B掺杂对单层g-C_(3)N_(4)光催化性能调控机制的第一性原理研究

First-principles study on the regulation mechanism ofB doping on the photocatalytic performance of Monolayer g-C_(3)N_(4)

光催化技术以太阳能为驱动,在环境治理、氢能制备等领域具有十分广阔的应用前景。g-C_(3)N_(4)是一种极具潜力的绿色光催化剂,但其有限的可见光响应范围以及较宽的能隙限制了其光催化性能的进一步提高。非金属元素掺杂是一种有效提升g-C_(3)N_(4)光催化活性的方法,采用第一性原理计算的方法研究了B元素掺杂对g-C_(3)N_(4)光催化活性的影响机理,考察了掺杂前后的电子结构以及光学性能。结果表明,g-C_(3)N_(4)(001)表面的H位点是B原子掺杂的最稳定位点,掺杂能为-7.81 eV,B元素的加入使g-C_(3)N_(4)(001)表面的能隙从未掺杂的1.468 eV降低到了0.732 eV,功函数从4.055 eV降低到3.108 eV,并提高了表面C原子的反应活性,从而使得g-C_(3)N_(4)(001)表面的光催化活性得到了有效地提高。光学性质研究表明,B元素的加入使得g-C_(3)N_(4)(001)表面发生了明显的“红移”现象,使表面的光响应能力得到了提高,从而获得了更高的光催化能力。

Photocatalytic technology is driven by solar energy and has a very broad application prospect in the fields of environmental governance and hydrogen energy preparation.g-C_(3)N_(4)is a promising green photocatalyst,but its limited visible light response range and wide energy gap limit the further improvement of its photocatalytic performance.Non-metallic element doping is an effective method to improve the photocatalytic activity of g-C_(3)N_(4).In this paper,the influence mechanism of B element doping on the photocatalytic activity of g-C_(3)N_(4)was studied by first-principles calculation,and the electronic structure and optical properties before and after doping were investigated.The results show that the H site on the g-C_(3)N_(4)(001)surface is the most stable site for B atom doping,and the doping energy is-7.81 eV.The addition of B element reduced the energy gap of g-C_(3)N_(4)(001)surface from 1.468 eV to 0.732 eV,and the work function decreased from 4.055 eV to 3.108 eV and improved the reactivity of surface C atoms,so that the photocatalytic activity of g-C_(3)N_(4)(001)surface was effectively improved.The study of optical properties shows that the addition of B element makes the g-C_(3)N_(4)(001)surface have an obvious“red shift”phenomenon,which improves the light response ability of the surface and obtains higher photocatalytic ability.