二维TiC 层表面H2的化学吸附与物理吸附

第一性原理计算研究发现由于二维TiC 单原子层具有高的比表面积与大量的暴露在表面的Ti 原子，其是一种非常有潜力的储氢材料. 计算结果显示H₂可以在二维TiC 单原子层表面进行物理吸附与化学吸附. 其中化学吸附能为每个氢分子0.36 eV，物理吸附能是每个氢分子0.09 eV. 覆盖度为1和1/4层（ML）时，H₂分子在二维TiC 单原子层表面的离解势垒分别为1.12 和0.33 eV. 因此，除了物理吸附与化学吸附，TiC 表面还存在H单原子吸附. 最大的H₂储存率可以达到7.69%（质量分数）. 其中，离解的H原子、化学吸附的H₂、物理吸附的H₂的储存率分别为1.54%、3.07%、3.07%. 符合Kubas吸附特征的储存率为3.07%. 化学吸附能随覆盖度的变化非常小，这有利于H₂分子的吸附与释放.

Hydrogen Chemisorption and Physisorption on the Two-Dimensional TiC Sheet Surface

The TiC monolayer sheet, a new two-dimensional structure, is proposed as a promising hydrogen storage material because of its high specific surface area and the large number of exposed Ti ions on the surface. First principles calculations showed that both chemisorption and physisorption of H₂ can take place on the TiC sheet surface, with adsorption energies of 0.36 and 0.09 eV per H₂, respectively. For 1 and 1/4 monolayer (ML) coverages, the dissociation barriers of H₂ on the TiC sheet surface were calculated to be 1.12 and 0.33 eV, respectively. Thus, as well as physisorption and chemisorption, there were dissociated H atoms on the TiC sheet surface. The maximum H₂ storage capacity was calculated to be up to 7.69% (mass fraction). The capacities were 1.54%, 3.07%, and 3.07% for dissociated H atoms, and chemisorption and physisorption of H₂, respectively. Considering only Kubas adsorption, the hydrogen storage capacity was 3.07%. The adsorption energy for H₂ chemisorption on the TiC sheet surface only slightly changed at different coverages, which benefits the storage and release of H₂.