Enhanced photocatalytic activity of La1-xSrxCoO3/Ag3PO4 induced by the synergistic effect of doping and heterojunction

Abstract

This study sought to design and synthesize a series of perovskite-based La1-xSrxCoO3/Ag3PO4 (with x = 0–1) heterojunction photocatalysts with different Strontium (Sr) doping contents by a simple sol-gel method and properties of the material were comprehensively characterized. Moreover, tetracycline (TC) was chosen as the target pollutant to assess the effect of Sr doping on the catalytic performance of LaCoO3/Ag3PO4. Our results demonstrated that the partial replacement of La3+ with Sr2+ coupled with shifting Co3+ to the mixed-valence state of Co3+-Co4+ led to the formation of substantially more oxygen vacancies in the crystal lattice of La1-xSrxCoO3/Ag3PO4. Therefore, the doped catalyst La1-xSrxCoO3/Ag3PO4 exhibited enhanced photocatalytic performance. When x = 0.9, the obtained La0·1Sr0·9CoO3/Ag3PO4 exhibit an optimal performance for TC degradation. Kinetic analyses demonstrated that the degradation rate constant of TC in La0·1Sr0·9CoO3/Ag3PO4 system was 0.0098 min−1, which is 1.78 times that of LaCoO3/Ag3PO4, and 2.45 times that of SrCoO3/Ag3PO4. Additionally, free radical sequestration experiments indicated that OH•, h+, and O2•− all participated in the degradation of TC in the following order: h+>O2•−>OH•. Finally, analyses of photocatalytic mechanisms suggested that the enhanced photocatalytic activity of La0·1Sr0·9CoO3/Ag3PO4 was due to its strong electron transfer properties and the formation of substantially more surface oxygen vacancies in Sr-doped La0·1Sr0·9CoO3.