二维Ti2C与Ti3C2表面OH、O、F、Au的吸附活性

Adsorption Activities of O, OH, F and Au on Two-Dimensional Ti_2C and Ti_3C_2 Surfaces

较高的比表面积与稳定性使得二维Ti_2C与Ti_3C_2结构在贵金属催化剂载体、锂离子电池、储氢材料等领域具有重要的应用前景.研究Ti_2C、Ti_3C_2的表面吸附活性有助于认识其表面特征.第一性原理计算研究显示:Ti_2C与Ti_3C_2对O、OH、F具有较强的吸附活性.通过比较Ti2_C、Ti_3C_2、Ti(001)、TiC(001)的表面电子结构,我们发现Ti_2C与Ti_3C_2较强的表面吸附活性来自于表面Ti原子未极化的3d轨道.这使得Ti_2C、Ti_3C_2表面通常覆盖有O、F、OH.吸附了O、OH基团的Ti_2C与Ti_3C_2结构(Ti_2CO_(2-2x)(OH)_(2x)、Ti_3C_2O_(2-2x)(OH)_(2x))对Au原子的吸附能随OH比例的增大而增大.

Two-dimensional Ti2C and Ti3C2 structures are highly stable and have high specific surface areas, and therefore represent promising materials with potential applications as carriers in transition metal catalysis, Li-ion batteries, and hydrogen storage devices. It was envisaged that investigating the surface adsorption activities of Ti2C and Ti3C2 would provide useful information about their surface properties. The results of a first-principles study showed that the adsorption energies of OH, O, and F on Ti2C and Ti3C2 surfaces were quite high. By comparing the electronic properties of Ti2C, Ti3C2, Ti（001）, and TiC（001）, we found that the un-polarized Ti-3d orbitals were responsible for the high surface adsorption activities of these materials. The high surface adsorption activities of the Ti2C and Ti3C2 materials caused them to be terminated with O, F, and OH surface groups. The surface adsorption energies of the Au particles on the Ti2CO2-2x（OH）2x and Ti3C2O2-2x（OH）2x） surfaces increase as the ratio of OH increased.