计算研究改性WS 2/GQDs异质结构的电学和光催化性能

Computational Study on Electronic and Photocatalytic Properties of Modified WS 2/GQDs Heterostructures

太阳能吸收和光诱导电荷的分离和转移是提高光催化性能的关键。基于密度泛函理论,通过密度泛函理论计算,研究了石墨烯量子点(graphene quantum dots,GQDs)、纯WS2和O改性WS2、GQDs基异质结构的结构、电学和光催化性能。通过形成能和结合能分析发现,O容易取代S原子,并且取代后形成的结构模型比较稳定。与GQDs相比,WS2/GQDs和O-WS2/GQDs异质结构的吸收峰红移,吸收强度也显著增加,同时形成了典型的type-Ⅱ能级结构,这能够捕获更多的太阳光和促进光生电荷的分离和转移。O掺杂可以改变O-WS2/GQDs的电子结构,使之有利于光催化。因此,这项工作为设计新的GQDs基异质结构,提高太阳能的吸收和转换效率提供了一个有前景的方法。

Solar energy absorption and photo-induced charge separation and transfer are crucial to enhance photocatalytic properties. Here,the structural,electronic and photocatalytic properties of graphene quantum dots(GQDs),pure and O-modified WS2 monolayers,GQDs-based heterostructures have been studied by theoretical calculations based on density functional theory(DFT). By analyzing the formation energy and the binding energy,it is found that O is easy to replace S atom,and the structural model after the substitution is relatively stable. Compared with the GQDs,the obvious red shifts of the absorption peaks can be observed,the absorption intensities increases evidently,and the typical type-Ⅱ band alignments can be formed after the construction of the pure and O-WS2/GQDs heterostructures,which is beneficial to promote photo-induced charge transfer and more visible light harvesting. O doping can change the electronic structure of O-WS2/GQDs,making it favorable for photocatalysis. Therefore,this work provides a promising approach in designing new GQDs-based heterostructures to enhance the solar energy absorption and conversion.