Enhanced optical absorption and photocatalytic H2 production activity of g-C3N4/TiO2 heterostructure by interfacial coupling: A DFT+U study. (13th April 2017)

• Record Type: Journal Article
• Authors: Lin, Yanming; Shi, Hailong; Jiang, Zhenyi; Wang, Guanshi; Zhang, Xiaodong; Zhu, Haiyan; Zhang, Ruiqin; Zhu, Chaoyuan
• Is Part Of: International journal of hydrogen energy. Volume 42:Number 15(2017)
• Page Start: 9903
• Page End: 9913
• Publication Date: 2017-04-13
• Subjects: g-C3N4/TiO2 heterostructure -- Electronic structure -- Photocatalytic H2 production -- Density functional theory; Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2017.02.172
• Languages: English
• ISSNs: 0360-3199

Abstract

Abstract: The electronic and optical properties of g-C3 N4 /TiO2 heterostructure are investigated using spin-polarized DFT+ U calculations. The equilibrium spacing (1.94 Å) and binding energy (24 meV/Å 2 ) show that g-C3 N4 /TiO2 is a van der Waals heterostructure. And the calculated band gap of g-C3 N4 /TiO2 is significantly reduced compared with TiO2 . Therefore, the visible light response of g-C3 N4 /TiO2 heterostructure is remarkably improved. Besides, the predicted type II band alignment would ensure that the electrons can migrate from g-C3 N4 monolayer to anatase TiO2 (101) surface, which leads oxidation and redox reactions can occur on g-C3 N4 and TiO2, respectively. Finally, a built-in electric field within the interface region will be set. Above processes can benefit the separation of photoexcited carriers and enhance the hydrogen-evolution activity. In addition, compared with TiO2, g-C3 N4 /TiO2 with higher conduction band minimum energy can effectively produce higher-energy electrons to reduce hydrogen ions. Moreover, the influence of composite distance and the number of g-C3 N4 layers are also investigated systematically. The results indicate that the optical absorption is enhanced over the whole spectrum with the increase of the number of g-C3 N4 layers. Similar visible light enhancing is also found when the composite distance is decreased. Graphical abstract: Image 1 Highlights: Visible light response of g-C3 N4 /TiO2 is remarkably improved due to reduced band gap. Type II lineup depress the photoexcited carriers recombination in g-C3 N4 /TiO2 . g-C3 N4 /TiO2 with higher CBM offers higher-energy electrons to produce H2 effectively. TiO2 loaded with more g-C3 N4 layers has higher photocatalysis. Our calculated results further explain the photocatalytic phenomenon in experiment.