Constructing a novel metal-free g-C3N4/g-CN vdW heterostructure with enhanced visible-light-driven photocatalytic activity for water splitting

• Published in: Applied surface science 2021-07, Vol.553, p.149550, Article 149550
• Main Authors: He, C., Liang, Y., Zhang, W.X.
• Format: Article
• Language: English
• Subjects: Photocatalytic water splitting; Type-II semiconductor; Van der Waals heterostructure
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2021.149550

[Display omitted] •The g-C3N4/g-CN vdW heterostructure is a typical type-II semiconductor with a low mismatch of 0.8%.•The band edge positions of g-C3N4/g-CN vdW heterostructure can stretch across the redox potentials of water.•Applying −2% biaxial strain, g-C3N4/g-CN vdW heterostructure can be modulated to better catalyze water splitting.•The optical absorption intensity of g-C3N4/g-CN vdW heterostructure is better than the isolate monolayer. With the increasing environmental pollution and energy crisis, developing and designing environmentally friendly, low-cost, metal-free and efficient photocatalyst for water splitting is vitally important. Herein, a novel g-C3N4/g-CN van der Waals (vdW) heterostructure is proposed and its structural, electronic and optical properties are systematically investigated based on first-principles method. The results show that the g-C3N4/g-CN vdW heterostructure is a type-II semiconductor, which satisfies band gap and band edge requirements of the redox potential of water splitting. In addition, the oxygen evolution reaction (OER) on g-C3N4 side and the hydrogen evolution reaction (HER) on g-CN side can proceed spontaneously in thermodynamics. Most notably, the electronic, thermodynamic and optical properties of the g-C3N4/g-CN vdW heterostructure can be modulated by applying biaxial strain to achieve the purpose of better catalytic water splitting. Also, the good visible-light absorption intensity of the g-C3N4/g-CN vdW heterostructure can also be exhibited without strain and it is much better under strain of −2%. Consequently, these findings suggest that the g-C3N4/g-CN vdW heterostructure has a promising potential as a photocatalyst for water splitting.