In-situ growth of high-density ultrafine Ag₃PO₄ nanoparticles on 3D TiO₂ hierarchical spheres for enhanced photocatalytic degradation of organic pollutants

Abstract

Silver phosphate (Ag 3 PO 4 , APO) has attracted intense attention as a visible-light-driven photocatalyst, but its large-scale application is limited by severe charge recombination and inevitable photo-corrosion. Various rational APO-based heterostructures composed of APO nanoparticles (NPs) and band-matched semiconductor support are designed to address the above issues. Nevertheless, the size, density, stability, and dispersion of APO NPs are critical challenges for the photocatalytic performance of APO-based photocatalysts. Here, three-dimensional (3D) self-assembled TiO 2 hierarchical spheres (THS) prepared by a simple one-step hydrothermal method are employed as innovative support, and ultrafine high-density APO NPs with an average size of about 3 nm are successfully deposited and uniformly dispersed throughout THS to form hierarchical THS/APO composites. The novel THS/APO microstructure provides abundant reactive sites for photocatalytic reactions and promotes the photogenerated charge separation and transfer due to the ultrafine size of APO NPs and the TiO 2 /APO Type-II heterojunction. As a result, the THS/APO composites show significant improvement in photocatalytic activity and stability in methylene blue (MB) degradation. The reaction constant of THS/APO composites far exceeds that of either THS or APO, roughly 16 and 7 times higher than that of THS and APO under full-spectrum light, and 41 and 4 times higher under visible light. Our results strongly suggest new insights into the low-cost, large-scale application of high-efficiency APO-based photocatalyst.

Combination of alkali treatment and Ag3PO4 loading effectively improves the photocatalytic activity of TiO2 nanoflowers

“…06–0505], respectively. 35–38 Meanwhile, the obvious diffraction peak of Ag 3 PO 4 indicates that its crystallinity is good and it is successfully grown on the surface of TiO 2 .…”

“…4e, the characteristic peak of P 2p is located at 132.8 eV, indicating that element P is present at +5 valence in the Ag 3 PO 4 /OH/TiO 2 -3 composite. 35,48–51 The Ag 3d spectrum of Ag 3 PO 4 /OH/TiO 2 -3 is shown in Fig. 4f.…”

“…The detailed steps are shown in the Experimental section of the ESI. † [35][36][37][38] Meanwhile, the obvious diffraction peak of Ag 3 PO 4 indicates that its crystallinity is good and it is successfully grown on the surface of TiO 2 .…”

“…After in situ growth of Ag 3 PO 4 , the new diffraction peaks at 2y values of 20.841, 29.661, 33.261, 36.541, 42.441, 47.751, 52.641, 54.981, 57.241, 61.601, 65.801, 69.901, 71.841, 73.821 and 77.691 are observed, which can be indexed to the {110}, {200}, {210}, {211}, {220}, {310}, {222}, {320}, {321}, {400}, {330}, {420}, {421}, {332} and {422} crystal planes of Ag 3 PO 4 [JCPDS No. 06-0505], respectively [35][36][37][38]. Meanwhile, the obvious diffraction peak of Ag 3 PO 4 indicates that its crystallinity is good and it is successfully grown on the surface of TiO 2 .The morphology of samples was characterized using SEM.…”