Feng Qingguo
Key Laboratory of Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu, Sichuan 610031, People's Republic of China.
J Phys Condens Matter. 2020 Aug 7;32(44). doi: 10.1088/1361-648X/aba387.
The graphitic carbon nitride (g-CN) is a promising layered two-dimension material with an opened bandgap. It is of interest to explore the tunability of the bandgap together with the magnetism by doping transition metal atoms. In this work, we investigated the transition metals (Mn, Fe, Co, Ni) and their hydroxides doped g-CNmonolayers. The electron correlations between the 3electrons of the doped transition metal atoms are self-consistently calculated and analyzed based on the density functional theory. The magnetism, electronic band structures and optical properties are systematically investigated. It reveals that the transition metal doped g-CNis ferromagnetic (FM) state at small doping concentration, where the two spins show different bandgaps. When the doping is high enough, it turns to metallic antiferromagnetic (AFM) state except that Mn doped g-CNis metallic FM state. On another hand, the system shows variable absorption spectra at different doping level. When the vacancy sites are fully occupied, a large absorption peak appears around 1.5 eV suitable for visible light. Moreover, within the transition metal hydroxides doped g-CN, the global ground state shows as AFM, and the absorption spectra within low energy range is distinct due to the presence of hydroxyl group. Therefore, doping with transition metal atoms and hydroxides can effectively tune the bandgap, magnetism and optical properties of g-CNso as to promote its applications.
石墨相氮化碳（g-CN）是一种具有前景的层状二维材料，具有开放的带隙。通过掺杂过渡金属原子来探索带隙的可调性以及磁性是很有意义的。在这项工作中，我们研究了过渡金属（Mn、Fe、Co、Ni）及其氢氧化物掺杂的g-CN单层。基于密度泛函理论，自洽地计算和分析了掺杂过渡金属原子的3电子之间的电子关联。系统地研究了磁性、电子能带结构和光学性质。结果表明，过渡金属掺杂的g-CN在低掺杂浓度下处于铁磁（FM）态，其中两个自旋具有不同的带隙。当掺杂量足够高时，除了Mn掺杂的g-CN处于金属铁磁态外，它会转变为金属反铁磁（AFM）态。另一方面，该系统在不同掺杂水平下呈现出可变的吸收光谱。当空位完全被占据时，在1.5 eV左右会出现一个适合可见光的大吸收峰。此外，在过渡金属氢氧化物掺杂的g-CN中，全局基态表现为反铁磁，并且由于羟基的存在，低能量范围内的吸收光谱是不同的。因此，掺杂过渡金属原子和氢氧化物可以有效地调节g-CN的带隙、磁性和光学性质，从而促进其应用。
