Conversion of Z-Scheme to type-II in dual-defective V2O5/C3N4 heterostructure for durable hydrogen evolution

Abstract

The carbon nitride (C3N4) materials and hybrids have been acknowledged as promising photocatalysts for decades. The precise design and modulation of C3N4-based photocatalyst in defects and energy bands for further promotion is of importance but less investigated. In this work, a type of defective V2O5/C3N4 heterojunction with dual oxygen and carbon vacancy on interface is designed through simple annealing and plasma etching. The incorporation of V2O5 enables to promote the separation efficiency for photo-induced carriers and enhance built-in electric field (BIEF) at junction boundary to accelerate charge transport. The designed double defects in V2O5/C3N4 further results in a type-II heterojunction and switch of redox reaction sites, preventing photocatalytic corrosion of unstable V2O5. As a result, owing to the integrated advantages of such composite photocatalyst, the defective V2O5/C3N4 heterojunction exhibits a comparable hydrogen evolution rate of 0.90 mmol·g−1·h−1 to V2O5/C3N4, and dramatically improved regeneration with a continuous hydrogen evolution rate of 0.83 mmol·g−1·h−1 for 5 cycles. Our study is envisaged to provide a toolbox for rationally designing compositive nanomaterials toward high-efficiency photocatalytic systems.

Keywords

• Photocatalysis
• Hydrogen evolution
• Heterojunction
• Carbon nitride
• V2O5