Preparation Of AGBR@AG/N-RGO Visible Light Catalyst And Its Degradation Of 2-chlorophenol In Water

It is well-known that environmental pollution has become one of the critical issues around the world.Refractory organic contaminants in aquatic system have drawn great attention because the presence of even low concentrations of these pollutants seriously affects human healthy and ecosystem safety.Moreover,these pollutants are difficult to be biodegraded or oxidized with the aid of chemicals.So far,photocatalytic oxidation technology has attracted extensive interest for wastewater treatment.Compared with the traditional photocatalysts,which has narrow band gap and is unstable for reuse,the visible-light-driven photocatalysis nanocomposites are much more attractive due to the well use of sunlight.In this study,a visible-light-driven photocatalyst AgBr@Ag/nitrogen-doped reduced graphene oxide(AgBr@Ag/N-rGO)was prepared by a hydrothermal-in situ oxidation method and used for the degradation of 2-chlorophenol(2-CP).The visible-light-driven photocatalyst was characterized by scanning electron microscope,transmission electron microscope,X-ray diffraction,Fourier-transform infrared spectra,Raman and X-ray photoelectron spectroscopy and UV-vis diffuse reflectance spectroscopy.The results verified that Ag nanoparticles(Ag NPs)were first chelated by N-groups of N-RGO and then enwrapped by AgBr generated by the in-situ oxidation of Ag.The active interaction among these three nano-materials at the interface enhanced the interfacial electron transfer in AgBr@Ag/N-rGO.The plasmon resonance was also strengthened as a result of the decrease in the the size of Ag NPs.The as-prepared AgBr@Ag/N-rGO was used for the photocatalytic degradation of 2-CP under visible light.The results showed that the 2-CP degradation rate was dependent on the recipe of AgBr@Ag/N-rGO preparation and solution pH.AgBr@Ag/N-rGO with the weight ratios of GO to Ag 3.0 wt%and the volume of Fe3+ 40 mL at natural pH(6.5)exhibited the fastest photodegradation rate.2-CP was completely removed within 45 min,which was 85.3 and 18 times faster than that using Ag/N-rGO and AgBr@Ag/rGO,respectively.In addition,approximately 79%of the TOC was removed.It was found that three kinds of intermediates,benzoquinone,maleic acid and malonic acid during the photodegradation of 2-CP.The photocatalytic mechanism suggested that O2·-was the main reactive species in the photocatalytic process.Furthermore,the two kinds of electron transfer paths were identified.The plasmon-induced electrons on Ag NPs core were transferred to AgBr shell.Together with the photoexcited electrons on AgBr,they were then transferred by N-rGO to dissolved O2 to form O2·-.On the other hand,the hydrogen bands and ?-? bands between the pollytants and N-rGO accerelated the electron transfer from the pollutants to the plasmon induced Ag NPs.Therefore,the pollutants were effectively degradated,and the stability of AgBr@Ag/N-rGO was well maintained.The degradation efficiency of 2-CP was barely changed during the five cycles of AgBr@Ag/N-rGO reuse.Besides 2-CP,the proposed catalyzer also exhibited excellent photocatalytic activity in the degradation of phenol and BPA under visible light.This study provides a new perspective in the development of visible-light-driven photocatalysts for water purification.