Concentration-dependent electronic structure and optical absorption properties of B-doped anatase TiO2

The concentration-dependent electronic structures and optical properties of B-doped anatase TiO₂ have been calculated using the density functional theory. The calculated results indicate that the electronic structures of B-doped TiO₂ have changed compared with those of pure TiO₂, which is mainly due to the new midgap states induced by B doping. As to the optical properties, we calculate the imaginary part of dielectric function ε₂(ω) and optical absorption spectra of pure and B-doped TiO₂. Two transitions E₁ and E₂ emerged after B doping. The intensity of absorption is enhanced by B doping both in the UV and visible regions. According to the results of imaginary part of dielectric function ε₂(ω) and DOS, it can be concluded that the two optical transitions correspond to the transitions from the O 2p states in the top of valence band to the midgap states and from the midgap states to the Ti 3d states in the bottom of conduction band, respectively. These results have important implications for the further development of photocatalytic materials.     

大面积B掺杂CVD金刚石膜的制备研究

研究了采用B2O3作为掺杂源以EACVD法沉积大面积掺杂CVD金刚石膜,用SEM、Raman、二次离子质谱仪、四探针电阻仪等对B掺杂金刚石膜进行了分析.结果表明直径达100mm的大面积B掺杂金刚石膜的晶粒分布均匀,非金刚石碳含量较少,生长速率达到10μm/h以上;B掺杂改变了金刚石膜的成分和结构,高浓度掺杂可以细化晶粒,在高浓度掺杂的膜中存在一定的非晶态碳;金刚石膜中B的含量在一定范围内随着掺杂源浓度的增加而正比增加;金刚石膜的电阻率随着掺杂源B2O3的浓度的增加而下降,当掺杂达到一定浓度时,金刚石膜的电阻率逐渐趋向稳定.     

缺陷对Pt在Graphene上吸附影响的研究

本文利用第一原理方法计算了空位缺陷和硼（B）掺杂时对Pt在graphene上吸附的影响.结果表明：Pt在graphene上吸附的稳定位置是Pt吸附在桥位;悬挂键的存在极大的增强了Pt在graphene空位处的吸附;B替位掺杂有利于Pt原子在杂质附近的吸附.