NH₃BH₃,AB）possesses high hydrogen content（19.6wt%）and good chemical stability has been considered as a potential hydrogen storage material.Hydrogen can be safely,stably and controllable released with the presence of suitable catalyst.The hydrolysis of AB relies on the catalysts used at room temperature.Thus,the development of efficiency,stable,and economy catalysts is the main issue for the AB hydrolysis.Transition metal carbides have attracted more attention due to their special electronic structure and similar properties with noble metals.In the first part of this work,Ni and Mo_xC are supported on theγ-Al₂O₃to prepare the 10Ni30Mo_xC/γ-Al₂O₃catalyst for highly efficient hydrolytic reaction of AB.In the second part,a core-shell structure Co₂C@C catalyst has been synthesized and tested in AB hydrolysis,and the reaction mechanism was also studied.The 10Ni30Mo_xC/γ-Al₂O₃was synthesized by the equal volume impregnation method.NH₃·H₂O was used as the solvent to form complex ions with the solute,which can increase the solubility of the solute,it can also make the ions evenly deposited on the surface of the carrier due to the effect of static electricity.The synergistic effect of Ni and Mo_xC enhances the catalytic activity for AB hydrolysis,the hydrogen production rate of 10Ni30Mo_xC/γ-Al₂O₃is higher than that of 10Ni/γ-Al₂O₃.The hydrogen generation rate of 10Ni/γ-Al₂O₃and 10Ni30Mo_xC/γ-Al₂O₃is 12407 m L·min^-1·g_Ni^-1and37719 m L·min^-1·g_Ni^-1,respectively.The hydrogen production rate of10Ni30Mo_xC/γ-Al₂O₃is 3.04 times with that of 10Ni/γ-Al₂O₃,and the TOF value is as high as 75.08 mol _H2·mol_Ni^-1·min^-1for 10Ni30Mo_xC/γ-Al₂O₃.Co@C was firstly prepared using ZIF-67 as the precursor,and then Co₂C@C was synthesized in the high pressure reactor.The core-shell Co₂C@C-260 catalyst with the appropriate ratio of Co₂C and Co,can be controllable synthesized via the adjustion of preparation parameters,such as temperature.For the synthesized Co₂C@C-260,the outermost layer is C coat,the middle layer is Co₂C,and the core is Co.At the temperature of 298 K,the hydrogen generation rate of Co₂C@C-260 is 9681m L·min^-1·g_Co^-1,and the apparent activation energy is as low as 26.9 k J/mol.In this part of work,the Co₂C is firstly synthesized using the high pressure reactor at high pressure,and this preparation method,with the advantages of less investment,facile operation,safe and controllable,high purity of Co₂C product,which provide the theoretical fundamental for the study of Co₂C material.