基于内非金属元素掺杂的外微波电场协同增强镁储氢机理研究  

Mechanism of magnesium based hydrogen storage enhanced by external microwave electric field based on internal nonmetallic element doping

作　　者：王欢 吴震[1] 黄雅琨 杨福胜[1] 张早校[1] WANG Huan;WU Zhen;HUANG Yakun;YANG Fusheng;ZHANG Zaoxiao(School of Chemical Engineering and Technology,Xi'an Jiaotong University,Xi'an,Shaanxi 710049,China)

机构地区：[1]西安交通大学化学工程与技术学院

出　　处：《天然气工业》2024年第7期199-207,共9页Natural Gas Industry

基　　金：国家自然科学基金项目“微波诱导活性氢负离子协同热效应强化氢化镁储氢机理研究”(编号:52176203)。

摘　　要：在众多的固态储氢材料中,镁基材料已被公认为极具应用前景,但镁在储氢过程中需要克服动力学性能差(氢解离扩散难)、反应能耗高等难题,因而阻碍了其大规模商业化应用。微波外场可高效加速化学反应并降低反应温度和能耗,已逐渐应用于改善储氢过程,但目前针对内非金属元素掺杂外微波电场协同增强镁储氢的研究鲜有报道。为此,基于第一性原理计算探究了内掺杂非金属元素外微波电场协同改善镁储氢的作用机制,分析了有无非金属元素掺杂下镁—氢气体系在微波电场作用前后的吸附能、电子特性、过渡态等热动力学性能变化机理。研究结果表明:①微波电场改变了氢气分子和镁表面的电荷分布,使得氢气分子出现电荷分离(发生极化);②态密度计算结果也表明微波电场改变了H-s轨道的电子态分布,使得H-s电子向高能量区域移动,从而增强H-s与Mg-sp轨道杂化,导致镁与氢气之间的相互作用增强;③内非金属元素掺杂外微波电场协同改性使吸氢过程的反应能垒从0.94 eV大幅降至0.77 eV。结论认为:①微波电场有助于氢气发生极化,激活了氢气的反应活性,降低反应能耗;②内非金属元素掺杂外微波电场协同改性促进了氢气在镁表面的反应进程,有效提高了镁吸氢过程的动力学性能。Among numerous solid-state hydrogen storage materials,magnesium-based materials have been well recognized to be prosperous in application prospect,but its large-scale commercial application is hindered because of magnesium's poor dynamic performance(difficult hydrogen diffusion)and high reaction energy consumption in the process of hydrogen storage.External microwave field has been gradually applied to improve hydrogen storage process,for it can efficiently accelerate chemical reaction and decrease reaction temperature and energy consumption.At present,however,there are few reports on the studies of the internal non-metal doping synergistic with external microwave electric field enhanced magnesium based hydrogen storage.Based on the first-principles calculation,this paper investigates the mechanism of internal non-metal doping synergistic with external microwave electric field in improving magnesium based hydrogen storage,and analyzes the thermodynamic change mechanisms(e.g.adsorption energy,electronic behavior and transition state)of magnesium-hydrogen system doped with non-metal elements before and after the action of microwave electric field.And the following research results are obtained.First,microwave electric field alters the charge distribution on the surface of hydrogen molecule and magnesium and results in charge separation of hydrogen molecule(polarization),so as to change the interaction between hydrogen and magnesium.Second,state density calculation results also indicate that microwave electric field changes the electronic state distribution of H-s orbitals,causing H-s electrons to move towards the high-energy region,which enhances the hybridization of H-s orbitals with Mg-sp orbitals and improves the interaction between magnesium and hydrogen.Third,the synergistic modification of internal non-metallic element doping and external microwave electric field significantly reduces the reaction energy barrier of hydrogen absorption process from 0.94 eV to 0.77 eV.In conclusion,microwave electric field help

关 键 词：固态储氢 镁金属 微波电场 非金属掺杂 第一性原理计算 

分 类 号：TK91[动力工程及工程热物理]