Facile synthesis of mesoporous hierarchical TiO2 micro-flowers serving as the scaffolding of 0D Ag3PO4 nanoparticles for the ultra-fast degradation of organic pollutants

Abstract

Using hierarchically structured TiO2 as scaffolding to construct heterojunctions has been proven to be an efficient method for enhancing photocatalytic activity. In this study, 0D/3D hierarchical Ag3PO4/TiO2 photocatalysts were prepared using an improved hydrothermal-induced solvent-confined assembly and an in-situ fabrication method. The SEM results suggest that with an increasing amount of Ag3PO4, an increasing number of agglomerated Ag3PO4 particles were detected. As a result, Ag3PO4/TiO2-1 exhibited the highest photocatalytic activity and decomposed 96.5% methylene blue in 9 min or 94.6% of rhodamine B in 12 min. A practical application of water remediation in four real water bodies for coexisting dyes was also performed. The remarkable photocatalytic activity of the obtained Ag3PO4/TiO2 composites can be attributed to the suitable size of Ag3PO4, unique hierarchical porous nature, and high efficiency of the photoinduced carrier separation and transfer. The proposed photocatalytic mechanisms and charge transfer pathways in heterojunction photocatalysts were investigated using valence-band X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, Mott–Schottky analysis, and scavenging experiments. These results illustrate the formation of a type-II heterojunction between Ag3PO4 and TiO2. This study provides novel insights into the design and construction of heterojunction photocatalysts for the decomposition of organic pollutants.