Stable LSPR effect and full-spectrum photocatalytic water purification by g-C3N4−x/MoO3−x with passivated interface oxygen vacancies

Abstract

Interface passivation to construct a Z-scheme heterojunction can not only improve the separation efficiency and redox ability of photo-generated carriers, but also retain the excellent optical properties of non-metallic plasma. In this work, the optical performance and carrier dynamics of g-C3N4−x/MoO2.69(OH)0.31 heterojunction were optimized by passivating the interface oxygen vacancies. The adsorption of -OH groups on the surface oxygen vacancy sites of MoO2.69(OH)0.31 was hindered due to the formation of heterogeneous interface. This in turn significantly inhibited the charge recombination at the oxygen vacancy-induced deep trap states, while maintaining the stable and continuously enhanced visible-near infrared light absorption. The conduction band of g-C3N4−x provided the appropriate energy platform to accept the photo-generated electrons of MoO2.69(OH)0.31, resulting in the high utilization of high-energy “hot electrons”. The prepared g-C3N4−x/MoO2.69(OH)0.31 heterojunction showed the enhanced full-solar-spectrum photocatalytic performance for the degradation of the organic pollutants. Moreover, Ti3C2 nanosheet-wrapped g-C3N4−x/MoO3−x was synthesized to alleviate the photo-corrosion of g-C3N4−x/MoO3−x. The composite photocatalyst exhibited the further improved photocatalytic activity while maintaining good recyclability and structural stability. This work provided a new strategy for the preparation of defect-mediated heterojunction photocatalysts with high activity and stability.