摘要
催化剂掺杂被认为是一种非常有效改善MgH_(2)储氢性能的途径。研究结果表明,过渡金属对氢原子具有很强的亲和力,在氢分子的解离或者氢原子的重组过程中,过渡金属的d电子和氢原子/氢分子轨道上的电子发生转移填充,由此产生的相互作用力促进氢分子的解离和氢原子的重组;掺杂过渡金属氧化物同样可以有效地催化MgH_(2)的吸放氢反应,而且在研磨过程中还可以作为润滑剂和分散剂,防止MgH_(2)颗粒的团聚,细化MgH_(2)颗粒尺寸,加速MgH_(2)的氢解吸动力学,催化MgH_(2)的吸放氢反应;过渡金属卤化物在吸放氢过程与MgH_(2)反应生成的过渡金属氢化物能够促进氢分子的解离和氢原子的扩散、在氢化过程中促进形核、减小吸放氢反应的活化能;金属硫化物或金属氢化物与MgH_(2)在球磨过程中的反应产物具有较高的催化活性,能在一定程度上解决脱氢/氢化动力学缓慢的问题,并且MgS能够提供丰富的成核活性位点。碳基材料的添加,能促进Mg/MgH_(2)相形核,细化颗粒尺寸,改善氢吸咐动力学,然而效果弱于金属基催化剂。但掺杂金属基和碳基复合催化剂,MgH_(2)能同时获得掺杂金属基和碳基催化剂的效果,即脱氢温度和脱氢活化能显著降低,又表现出优异的循环稳定性。
As a potential hydrogen storage material for solid hydrogen storage,the binary hydride MgH_(2) had the advantages of high hydrogen storage density and reversible hydrogen absorption and desorption.However,the applications of MgH_(2) were restricted due to the slow rate of hydrogen absorption and desorption,and the high working temperature.To date,in order to meet the requirements of solid hydrogen storage materials for vehicular hydrogen storage,many methods to improve the hydrogen storage performance of MgH_(2) were developed by scientific researchers such as alloying,nanocrystallization,and catalyst doping.These methods reduced the hydrogen desorption temperature of the system,increased the hydrogen absorption and desorption cycle stability.Among them,catalyst doping was the most extensively studied one,and it was considered to be a very effective way to improve the performance of magnesiumbased hydrogen storage.A mechanical ball milling process was used to add the catalyst.During the ball milling process,the catalyst might react with the magnesium hydride in a solid state.Ball milling was a very important method of structural modification.It could not only conveniently control the composition of the alloy,but also could directly obtain materials with metastable structures such as nanocrystalline,amorphous and supersaturated solid solutions.In this method,metals(such as Fe,Co,Ni,Cu,etc.),metal compounds(such as Nb_(2)O_(5),CeO_(2),TMTiO_(3)(TM=Ni,Co),etc.),transition metal halides(such as CeF_(4),CeF_(3),LaCl_(3),etc.),carbonbased materials(such as graphite,graphene,AC,CFs,etc.),metal-based and carbon-based composites were used as catalysts,and added single or in combination to magnesium-based alloys by mechanical ball milling.The research results showed that transition metals had a strong affinity for hydrogen atoms.During the dissociation of hydrogen molecules or the recombination of hydrogen atoms,the d electrons of transition metals and the electrons on the hydrogen atom/hydrogen molecular orbital were tran
作者
石伟和
贾陈忠
陆必旺
马志鸿
Shi Weihe;Jia Chenzhong;Lu Biwang;Ma Zhihong(School of Materials Science and Engineering,Baise University,Baise 533000,China)
出处
《稀有金属》
EI
CAS
CSCD
北大核心
2022年第1期87-95,共9页
Chinese Journal of Rare Metals
基金
广西自然科学基金项目(2020JJA160086)
2017年度广西壮族自治区中青年教师基础能力提升项目(2017KY0734)资助。
关键词
固态储氢
机械球磨
摧化掺杂
MgH
储氢性能
solid state hydrogen storage
mechanical ball milling
catalytic doping
MgH2
hydrogen storage performance
