利用氧还原反应提高材料储氢性能的理论研究

One of the primary barriers preventing the large-scale use of hydrogen is the lack of appropriate hydrogen storage medium. Because the oxygen interferes with hydrogen adsorption, nanomaterials can not store hydrogen reversibly. This project is to remove the interference of the oxygen in the process of storing hydrogen and design hydrogen storage nanomaterials. Using first-principles calculations based on density functional theory, we explore the method of storing hydrogen selectively with the help of oxygen reduction reaction, further realize storing hydrogen reversibly near ambient temperature. First, we study the adsorption properties of graphene like materials decorated by different metal atoms, and the catalytic property of transition metal and noble metal decorated graphene like material for oxygen reduction reaction. On the basis of the above results, we study hydrogen storage property and the catalytic property of the graphene like materials co-decorated by noble metal and other metal atoms. Second, we design the clusters composed of Li and O in varying proportions and investigate the hydrogen storage properties of the LinO clusters. Based on this, we investigate the catalytic property of the LinO cluster doped by transition metal and noble metal. At last, we study the modulation of the hydrogen storage properties and the catalytic property by electric field or charge. The research of this project would provide the theoretical models for modulating the hydrogen storage properties of the nanomaterials, provide the theory basis of reducing the influence of the oxygen on the hydrogen storage, and provide good medias for storing hydrogen to use the hydrogen energy.

缺少合适的储氢方式是阻碍氢能源大规模应用的重要因素之一，在纳米材料吸附储氢过程中，由于氧气会干扰氢气的存储，不利于氢气的可逆利用。本课题致力于消除氧气等杂质气体对储氢的影响，设计可调控的纳米储氢材料。通过第一性原理计算方法，利用氧还原反应来消除氧气对材料储氢的抑制作用，进一步实现室温下可逆储氢。首先研究不同金属原子修饰的类石墨烯材料对氢和氧的吸附特点、利用过渡金属和贵金属修饰后对氧还原反应的催化作用。在此基础上研究少量的贵金属与其它原子共修饰类石墨烯材料后对ORR的催化作用和储氢性能。然后研究锂氧团簇的稳定性和储氢性能。进一步研究过渡金属和贵金属掺杂锂氧团簇后形成的复合团簇对ORR反应的催化作用。最后研究外场和电荷对材料储氢性能、催化ORR的调控作用。本课题的研究将为可调控储氢材料的应用提供理论模型，为消除氧气对储氢的影响提供理论依据，为氢能源的利用提供良好的存储介质。

在纳米材料吸附储氢过程中，由于氧气会干扰氢气的存储，不利于氢气的可逆利用。本课题致力于消除氧气等杂质气体对储氢的影响，设计可调控的纳米储氢材料。采用基于密度泛函理论的第一性原理计算方法研究了金属修饰的类石墨烯二维材料的储氢性能, 利用过渡金属或贵金属修饰后对氧还原反应的催化作用，进一步消除氧气对材料储氢可逆性的影响。结果表明锂修饰的WS2、锂和钙修饰的SiC都是较好的储氢材料。以钙修饰的MoS2为例研究了外加电场对材料储、放氢过程的调控。碱金属Li，Na和K对H2和O2的吸附能相差不大，所以O2对 Li，Na，K修饰的纳米材料储氢影响不大，可以和H2同步存储和释放。对于过渡金属修和贵金属修饰的硅烯，对O2的吸附较强，氧气被活化，可以使H2和O2容易发生氧还原反应。而贵金属修饰的硅烯对H2O的吸附较弱，可以很容易的释放出去。AlN单层材料也是一种类石墨烯的二维材料。由于Al-N键具有极性，所以可以吸附气体分子。AlN对H2和O2的吸附强度相差不大。如果用AlN来储氢的话，氧气的影响较小。本项目的研究对于纳米材料储氢、消除杂质气体对材料可逆储氢的影响具有学术意义和应用价值。