Synthesis Of Ti₃C₂T_x Mxene-supported Ni-based Nanomaterials For Catalytic Dehydrogenation Of Nitrogen Hydrides

As a high-calorie renewable clean energy,hydrogen has received widespread attention in the context of the current energy and environmental crisis.How to realize the safe and convenient storage and transportation of hydrogen energy is a difficult point in the practical application of hydrogen energy.Hydrazine hydrate?N₂H₄·H₂O?and hydrazine borane?N₂H₄BH₃?have many characteristics such as high hydrogen storage per volume,low activation temperature,safety and stability to be ideal liquid and solid chemical hydrogen storage materials.The system field has broad application prospects for the future hydrogen energy vehicles and portable mobile energy.The development of a catalyst with high selectivity and catalytic activity for hydrazine borane hydrolysis and hydrazine decomposition dehydrogenation is the key to its practical application.In this thesis,the catalytic hydrogen generation system of hydrazine borane and hydrazine is taken as the research object,and catalysts with high selectivity and high activity for these two hydrogen storage materials are designed and synthesized.The main research contents are as follows:?1?As a new type of two-dimensional material,MXene has a diversified structure and is one of the new stars in the field of functional materials research in recent years.MXene,represented by Ti₃C₂T_x,has metal-like conductivity and rich functional groups such as-F and-OH on the surface also give it excellent chemical reactivity and hydrophilicity,and it is expected to be an ideal carrier for constructing nanocomposite structures.The Ni/Ti₃C₂T_x nano-catalyst was prepared by using ultrasonic method to immobilize metallic Ni nanoparticles on the surface of two-dimensional Ti₃C₂T_x.In the alkaline environment of 323 K,its hydrogen conversion frequency?TOF?is as high as 302 h-1,which is higher than that of most non-noble metal catalysts.It is also one of the few single-metal nanocatalysts that can efficiently produce hydrogen by hydrazine borane.?2?Pre-oxidation method was used to modify TiO₂ in situ on the surface of Ti₃C₂T_x to improve the performance of Ti₃C₂T_x.On this basis,NiPt alloy was introduced to prepare NiPt/DT-Ti₃C₂T_x nanocomposites.It was used to catalyze the decomposition of hydrazine hydrate to produce hydrogen to investigate its catalytic performance.The results showed that the formation of NiPt alloy and the in-situ modification of TiO₂ on the surface of Ti₃C₂T_x effectively enhanced the interaction between the active metal and the support,and was alkaline at 323 K.Under the environment,the TOF value of the NiPt/DT-Ti₃C₂T_x catalyst for the decomposition of hydrazine hydrate to produce hydrogen reached 1220 h^-1,and the TOF value for the hydrolysis of hydrazine borane to produce hydrogen was as high as 2027 h^-1.?3?The limited interaction between a single MXene material and metal nanoparticles,it is designed to modify the cobalt nitrogen carbon derived from MOF in situ on MXene to further enhance the interaction between active metal and carrier.ZIF-67 was grown in situ on Ti₃C₂T_x and annealed at high temperature to obtain NC-Co-Ti₃C₂T_x composite material.Subsequently,NiRh/NC-Co-Ti₃C₂T_x nanocatalyst was prepared by surface alloying modification,and its catalytic performance for hydrazine hydrate was tested.The results show that the in-situ modification of cobalt-nitrogen-carbon on Ti₃C₂T_x further enhances the interaction between the metal and the carrier and greatly improves the catalytic activity of the catalyst.In the 323 K alkaline solution,the NiRh/NC-Co-Ti₃C₂T_x catalyst pair The TOF value of hydrazine hydrate decomposition for hydrogen production is as high as 2357 h^-1,which is higher than most current catalysts that catalyze the decomposition of hydrazine hydrate for hydrogen production.