The Synthesis Of Co-based Catalysts For Application In The Hydrogen Generation From Chemical Hydrides

Chemical hydride is a promising material for hydrogen storage and transportation,which is stable,inexpensive and non-toxic.Although the chemical hydrides were spontaneously hydrolyzed at room temperature,the rate of hydrogen production is low in the progress of the hydrolysis.Therefore,in order to improve the reaction rate of the hydrolysis,the catalysts are necessary during the progress of hydrogen production.Among so many catalysts of the hydrogenation,cobalt-based nanocatalysts have been attracted much attention because of their high catalytic activity and low cost.In this paper,cobalt-based catalysts were prepared by different methods and applied to catalyze the hydrolysis of the chemical hydride.This work is focused on the preparation of cobalt-based materials and the application in the hydrolysis of chemical hydride.The main work includes the catkin-like CoB composed of nanosheets were prepared via a ball-milling-assisted liquid–liquid interfacial reaction,magnetic field induced synthesis of the amorphous CoB alloy nanowires and the core-shell structure of the nanochain CoB@Ni（OH）₂.And the three kinds of nanomaterials were applied to catalyze the hydrolysis of chemical hydride in the alkaline medium.The composition,morphology,structure and catalytic performances of the catalysts were characterized and were compared with those which prepared by common synthesis methods.The work consists of three parts,as follows:Part 1 Preparation of amorphous ultra-thin nanosheet CoB alloy catalyst by ball-milling assisted interface and its catalytic performance for NaBH₄Catkin-like CoB composed of ultrathin nanosheets were synthesized via a ball-milling-assisted liquid–liquid interfacial reaction free of any capping agent.The specific surface area of the as-prepared catkin-like CoB alloy sample could reach224.7 m²g^-1 with mesoporous structure.When the catkin-like CoB acted as a catalyst in the hydrolysis of sodium borohydride,the hydrogen generation rate was higher than the as-prepared CoB nanoparticles and the catalyst exhibited good reusability.Part 2 Magnetic field induced synthesis of amorphous CoB alloy nanowires catalyst and its catalytic performance for NH₃BH₃Amorphous CoB nanowires with a diameter of ca.80 nm were prepared at room temperature by a cost-effective magnetic-field-assisted process independent of any template and capping agent.When the as-prepared amorphous CoB nanowires was used as the catalyst in the hydrolysis of ammonia borane for hydrogen production,the amorphous CoB nanowires exihibited high catalytic activity and good reusability comparing with CoB nanopaticles synthesized without magnetic field induction.Part 3 Preparation of CoB@Ni（OH）₂ nanochains with core-shell structure and its catalytic performance for NH₃BH₃CoB@Ni（OH）₂ nanochains with core-shell structure were prepared by Ni（OH）₂supported on amorphous CoB.CoB alloy was prepared at room temperature by a cost-effective magnetic-field-assisted process independent of any template and capping agent.The composition,structure and catalytic performance of CoB@Ni（OH）₂ nanochains were characterized.The catalytic tests show that the activity of CoB@Ni（OH）₂ nanochains was higher than CoB alloy without loading Ni（OH）₂ and CoB@Ni（OH）₂ nanochains exihibited higher stability.