Fabrication of highly stabilized Zr Doped g-C3N4/Nb2O5 heterojunction and its enhanced photocatalytic performance for pollutants degradation under visible light irradiation

Abstract

A series of Zr doped g-C3N4/Nb2O5 photocatalysts with high visible light response and strong redox properties were synthesized for wastewater treatment under visible light, which achieved the synergistic effect of transition metal doping and semiconductor compounding. The doping of Zr promoted charge transfer due to the formation of Schottky barrier. As an electronic medium, Zr was devoted to formating the Z-scheme heterojunction between g-C3N4 and Nb2O5, which effectively improved the redox ability of the catalyst as well as promoted the separation of photogenerated electrons and holes in semiconductors. The morphology, chemical structure, optical and electronic properties of Zr/g-C3N4/Nb2O5 photocatalysts were well characterized. Compared with monomeric g-C3N4, the as-prepared Zr/g-C3N4/Nb2O5 exhibited improved visible light response and enhanced separation efficiency of photogenerated carriers as a result of the synergistic effect of ion doping and semiconductor compounding. Subsequently, the activity of organic pollutant degradation were tested using as-prepared Zr/g-C3N4/Nb2O5 under the representative organic pollutants methylene blue (MB) and levofloxacin (LF) as the targets. The Zr/g-C3N4/Nb2O5 showed efficient photocatalytic activity toward degrading dye wastewater and pharmaceutical wastewater under visible light irradiation (λ＞410 nm) comparing with bare g-C3N4 and Zr/g-C3N4. The content of Zr and Nb2O5 has a crucial effect on catalyst activity, and the Zr/g-C3N4/Nb2O5 with 5 at% Zr and 4 wt% Nb2O5 was of the best photocatalytic activity, which degraded 98.5% of MB in 120 min for visible light irradiation. The excellent performance of Zr/g-C3N4/Nb2O5 is mainly due to the Z-scheme charge transfer mode.