LaCoO3 co-catalyst modified Ag2CrO4 for improved visible-light-driven photocatalytic degradation of tetracycline

Abstract

Exploiting highly efficient and stable noble metal-free co-catalysts is of great importance to improve the photocatalytic activity of the given photocatalyst. To this end, perovskite-type LaCoO3 as an effective noble-metal-free co-catalyst was successfully decorated on the surface of Ag2CrO4 to construct a unique binary LaCoO3/Ag2CrO4 hybrid through a facile in situ precipitation method. As expected, the synthetic LaCoO3/Ag2CrO4 hybrid exhibited greatly enhanced photocatalytic degradation of tetracycline (TC) under visible light irradiation. More importantly, the modified LaCoO3(20.0 wt%)/Ag2CrO4 sample presented the optimal photocatalytic activity, which was around 8.4 and 3.6 times higher than those of pure Ag2CrO4 and LaCoO3, respectively. The improved activity was mainly originated from the introduction of LaCoO3 co-catalyst with good platform, excellent electronic conductivity and high charge carrier mobility, which acted as an electron collector for the rapid capturing the photogenerated electrons of the excited Ag2CrO4, which could not only promote the separation of photogenerated electron-hole pairs and suppress the photocorrosion of Ag2CrO4, but also provide more active sites to react with TC molecules to form degradation products. Moreover, the radical trapping experiments manifested that the superoxide radicals and photogenerated holes both played a critical role in the degradation of TC under visible light irradiation. Finally, a possible mechanism for the improved photocatalytic activity was also discussed. This work may open new ways for the developing noble-metal-free co-catalysts modified Ag-based photocatalysts with the potential application in the energy conversion and environmental governance.