Construction of self-sufficient Z-scheme Ag3PW12O40/TiO2 photocatalysts for the improved visible-light-driven photo-degradation of rhodamine B

Abstract

Nanotube titanic acid (denoted as NTA), a tubular mesoporous material, after it undergoes heat-treatment at high temperature, is a novel kind of TiO2 containing a single-electron-trapped oxygen vacancy (V O • ) originating from the intra-layered dehydration of NTA that can be achieved. Unfortunately, the presence of oxygen vacancy arouses the response of the novel TiO2 to visible light, but it is inert under visible-light irradiation because of the absence of the efficient electron acceptors. Just making up for the rapid charge recombination of unitary system photocatalyst, by facilitating the electron fast transfer simultaneously, a series of Ag3PW12O40/TiO2 composite photocatalysts were synthesized via a facile hydrothermal route using Ag3PW12O40 (a kind of saturated Keggin polyoxometallate) and nanotube titanic acid (NTA) as starting material. As-fabricated photocatalysts were characterized by XRD, UV–Vis DRS, XPS, ESR, BET, SEM, TEM, PL and photoelectrochemical measurements. The photocatalytic performance of these composites was appraised by monitoring the photo-degradation of organic pollutant rhodamine B (10 mg/L) under visible-light irradiation (420 nm < λ < 800 nm) a with spectrophotometer. The as-prepared Ag3PW12O40/TiO2 composites displayed enhanced photocatalytic performance towards the decomposition of rhodamine B. The active species trapping experiment revealed that the significantly improved photocatalytic activity was attributed to the constructing of Z-scheme Ag3PW12O40/Ag/TiO2, greatly inducing the efficient separation of the photo-generated carriers by means of Ag nanoparticles serving as the charge transmission channel. Herein, Ag nanoparticles were formed via the reduction of Ag+ by the electrons in the oxygen vacancy state during hydrothermal preparation. At the same time, the present work provides a new way to extend application of other polyoxometalates in the photocatalysis field.