摘要
基于密度泛函理论的第一性原理方法,计算了Se掺杂单层MoS_2能带结构和光吸特性,并分析了对其光解水性质的影响。结果表明:本征单层MoS_2为直接带隙结构,禁带宽度为1.740 e V,导带底电位在H+/H2还原势之上0.430 e V,价带顶电位在O2/H2O的氧化势之下0.080 e V,具有可见光催化分解水的能力,但氧化和还原能力不均衡,导致单层MoS_2作为光催化剂分解水的效率不高。通过Se掺杂计算发现,单层MoS_2的禁带宽度变为1.727 e V,相应的光吸收谱变化幅度几乎不变,且体系的形成能较低,表明其热力学稳定性良好。然而,导带底电位调整到H+/H2还原势之上0.253 e V,价带顶电位处于O2/H2O的氧化势之下0.244e V,平衡了氧化与还原能力,单层MoS_2可见光催化分解水的效率得到提高。
Based on the first principles method of density functional theory, the band structure and optical absorption properties of single-layered MoS2 doped with Se were calculated. Additionally, its effect on the properties of water splitting was analyzed. The calculations showed that the intrinsic MoS2 monolayer has a direct band gap structure with a value of 1.740 eV. The bottom edge of the conduction band was 0.43 eV above the reduction potential of H＋/H2, while the top edge of the valence band was only 0.08 eV below the oxidation potential of O2/H2O. The results indicated that the intrinsic MoS2 monolayer has the potential for the photocatalytic decomposition of water when exposed to visible light. However, as the values of the oxidation and reduction processes were not balanced, the water splitting efficiency of a single-layer MoS2 photocatalyst would be low. When the MoS2 layer was doped with Se the band gap decreased to 1.727 eV, while the corresponding optical absorption spectrum was almost unchanged, and the formation energy of the system was relatively low. These results indicated that single-layered MoS2 should be thermally stabile following doping with Se. Significantly,
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
2016年第12期2905-2912,共8页
Acta Physico-Chimica Sinica
基金
国家自然科学基金(61674113
51622507
61471255)
山西省自然科学基金(2014011019-1
20141001021-2
2016011040)
山西省回国留学人员科研项目(2013-036)
山西省人社厅留学人员择优资助项目([2013]251)
人社部留学人员择优资助项目([2014]240)
山西省高校科技创新研究项目(2016138)资助~~
关键词
单层MoS2
掺杂
光解水
第一性原理
Single layer MoS2
Doping
Photocatalytic splitting of water
First principles
