Application of Z‐scheme Bi₂O₃‐Ag₃PO₄ Composite Photocatalyst in Degradation of Tetracycline and Methyl Orange

Abstract

A new type of visible light Z‐scheme Bi2O3‐Ag3PO4 composite photocatalyst was created in this work using a simple in‐situ precipitation process. On this basis, the morphology, optical properties and electrochemical performance of the photocatalyst were studied by N2 adsorption‐desorption analysis and XRD, FT‐IR, XPS, SEM, TEM, UV‐vis DRS, PL, EIS, and other characterization methods. To further explore the photocatalytic performance of the composites, visible light degradation experiments were carried out on the antibiotic TC and the organic dyes MB and MO. The results show that the 0.025BA composite material exhibits higher photocatalytic performance than other comparative samples. In addition, the 0.025BA composite after five cycles of experiments also has a satisfactory photodegradation rate. The active species capture experiment and ESR showed that the active species h+, ⋅O2− are the main factors affecting the photocatalytic degradation, and ⋅OH played a minor role. The intermediates and possible decomposition pathways of TC were illustrated through LC–MS technology. Finally, the possible photocatalytic reaction mechanism was speculated. On the whole, the high photocatalytic activity of the 0.025BA composite is perhaps the result of the formation of its Z‐scheme heterojunction, which enables fast transfer and high separation of photogenerated carriers at the heterojunction interface, and also accelerates the rate of redox reactions on electron‐hole pairs.

Ag/AgX (X = Cl, Br, or I) Nanocomposite Loaded on Ag3PO4 Tetrapods as a Photocatalyst for the Degradation of Contaminants

“…The band gap ( E g ) is calculated through the Kubelka–Munk equation α h ν = A ( h ν – E g ) n /2 . According to the type of semiconductor, n equals 1 for Ag 3 PO 4 , while it equals 4 for AgX.…”

Photocatalytic Performance and Degradation Pathways of Z‐Scheme BiO2−X−Ag3PO4 Photocatalysts with Oxygen‐Deficient Structures

“…According to the above experiments, the possible photocatalytic mechanism of the BOA composite was proposed as Figure 13: By DRS and XPS VB spectroscopic analysis, we obtained the E CB , E VB potentials of BiO 2−X and Ag 3 PO 4 . Under the irradiation of visible light, electrons and holes are generated on the CB and VB of BiO 2−X and Ag 3 PO 4 [25,28] . If the BOA composite follows a type II heterojunction, since the E CB of BiO 2−X is more negative than Ag 3 PO 4 , the E VB of Ag 3 PO 4 is more positive than BiO 2−X , the photogenerated electrons are more easily transferred from BiO 2−X to the CB of Ag 3 PO 4 , and the holes are transferred from Ag 3 PO 4 to the VB of BiO 2−X , thus forming a built‐in potential field [32] .…”

“…Under the irradiation of visible light, electrons and holes are generated on the CB and VB of BiO 2À X and Ag 3 PO 4 . [25,28] If the BOA composite follows a type II heterojunction, since the E CB of BiO 2À X is more negative than Ag 3 PO 4 , the E VB of Ag 3 PO 4 is more positive than BiO 2À X , the photogenerated electrons are more easily transferred from BiO 2À X to the CB of Ag 3 PO 4 , and the holes are transferred from Ag 3 PO 4 to the VB of BiO 2À X , thus forming a built-in potential field. [32] However, the E CB of Ag 3 PO 4 and the E VB of BiO 2À X are more negative than the standard redox potential of •O 2 À /O 2 , which is À 0.33 eV, [26] and the standard redox potential of •OH/À OH, which is 1.99 eV, so they can not produce •O 2 À and •OH.…”

“…Ag 3 PO 4 is an excellent silver based photocatalyst, which has a unique highly dispersed energy band structure and high visible light response, and is widely used in the field of photocatalysis. [27,28] However, it has high recombination rate of photogenerated electron pairs and photocorrosion phenomenon. These defects greatly affect its further promotion and application.…”